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Artykuły w czasopismach na temat "Fisheries Resources Assessment"
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Torkelson, Thomas C., Thomas C. Austin i Peter H. Wiebe. "Multifrequency acoustic assessment of fisheries and plankton resources". Journal of the Acoustical Society of America 103, nr 5 (maj 1998): 3069. http://dx.doi.org/10.1121/1.422854.
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Calicdan, Melanie, Ericson Gumiran, Angel Encarnacion i Jovita Ayson. "Assessment of Fisheries Resources in the Babuyan Channel". Philippine Journal of Fisheries 25, nr 1 (2018): 14–24. http://dx.doi.org/10.31398/tpjf/25.1.2017c0003.
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Prestes, Luiza, Fabiana Calacina da Cunha, Maria Gercilia Mota Soares, Marcos Sidney Brito Oliveira, Netie Izabel Oliveira i Alexandro Cezar Florentino. "Stock Assessment: Sustainable management in high and medium Araguari River, Amapá, Brazil." Ciência e Natura 42 (29.06.2020): e71. http://dx.doi.org/10.5902/2179460x40186.
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Fisheries in Araguari river is an alternative income for families that depend on exploitation of natural resources. This study evaluates fisheries production in high and medium Araguari river to determine the bioeconomic reference points of fishery activities. Logbooks of fisheries were used from Fishermen Colony Z-16 from 2003 to 2010. The Maximum Sustainable Yield (MSY) and Effort at Maximum Sustainable Yield (fmsy) was: MSYSchaefer = 11246 kg and fmsy = 754 fisheries/year, and MSYFox = 11478 kg and fmsy = 1214 fisheries/year and at Bioeconomic Equilibrium (Eebe) Eebe = 10712 kg and Effort at Bioeconomic Equilibrium (febe) febe = 918 fisheries/year. The status of fisheries from Araguari River was declared as overfishing and in this study, we found the same results. The Maximum Economic Yield (MEY) was reached too, as the fisheries were at Bioeconomic Equilibrium (EBE). The fishery mortality (Fyear/Fmsy) and fishery effort (fyear/fmsy) trends show that from 2003 to 2009 the values were sustainable. In 2010 those trends became unsustainable, and the Maximum Economic Yield (MEY) for all years is unsustainable too. It is required this study be considered in future management agreements.
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Sherman, Kenneth. "Sustaining the world's large marine ecosystems". ICES Journal of Marine Science 72, nr 9 (15.09.2015): 2521–31. http://dx.doi.org/10.1093/icesjms/fsv136.
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Abstract In this essay, I review nearly six decades of a career in marine science and fisheries considering scientific contributions, successes, failures, and changes in my field of practice. My body of work has been in plankton research to support fisheries assessments, and in ecosystems programme development and implementation. I describe my early studies on Pacific plankton oceanography in relation to fisheries assessment, and subsequent studies of plankton oceanography and fisheries in relation to coastal ocean fisheries and management. Early in my career, realizing that applications of my published results and those of other fisheries ecologists were generally not included in fish stock assessments, I participated in a national planning group that introduced a system for marine resources monitoring, assessment, and prediction (MARMAP) that included primary productivity, ichthyoplankton, zooplankton, and oceanographic assessments as important components for large-scale fisheries ecology assessment. I joined with European colleagues in ICES to advance fisheries ecology studies in fish stock assessments in the 1970s and 1980s. In 1983, I conceived with Professor Lewis Alexander of the University of Rhode Island a system for assessing and managing marine resources within the spatial domain of ecologically delineated large marine ecosystems (LMEs). On behalf of the National Oceanic and Atmospheric Administration, and in partnership with developing countries, international financial organizations, UN agencies, and NGOs, I am currently contributing scientific and technical advice to a global network of assessment and management projects in 22 LMEs with 110 developing countries and $3.1 billion in financial support. The participating countries are applying a modular framework of natural science and social science indicators for assessing the changing states of LMEs. I conclude the essay with a retrospective viewpoint on my career and changes over half a century of practicing the application of marine science in relation to sustaining the goods and services of the ocean Commons.
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Tanaka, Kengo. "Assessment and Management of Fisheries Resources in Japanʼs EEZ". Marine Engineering 56, nr 2 (1.03.2021): 206–9. http://dx.doi.org/10.5988/jime.56.206.
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Talhelm, Daniel R., Jack A. Donnan, Delano R. Graff, A. P. Grima, Lawrence W. Libby, Scott Milliman i Margaret Ross Dochoda. "Introduction to the Social Assessment of Fisheries Resources Proceedings". Transactions of the American Fisheries Society 116, nr 3 (maj 1987): 289–92. http://dx.doi.org/10.1577/1548-8659(1987)116<289:ittsao>2.0.co;2.
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Sutaman, Sutaman, Yusli Wardiatno, Mennofatria Boer i Fredinan Yulianda. "Assessment of Sustainable Use of Coastal Resources of Regional Waters Conservation Area Biak Numfor Regency, Papua Province, Indonesia". ILMU KELAUTAN: Indonesian Journal of Marine Sciences 22, nr 2 (5.06.2017): 75–84. http://dx.doi.org/10.14710/ik.ijms.22.2.75-84.
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Efforts to exploit fish resources optimally, continuous and sustainable is an urgent demand for the greatest prosperity of the people, especially to improve the welfare of fishermen and fish farmers. The level of sustainable use of coastal resources in water conservation is very important, so that the utilization does not exceed the carrying capacity of the environment. The purpose of this study was to determine the level of sustainable use of coastal resources Biak Numfor, associated with the utilization of fisheries, aquaculture and tourism. The study was conducted in June to December 2015 and October to November 2016. The primary data obtained by interview and direct discussion through Focus Group Disscution (FGD) with fishermen community, tourist and tourist entrepreneurs as well as related officials in the Office of Fisheries and Marine Affairs, and Tourism Office of Biak Numfor Regency. Methods of data analysis approach sustainability analysis conducted by the method of MDS (Multi-Dimensional Scaling) with the help of software Rapfish. Based on the survey results revealed that the value of fisheries ordinated to achieve 57.66%, 44.80% aquaculture, and tourism 46.25%. With these achievements ordinated value, it can be concluded that the use of sustainable capture fisheries are still classified by the lever sustainability attributes include; the type of fishing gear, vessel types used and the catch per unit effort (CPUE). Meanwhile the relatively less sustainable aquaculture with the sustainability lever attributes include; cultivation technology, the number of business units with different types and species of fish. For tourism utilization is still considered less sustainable with levers sustainability attributes include the number of tourists, the type and number of amenities and facilities and infrastructure Keywords: Sustainability, utilization, waters conservation area (KKPD), MDS-Rapfish
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PAPACONSTANTINOU, C., i H. FARRUGIO. "Fisheries in the Mediterranean". Mediterranean Marine Science 1, nr 1 (1.06.2000): 5. http://dx.doi.org/10.12681/mms.2.
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The aim of this paper is to give a description of the Mediterranean fisheries, and its level of exploitation and to address the main questions dealing with its management. The Mediterranean is a semi-enclosed marine area with generally narrow continental shelves. The primary production of the Mediterranean is among the lowest in the world (26-50g C m-2 y-1). The Mediterranean fisheries can be broken down into three main categories: small scale fisheries, trawling and seining fisheries, which operated on demersal, small pelagic and large pelagic resources. After a general description of the state of the resources in the different areas of the Mediterranean it is concluded that (a) the overall pictures from the western to the eastern Mediterranean are not considerably different, (b) the total landings in the Mediterranean have been increased the last decades, and (c) from the perspective of stock assessment, the very few available time series data show stable yield levels. In general fisheries management in the Mediterranean is at a rela- tively early stage of development, judging by the criteria of North Atlantic fisheries. Quota systems are generally not applied, mesh-size regulations usually are set at low levels relative to scientific advice, and effort limitation is not usually applied or, if it is, is not always based on a formal resource assessment. The conservation/management measures applied by the Mediterranean countries can be broadly separated into two major categories: those aiming to keep the fishing effort under control and those aiming to make the exploitation pattern more rational. The most acute problems in the management of the Mediterranean resources are the multispecificity of the catches and the lack of reliable official statistics.
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Yang, Hyun-Joo, Daomin Peng, Honghong Liu, Yongtong Mu i Do-Hoon Kim. "Is China’s Fishing Capacity Management Sufficient? Quantitative Assessment of China’s Efforts toward Fishing Capacity Management and Proposals for Improvement". Journal of Marine Science and Engineering 10, nr 12 (15.12.2022): 1998. http://dx.doi.org/10.3390/jmse10121998.
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As the country with the world’s largest fishing capacity, China suffers from the depletion of living marine resources, mainly caused by overexploitation, the effects of which also distinctly influence global sustainable utilization of marine resources and maritime order. The country has implemented a series of measures to control its national fishing capacity, notably since the late 1980s, and strongly expressed its responsibility and commitment to sustainable resource utilization in the 13th Five-Year Plan (2016–2020). This study quantitatively assesses the effect of China’s fishing capacity management efforts by examining changes in the fishing capacity of marine capture fisheries by region from 1979 to 2019 in Chinese waters, based on window data envelopment analysis (DEA), and further proposes directions for policy adjustment. The results suggest that China’s coastal and offshore fisheries are still subject to overcapacity of approximately 20%, despite major corrective efforts invested in past decades. This implies that China needs to further improve its fishing capacity management and set clear objectives, as determined by the availability of resources and regional features. Global fisheries management’s focus is shifting from input to output control, but overcapacity still threatens the sustainable use of fisheries resources in China and poses obstacles to other systems.
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Torell, Elin, Chikondi Manyungwa-Pasani, Danielle Bilecki, Innocent Gumulira i Gordon Yiwombe. "Assessing and Advancing Gender Equity in Lake Malawi’s Small-Scale Fisheries Sector". Sustainability 13, nr 23 (24.11.2021): 13001. http://dx.doi.org/10.3390/su132313001.
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Women play important, but often invisible, roles in Lake Malawi’s small-scale fisheries sector. This paper augments previous research by exploring the productive and reproductive roles that men and women have in fishing communities and how this shapes women’s access and control over fisheries resources. Contributing to advancing the understanding of how to strengthen women’s roles in the fisheries sector, this paper reports on a qualitative assessment conducted in seven Malawian lakeshore districts. Data collected via focus group discussions, which included gendered resource mapping exercises, revealed belief systems and gender norms that shape men’s and women’s access to and control over lacustrine resources. While both men and women have access to lake and land resources, their roles differ. Men dominate fishing resources whereas women dominate resources that are tied to household management. While all value chain nodes are open to men, women tend to be concentrated in lower-value processing and trading activities. Social norms and values shape people’s access and control over communal resources. It is noteworthy that women who earn an income from the fisheries value chain have more access to savings and credit and have more equal household bargaining power.
Rozprawy doktorskie na temat "Fisheries Resources Assessment"
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Ebil, Syazana. "Assessment of demersal fishery resources in Brunei Darussalam". Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/57704/.
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A problem commonly encountered in stock assessments of tropical marine resources in developing countries is data paucity, which invariably results from the lack of both human and economic capacity within the government to implement and maintain programmes for data collection and analysis. With special reference to the demersal fishery of Brunei Darussalam, this thesis examines approaches for extracting useful information from data-poor fisheries to assess the state of resources and inform fishery management actions. By using official fishery statistics, augmented by local ecological knowledge (LEK) obtained from fishers engaged in either the large-scale (LS) or small-scale (SS) fisheries in Brunei, changes in demersal fishery resources over the years were assessed. The sustainability of Brunei’s demersal capture fishery was evaluated in the face of its ongoing development and climate change. Using trophodynamic indicators such as mean trophic level (MTL), Fishing-in- Balance (FiB), trophic spectra (TS) and community structure analyses, LS fishery catches of Brunei between 2000 and 2009 revealed a deteriorating state of the coastal demersal ecosystem. Closer examination of the abundance of overall demersal finfish stocks, using the Catch-Per-Unit-Effort (CPUE) index – standardised for other factors not related to abundance – indicated a declining trend, even when total catches remained stationary, although trends in abundance of the different demersal fish families varied. This rapid significant change in recent years is further supported by fishers’ LEK on relative abundance of Brunei marine resources. The study on LEK has also revealed the ‘shifting baseline syndrome’ (SBS) among currently active fishers and their exploited populations, a phenomenon not previously reported for Brunei fisheries. Findings from the study are synthesised with other information, where a number of key issues and policy options are discussed, and recommendations for the management of the fishery are made. This thesis demonstrates that researchers in data-poor fisheries can utilise different assessment tools, given the resources at their disposal, to assist in the management of marine resources.
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Rahman, Md Khalilur. "Fish-based assessment of ecological health of English lowland rivers". Thesis, University of Hull, 2001. http://hydra.hull.ac.uk/resources/hull:11842.
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Riverine fisheries in England are under pressure from a variety of activities, including increasing intensification of land-use, urbanisation, rising demands for water abstraction, pollution, proliferation of exotic species, climate change and recreational activities. As a result, the integrity of English rivers has changed. In this study, an attempt was made to measure the ecological health of 22 English lowland rivers from the Thames, Trent and Yorkshire Ouse catchments using a variety of tools. The objective was to modify the Index of Biotic Integrity (IBI) for use on English lowland rivers and compare it with existing indices. A number of diversity indices, Margalef (DMg), Simpson (Dsm) and ShannonWiener (H') were used to evaluate the status of fisheries in the study rivers. The Abundance / Biomass (ABC) method and computer-based multivariate analyses, UPGMA, TWINS PAN, DECORANA, were also used to evaluate the status of fish communities. In addition to these indices, the ABC method and multivariate analyses, the IBI, a multimetric index was also used to evaluate the ecological health of study rivers. The IBI is based on structural and functional attributes of fish communities and is capable of evaluating health and condition of an aquatic ecosystem. The IBI requires a reference condition with which to compare the output. In English rivers, no pristine (reference) sites were considered available, consequently best available data were used to develop a reference condition. In this study, the IBI was modified from Karr (1981), which was based on 12 metrics (community characteristics) of fish assemblages. For the study rivers, 15 metrics which described the status of the fish communities were selected to calculate the IBI. Each metric was scored on a simple scale from 0 (absence) to 5 (high quality). The sum of all the metrics (range 0 - 75) was used to assign sites to qualitative classes of biotic integrity. Six integrity classes on a continuous scale were chosen with the following class boundaries: Excellent (56 - 75), Good (42 - 55), Fair (28 - 41), Poor (16 - 27), Very Poor (1 - 15) and No Fish (0). In the study rivers, the DMg, Dsm and H' indices were unable to measure anthropogenic impacts on fish communities as all these indices were based on structural properties of fish communities. These indices also failed to take account of the presence of juveniles in the fish community in a river. Moreover, these indices were influenced by dominant species abundance and sampling strategies, giving an inaccurate assessment of the status of the fisheries. The ABC method was better at evaluating fish communities than diversity indices as the method considered fish abundance and biomass. However, the method did not include functional components of the fish community and was over influenced by juvenile fishes. Consequently, the ABC method was not considered a good indicator of ecosystem health based on fish assemblages. The UPGMA, TWINSPAN and DECORANA analyses, successfully grouped and separated river reaches with rich or poor fish stocks. These analyses however, did not take into account the functional attributes of the fish communities and were not sufficient to explain the status of a fishery without support from other indices. The IBI assessed the ecological health of the middle and lower reaches of the study rivers more accurately than the other diversity indices, ABC method and multivariate analyses. The selected IBI metrics were able to evaluate many perturbations and disturbances as the metrics represented both structural and functional attributes of fish communities. The DMg, Dsm, H', ABC, UPGMA, TWINSPAN and DECORANA were designed to highlight a specific attribute and lost information during calculation but the IBI included a greater variety of information and produced an appropriate index. Spearman's rank correlation indicated the IBI outputs were more similar to diversity indices than other measures, as significant relationships were found between the IBI and DMg, the IBI and Dsm, and the IBI and H' at a = 0.01 level. Significant relationships were probably due to the use of fish density and abundance in the models. However, this did not mean that all diversity indices and the IBI were similar in measuring ecological conditions of a river, rather it was probably numerical similarity. No significant relationship was found between the IBI and ABC, as the ABC index was a ratio of abundance and biomass while the IBI used absolute values of biomass and abundance separately. All the diversity indices, ABC method and multivariate analyses mentioned reinforced the view that the IBI developed in this study was an appropriate index at evaluating ecological health of the middle and lower reaches of the study rivers. The IBI, however, failed to predict the quality of the fisheries in headwater streams because of the exclusion of salmonid species, minor species and general low species diversity found in these zones. Consequently, it was identified that reference conditions and metrics chosen for the middle and lower reaches of the study rivers were not appropriate to assess the ecological health of headwaters. The existing monitoring programmes of the Environment Agency (EA) for fishery data collection, were considered appropriate for calculating IBIs. Sampling strategies of the EA, i.e. daytime, electric fishing both in summer and winter periods irrespective of lunar cycle and breeding season were also considered acceptable to calculate the IBI. Further research was recommended to test the IBI on a wide range of rivers to assess whether the IBI is appropriate for assessing ecological health of middle and lower reaches of rivers in all regions of the UK. Separate IBIs for headwaters, still waters and estuaries were proposed as these zones / waterbodies have different fish communities. Investigation should be directed at developing a simplified IBI using other cost-effective data sources if suitable resources are not available. It is also recommended that the possibility of including the IBI in wider aquatic resource monitoring programmes (e.g. WFD) be investigated. It is also recommended that the possibility of using the IBI to detect change in the pre and post implementation periods of any management action or anthropogenic activity be investigated. Research is also needed to integrate the IBI with other bioassessment methods (e.g. Habitat index, Diatom index, Microinvertebrate index, Chemical index and GQA index). For more effective application and understanding, the IBI may be built into a GIS (Geographical Information System) environment. It is suggested that a suitable computer package be developed to simplify calculations of the IBI. The interpretation should however, be carried out by the fishery manager or scientist.
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Mkumbo, Oliva Charles. "Assessment and management of Nile perch (Lates niloticus L.) stocks in the Tanzanian waters of Lake Victoria". Thesis, University of Hull, 2002. http://hydra.hull.ac.uk/resources/hull:13307.
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Lake Victoria contributes more than 60% of the total fish yield in each of the respective riparian countries, Kenya, Uganda and Tanzania. Nile perch Lates niloticus contributed more than 60% to the total yield from the lake. Although accused of causing ecological instability of the ecosystem due to its predatory effects, the fishing industry became socially and economically dependable on the Nile perch. In the mid 1990s signs of overfishing were observed and concerns for the sustainability of the fishery were raised. To properly manage a fishery, knowledge of the factors that regulate the dynamics of the stock(s), their abundance and distribution is essential. Unfortunately data on the status of the Nile perch stocks are inadequate. This study was conducted on the Tanzanian part of Lake Victoria from 1997 to 2001 to address this problem. Reference is also made to the Kenyan and Ugandan national waters for comparison. Bottom trawl and catch assessment surveys were conducted to assess the status of the stocks. Abundance estimates and distribution patterns were determined. Current exploitation levels and practises were analysed and linked to growth and mortality, feeding and reproductive characteristics of the stock to determine status. Key environmental parameters were investigated and linked to the variations in the biological aspects and distribution patterns observed. There was an indication of reduced anoxic problems in the offshore deep waters and signs of improvement in the eutrophic state of the lake. Mean oxygen concentrations in the waters sampled varied from 8.02±0.73 mg L⁻¹ in the surface waters to 3.2±4.36 mg L⁻¹ in the bottom waters of 68 m deep, while Secchi disk readings at stations of 5-10 m depth ranged from 0.84±0.3 m in November to 1.9±1.02 m in August/September and in offshore waters of 50-6Om depth the readings were 3.08±0.62 m in February to 5.52±1.7 m in August/September. Distribution patterns of fish were highly aggregated but variable and were greatly influenced by seasonal patterns of oxygen and temperature, while reproduction and recruitment were related to rainfall patterns. Using the swept area method, biomass was estimated at 306,000 t for the Tanzanian waters and around 620,000 t for the whole lake, with a mean density of 9.87 t km⁻² and 10.56 t km⁻² respectively. Very high fishing mortality (1.55 yr⁻¹) and exploitation rates (0.84) were estimated using an L∞ of 218 em TL and a growth constant (K) of 0.16 estimated during the study. Excessively high fishing effort was observed in the 2000 frame survey while catch compositions reveal high dependence on juveniles for the Nile perch fishery. The size at first maturity was at 54.3 cm TL (1.6-yr.) and 76.7 em TL (2.5 yr.) for males and females respectively. About 83% of the catch survey data were below size at first maturity for males and 99% for females. Bottom trawl data (88% juveniles) suggested high recruitment in the stock. However the models indicated unsustainable exploitation of the fishery. A reduction of exploitation rate by 50% and increase of size at capture for optimum yield is recommended. The dominance of juveniles in the catch with the current yields (estimated at 138 323.85±6 229.14 t) higher than the sustainable yield (calculated at 108941.9 t yr⁻¹, using Cadima's formula) demands immediate management initiatives. Co-management is singled out as the most effective option for a functional system to implement control, monitoring and surveillance strategies within management process. With dynamic systems within the stocks, the environment as well as socioeconomic influences, and with continuous monitoring, adaptive and precautionary management strategies are recommended. Without reliable catch trend data it is difficult to confidently make predictions. The need to have a well-structured catch assessment survey system for reliable catch statistics is recommended. Priority areas to further research are also identified.
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Al-Oufi, Hamed Said. "Social and economic factors influencing the emergence of collective action in a traditional fishery of Oman : an empirical assessment of three coastal fishing towns in south Al-Batinah". Thesis, University of Hull, 1999. http://hydra.hull.ac.uk/resources/hull:3871.
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Overexploitation of many fish stocks underlines the need for more effort directed towards stock management so that the sustainability of resources is assured. To avert the tragic consequences of overfishing in coastal waters, a growing body of theoretical and empirical research provides evidence in support of cooperation among resource users to manage their commons. This study aimed to investigate the factors that contribute to the emergence and evolution of collective action in fishermen's communities to manage their coastal fish resources in South Al-Batinah, Sultanate of Oman. The study emphasises the importance of a collective action approach to fish resource management with examples from three fishing towns.In order to understand why fishermen choose to participate (or not to participate) in local collective action to manage fish resources, the researcher focuses on six main sets of issues that influence fishermen's decisions: economic factors; awareness of resource exploitation problems; institutional rules in use; social identity, group size and heterogeneity among resource users. Social and demographic factors as well as vessel configuration were also considered.Data collection for the study was carried out using three methods: questionnaire, semi-structured interview and observations of fishermen's activities. Statistical reports and other research papers carried out in Oman were also reviewed. The study found that there is a management institution that governs the fishing activities of the fishermen in the study area. Fishermen in the area inherited an indigenous management institution, which was established hundreds of years ago. It was also found that fishermen were very aware of the resource exploitation problems. High awareness of the resource exploitation problems coupled with high interdependence among users might induce them to work collectively to mitigate harm to their long-term welfare.The results of testing a number of hypotheses indicated that among the reasons which may influence collective action, are high economic dependence on the fishery,individuals' social identity as fishermen, awareness of the resources exploitation problems, risk aversion and heterogeneity (differences in objectives and interests).The study findings indicated that individuals using common resources are faced by various "assurance" and "chicken" problems. In both the PD game and the Assurance game, the preferred outcome is mutual cooperation. Whereas the predicted outcome of the former is defection, the latter suggests the possibility that the preferred outcome (i.e., cooperation) will occur, because individuals' decisions in the commons are influenced by a complex set of factors, rather than strictly materialistic self-interest. The analysis presented in this study examined several of those factors for their influence on individual behaviour. The findings of this study strongly suggest that the presence of local management institutions to coordinate the fishermen's activities in the study area is the key factor in avoiding the worst outcome (universal defection). The game structure has been changed from a Prisoner's dilemma to a Privileged game or a game of Chicken where the benefits from cooperation are maximized. It is the role of the institutions to determine how the cost of providing the public goods might be shared among participants.
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Huynh, Quang C. "Extensions and Applications of Mean Length Mortality Estimators for Assessment of Data-Limited Fisheries". W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1516639583.
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For data-limited fisheries, length-based mortality estimators are attractive as alternatives to age-structured models due to the simpler data requirements and ease of use of the former. This dissertation develops new extensions of mean length-based mortality estimators and applies them to federally-managed stocks in the southeastern U.S. and U.S. Caribbean.
Chapter 1 presents a review of length-based methods from the literature. Common themes regarding the methodology, assumptions, and diagnostics in these length-based methods are discussed. In Chapter 2, a simulation study evaluates the performance of the length-converted catch curve (LCCC), Beverton-Holt equation (BHE), and Length Based-Spawner Potential Ratio (LB-SPR) over a range of scenarios. Although the LCCC and BHE are older methods than LB-SPR, the former outperformed LB-SPR in many scenarios in the simulation. Overall, it was found that the three length-based mortality estimators are less likely to perform well for low M/K stocks (M/K is the ratio of the natural mortality rate and the von Bertalanffy growth parameter; this ratio describes different life history strategies of exploited fish and invertebrate populations), while various decision rules for truncating the length data for the LCCC and BHE were less influential. In Chapter 3, a multi-stock model is developed for the non-equilibrium mean length-based mortality estimator and then applied to the deepwater snapper complex in Puerto Rico. The multispecies estimator evaluates synchrony in changes to the mean length of multiple species in a complex. Synchrony in mortality can reduce the number of estimated parameters and borrows information from more informative species to lesser sampled species in the model. In Chapter 4, a new method is developed to estimate mortality from both mean lengths and catch rates (MLCR), which is an extension of the mean length-only (ML) model. to do so, the corresponding behavior for the catch rate following step-wise changes in mortality is derived. Application of both models to Puerto Rico mutton snapper shows that the MLCR model can provide more information to support a more complex mortality history with the two data types compared to the ML model. In Chapter 5, a suite of mean length-based mortality estimators is applied to six stocks (four in the Gulf of Mexico and two in the U.S. Atlantic) recently assessed with age-structured models. There was general agreement in historical mortality trends between the age-structured models and the mean length-based methods, although there were some discrepancies which are discussed. All models also agreed on the overfishing status in the terminal year of the assessment of the six stocks considered here when the mortality rates were compared relative to reference points. This dissertation develops new length-based assessment methods which consider multiple sources of data. The review guides prospective users on potential choices for assessment with length-based methods. Issues and diagnostics associated with the methods are also discussed in the review and highlighted in the example applications.
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Drumm, Darrin Jared, i n/a. "Habitats and macroinvertebrate fauna of the reef-top of Rarotonga, Cook Islands : implications for fisheries and conservation management". University of Otago. Department of Marine Science, 2005. http://adt.otago.ac.nz./public/adt-NZDU20060901.134208.
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Throughout the Pacific, many species of echinoderms and molluscs have cultural value and are harvested extensively in subsistence fisheries. Many of these species are sedentary and often associated with distinct reef-top habitats. Despite the significance of reef habitats and their fauna for fisheries and biodiversity etc, little information has been available on the distribution of habitats and their influence on the reef-top fauna in the Cook Islands. This thesis developed a novel approach to assess the status of the shallow-water reef-tops of Rarotonga, Cook Islands, to provide critical information to fisheries and conservation managers. The approach used remote sensing (aerial photography with ground truthing) to map the spatial arrangement and extent of the entire reef-top habitats accurately, and historical wind data and coastline shape to determine the windward and leeward sides of the island. The benthic habitat maps and degree of wind exposure were used to design and undertake a stratified sampling programme to assess the distribution and abundance of the epibenthic macroinvertebrate fauna of the reef-top. I quantified the distribution and abundance of the epibenthic macroinvertebrates and how they varied with habitat, assessed the effectiveness of a traditional ra�ui (marine protected area) for conserving stocks of Trochus niloticus and other invertebrates, and investigated the reproductive biology and impacts of traditional gonad harvesting on Holothuria leucospilota.
There were four major habitat types (rubble/rock, sand/coral matrix, algal rim and sand) identified, the most extensive being rubble/rock (45%) and sand/coral matrix (35%). The degree of exposure to winds was found to correlate with the reef development and habitat distribution.
The assemblage composition of each major habitat type differed significantly from every other habitat. The rubble/rock habitat had the greatest substratum heterogeneity and structural complexity, and the highest number of species and individuals. The overall abundance of the fauna was dominated by holothurians (68%) and echinoids (30%), while Trochus niloticus and Tridacna maxima accounted for the remaining 2% of the total invertebrate assemblage. Clear habitat partitioning was also found for adult and juvenile Trochus niloticus and Tridacna maxima.
In the traditional fishery for Holothuria leucospilota, the mature gonads of males are harvested by making an incision in the body-wall of the animal, removing the gonads and then returning the animal to the reef to allow regeneration. Monthly collections of H. leucospilota were used to describe the reproductive biology of this species. Gametogenesis and spawning were synchronous between the sexes and spawning occurred annually during summer, when water temperature and photoperiod were at their highest. Although the incision in the body-wall and gonad removal had no impact on the survival of H.leucospilota in experimental cages, their body weight, and general sheltering and feeding behaviors were affected. Gonads took at least 41 days to start regenerating, suggesting a considerable delay in the spawning of fished individuals.
In 1998, five Rarotongan communities re-introduced the traditional ra�ui system of resource management, prohibiting all fishing and gathering from their reefs. The performance of the Nikao ra�ui, which had been put in place to allow trochus stocks to increase, was investigated. Comparisons of macroinvertebrate assemblage composition and species density were made between three fishing treatments, i.e. fished areas adjacent to the ra�ui, within the ra�ui after two years of protection, and in the ra�ui after it had been lifted for three weeks to allow a commercial trochus harvest. Analysis of variance on the count data for the twelve most abundant species, and non-metric multi-dimensional scaling indicated that there were no differences in the microhabitat or the invertebrate assemblage composition between the three fishing treatments. However, there were significant differences between the rubble/rock and sand/coral matrix habitat types. The results on the effectiveness of the Nikao ra�ui are equivocal, due to the small sample size, and the variability between samples which was highlighted by the wide confidence intervals.
This study highlights the importance of habitat to the macroinvertebrate fauna of the reef-top and the need for accurate habitat maps to increase the cost-effectiveness of future resource surveys, to provide information to management, and for the design of Marine Protected Areas. The mapping and survey methods must be reliable and repeatable in terms of the limitations of time, and the availability of expertise, funding and resources. The results provide important information for fisheries and conservation managers of Rarotonga and other Pacific Islands to better design rigorous sampling programmes for monitoring the status of reef-top resources, and for evaluating and planning Marine Protected Areas.
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Huchzermeyer, Carl Friedrich. "Fish and fisheries of Bangweulu wetlands, Zambia". Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1003927.
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Bangweulu Wetlands is a 6000 km² public-private-partnership conservation area in northeastern Zambia, lying on the south-eastern margins of the Bangweulu Swamps, Congo River system. The area is important for wildlife conservation, tourism and as a fishing ground for the local inhabitants. This study provides a baseline of the fish and fisheries of this area. The conservation area is situated on the transition zone between woodland, floodplain and swamp. A total of 42 fish species representing 12 taxonomic families were collected. The fish fauna of the area was characterised by a diversity of small cyprinids (14 species), cichlids (9 species), clariid catfishes (4 species) and mormyrids (4 species). Species such as Clarias gariepinus, C. ngamensis, Marcusenius macrolepidotus, Tilapia rendali, T. sparrmanii and several small Barbus species were shared with adjacent floodplain systems such as the upper Zambezi and Kafue rivers. Fishing was undertaken by fishing groups consisting of a fisherman and his family, or a group of men fishing together. Access to the fishing grounds was controlled by traditional fishing leaders, who collected tribute from fishermen. Fishing groups utilised fixed, distinct fishing areas determined by ancestry. The most important time for fishing was during the drawdown phase of the floodplains, from March until June. During the dry season fewer groups were engaged in fishing, with many having returned to farming activities. The main fishing methods of the floodplain fishery were basket traps and mosquito-mesh funnel nets set into earth fish barriers (fish weirs) constructed on the plains, various mesh sizes of gillnets, hook longlines and seine nets. The use of fish spears, drag baskets and piscicides was of lesser importance. Most fishing gears were constructed of a variety of natural and modern, manufactured materials. The fishery was multi-species and 23 fish species were recorded from in catch. The three most important species in the catches were C. gariepinus, T. rendalli and M. macrolepidotus. Together these contributed 67% by weight to the catch. Catch-per-unit-effort (CPUE) for the different gears was 0.4 ± 0.3 kg.trap.night⁻¹ for basket traps, 2.7 ± 4.6 kg.net.night⁻¹ for funnel nets, 0.3 ± 0.5 kg.50 m net.night⁻¹ for gill nets, 3.5 ± 6.3 kg.100 hooks.night⁻¹ for longlines, 1.79 ± 1.11 kg.haul⁻¹ for mosquito-mesh seine nets and 6.87 ± 6.27 kg.haul⁻¹ for larger-mesh seine nets. The weight of average daily landings of fishing groups, using a variety of gears was 7.8 ± 7.4 kg. Fishermen were able to maintain the same catch rate between dry and wet seasons, with no significant differences (p < 0.05) in daily landings between seasons. Yield per fisherman for a seven month season, which required 2-3 relocations due to falling water level, was 1.64 t based on catch assessment, and 1.9 t from a socio-economic survey. A tentative yield per area estimate for the area was 2I7 kg.ha⁻¹ over the three month shallow-floodplain fishing season. Most fish landed in the fishery were processed into sundried or smoke-dried products. These were used for 1) home consumption, 2) trade with village farmers (from up to 70 km inland of the fishing grounds) in exchange for staple starch meal, and 3) sold to urban fish traders, reaching markets as distant as Lubumbashi in Democratic Republic of Congo. Fish traders toured fishing camps to buy fish, supporting auxiliary industries such as transport and accommodation services. The price for dried fish at source was 3.14 ± 1.34 USDlkg and the market price reported for the Zambian Copperbelt was 6.14 ± 2.54 USD/kg. Typical returns on investment in fish trading were estimated as 68-77%. The fishery was considered to be biologically and socially sustainable. By harvesting a seasonally transient assemblage of species with high productivity and biological turnover rates and with life histories adapted to high mortality, fishermen were able to maintain a stable and viable livelihood. Management recommendations for the area were that a fisheries management plan be developed that would seek to strengthen the traditional system of rights-allocation, address problems between fishing and tourism activities, and enhance communication between fisheries and conservation stakeholders. To do this it was recommended that: 1) conservation authorities recognise the importance of the fishery, 2) no changes to current effort levels and fishing methods were necessary, 3) points 1 and 2 above be used to improve communication and trust between conservation authorities and fishermen, 4) customary resource-access mechanisms be understood and strengthened so that local inhabitants' rights to the resource are protected, 5) fishermen help formulate and accept conservation and tourism rules, 6) tourists and guides be made aware of the function of the fishery, 7) a fisheries management forum of key community, government and conservation stakeholders be formed to shape and implement the fisheries management plan, 8) locally-adapted bylaws be created to legitimise crucial floodplain gears currently considered illegal (e.g. mosquito-net gears, fish weirs), 9) no intervention to formalise fish trading be made, and 10) a trained person with a fisheries background be hired oversee the implementation of the recommendations.
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Masi, Michelle D. "An Ecosystem-Based Approach to Reef Fish Management in the Gulf of Mexico". Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6541.
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Fisheries managers have the potential to significantly improve reef fish management in the Gulf of Mexico through the use of ecosystem-based approaches to fisheries management. Ecosystem-based approaches are needed to address the effects of fishing on trophodynamic interactions, to better account for ecosystem-scale processes in model projections, and to recognize the short and long-term biomass tradeoffs associated with making regulatory choices. My research was concentrated around three objectives: (1) characterizing the trophodynamic interactions between Gulf of Mexico fishes, in order to construct an invaluable tool (a Gulf of Mexico Atlantis model) to be used in ecological hypothesis testing and policy performance evaluation for years to come; (2) predicting ecological indicators for the Gulf of Mexico that both respond to fishing pressure and are robust to observational error, and; (3) evaluating the performance of an ecosystem-based policy options for managing reef fish species in the Gulf of Mexico. To accomplish these objectives, a spatial, trophodynamic ecosystem model- Atlantis, was employed to represent the Gulf of Mexico marine ecosystem.
To characterize trophic interactions between modeled species, I applied a maximum likelihood estimation procedure to produce Dirichlet probability distributions representing the likely contribution of prey species to predators’ diets. This provided mode values (the peak of the distribution) and associated error ranges, which describe the likely contribution of a prey item in a predator’s diet. The mode values were used to parameterize the availabilities (diet) matrix of the Gulf of Mexico Atlantis model. Investigating trophic interactions was useful for determining which species within the Atlantis model were data rich, and justified the emphasis on reef fish species and their prey items in subsequent analyses.
Once parameterized and calibrated, I used the Atlantis model to project ecological indicators over a 50 year time horizon (2010-2060) under varying levels of fishing mortality. Principal component analysis was used to evaluate ecological indicator trajectories in multivariate space, to rank indicators according to how well they describe variability in ecosystem structure (termed ‘importance’), to reveal redundancies in the information conveyed, to quantify interannual noise and to determine how robust indicators are to observational error. Reef fish catch, Red snapper biomass, King mackerel biomass and Species richness indicators ranked the highest in terms of importance and robustness to error and in having low levels of interannual noise (i.e., requiring less frequent monitoring). I then used a management strategy evaluation (MSE) framework in Atlantis to evaluate some of these same indicators under an ecosystem-based approach to fisheries management – using robust harvest control rules to manage reef fishes. I found that this ecosystem-based policy option was able to maintain higher reef fish biomass, catch and ecosystem-wide biodiversity under any given level of fishing mortality when compared to a status quo management approach. These results suggest that harvesting under the HCRs encourages an alternative ecosystem state with a more Pareto-efficient tradeoff frontier than the status-quo policy. A potentially reduced extinction risk for reef fish is plausible under this ecosystem-based policy option.
This research provides a quantitative look at the fishery performance and ecological tradeoffs associated with various policy options. MSE methodology using ecosystem-based policy performance metrics is also demonstrated. Tool development and findings from this research should aid in the development of ecosystem-based policies for this region.
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Currie, Jock. "Historical baselines and a century of change in the demersal fish assemblages on South Africa's Agulhas Bank". Doctoral thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27385.
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Accurate interpretation of recent variability observed in fish populations, species compositions, distribution ranges or ecological indicators, depends on knowledge of their past dynamics and historical states. The onset of systematic fisheries data collection typically lagged decades or even centuries behind modern fishing exploits. As a consequence, pre-disturbed reference points and descriptions of subsequent change are rarely available. A remarkably detailed set of historical trawl survey data from South Africa provided such a rare opportunity. Government-funded exploration of the Agulhas Bank fishery potential resulted in meticulously-documented trawl survey data from 1897-1904, when prior human impacts on those resources were negligible. Although they used less effective technology, the information recorded and methods used were similar to modern surveys. This thesis investigated change in demersal fish fauna of the Agulhas Bank and documents comparisons between historical trawl surveys and modern re-enactments at the same locations. In comparing trawl survey catches over multiple decades or among different periods, unquantified changes in fishing power pose a key challenge. The shape, size, materials, mesh sizes and speed at which trawl nets are dragged, interact with the behaviour, size and shape of fish, influencing fishing performance. To accurately compare current catch rates with those of historical trawl surveys, the same trawl gear and methods were carefully replicated in repeat surveys at three sites. An investigation of literature and photographs of the original vessel and equipment were conducted to support the construction of a replica 'Granton' otter trawl net. The net was composed of Manila hemp with a headline length of 27 m (90 ft) and was attached to flat wooden trawl boards. The historical towing speed was estimated as 1.34 m s⁻¹ (2.6 knots). Three parts of the shallow Agulhas Bank that were surveyed 111 years prior, were re-surveyed in 2015. Species composition was contrasted between the historical and re-survey periods by way of unconstrained ordination, permutational multivariate analysis of variance and tests of the homogeneity of multivariate group dispersions. Taxa discerning between periods were identified with similarity percentage analyses. Changes of standardised catch between periods were tested for 27 taxa, using a non-parametric bootstrap approach. Proportions among size-classes, recorded for three taxa, were tested using Fisher's exact test. Results revealed a substantially transformed demersal catch assemblage, where the period effect explained almost half of the measured variance among samples. These changes included the disappearance or heavy depletion of kob (Argyrosomus spp., absent in re-surveys), panga (Pterogymnus laniarius; 2.4% of historical catch abundance) and east coast sole (Austroglossus pectoralis; 4.6% of historical catch abundance), which had jointly contributed 70-84% of historical catch composition. Average re-survey catches were largely made up of gurnards (Chelidonichthys spp.; 3 792% of historical abundance), horse mackerel (Trachurus trachurus; 4 738% of historical abundance), spiny dogfish (Squalus spp.; 3 121% of historical abundance), hake (Merluccius capensis; 558% of historical abundance) and white sea catfish (Galeichthys feliceps; 13 863% of historical abundance). Analysis of available length information confirmed the expectation that fish sizes (specifically M. capensis and A. pectoralis) had declined. This implies that comparisons by weight would be more severe for declined abundances and less severe for those that increased, relative to contrasts of numerical abundance. Habitat preferences as well as geographic and depth distribution appeared to separate the taxa that increased from those that declined. These factors, together with reproductive and growth characteristics, as well as indirect trophic impacts, likely shaped the responses of demersal fauna to fishing and other human impacts during the 111 years between trawl surveys. An assessment of distribution changes of 44 common demersal taxa was undertaken. These analyses were restricted to the last 30 years of trawl survey data as the units and spatio-temporal resolution of prior data were incompatible. Standardised catches were used from annual spring and autumn south coast trawl surveys conducted by the government fisheries department. Geostatistical delta-generalised linear mixed models were used to predict species distribution functions, which were used to calculate annual estimates of latitude/longitude centres of gravity and effective areas occupied by each population. Average trends over the study period (1986-2016) were assessed using a Bayesian state-space model. Of nine species found to have a trend in average location, six moved westward or south-westward, while three moved eastward or north-eastward. Two species showed a trend of contracting spatial extent and one showed an expansion. Across the entire assemblage combined, there was a significant contraction in extent and a westward shift in average location. These assemblage-wide average trends are interpreted to be driven by climate forcing. Fishing impacts are expected to have contributed to the eastward movement in centre of gravity for kob, lesser sandshark (Rhinobatos annulatus) and white stumpnose (Rhabdosargus globiceps). Interpretation of these distribution shifts is hampered by a lack of knowledge on subsurface hydrographic trends on the Agulhas Bank, which is identified as a research priority. My research revealed substantial change in demersal fish communities on South Africa's Agulhas Bank and adds novel insight to the history underlying current states of demersal ecosystems. Valuable additions include a) documentation of the extent to which demersal assemblages have transformed during the last century at three representative inshore sites; b) estimates of current abundances relative to pre-disturbed baselines at those sites, which c) highlights drastic local depletion for certain taxa and d) reveals substantial abundance increases of certain species during the post-industrial fishing period; e) novel evidence of distribution trends in south coast demersal species; and f) identification of trends in the average distribution of the demersal fish assemblage, suspected to be climate-forced. Long-term comparisons, using minimally-disturbed baselines, revealed drastic transformation of the fish assemblage during a century of industrialisation, which points to trawling-induced alteration of benthic habitats and substantial changes in ecosystem structure. Besides the provision of novel historical context for current and future studies and decision-making, this work counters the erosive nature of shifting baselines in South Africa's marine environment.
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Uzonnah, Nwamaka Mary-Immaculata. "Assessment of the population structure of the South African sardine Sardinops sagax using a multi-method approach and the morphological and molecular characterization of a stock-discriminating digenean parasite biotag of the genus Cardiocephaloides". Doctoral thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27244.
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An understanding of the population structure of commercially exploited species is essential for effective fisheries management. Fish stocks are typically identified based on the observation of differences in genetic and/or phenotypic characteristics between fish from discrete units. Recent deliberations on the management of the South African purse-seine sardine fishery recognises the likely existence of two stocks, one on the west and another on the south coasts, following studies that have documented spatial variability in several phenotypic characteristics of this species around South Africa. Those studies typically examined spatial variability in a single characteristic (e.g. gill raker morphology and meristics, body shape, otolith shape, vertebral count, parasite loads), but the application of multiple stock identification methods to the same individual fish has been recommended in order to maximize the likelihood of correctly inferring and identifying fish stocks. This study seeks to assess the population structure of South African sardine Sardinops sagax using a combination of stock identification methods including meristic, morphometric and parasite markers. Most of the sardine samples used in this study were obtained off the west and south coasts of South Africa during pelagic surveys conducted in 2013 and 2014 by Fisheries Branch of the Department of Agriculture, Forestry and Fisheries, with some additional samples obtained from commercial fisheries. Fish caught from the west and south coasts are presumed to be part of the putative western and southern stocks respectively. The variables examined included body shape, gill arch length, gill raker spacing, number of gill rakers, otolith shape indices (otolith circularity and form factor), the number of vertebrae, and the abundance of a 'tetracotyle' type metacercarian parasite found in the eyes of sardine; these were first analysed individually and then collectively (excluding body shape data) in a multivariate analysis to test their effectiveness in discriminating between sardine from the putative western and southern sardine stocks. Analysis using geometric morphometrics revealed significant differences in body shape between sardine from the putative western and southern stocks. Results of GLM analyses indicated that gill arch length, the number of gill rakers, otolith form factor and circularity, and parasite abundance were effective univariate discriminators of sardine stocks. No significant difference in gill raker spacing and the number of vertebrae was found between individuals from the two stocks. A Stock Identification Index (SDI) of 0.75 derived from the univariate analyses, as well as results of the multivariate analysis of data provided strong evidence for the existence of two mixing stocks, therefore, supporting the two-stock hypothesis. The five multivariate classification models used in the study showed varying degree of allocation success. Overall classification accuracy ranged from a low 47% in the Linear Discriminant Analysis model to highs of 82% and 91% in the Classification Tree Analysis and Random Forest models, respectively. Both CTA and RF revealed the combination of variables with the strongest spatial discriminatory power to be the number of vertebrae and abundance of the 'tetracotyle' type metacercarian parasite. These results agree with those of previous studies and further support the inclusion of sardine population structure into management strategies for the purse-seine fishery for South African sardine. Given the importance of the 'tetracotyle' type metacercaria in the discrimination of South African western and southern sardine stocks, further studies were undertaken to identify and describe this parasite using light and scanning microscopy, as well as molecular tools. Such information will assist in the definitive identification of the first intermediate host of the parasite, presently hypothesized to be a sub-tidal gastropod occurring off the west coast only. Definitive identification of the first intermediate host (or hosts) will enable the full life cycle of this parasite to be determined and the parasite endemic area to be identified; a critical knowledge gap in application of the parasite biotag approach to stock discrimination using this 'tetracotyle' type metacercarian parasite. Metacercariae collected from fresh sardine sampled from a commercial landing in Gans Baai, South Africa, were manually excysted, relaxed in warm water, fixed in 70% ethanol and stained with haematoxylin for light microscopy. The metacercarial body is oval-shaped, measuring 762 - 967 x 512 - 677μm. It is divided by transverse folds into a forebody, midbody and hindbody. Diagnostic features include the unique, large excretory bladder lobes situated on the lateral sides of the body; two large pseudosuckers in the anterior part of the midbody; an acetabulum which is larger than the oral sucker; and a large lobulated holdfast organ in the posterior half of the midbody. These features are those of the metacercariae of the genus Cardiocephaloides, confirming the previous hypothesis regarding the genus of this digenean biotag. Analysis of partial 28S rDNA region sequence data showed that the metacercariae and the adult Cardiocephaloides found in the African penguin Spheniscus demersus are of the same species, likely C. physalis. This study is the first documentation of the morphological and molecular characterization of the stock-discriminating Cardiocephaloides metacercaria found in the eyes of Sardinops sagax in South Africa.
Książki na temat "Fisheries Resources Assessment"
1
Gunderson, Donald R. Surveys of fisheries resources. New York: Wiley, 1993.
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G, Cowx I., red. Stock assessment in inland fisheries. Oxford, [England]: Fishing News Books, 1996.
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Sector, SADC Inland Fisheries, SADC Marine Fisheries and Resources Sector. i SADC Inland Fisheries Sector. Technical Coordination Unit., red. Fisheries training needs assessment study for SADC Inland Fisheries and Marine Fisheries and Resources sectors. Lilongwe: SADC Inland Fisheries Sector, Technical Coordination Unit, 1997.
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Commission, South Pacific, red. An assessment of the skipjack and baitfish resources of New Caledonia. Noumea, New Caledonia: South Pacific Commission, 1985.
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Fehring, Joseph P. Pickwick reservoir water quality, limnological, and fisheries assessment. Chattanooga, Tenn: Tennessee Valley Authority, Office of Natural Resources and Economic Development, Division of Air and Water Resources, 1986.
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1958-, Fletcher Rick, i Fisheries Research & Development Corporation (Australia), red. The ESD assessment manual for wild capture fisheries. Canberra: Fisheries Research & Development Corp., 2003.
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Sean, Pascoe, i Greboval D. F, red. Measuring capacity in fisheries. Rome: Food and Agriculture Organization of the United Nations, 2003.
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Philipson, Peter W. An assessment of development options in the longline fishery. Honiara, Solomon Islands: Forum Fisheries Agency & Pacific Islands Forum Secretariat, 2006.
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South Pacific Forum Fisheries Agency. i Pacific Islands Forum, red. An assessment of development options in the longline fishery. Honiara, Solomon Islands: Forum Fisheries Agency & Pacific Islands Forum Secretariat, 2006.
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T, Sakagawa G., Stocker Max i World Fisheries Congress (1992 : Athens, Greece), red. Assessment methodologies and management: Proceedings of the World Fisheries Congress, theme 5. Lebanon, NH: Science Pub., 1995.
Znajdź pełny tekst źródłaCzęści książek na temat "Fisheries Resources Assessment"
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Chen, Xinjun, i Qi Ding. "Assessment of the Sustainable Use of Fishery Resources and an Early Warning System". W Fisheries Resources Economics, 215–81. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-33-4328-3_5.
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Kayanda, R. J., A. I. Chande, Yunus D. Mgaya, E. Mlaponi i O. C. Mkumbo. "Stock Assessment of Commercial Fish Species of Lake Victoria". W Lake Victoria Fisheries Resources, 107–35. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-69656-0_6.
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Mitson, R. B. "Fisheries Acoustics: Assessment of Fish Stocks and Observation of Fish Behaviour". W Ocean Resources, 251–58. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-2131-3_20.
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Piñeiro-Corbeira, Cristina, Sara Barrientos, Rodolfo Barreiro, Shankar Aswani, José J. Pascual-Fernández i Raquel De la Cruz-Modino. "Can Local Knowledge of Small-Scale Fishers Be Used to Monitor and Assess Changes in Marine Ecosystems in a European Context?" W Human-Nature Interactions, 299–314. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-01980-7_24.
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Significance StatementIn the last decades, many coastal areas have observed dramatic changes in marine ecosystems, due to anthropogenic and environmental alterations. The general absence of long-term data sets in the marine environment and, more specifically, on benthic and demersal communities represents a severe issue for management and conservation. We propose to incorporate the small-scale fishers’ knowledge and science for better policy recommendations, both in terms of fisheries optimization and resource conservation. Based on two different cases of study with diverse ecosystems, we explore the combination of quantitative and qualitative tools, and participative techniques used to incorporate fishers’ local ecological knowledge. The results highlight fishers’ capacity to identify coastal and marine landscapes resources and changes, reinforcing and complementing the scientific assessment.
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"Incorporating spatial population structure into the assessment- management interface of marine resources". W Management Science in Fisheries, 339–67. New York : Routledge, 2016.: Routledge, 2016. http://dx.doi.org/10.4324/9781315751443-25.
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"Mitigating Impacts of Natural Hazards on Fishery Ecosystems". W Mitigating Impacts of Natural Hazards on Fishery Ecosystems, redaktorzy Benedict C. Posadas, Ruth A. Posadas i William S. Perret. American Fisheries Society, 2008. http://dx.doi.org/10.47886/9781934874011.ch11.
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<em>Abstract.</em>—An economic assessment of the commercial and recreational fisheries was undertaken in Mississippi from November 2005 to February 2006 to determine the level of damage sustained as a result of Hurricane Katrina. This assessment was a collaborative effort arising from the federal (National Marine Fisheries Service [NOAA Fisheries]) and state (Mississippi Department of Marine Resources [DMR]) government agencies’ urgent and compelling need to complete damage assessments in the affected areas in as short a period as possible. An accurate assessment of the damage created by this storm was needed to ensure that federal funds are both adequate and allocated to the appropriate sectors and recipients. The Mississippi State University– Coastal Research and Extension Center (CREC) and the Mississippi–Alabama Sea Grant Extension Program accepted the task of estimating the damages brought about by the hurricane to the state’s fishery resources and communities. The assessment of the impacts on the state commercial and recreational fisheries industries covered commercial seafood processors and dealers, the commercial fishing fleet, live-bait dealers, marinas, for hire charter boats, and land-based support facilities. Data were collected from survey questionnaires mailed to all resident vessels and facilities licensed in the state of Mississippi. In addition, personal interviews with fishermen and site visits of facilities were conducted in four coastal locations by DMR and CREC personnel. The results of the assessment indicated that all of the seafood processing plants, support facilities, and live-bait dealers, 86.7% of the commercial fleet, 60% of the seafood dealers, and 69% of the for-hire charter fleet that responded to the survey were damaged by the storm. Disaster assistance programs developed by NOAA Fisheries, which were approved by Congress in 2006, were administered by DMR to participating licensed operators of commercial fishing and for-hire charter boats. It is suggested that the hazardrelated decision-making processes of marine establishments and fishing community households need to be further evaluated to improve the overall mitigation process.
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Punt, A. E., i R. D. Methot. "The Impact of Recruitment Projection Methods on Forecasts of Rebuilding Rates for Overfished Marine Resources". W Fisheries Assessment and Management in Data-Limited Situations, 571–94. Alaska Sea Grant, University of Alaska Fairbanks, 2005. http://dx.doi.org/10.4027/famdis.2005.31.
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"Freshwater Fisheries in Canada: Historical and Contemporary Perspectives on the Resources and Their Management". W Freshwater Fisheries in Canada: Historical and Contemporary Perspectives on the Resources and Their Management, redaktorzy Peter A. Cott, Louise Chavarie, Cynthia A. Paszkowski, Heidi K. Swanson i William M. Tonn. American Fisheries Society, 2023. http://dx.doi.org/10.47886/9781934874707.ch6.
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Abstract.—Canada’s three northern territories comprise nearly 40% of the country’s land and more than 35% of its freshwater resources. The physical geography and climate of the region are diverse and include nine of Canada’s 18 terrestrial ecozones. Freshwater habitats include thousands of systems, ranging from small ponds and streams to the Mackenzie and Yukon rivers and 39 lakes greater than 500 km2. The freshwater and anadromous fish fauna (56 species) is dominated by Salmonidae (25 species). Regional diversity of fishes tends to decrease with increasing latitude and decreasing longitude; freshwater productivity is generally low. Fisheries management varies considerably across the territories. In the Yukon, Fisheries and Oceans Canada (DFO) manages the transboundary anadromous fishes with the USA, whereas freshwater fisheries management is territorial, in collaboration with First Nations. Most freshwater fishes harvested in the territory are by recreational anglers. In most of the Northwest Territories, fisheries management is a co-management process involving DFO and four regional co-management boards and relies heavily on community consultation. The commercial fishery is concentrated on Lake Whitefish Coregonus clupeaformis in Great Slave Lake. Sportfishing, regulated by the territorial government, is popular with many residents and tourists. In Nunavut, subsistence fisheries are most prevalent; the limited commercial fisheries are primarily coastal and focused on Arctic Char Salvelinus alpinus. Sport fishing is also limited but viewed as a growth opportunity. Despite differences in management among the three territories, they share several management and conservation challenges. Specific changes in aquatic ecosystems related to climate change are difficult to predict but will be significant. Despite low overall human population densities, overexploitation can be a concern locally. Other management challenges result from the occurrence of mixed stocks, the impracticality of obtaining stock assessment data, and impacts from resource development. Consultation and adaptive co-management with Indigenous governments, including incorporation of traditional knowledge, are critical to successful management.
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Ma, Xiaogang, Stace E. Beaulieu, Linyun Fu, Peter Fox, Massimo Di Stefano i Patrick West. "Documenting Provenance for Reproducible Marine Ecosystem Assessment in Open Science". W Information Retrieval and Management, 1051–77. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-5191-1.ch045.
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Open Science not only means the openness of various resources involved in a scientific study but also the connections among those resources that demonstrate the origin, or provenance, of a scientific finding or derived dataset. In this chapter, the authors used the PROV Ontology, a community standard for representing and exchanging machine-readable provenance information in the Semantic Web, and extended it for capturing provenance in the IPython Notebook, a software platform that enables transparent workflows. The developed work was used in conjunction with scientists' workflows in the Ecosystem Assessment Program of the U.S. NOAA Northeast Fisheries Science Center. This work provides a pathway towards formal, well-annotated provenance in an electronic notebook. Not only will the use of such technologies and standards facilitate the verifiability and reproducibility of ecosystem assessments, their use will also provide solid support for Open Science at the interface of science and ecosystem management for sustainable marine ecosystems.
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"Freshwater, Fish and the Future: Proceedings of the Global Cross-Sectoral Conference". W Freshwater, Fish and the Future: Proceedings of the Global Cross-Sectoral Conference, redaktor Chris Barlow. American Fisheries Society, 2016. http://dx.doi.org/10.47886/9789251092637.ch24.
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<em>Abstract</em> .—Development of hydropower dams on the mainstream of the Mekong River is highly contentious, particularly in Laos where two mainstream dams are under construction and another seven are planned. The debate revolves predominantly around the economic development associated with increased electricity supply and sales, versus the livelihood disruption resulting from the degradation of the traditional uses of the river (primarily fisheries) and other ecosystem services. Assessment of policy and management indicates six lessons relating to the governance of the Mekong and potentially other large transboundary rivers. These are that decisions about resource use can be unrelated to resource management, different public viewpoints and value judgments by political leaders must be acknowledged, integrated planning is essential for rational development of natural resources, decentralization of government hinders sustainable management of natural resources, technical information is essential for decision making and assessment of trade-offs, and difficulties in comparing monetary and nonmonetary values encumber policy development.
Streszczenia konferencji na temat "Fisheries Resources Assessment"
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Rempel, Laura L., i Michael Porter. "A Risk Assessment Tool for Evaluating Geohazards and Fisheries Sensitivity at Pipeline Water Crossings". W 2008 7th International Pipeline Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/ipc2008-64560.
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The Fisheries Act legislates Fisheries & Oceans Canada (DFO) to regulate all development activities affecting fish-bearing waters to ensure no net loss in habitat productivity. To meet the increasing regulatory demands of oil and gas development, DFO is developing a Fisheries Risk Assessment Tool (FRAT). The current focus is along the Mackenzie River Valley, Northwest Territories. The FRAT is applied to proposed pipeline stream crossings and evaluates the risk to fisheries resources from geohazards causing sedimentation impacts. Ultimately, the FRAT may be applied across Canada to streamline DFO’s regulatory process for pipeline stream crossings. The FRAT consists of a Geophysical Database that characterizes physical attributes of the river valley and channel in the vicinity of a crossing, plus a Fisheries Database that characterizes the fisheries resources and habitat of the stream. Algorithms have been developed to quantitatively estimate sedimentation hazard likelihood and fisheries sensitivity, which are coupled in a qualitative risk matrix that assigns an overall risk rating to each stream crossing. The overall risk rating then designates the level of regulatory review and authorization process carried out by DFO under the Fisheries Act. Geohazard algorithms are being calibrated and tested using field data and stream crossing construction scenarios are being incorporated into the risk assessment tool. This paper describes the FRAT and its application in the Mackenzie Valley, and presents preliminary results from risk analysis of pipeline stream crossings.
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Chen, Xinjun, i Wang Yali. "Preliminary study on sustainable utilization assessment and its early-warning model for marine fisheries resources in the East China Sea". W 2011 International Conference on Business Management and Electronic Information (BMEI). IEEE, 2011. http://dx.doi.org/10.1109/icbmei.2011.5921067.
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Berman, C. "Using Computer Modeling to Evaluate Fixed VS. Random Grid Sampling for Fisheries Resource Assessment". W OCEANS '87. IEEE, 1987. http://dx.doi.org/10.1109/oceans.1987.1160710.
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Konkovs, Karlis Aleksandrs, Rasa Ikstena, Ilze Zvera, Maris Ozolins i Raimonds Ernsteins. "Lake governance developments in Latvia: lake Lubans governing process studies applying governance system framing model". W 23rd International Scientific Conference. “Economic Science for Rural Development 2022”. Latvia University of Life Sciences and Technologies. Faculty of Economics and Social Development, 2022. http://dx.doi.org/10.22616/esrd.2022.56.019.
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The overall frame of this research was the governance process of surface water resources in Latvia, particularly, public lakes, to be studied by applying triple dimensional governance framing model of complementary dimensions of governance stakeholders, governance content and governance instruments. Studies were realized in the area of Lake Lubans, administratively located on the border areas between two municipalities of Madona and Rezekne in the eastern part of the country. Lake Lubans is the largest lake in Latvia, as well as the largest dammed lake in Europe, included in surrounding NATURA 2000 nature reserve territory as also nationally largest inland protected wetland complex (Lubana Wetland/Ramsar site, 2009). Case Study Research methodology was applied by approaching the study area not only as a nature protection area but especially as a socio-ecological territorial and human system, using indepth semi-structured interviews in the surrounding areas/administrative territories with all main local-regional and also national stakeholder groups, as well as, applying document studies and territorial/objects’ observations. The National Nature Protection Agency’s Latgale region branch as the legal administrator supervises all nature protection territories in the region and also the Lubana Wetland, which is still lacking statutory Nature Protection Plan for the area; and, due to very limited administrative capacities, Agency is to be oriented more towards c ooperation with various other national and regional institutions from very different sectors, being organized under mainly two ministries involved – Environmental and Regional Development Ministry (nature, environmental, municipal and regional development sectors) and Agriculture Ministry (agriculture, forestry, fisheries, water infrastructure sectors), as well as, particularly, with many municipalities in the wetland area. But municipalities have to take into account also interests of local communities, the basic socio-economic development situation and possibilities, having also limited capacities, sometimes also approaches, which all is to be combined with strong nature protection requirements and limitations. This governance landscape requires co-relation of various and diverse interests and creates a rather fragmented and underdeveloped management of the lake. Lake water levels are fully regulated by the national Water infrastructure agency using dams and other hydro-technical systems, while water areas are used not only for highly popular angling, but also for active commercial fishing and various recreational activities, tourism, esp. bird watching etc., thus also keeping strong nature protection status in the same time, which all represent a unique challenge for to be developed multi-stakeholders and socioecological system (SES) approach for lake governance (assessment, planning, collaborative management, monitoring, and communication) developments in Latvia and alike.
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Sulistyo, Broto Wahyono, i Wiwik Widyo Widjajanti. "Assessment of the existence of green open space in fishermen village, Surabaya". W HUMAN-DEDICATED SUSTAINABLE PRODUCT AND PROCESS DESIGN: MATERIALS, RESOURCES, AND ENERGY: Proceedings of the 4th International Conference on Engineering, Technology, and Industrial Application (ICETIA) 2017. Author(s), 2018. http://dx.doi.org/10.1063/1.5042973.
Pełny tekst źródłaRaporty organizacyjne na temat "Fisheries Resources Assessment"
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Naddafi, Rahmat, Göran Sundblad, Alfred Sandström, Lachlan Fetterplace, Jerker Vinterstare, Martin Ogonowski i Nataliia Kulatska. Developing management goals and associated assessment methods for Sweden’s nationally managed fish stocks : a project synthesis. Department of Aquatic Resources, Swedish University of Agricultural Sciences, 2023. http://dx.doi.org/10.54612/a.31cfjep2i0.
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This report summarizes and synthesizes results from the Swedish Agency of Marine and Water Management (SwAM, or HaV) funded project “Förvaltningsmål för nationella arter (Management goals for nationally managed species)”. The objectives of the project have been to promote the development of management goals and associated status assessment methods and indicators, as well as reference points, for some nationally managed fish stocks both in coastal as well as freshwater areas. The report focusses largely on species and stocks that can be defined as data-poor. Such stocks are characterised by marked limitations in data availability and/or resources allocated to detailed analytical stock projections. Data-poor stocks also often lack carefully formulated management goals and associated methods and indicators for assessing stock status. In this report, we provide an overview of potential assessment methods and indicators and try to synthesise how they work and what the strengths and weaknesses are by applying them to selected data poor stocks such as pikeperch, pike, whitefish, and vendace. We also discuss how they relate to different potential management goals and provide recommendations for their application. We grouped the indicators and assessment methods by the three categories that are now used in the yearly status assessment framework provided by SLU Aqua (Resursöversikten/Fiskbarometern) – i) mortality, ii) abundance/biomass and iii) size/age structure. The results are also described for these three main categories of assessment indicators. Included is also a status report from a size- and age-based population dynamics model (Stock Synthesis 3) that is being developed for pikeperch in Lake Hjälmaren. An important experience from the project is that to improve the assessment methods for Swedish national fish stocks, it is important that managers develop both general as well as more detailed quantitative goals for the individual stocks. This should ideally be conducted in various forms of collaboration with the main stakeholders and scientists involved with assessment as participatory processes foster legitimacy. Carefully articulated management goals, which are possible to translate into quantitative targets, will facilitate the development of various approaches and methods to monitor stock statuses. Given the strong and complex interactions of fish and their environments it is also important to consider other pressures than fisheries when developing indicators and assessment methods. Our synthesis highlights a number of areas where the assessment of data-poor stocks can be improved: 1. Apply precautionary principles for data-limited stocks, particularly ones that are known to be vulnerable to exploitation. 2. Tailor approaches to how fisheries are managed in Sweden. Swedish nationally managed fish stocks are not managed by quotas (with one exception, vendace in the Bothnian Bay) and do not aim for maximum sustainable yield. Instead, the coastal and inland fisheries are managed by regulating the effort in the small-scale commercial fisheries (number of fishers/licenses and amount of gear). Regulation of recreational and subsistence fisheries effort, in terms of licenses or number of fishers) is not applied, nor possible since the fisheries is lacking obligatory notification and reporting systems. All national fisheries, however, are regulated by various technical measures (closed areas, size-limits, bag-limits, gear restrictions etc). Thus, goals and assessment methods that result in harvest limits or quota recommendations expressed in e.g. biomass/numbers are difficult to use as basis for management. Instead, there is a need for alternative management goals and associated assessment methods. 3. Use best practice methods and indicators and adapt as scientific knowledge is developed. Data-limited methods are developing rapidly, and new methods/approaches are proposed in the scientific literature every year. It is thus important to be updated on the most recent developments. 4. Clearly describe limitations/assumptions of methods used. It is important to be aware of and critically evaluate the assumptions underlying the analyses, and to carefully communicate uncertainty together with the stock status assessment. 5. Be particularly careful with low sample numbers. Many indicators and methods can be applied also on small sample sizes, however, the accuracy and precision of the estimates risk being low in such cases. 6. Accept that there is no "gold standard" for fisheries assessment. Each case study is unique and needs to be balanced against data availability, local needs and other important factors. This also means that analysts need to be careful when using generic reference levels or “borrowing” data from other stocks. 7. If possible, use several different methods/indicators. Although several indicators aim to measure similar aspects of the stock, small methodological differences can support the overall interpretation of individual indicator values. It is particularly important to incorporate many aspects and indicators (size/age/abundance/mortality) in order to produce a balanced assessment. 8. Develop means of communication. Indicators and goals should be easy to understand. However, interpretation of results from multi-indicator frameworks can be challenging. There is thus a need for finding ways of communication that can convey complicated results in a simple-to-understand manner. 9. For details on additional improvements, we refer the reader to the sub-header “recommendations for the future” found under each chapter. The implementation of Stock Synthesis for pikeperch in Lake Hjälmaren showed that it is possible to develop a more ambitious and detailed stock assessment model for a relatively data-poor stock. The model results partly support earlier interpretations of the development of the stock and the importance of the changes in regulations in 2001 (increased minimum size, increased mesh size and reduced mortality of undersized pikeperch). Before the model can be implemented and used for practical management, a number of actions for improvement are needed, which are highlighted in the relevant chapter. The most important next step is establishing management goals and reference levels for this stock. We recommend that such a dialogue is initiated by managers. The fisheries management goals should consider both biomass, fisheries mortality and size-based targets. To conclude, we stress the importance of improving all ongoing aspects related to the assessments of data-poor Swedish stocks. Strong local stocks and sustainable fisheries are vital for a variety of fisheries-related businesses and practices, particularly in rural areas, providing economical and societal value. Fishes also have important roles in aquatic food-webs and it is important that ecological values are managed wisely in order to reach targets for water quality, ecosystem structure and diversity. Given the strong and complex interactions of fish and their environments it is also important to consider other pressures than fisheries when developing indicators and assessment methods.
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Financial Analysis and Risk Assessment of Selected Aquaculture and Fishery Activities in the Mekong Basin. Vientiane, Lao PDR: Mekong River Commission Secretariat, kwiecień 2002. http://dx.doi.org/10.52107/mrc.akbold.
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The report assesses the financial feasibility and risks for low income target groups of interventions in aquatic resource development; interventions in resource/habitat protection and the enhancement produced or proposed under the MRC fisheries programme.