Dissertations / Theses on the topic 'Fishery management'

Thesis (Doctoral)--Helsingin yliopisto, 2005.
Tiivistelmäosa ja 5 julkaisua Includes bibliographical references. Saatavana myös elektronisena (ISBN 952-10-2740-1 pdf), Available in PDF format via the World Wide Web. http://ethesis.helsinki.fi

Thesis (Ph. D.)--Faculty of Agriculture, Food & Natural Resources, University of Sydney, 2007.
Title from title screen (viewed on August 9, 2007). Includes graphs, tables. Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Faculty of Agriculture, Food and Natural Resources. Bibliography: leaves 304-313. Also issued in print.

Dissertação de mestrado, M.A. (Econ), Department of Econometrics, Faculty of Economic and Social Studies,University of Manchester, 1995.
This dissertation analyses the optimal management of fisheries in the framework of dynamic game theory. The analysis rests upon a blend of the economic model of the fishery confined to the waters of a single state, with the theory of dynamic games. In order to accomplish this objective, this dissertation has been organised as follows. Chapter 1 presents some background material concerning noncooperative and cooperative game theory as well as a general formulation of continuous-time infinite dynamic games, also known as differential games. In Chapter 2 we provide some material concerning the dynamics of the fishery by summarising the Gordon-Schaefer bioeconomic model, which provides the foundation for our analysis. Finally, in Chapter 3, and by combining the subject presented in the preceding chapters, we examine the insights which dynamic game theory can provide in analysing fisheries management.

This thesis is the culmination of 35 years of fisheries management experience shaped by reflections and academic study. While New Zealand is often positioned as an acclaimed success with the development and application of the Quota Management System, this thesis outlines some of the serious flaws that underpin current trajectories. Tensions have been created by the Ministry of Fisheries focusing almost exclusively on developing solutions for New Zealand's fisheries policy and management problems through the commercial sector management regime. The 'command and control' management approach sits uneasily with the 'rights-based' management regime in the commercial fishery and the common property resource management regime in the customary Maori fishery.This study attempts to identify how the management of New Zealand inshore fisheries could be improved by using an integrated approach - a trinity of fisheries (institutions, rights, and governance) to manage all three sectors (commercial, recreational and customary Maori). The international literature provides a narrow view of fisheries policy and management in New Zealand and the discussion is strongly oriented around a limited range of issues - particularly commercial fisheries and a 'rights-based' approach. Drawing on a depth of experience in both central policy development and fisheries management (particularly in the Auckland Fisheries Management Area), four arguments are identified: Firstly, that New Zealand's fisheries management policies for both commercial and non-commercial fisheries management have been largely based on the commercial fishery. Secondly, that the international literature is heavily skewed towards issues and events in the commercial fishery without adequate recognition of the non-commercial (customary Maori and recreational) fisheries. Thirdly, that the three fisheries in the inshore waters cannot be managed effectively unless the management of all sectors is integrated under a common policy and management framework. And finally, that the 'rights-based' focus is faltering because of inadequate and inappropriate institutions and governance. The trajectories of the three inshore wild harvest sectors (commercial, recreational, and customary Maori) are explored, with a particular interest on how they influence and impact on each other. The primary focus of the analysis is the role that institutions, rights and governance play on the management and development of the three sectors. The thesis concludes with a chapter on the current positioning of institutions, rights, and governance within a three-sector trajectory and suggests tentative principles which could be used in New Zealand's inshore wild stock fisheries to build an integrated policy and management. It concludes that New Zealand's inshore fishery requires a re-conceptualisation to a governance approach, based on ecosystem management. A common management approach across all sectors of fisheries can be achieved by incorporating a wider institutional framework than a rights-based approach and moving beyond a focus on harvesting alone.

Multispecies fisheries with technical interactions and sparse data present a challenge for assessment scientists, many of whom are now legally required to provide species-specific management advice. A key question is can these data be used to provide species-specific assessments and management advice? Secondly, in light of new assessment approaches, how would new management procedures perform with respect to the status quo? This thesis uses a novel multispecies model to reconstruct historical abundances using fishery-dependent data from the Hawaiian bottomfish fishery. In this handline fishery, hook competition and time spent handling fish limits catch rates, resulting in nonlinear relationships between CPUE and abundance. The model is jointly fit to species-specific catch and is conditioned on historical fishing effort. The model allows for hook competition and partitions time spent fishing and time spent handling fish, h. Simulation experiments showed this approach provided nearly unbiased parameter estimates unless an incorrect assumption was made about h. Empirical h estimates were unavailable, so a range of h values were imputed from information on fishing gears and sensitivity to h was evaluated. Species-specific information was disentangled using h, but no single value best described all species-specific catch equally. Leading and management parameter estimates were relatively insensitive to the assumed value of h, except for catchability at low stock size. Given the uncertainty about h, management procedure evaluation was used to evaluate management performance of the multispecies model to an aggregate model and evaluate alternative management procedures (MPs), defined by the decision rule, assessment model, and data types. Trade-offs among management objectives describing stability in catch, fishery productivity, and over-exploitation risk were compared. Trade-offs between catch and conservation objectives were largely determined by the decision rule. MPs associated with an aggregate assessment represented a balance from the aggregate perspective, but led to over-exploitation of one or more species. Average annual variation in catch was high for all MPs and highest for MPs using the multispecies approach in combination with a tag-recapture program. These results were largely robust to the assumptions about h in the assessment model and demonstrated the difficulty of co-managing multiple species.

Thesis (Ph. D.)--University of California, San Diego, 2007.
Title from first page of PDF file (viewed October 3, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 68-72).

Marine reserves are promising tools for fisheries management, and are especially suited for complex, multi-species fisheries. Recent work has focused on the design of reserves to achieve particular management objectives and on defining appropriate indicators for monitoring to determine whether these objectives are being met. In principle, there should be a strong correlation between biological, social and economic indicators that are all correlated with fish abundance and ecosystem health. In practice, different indicators are often inconsistent, and it is common for researchers and fishers to have conflicting opinions on how well reserves are meeting management goals. I suggest that these discrepancies are not necessarily due to conflicting opinions regarding management objectives, but rather that the inherent biases in different sampling schemes may cause different measures of the same parameter to be uncorrelated. For example, scientists tend to sample only snapshots in time and space in randomly chosen locations, while fishers sample over much greater temporal and spatial scales but in non-random locations. Furthermore, marine ecosystems are extremely complex, and failing to account for the full extent of this complexity may lead to erroneous measurement of biological trends. The purpose of this dissertation is to determine the causes of discrepancies between different types of indicators using a multidisciplinary approach. A detailed study of the Glover’s Reef Marine Reserve (GRMR) in Belize provides a basis for comparison. Chapters 2 to 4 of the dissertation focus on understanding how the GRMR has functioned to produce fisheries benefits, and elucidating some of the factors responsible for variation in species’ responses to reserve protection. Chapters 5 to 7 of the dissertation focus on comparisons of different indicators of changes in fish abundances, and explain the circumstances under which indicators may disagree. With a better understanding of the functioning of the GRMR based on both scientific and local knowledge, efforts can be made to develop more appropriate indicators, and these indicators can then be tested for use in other coral reef reserves worldwide.

This dissertation tests theories about catch share approaches to fishery management, examining their validity and limits relative to the Northeast groundfish sector program, and potentially modifies them in light of research outcomes. Participants of the groundfish fishery based in New Hampshire are the particular focus of research, but broader impacts are considered. Studies of this catch share program have been limited to date, and studies of catch share programs generally have focused on a particular dimension (e.g., biological, social, economic) rather than integrate across dimensions, despite increasing needs to do so for management. Here, six key aspects of fishing are investigated: fishing practices, social capital, bycatch, economic performance, safety, and well-being. Thus, this work is a novel contribution to the field of impact assessment research, both in its topic and scope.

The primary research question is: How has the advent of catch shares impacted the Northeast commercial multispecies fishery, particularly in New Hampshire? This is answered through a case study that involved a mix of quantitative and qualitative approaches, using semi-structured interviews of 2 informants, including members of groundfish sectors, common pool members, former fishermen, and fish dealers. Although social research often involves a process of theory generation, in the case of the Northeast groundfish fishery, and catch share programs more generally, a number of theories have already emerged that are ripe for testing. It was hypothesized here that fishing under the control rules governing sectors has resulted in: more efficiency and flexibility for fishermen to decide where, when, and how to fish; greater social capital among fishermen; reduced bycatch; and improved economic performance, safety, and well-being.

The groundfish fishermen of New Hampshire revealed that the theorized benefits of catch share programs do not necessarily hold true. Of the six key aspects of fishing investigated here, only the benefits related to fishing practices, bycatch and safety aligned with what has occurred in this local fishery, but even some of those benefits have qualifiers. The informants who were sector members generally felt that fishing in a sector was more efficient and flexible than the former Days-At-Sea program had been, generally due to shifting catch limits from a trip basis to an annual one. This had allowed more concentration of effort during times with greater potential for profitability (e.g., fish availability, favorable markets). Reducing bycatch was an important goal of the informants, and the sector participants indicated that their level of bycatch had decreased, primarily through eliminating the trip limits and discards of legal-sized fish. Some informants went above and beyond regulations to avoid bycatch in recognition of the need to steward stocks for the future. However, some sector members identified new pressures to discard when unobserved, driven largely by the high lease costs of choke stocks. There were no major changes in safety, because the informants largely strive to be safe no matter the management program. However, removal of trip limits for sector participants created flexibility and less pressure to fish in unsafe conditions.

Theorized benefits for social capital, economic performance, and well-being did not hold true. Despite being a novel focal point for industry organization, informants felt that sectors have not been catalysts for social capital. Rather, sectors have been based on and built off of pre-existing social capital. In some cases, social capital was reduced as increased organizational responsibilities were seen as a burden and fishing became more competitive and secretive. Economic profitability and predictability had not been realized, though the concomitant decline in, and persistently low, catch limits for certain key species (e.g., cod, yellowtail flounder) vanquished any potential that catch shares had for the economic success of this fishery. The need to lease quota of constraining stocks to harvest the available fish in one’s own portfolio has been a substantial and new cost, with risky debt obligations, for several informants. Business predictability declined for a majority of informants. Catch shares has, however, transformed the business climate of the groundfish industry, with more focus on maximizing one’s utility. With declines in fishery participation, and dim potential for positive economic performance, the sense of well-being and future outlook for self and fishery had diminished since the advent of the catch share program. Job satisfaction decreased for most of the sector members, and a majority of all informants said that they would not advise a young person to enter fishing. The New Hampshire-based fishermen have, on the whole, not fared as well as could be assumed based on theory, exemplifying the consequences of catch shares, the potential for declining performance by those participants unable to adapt.

The North Sea Regional Advisory Council serves as a case study. Established during the 2002 Common Fisheries Policy, the North Sea Regional Advisory Council (NSRAC) offers stakeholder participation in the decision-making process. Its establishment was to some extent an experiment based on a leap of faith that better governance could help the ailing fisheries policy. A short analysis reveals the shortcomings of the previous fisheries policy, all of which root in the discrepancy between political motivation and legal objectives. The 'Tragedy of the Commons' suggests that democracy might indeed not be perfect for fisheries management. Past decision-making procedures in the European Community lent themselves to state competition and 'tragic' decision-making in the Council. In this situation, Regional Advisory Councils were hoped by some to provide self-regulation fora. EC/ EU constitutional law prevents this. The Common Fisheries Policy requires balancing of highly diverse interests. The NSRAC is not suited for such balancing, due to its (enshrined) industry majority. Nevertheless the NSRAC has already made valuable contributions and offers some potential for more. The double-bind between decision-makers and grass roots fishermen incentivises industry representatives in the NSRAC to propose conservation measures. They are less inclined to be hard-handed on the industry, though. NSRAC members stepped beyond 'stalling tactics' with regard to scientific assessments and proactively support them. In return, the decision-making system needs to acknowledge NSRAC commitment and provide sufficient funds.

Nell’ambito della Ricerca moderna si fa sempre più spesso uso di Modelli Matematici e Fisici per simulare il comportamento dell’Ambiente che ci circonda, la sua evoluzione nel breve e nel lungo periodo e, dove possibile, valutarne la risposta alle sempre più incisive e rapide sollecitazioni che l’Uomo esercita su di esso. Negli ultimi anni si è fatto più evidente il problema del cambiamento climatico in atto che sempre più spesso ha effetti devastanti per l’ambiente e soprattutto per la vita dell’uomo. L’effetto più rilevante che questo cambiamento sta avendo alle nostre latitudini e in, particolare, nel nostro Paese, è legato all’estremizzazione dei fenomeni atmosferici, per quanto riguarda le temperature, molto più calde o più fredde e le precipitazioni, che si fanno più intense, concentrandosi in eventi di pioggia sempre più violenti e di breve durata, contrapposti a periodi relativamente secchi. Le conseguenze più evidenti sono catastrofiche per la vita dell’uomo ma anche i fiumi ne stanno risentendo, modificando il loro regime idrologico. Anche il Mare sta risentendo di questi effetti, in particolare l’Adriatico che, essendo un bacino chiuso e di piccole dimensioni risulta fortemente condizionato dall’apporto dei fiumi afferenti, sia dal punto di vista idrodinamico che biologico. Acque più calde, differente apporto di sostanze nutrienti, interazione con le correnti di acqua dolce riversate in mare, hanno diretta conseguenza sulle attività di pesca, soprattutto dei piccoli pesci pelagici (Alici e Sardine) che sono le specie più abbondanti e redditizie in Adriatico (41% delle catture totali). Le grandi fluttuazioni annuali nella quantità di pesce pescato, il ciclo di vita breve che permette di stabilire una relazione quasi diretta tra le condizioni ambientali al momento della nascita e del reclutamento dei pesci e l’abbondanza della cattura, hanno spinto a chiedersi se fosse possibile utilizzare dei modelli fisici e biologici di previsione, insieme ad analisi di dati e parametri ambientali, per poter gestire meglio la risorsa ittica, cercando di stabilire se possibile, quali aree tutelare maggiormente per preservare la risorsa e come regolare lo sforzo di pesca, in relazione alle condizioni climatiche e idrodinamiche sperimentate nel corso dell’anno. Il punto di partenza della Ricerca è stato lo studio della letteratura riguardante la vita, la riproduzione e le condizioni ottimali per lo sviluppo e la crescita dei piccoli pesci pelagici per poter utilizzare al meglio il Modello, simulando condizioni il più vicine possibile alla realtà. In particolare si è scelto di concentrare l’attenzione sulle Alici (Engraulis encrasicolus). È stato utilizzato il Modello Lagrangiano, di tipo IBM (Indivual Based Model), Ichthyop, nella Versione 3.2, sviluppato da Philippe Verlay. Lo strumento è nato per studiare la dinamica dell’ictioplancton, in base alle condizioni fisiche (campi di velocità e correnti, temperatura, salinità) e biologiche (crescita, mortalità) che esso incontra dal momento in cui viene rilasciato l’uovo (deposizione, schiusa, movimento) fino al momento in cui la larva raggiunge una dimensione tale da essere considerata “reclutata”. Per ogni istante di “vita” dell’uovo rilasciato, il Modello fornisce la localizzazione (latitudine, longitudine e profondità), le condizioni ambientali in cui si trova (salinità e temperatura), lo stadio della larva e la sua dimensione. In base a studi di letteratura, si definiscono delle cosiddette “Aree di Rilascio”, corrispondenti alle zone dove notoriamente le Alici depongono le uova e si fa partire la simulazione che le trasporterà fintanto che saranno “passive” cioè in balia delle correnti ,perché non abbastanza grandi da nuotare contro. La legge di crescita che il Modello utilizza per le larve è dipendente dal tempo e dalla temperatura. Quando l’Alice raggiunge una dimensione tale da essere considerata, appunto, “reclutata”, il Modello smette di seguirla e la lascia in una zona detta “Area di Reclutamento”. A questo punto bisogna valutare se l’area in questione presenta le condizioni ambientali più adatte alla crescita della recluta, che in determinate condizioni non sopravviverebbe. Le variabili di tipo oceanografiche su cui si basa il Modello Ichtyop sono prese dagli output delle simulazioni del Modello ROMS (Regional Ocean Modeling System), disponibili presso il Dipartimento DiSVA, dell’Università Politecnica delle Marche. Sono state rilasciate 100000 particelle per ogni simulazione, una al giorno, a partire dal 1 marzo fino al 30 novembre, corrispondenti al periodo di deposizione delle uova per le Alici, dall’anno 2008 al 2013. A questo punto sono stati analizzati dati ottenuti dal Modello, scegliendo opportunamente, in base alle condizioni ambientali le aree più adatte al reclutamento, in base alle condizioni di salinità e di temperatura sperimentate dalle larve durante il tempo della simulazione e si è andato a vedere, zona per zona, quante delle uova rilasciate sono riuscite effettivamente e diventare reclute. Si è poi operato un confronto con i dati di portata del Po, per valutare se le piene improvvise avvenute durante i mesi della deposizione potessero avere influito in maniera positiva o negativa sulla quantità di uova reclutate. Infine si sono confrontati i dati di cattura reali di Alici, con i dati ottenuti dal Modello per valutare se ci fosse una corrispondenza tra l’abbondanza della cattura e l’abbondanza delle reclute, considerando che il pesce reclutato, sarà pescato circa due anni dopo. Dopo un’analisi di dati ottenuti da Modello, comparati a dati ambientali e dati reali i risultati sembrano essere positivi. Risultano più fruttuose, come aree di rilascio tutte quelle poste nel Nord Adriatico, sia nella parte orientale che occidentale. In particolare, indipendentemente dalle condizioni climatiche e dal periodo, l’area con il maggior successo di reclutamento è risultata essere la cosiddetta Area 40, situata a Nord della Penisola Istriana. Le altre aree che hanno costantemente dato risultati molto positivi sono tutte quelle a ridosso della penisola e di fronte alla Laguna di Venezia, fino alla foce del Po. Quindi il Modello sembra dare maggiore importanza alle aree occidentali e del Nord rispetto a tutte le altre, soprattutto per quanto riguarda le stagioni invernali, ma questo potrebbe essere dovuto alla natura stessa del Modello. Per quanto riguarda il reclutamento, le aree che sembrano essere più adatte, per posizione e per condizioni di temperatura e salinità risultano essere proprio quelle alla foce del Po. Mano a mano che si scende verso Sud, lungo la costa Italiana, le percentuali di reclutamento diminuiscono, però resta degna di nota, l’area del Golfo di Manfredonia, caratterizzata da temperature leggermente più elevate e da salinità più basse rispetto alle altre aree e che resta, nel Sud Adriatico, l’area con maggiore successo di reclutamento. Tra i fiumi dell’Alto Adriatico è stato analizzato in modo particolare solo il Po, perché nel modello si utilizza la sua portata in tempo reale. Le piene avvenute durante gli anni di simulazione non hanno inciso direttamente sulla quantità di uova reclutate, quanto piuttosto sulla destinazione. Sembrerebbe, da un’attenta osservazione che in corrispondenza di alcuni eventi, le uova deposte in alcune aree siano finite in aree differenti dalle solite. Purtroppo il basso numero di eventi di piena straordinari non permette di fare una buona statistica. L’anno meno adatto per il reclutamento è risultato essere il 2011, mentre il 2008 e il 2010 hanno dato discrete percentuali di reclutamento. Dal confronto con i dati di cattura, considerando i due anni di ritardo, sembrerebbe esserci una buona corrispondenza tra i dati da Modello e dati reali. L’utilizzo di Modelli matematici come sostegno ad una gestione sostenibile della pesca è possibile ma non immediato. Le variabili da prendere in considerazione sono troppe e si hanno a disposizione ancora troppi pochi anni di dati su modello per poter far una buona statistica. Tutto sommato, il modello Ichthyop sembra dare delle buone indicazioni riguardo alle condizioni generali più o meno buone per lo sviluppo e la crescita delle larve di pesce, ma i fattori che non vengono considerati, sono troppi, come ad esempio, la mortalità, i predatori (in particolare le meduse) che negli ultimi anni stanno subendo un vero e proprio boom demografico. Ichthyop considera uno stock parentale costante di anno in anno, mentre nella realtà lo stock è legato all’abbondanza della risorsa. Inoltre, per quanto riguarda i fiumi, sarebbe interessante avere dei dati in tempo reale o dei monitoraggi in corrispondenza degli eventi di piena, il parametro salinità è fondamentale, anche nel modello, per dare una stima più veritiera della crescita e del buon reclutamento delle larve. Un ulteriore risultato, non marginale in una gestione più attenta della risorsa ittica, è l’evidente importanza di alcune aree che sembrano particolarmente indicate per la deposizione delle uova. Sarebbe opportuno monitorare tali aree ed eventualmente creare politiche di gestione che siano sostenibili per tutelare le risorse ittiche.
The use of numerical models in order to simulate or to predict the behaviour of a particular aspect of the environment is increasing day by day. The purpose of a model is trying to reproduce a natural phenomenon, making it simple and giving the opportunity to study its evolution changing some parameters. Modelling the Sea and the dynamics of the stock of fishes is not really simple because there are many variables and it is not easy to get real data to validate the Model in use. Unfortunately the best way to get information about the Sea is the extrapolation from a validated Model because it is not possible to get on time data of a whole marine basin. For these reasons the science of modelling is always on development and thank to the improvement of the computational power of the machines can give every day better results. So the present work is based on the use of an IBM Model, Ichthyop in particular, in the Adriatic Sea to investigate how the hydrodynamic conditions of this area can affect the dynamics of the populations of the little pelagic fishes, from the spawning up to the moment when they become able to swim against the currents. The task is to check if this model gives reliable results and could be used for the stock assessment year by year, helpful for a more conscious and sustainable management of this fishery resource which is extremely variable and strictly connected with the environmental conditions experimented by every eggs since the first stage of life. The version of the Model used allows to set a big number of parameters, in order to better simulate the behaviour of eggs and larvae from the biological point of view, taking into account the characteristic typical of this species and which can make a big difference between a simple passive transport made by the currents and a more realistic movement dynamics experimented by every larva. The issue is that more specific is the behaviour simulated, bigger is the possible error due to the lack of accuracy in the set of data used as input. For this work it has been used a tool designed to study the effects of physical and biological factors on ichthyoplankton dynamics, but using as input time series of velocity, temperature and salinity fields archived from others oceanic models (in this case, ROMS). The accuracy of the results depends strictly from the accuracy of the input, coming from another model. For this reason, when a Model is used it is important to have the chance to compare the results with real or almost validated data. The Ichthyop Model has big potentiality and one of the purpose of this work was trying to apply the Model in the Adriatic basin with an established but simple strategy and check the reliability of the results. For this, the choices made for this set of simulations has not been too much specific. Through the setting of many different parameters, the effect of hydrodynamics and biological factors on the growth and development of the small pelagic fishes has been investigated. After a post processing analysis of the results it has been checked the reliability of the output data and through a comparison with environmental data, especially connected with the rainfalls and Po River discharge. The task of these comparisons was to find any relations between the success in recruitment of the little larvae and the effects of the changing distribution of the rainfalls, due to effect of the global warming on the regional scale. In fact, observations show less rainy days but more intensive phenomena, so that in spite of the more or less similar mean value of the rainfalls along the year, we have huge quantity of water concentrated in less time. The effects of this phenomena affects the lands but also the sea, especially a close and isolated basin as the Adriatic Sea. In fact it is heavily affected by the temperature, the wind and most of all, by the rivers discharge. Really, one of its distinguishing feature, is the presence of all these rivers bringing freshwaters that can change the main typical marine and oceanographic parameters, like salinity and temperature and then, transporting quite all the nutrients load. So, starting from the present work, it is possible to increase and improve the use of the Models, trying to find the optimal set of parameters to better simulate the real dynamics of the stock. Of course, it is necessary to focus the attention on the measurement of physical and environmental characteristic of the marine areas not only to have more data available to validate the results coming out from the Model but also to have the opportunity to estimate the environmental conditions of the recruitment areas which can guarantee the more suitable condition for the life of the recruited larvae. The hydrodynamic conditions coupled with the salinity and temperature strongly affected the results obtained, so going on and making more analysis it could be possible to get more realistic number of recruits and try to predict every year the abundance of the biomass of anchovies relative to the successive fishing season.

Visual surveys provide for non-invasive sampling of organisms and habitats in the marine environment. They are particularly important in deep-sea habitats which are vulnerable to damage caused by alternative destructive sampling devices such as bottom trawls. However, traditional visual survey platforms tend to have limited area coverage which is insufficient for mapping the vast expanses of the deep-sea, particularly for relatively sparsely distributed organisms such as fish. This thesis presents the development of a visual survey method capable of surveying large areas of the seabed in deep waters (> 200 m) using a towed video camera system. The area of seabed sampled was similar to that sampled by a bottom trawl, making the system effective for surveying fish. Anglerfish densities were found to be comparable to those determined by trawl surveys in adjacent areas. For other deep-sea fish, the two survey methods (towed camera and bottom trawl) provided different results which were explained by the behavioural reactions of different fish taxa to the respective gears. Fish that exhibited detectable avoidance behaviour to the towed video camera system (e.g. Chimaeridae) resulted in significantly lower density estimates than trawl estimates. On the other hand, skates and rays showed no reaction to the towed video camera system, and density estimates of these were an order of magnitude higher than the trawl. The towed video camera survey was also deployed to gather data on the cold-water coral Lophelia pertusa on the Rockall Bank. These data were used together with Species Distribution Modelling (SDM) to predict the distribution of Lophelia pertusa habitat. The current closed areas on the Rockall Bank cover sizeable areas of potential Lophelia pertusa habitat, however, based on the predictions further areas could be considered to ensure the continued protection of this species.

Allozyme frequencies and general protein patterns were surveyed among selected Texas marine fishes and shellfishes to illustrate the application of biochemical genetic techniques to stock and species identification in fisheries management.

A quota-based integrated commercial fishery owns fishing trawlers, processing plants, and fish quotas. Such a fishery must decide how to schedule trawlers for fishing and landing, how to schedule processing of products, how to schedule labour for processing, and how to plan inventory of raw materials and products. This problem is of great economic significance to New Zealand, whose economy depends to a large extent on the fishery industry. To assist the fishery manager, we develop a mixed integer linear program (MILP) for optimal scheduling of fishing trawlers, production planning (processing) and labour allocation for a quota-based integrated fishery of New Zealand. The model decides when and where each trawler should go for fishing, how much fish each trawler should land, and how much product to produce in each period. Since the fishery is a private farm, its main objective will be profit maximization (or cost minimization if its demand is on contract). The government manages the conservation of fish through the quota allocation. In this thesis the objective of the fishery model is to maximise the total profit. We demonstrate our model with examples based on data from a major New Zealand fishery. We investigate ways to manage the uncertainties involved in trawler scheduling and production planning of the fishery. To manage end-of-planning-horizon effects in the fishery, we develop a simple safety stock approach. We also analyse the workability of a rolling horizon approach to solve the longer planning horizon models and to deal with the end-of-planning horizon effects. We investigate the effect of initial and final position of the trawlers on the profit. We also investigated many different challenging data sets to observe the impact on the effectiveness of our IFPM. The second objective of this thesis is to develop an efficient solution procedure for the MILP, named integrated fishery planning model (IFPM). The IFPM consists of a fishing subproblem, a processing subproblem, and complicating side constraints. We have tried techniques including LP relaxation, Lagrangean relaxation (LR), Dantzig-Wolfe decomposition (DWD) and decomposition-based pricing (DBP). We develop a new DBP method to solve the IFPM. It gives excellent computation times. We also develop a decomposition-based O'Neill pricing (DBONP) method to improve the solution obtained from DBP procedure. It improves the DBP solutions but takes longer time to solve the IFPM. Finally, we develop a simple and efficient reduced cost-based pricing (RCBP) method. It takes less time to solve the IFPM and yields excellent results. The initial formulations for several planning horizons are solved using the AMPL modelling language and CPLEX with branch and bound. Relevant results and computational difficulties are reported.

Thesis (Ph. D.)--University of Oregon, 2004.
Typescript. Includes vita and abstract. Includes bibliographical references (leaves 247-261). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (M.S.)--University of Wisconsin--Stevens Point, 2009.
Submitted in partial fulfillment of the requirements of the degree Master of Science in Natural Resources (Fisheries), College of Natural Resources. Includes bibliographical references.