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1
van der Meulen, Dylan E., Chris T. Walsh, Matthew D. Taylor und Charles A. Gray. „Habitat requirements and spawning strategy of an estuarine-dependent fish, Percalates colonorum“. Marine and Freshwater Research 65, Nr. 3 (2014): 218. http://dx.doi.org/10.1071/mf13060.
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Determining the links among estuarine hydrography, habitat and spawning of estuarine-dependent fish is essential for understanding reproductive dynamics, recruitment processes and directing conservation efforts. Acoustic tracking was used to evaluate fine-scale spatial and temporal patterns in spawning activity of Percalates colonorum (estuary perch) within the Shoalhaven River, south-eastern Australia. Plankton tows were used to determine the timing of spawning events. Tagged P. colonorum exhibited movements restricted to areas of structurally complex large wooden debris and a concrete ferry landing. Egg counts confirmed that spawning events coincided with adult aggregations, whereas egg abundances peaked at night during the first 2 h of the run-out tide. We postulate that spawning and recruitment success of P. colonorum is attributable to its selective spawning habitats that are (1) structurally complex to provide refuge and protection from predation, as well as congregate prey items, (2) adjacent to deep water of high velocities to maximise egg dispersal and (3) in close proximity to river entrance to facilitate coastal dispersal of eggs and inter-estuarine connectivity of larvae.
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Overholtz, William J. „Harvesting Strategies and Fishing Mortality Reference Point Comparisons for the Northwest Atlantic Stock of Atlantic Mackerel (Scomber scombrus)“. Canadian Journal of Fisheries and Aquatic Sciences 50, Nr. 8 (01.08.1993): 1749–56. http://dx.doi.org/10.1139/f93-196.
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Previous research indicated that density dependence in population-level responses such as growth and predation mortality rate may play a major role in regulating the dynamics of the Northwest Atlantic stock of Atlantic mackerel (Scomber scombrus). Simulation studies, utilizing this compensatory model of the mackerel stock, suggest that expected yields and spawning stock sizes under conditions of constant harvest rate or constant catch would be quite disparate. Yields and spawning stock size would be less variable and slightly larger under a constant catch strategy for catches of mackerel up to approximately 200 000 t. However, a constant harvest rate strategy would provide higher long-term yields and a more stable spawning stock at catches greater than 200 000 t. A comparison of a constant catch policy with F0.1, F20, and Fmax fishing strategies (constant F) suggests that the Fmax and F20 strategies would cause a long-term decline in the spawning stock below the current minimum spawning stock target and provide highly variable yields. A constant catch strategy could produce nearly the same level of yield with considerably less variability and maintain a larger mean spawning stock biomass than the F0.1 strategy.
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MacCall, Alec D., Tessa B. Francis, André E. Punt, Margaret C. Siple, Derek R. Armitage, Jaclyn S. Cleary, Sherri C. Dressel et al. „A heuristic model of socially learned migration behaviour exhibits distinctive spatial and reproductive dynamics“. ICES Journal of Marine Science 76, Nr. 2 (12.07.2018): 598–608. http://dx.doi.org/10.1093/icesjms/fsy091.
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Abstract We explore a “Go With the Older Fish” (GWOF) mechanism of learned migration behaviour for exploited fish populations, where recruits learn a viable migration path by randomly joining a school of older fish. We develop a non-age-structured biomass model of spatially independent spawning sites with local density dependence, based on Pacific herring (Clupea pallasii). We compare a diffusion (DIFF) strategy, where recruits adopt spawning sites near their natal site without regard to older fish, with GWOF, where recruits adopt the same spawning sites, but in proportion to the abundance of adults using those sites. In both models, older individuals return to their previous spawning site. The GWOF model leads to higher spatial variance in biomass. As total mortality increases, the DIFF strategy results in an approximately proportional decrease in biomass among spawning sites, whereas the GWOF strategy results in abandonment of less productive sites and maintenance of high biomass at more productive sites. A DIFF strategy leads to dynamics comparable to non-spatially structured populations. While the aggregate response of the GWOF strategy is distorted, non-stationary and slow to equilibrate, with a production curve that is distinctly flattened and relatively unproductive. These results indicate that fishing will disproportionately affect populations with GWOF behaviour.
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Albers, J. L., und M. L. Wildhaber. „Reproductive strategy, spawning induction, spawning temperatures and early life history of captive sicklefin chubMacrhybopsis meeki“. Journal of Fish Biology 91, Nr. 1 (13.06.2017): 58–79. http://dx.doi.org/10.1111/jfb.13329.
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Rifi, Mouna, Gaël Le Pennec, Mohamed Ben Salem und Jamila Ben Souissi. „Reproductive strategy of the invasive cockle Fulvia fragilis in the Bay of Tunis (Tunisia)“. Journal of the Marine Biological Association of the United Kingdom 91, Nr. 7 (14.03.2011): 1465–75. http://dx.doi.org/10.1017/s0025315411000099.
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This study is the first work on the reproductive biology of lessepsian bivalve Fulvia fragilis. Monthly and bimonthly samplings were made in the period from April 2006 to October 2007, at the Bay of Tunis (northern Tunisia). From histological preparations of gonad, a gametogenic scale was drawn up based on eight stages: sexual rest; initiation of gametogenesis; advanced gametogenesis; ripe; partial spawning; advanced spawning; restoration; and spent. After examination of gonad preparations, F. fragilis appeared to be a simultaneous hermaphrodite species. Spawning was continuous all along the year, scarce in winter and with peaks during the rest of the year. The spawning peaks were positively correlated with the rise of the sea surface temperature and the nutrient availability. Furthermore, the presence of oocytes surrounded by spermatozoa in female and male follicles and in male gonoducts was observed. Self-fertilization may occur in this species. High summer mortalities probably due to the combination of vulnerability of the bivalve in response to the reproductive effort and high temperature stress were recorded. The F. fragilis reproduction strategy explains the success of its installation on the Tunisian coast.
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Melvin, Gary D., Robert L. Stephenson und Michael J. Power. „Oscillating reproductive strategies of herring in the western Atlantic in response to changing environmental conditions“. ICES Journal of Marine Science 66, Nr. 8 (23.06.2009): 1784–92. http://dx.doi.org/10.1093/icesjms/fsp173.
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Abstract Melvin, G. D., Stephenson, R. L., and Power, M. J. 2009. Oscillating reproductive strategies of herring in the western Atlantic in response to changing environmental conditions. – ICES Journal of Marine Science, 66: 1784–1792. Herring are broadly distributed in the western Atlantic, but reproductive activity is restricted to the central portion, from Cape Cod to northern Newfoundland. Spawning extends from early spring to late autumn. Two spawning types are recognized: spring spawners and autumn spawners. At the southern extreme, spawning occurs almost exclusively in autumn, whereas in the north, spring spawners prevail. Mid-range, both strategies are common, with spawning occurring throughout the entire season. We postulate that the temporal intra-stock dominance of spawning type is an adaptive reproductive strategy to changing environmental conditions. A conceptual model is presented to describe how reproductive success can oscillate between spawning strategies. In most years, environmental conditions appear to favour one type or the other, although strong year classes can co-occur when conditions are right. The recent change in environmental conditions, characterized by a general warming trend, favours autumn spawners and is consistent with our model. At the distributional extremes, stocks are restricted to a single spawning strategy, and broad-scale environmental changes can introduce large interannual variability and limit the reproductive and recovery potential of a stock. The dependence of a stock on a single spawning season may result in longer times to recover to target levels.
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Hall, D. L., R. Hilborn, M. Stocker und C. J. Walters. „Alternative Harvest Strategies for Pacific Herring (Clupea harengus pallasi)“. Canadian Journal of Fisheries and Aquatic Sciences 45, Nr. 5 (01.05.1988): 888–97. http://dx.doi.org/10.1139/f88-107.
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A simulated Pacific herring (Clupea harengus pallasi) population is used to evaluate alternative management strategies of constant escapement versus constant harvest rate for a roe herring fishery. The biological parameters of the model are derived from data on the Strait of Georgia herring stock. The management strategies are evaluated using three criteria: average catch, catch variance, and risk. The constant escapement strategy provides highest average catches, but at the expense of increased catch variance. The harvest rate strategy is favored for its reduced variance in catch and only a slight decrease in mean catch relative to the fixed escapement strategy. The analysis is extended to include the effects of persistent recruitment patterns. Stock–recruitment analysis suggests that recruitment deviations are autocorrelated. Correlated deviations may cause bias in regression estimates of stock–recruitment parameters (overestimation of stock productivity) and increase in variation of spawning stock biomass. The latter effect favors the constant escapement strategy, which fully uses persistent positive recruitment fluctuations. Mean catch is depressed for the harvest rate strategy, since the spawning biomass is less often located in the productive region of the stock–recruitment relationship. The model is used to evaluate the current management strategy for Strait of Georgia herring. The strategy of maintaining a minimum spawning biomass reserve combines the safety of the constant escapement strategy and the catch variance reducing features of the harvest rate strategy.
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Rodrigues, Marcelo, Manuel E. Garcí, Jesús S. Troncoso und Ángel Guerra. „Spawning strategy in Atlantic bobtail squid Sepiola atlantica (Cephalopoda: Sepiolidae)“. Helgoland Marine Research 65, Nr. 1 (06.04.2010): 43–49. http://dx.doi.org/10.1007/s10152-010-0199-y.
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Embke, Holly S., Patrick M. Kocovsky, Tatiana Garcia, Christine M. Mayer und Song S. Qian. „Modeling framework to estimate spawning and hatching locations of pelagically spawned eggs“. Canadian Journal of Fisheries and Aquatic Sciences 76, Nr. 4 (April 2019): 597–607. http://dx.doi.org/10.1139/cjfas-2018-0047.
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Identifying spawning and hatching locations is vital to controlling invasive fish and conserving imperiled fish, which can be difficult for pelagically spawning species with semi-buoyant eggs. In freshwater systems, this reproductive strategy is common among cyprinid species, such as Chinese carp species currently threatening the Great Lakes. Following the confirmation that one of these species, grass carp (Ctenopharyngodon idella), was spawning in a Great Lakes tributary, we developed a modeling framework to combine field data with hydraulic models to calculate the most probable spawning and hatching locations for collected eggs. Our results indicate that the estimated spawning location encompassed habitat consistent with spawning sites in grass carp’s native range. Additionally, all eggs were identified to have hatched in the river, increasing the likelihood of successful recruitment. This modeling framework can be used to estimate spawning and hatching locations for Chinese carp species, as well as all pelagic, riverine spawners. Spawning and hatching locations provide key information to researchers about the reproductive requirements of species and to agencies about how best to manage populations for control or restoration.
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Waddy, S. L., und D. E. Aiken. „Intermolt Insemination, an Alternative Mating Strategy for the American Lobster (Homarus americanus)“. Canadian Journal of Fisheries and Aquatic Sciences 47, Nr. 12 (01.12.1990): 2402–6. http://dx.doi.org/10.1139/f90-267.
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American lobster (Homarus americanus) have a dual mating strategy. Although most females mate when they are newly molted, mating can occur at any molt stage if necessary, in the laboratory, virtually all uninseminated preovigerous females mate prior to spawning. Male aggression is a major factor in the success of intermolt mating and males can discriminate between immature and mature females, and between inseminated and uninseminated females. Female receptivity is affected by both ovarian stage and the presence of stored sperm, but not by molt stage. Most females become unreceptive after insemination, but their receptivity returns once the supply of stored sperm is exhausted. Intermolt mating occurs in smaller lobster that for some reason did not mate at molt, and it is an important part of the reproductive strategy of larger lobster. Lobster s[Formula: see text] carapace length frequently spawn twice without molting and often fail to store sufficient sperm to fertilize consecutive spawnings. Intermolt mating ensures these females will produce fertile second broods.
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GRAU, A., F. SABORIDO-REY, E. PASTOR, M. PALMER, E. MASSUTÍ-PASCUAL, A. QUETGLAS, I. RIERA und B. MORALES-NIN. „Reproductive strategy of common dentex Dentex dentex: management implications“. Mediterranean Marine Science 17, Nr. 2 (29.07.2016): 552. http://dx.doi.org/10.12681/mms.1156.
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Common dentex Dentex dentex is an iconic endangered species in the Mediterranean where is a sought after target species for small-scale, recreational and spearfishing fisheries. The reproductive biology of D. dentex in the natural environment is poorly known; therefore the reproductive strategy of the species was assessed by combining reproductive traits with the growth characteristics (estimated from length-at-age data), the size/age of sexual maturity and the energetic dynamics. A total of 358 wild fish were sampled on Mallorca Island (W Mediterranean) from March 1996 to June 1999 with a 19 to 84.7 cm total length (LT) range. The sex ratio was skewed towards females (1.361) albeit the length composition was not different between sexes (p = 0.551). Three young immature individuals (< 28 cm LT, 0.8% individuals) were rudimentary hermaphrodites supporting the late gonochoristic species classification. The age composition determined from sagitta otolith interpretation ranged from 0 to 26 years (yr). Concerning growth, between sex differences in von Bertalanffy parameters were not relevant, even after accounting for potential between-year differences. The most noticeable difference was found for L∞ (64.7 cm for females versus 61.6 for males) but even in this case, the bayesian credibility interval of between-sex differences included zero. Maturity ogives at size and age showed that females achieved 50% maturity at 34.9 cm LT and 3.3 years, while males did at 33.8 cm LT and 2.5 years. The onset of gonad developing phase took place in December, while it progresses until April. The spawning peak was in April and May for both sexes. A generalized linear model showed that female size didn’t affect significantly the spawning season, whilst there was a strong seasonality in the spawning. Most of the evidences showed that fecundity is likely determinate, with an asynchronous oocyte development before spawning and a clear ovarian bimodal organization after the onset of spawning. Female weight explained 84% of the observed variance for fecundity. The gonadosomatic, hepatosomatic and condition indexes varied significantly with the reproductive season for females and only the gonadosomatic index for males. Storage in muscle seemed to be the primary source of energy for reproduction, although liver appeared to play a short-term role in egg production, suggesting a combination of capital and income breeding. The results indicate that the life history strategy of common dentex possess consist on maturing well before reaching maximum size, investing in growth after maturation, and therefore the reproductive effort is distributed through a longer lifespan and related with the size attained after maturation. At present no management measures are directed to D. dentex; given its life history strategy we suggest that a slot limit should be implemented, i.e. a minimum and a maximum landing size, with a minimum size of 35 cm. The upper threshold, to protect the higher reproductive potential of older and larger fish, should still be defined.
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Araújo, Francisco G., Aparecida A. Nascimento, Iracema D. Gomes, Armando Sales und Beatriz A. Chagas de Oliveira. „Gonadal development and reproductive period of the characin Astyanax aff. bimaculatus (Characiformes: Characidae) in a tropical reservoir in southeastern Brazil“. Zoologia 36 (30.10.2019): 1–14. http://dx.doi.org/10.3897/zoologia.36.e30610.
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The gonadal development of the characin Astyanax aff. bimaculatus from Funil Reservoir, an impoundment in the middle reaches of the Paraiba do Sul River in southeastern Brazil was analysed through histological, histochemical and histometric techniques, and the spawning season was determined. Unbalanced sex ratio was found, with females outnumbering and reaching larger sizes than males. The following stages of oogenic cell development were identified for females: primary growth, pre-vitellogenic (cortical alveolar) and vitellogenic. In males, the following stages were determined: spermatogonia primary and secondary, spermatocyte primary and secondary, spermatid and spermatozoa. The spawning occurs most of the year, peaking in January-February, as indicated by the gonadosomatic index. In the peak of the spawning period, the condition factor and hepatosomatic indices decreased suggesting use of stored body energy reserves during the reproduction. Spawning in batches, small-sized oocytes and a long reproductive season suggest that Astyanax aff. bimaculatus fits to an opportunist strategy. Such strategy may facilitate the use of a wide range of lentic and lotic body waters in the Neotropical region.
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Skaret, Georg, und Aril Slotte. „Herring submesoscale dynamics through a major spawning wave: duration, abundance fluctuation, distribution, and schooling“. ICES Journal of Marine Science 74, Nr. 3 (25.10.2016): 717–27. http://dx.doi.org/10.1093/icesjms/fsw180.
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In this study, a series of 17 repeated acoustic trawl surveys within a ca. 1500 km2 area covering the major spawning location for Norwegian spring-spawning herring (Clupea harengus) was conducted over a period of about 1 month. Local herring abundance increased from ca. 25 000 to 237 000 t, a significant proportion of the total spawning stock, in just 3 d and subsequently decreased to <30 000 t over the next 7 d. The abundance change was due to a single major spawning wave developing over the observation period, and an estimated 46 000 t of eggs and milt were deposited during the short time spent at the spawning ground. There was no difference in spawning activity between day and night, but herring were more associated with deep trenches and also generally stayed deeper in more dense schools during daylight than night-time. Schooling behaviour and distribution were also strongly state-dependent, and both school swimming depth and school height decreased as spawning progressed, as did the bottom depth where the schools were located. The massive herring spawning events seem to be low-risk adaptations to an environment where predators are abundant, with rapid spawning in huge aggregations as a strategy for predator swamping.
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Setyono, Dwi E. D. „REPRODUCTIVE ASPECTS OF THE TROPICAL ABALONE, HALIOTIS ASININA, FROM SOUTHERN LOMBOK WATERS, INDONESIA“. Marine Research in Indonesia 30 (11.05.2018): 1–14. http://dx.doi.org/10.14203/mri.v30i0.420.
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The main objective of this study was to determine reproductive strategy including major spawning season of tropical abalone (Haliotis asinina) from southern Lombok waters, Indonesia. Gonad bulk index, maturity stages and oocyte size frequency distribution were applied to document gonadal development and major spawning season. The results of this study show that H. asinina in southern Lombok waters displayed year-round spawning with a high proportion occurring in August - November, when gonad index dropped to a lower level and high proportion of partly spawned and/or spent ovaries occurred in the population. Gonad development and spawning in males and females occurred synchronously. The correlation between gonadal development and environmental factors are described and discussed.
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Gutmann Roberts, Catherine, und J. Robert Britton. „Spawning strategies in cypriniform fishes in a lowland river invaded by non-indigenous European barbel Barbus barbus“. Hydrobiologia 847, Nr. 19 (04.09.2020): 4031–47. http://dx.doi.org/10.1007/s10750-020-04394-9.
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Abstract Spawning strategies of lowland river fishes include single spawning, where reproduction generally occurs in early spring to provide 0+ fish with an extended growth season through the summer, but with a high risk of stochastic mortality events occurring, such as early summer floods. This risk can be reduced by multiple or protracted spawning strategies, where 0+ fish are produced over an extended period, often into mid-summer, but with the trade-off being a shorter growth season. The spawning strategies of cypriniform fish were explored in the River Teme, a spate river in Western England, which has non-indigenous European barbel Barbus barbus present. Sampling 0+ fish in spring and summer and across three spawning periods, B. barbus, chub Squalius cephalus and minnow Phoxinus phoxinus always revealed multiple spawning events, with 0+ fish of < 20 mm present in samples collected from June to August. Fish below 20 mm in August remained relatively small by the end of their growth season (October). For dace Leuciscus leuciscus, only single spawning events were evident, but with 0+ dace always being relatively large. Therefore, multiple spawning appears to be a common strategy that provides resilience in 0+ fish against stochastic mortality events in lowland rivers.
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Rodrigues, Karina A., Gustavo J. Macchi, Agueda Massa und María I. Militelli. „Seasonal analysis of condition, biochemical and bioenergetic indices of females of Brazilian flathead, Percophis brasiliensis“. Neotropical Ichthyology 11, Nr. 1 (März 2013): 153–62. http://dx.doi.org/10.1590/s1679-62252013000100018.
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Percophis brasiliensis is a demersal species that constitutes an important resource of Argentine coastal fisheries. Nevertheless, information about bioenergetic dynamic of reproduction has not been reported. Therefore, seasonal variations of condition factors, biochemical composition and energy density of different tissues were analyzed in order to determine the strategy of energy allocation during the reproductive cycle of this species. Condition indices (hepatosomatic and K) showed a seasonal pattern opposite to that observed for gonadosomatic index, which was characterized by higher values during the reproductive period (spring-summer), decreasing at the end of spawning. Biochemical composition of different tissues also showed a clearly seasonality associated to reproductive cycle. Analysis of energy density variation of liver indicates that P. brasiliensis accumulate reserves in winter before reproduction, which later decrease during the spawning season. In contrast, the energy density in muscle did not show significant differences among seasons, indicating that individuals could be also using an external source of energy during spawning. Therefore, it is possible that P. brasiliensis respond to an intermediate strategy of energy allocation, combining characteristics of both capital breeders (stores energy previous to the onset of reproductive activity) and income breeders (acquire energy by active feeding during spawning period).
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Zheng, J., M. C. Murphy und G. H. Kruse. „Analysis of harvest strategies for red king crab, Paralithodes camtschaticus, in Bristol Bay, Alaska“. Canadian Journal of Fisheries and Aquatic Sciences 54, Nr. 5 (01.05.1997): 1121–34. http://dx.doi.org/10.1139/f97-003.
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A modifiable harvest rate constrained by a minimum spawning abundance (threshold) is currently used to set the annual harvest level for Bristol Bay red king crab, Paralithodes camtschaticus. A length-based simulation model was constructed to evaluate effects of recruitment, natural mortality, and handling mortality on this harvest strategy. Evaluation criteria included mean yield, stability of yield, harvest opportunity, and stability of spawning stock. Optimal mature male harvest rates were strongly negatively related to handling mortality. For any given harvest rate, handling mortality is a key factor influencing optimal thresholds. The current harvest strategy produces a high mean yield and low variability in yield under low handling mortality scenarios, but the population is at high risk of collapse with a high handling mortality. Given uncertainties of recruitment, natural mortality, and handling mortality estimates, we recommend reducing mature male harvest rate from 20 to 15% and maximum legal male harvest rate cap from 60 to 50%. If handling mortality rate is greater than 30%, then we recommend increasing the threshold from 6600 to 11<|>000 metric tons of effective spawning biomass. Our recommended harvest strategy produces a mean yield similar to the current harvest strategy and safeguards against recruitment overfishing.
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Cavalheiro, Laísa W., und Clarice B. Fialho. „Reproductive strategy of a non-annual rivulid in a perennial wetland“. Iheringia. Série Zoologia 105, Nr. 3 (September 2015): 288–96. http://dx.doi.org/10.1590/1678-476620151053288296.
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ABSTRACT Atlantirivulus riograndensis (Costa & Lanés, 2009) is a fish registered to the basin of Patos lagoon and the adjacent coastal plains in southern states of Rio Grande do Sul and Santa Catarina, Brazil, found in shallow water courses with that have large quantities of aquatic vegetation and forest edges. The objective of this study was to investigate the reproductive strategy and tactics of this species including the sex ratio, the length at first maturity, spawning type, fecundity and the possible associations among reproduction and abiotic factors. Sampling of specimens occurred in perennial wetlands within the Banhado dos Pachecos wildlife refuge, in the city of Viamão, state of Rio Grande do Sul, Brazil, which is a conservation unit that belongs to an area of environmental protection in the Pampa Biome. The capture of 30 A. riograndensis specimens per month occurred from January to December of 2012. A total of 188 females and 172 males were captured and the total sex ratio was 1:1 in the sampled population. Sexual maturity of the species occurs after 13.59 and 11.92 mm (SL) for females and males, respectively. Both a multiple spawning and a long reproductive period (since August to March) were confirmed by the presence of post-ovulatory follicles that were observed through histological analysis and the values of the gonadosomatic index in females considered spawning capable. The average absolute fecundity of the species is of 19.33 (± 6.18) vitellogenic oocytes in mature ovaries. No significant relationship was found between mean GSI and the abiotic data. Reproductive tactics presented by A. riograndensis indicate a species with an opportunistic reproductive strategy, following the pattern of other species of the Rivulidae family.
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Machaieie, Sidonio, und Isabel M. Silva. „Spawning aggregations of fish in Cabo Delgado, Northern Mozambique: An interview-based survey of artisanal fishers“. Western Indian Ocean Journal of Marine Science 19, Nr. 1 (29.10.2020): 33–43. http://dx.doi.org/10.4314/wiojms.v19i1.3.
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Seasonal aggregations at specific sites are common among some fish species. Experienced fishermen know where and when these aggregations happen, often targeting these spawning sites to increase their catch. This strategy can further contribute to endangering the survival of these species, especially for those already threatened by other forms of pressure. This study contributes knowledge to the spawning aggregation of fish in the north of Mozambique following survey work conducted around Cabo Delgado Province in six coastal villages in 2016, 2017 and 2018. The objectives of the study were 1) to identify the species and sites of spawning aggregation and 2) to determine the timing of spawning aggregations. Data collection consisted of interviews targeting the most experienced fishermen to obtain information on these subjects. The results indicate that out of 124 fishermen interviewed, 59% had knowledge of spawning aggregations. The information collected from fisher interviews revealed that there are at least six spawning locations and at least eight species aggregate to spawn (Leptoscarus vaigensis, Lethrinus harak, Lethrinus nebulosus, Lethrinus obsoletus, Lethrinus olivaceus, Plectorhinchus gaterinus, Plectorhinchus schotaf, Siganus sutor). Only Siganus sutor was reported to spawn in at least one of the fishing areas used by every village. The timing of spawning aggregations most reported by fishermen was during the Kusi (South) monsoon period.
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Stewart, John, Anne-Marie Hegarty, Caitlin Young und Ashley M. Fowler. „Sex-specific differences in growth, mortality and migration support population resilience in the heavily exploited migratory marine teleost Mugil cephalus (Linnaeus 1758)“. Marine and Freshwater Research 69, Nr. 3 (2018): 385. http://dx.doi.org/10.1071/mf17135.
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Understanding mechanisms supporting the resilience of exploited fish populations is fundamental to sustainable management. Herein we identify sex-specific differences in life history traits that confer resilience in the heavily exploited population of Mugil cephalus along eastern Australia. M. cephalus in this region emigrate from estuaries and undergo an annual northerly spawning migration that is dominated by males. Males mature, on average, at younger ages than females and were most abundant in the spawning migration at age-4, whereas females were most abundant at age-5. Females grew significantly faster and larger than males, with both sexes being aged up to 14 years. These sex-specific differences relate directly to the population stability of M. cephalus under the reproductive strategy of a spawning migration. Males participate in the spawning migration at younger ages and in greater numbers than females to ensure a sufficient number of males for successful spawning. Females partition more energy to growth than males, maturing and participating in the spawning migration at older ages and larger sizes. The larger body size of females is related to increased fecundity, increased survivorship and more efficient swimming ability. These traits, combined with population strategies of both delayed and skipped spawning, convey substantial resilience.
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van Damme, Cindy J. G., Anders Thorsen, Merete Fonn, Paula Alvarez, Dolores Garabana, Brendan O'Hea, José R. Perez und Mark Dickey-Collas. „Fecundity regulation in horse mackerel“. ICES Journal of Marine Science 71, Nr. 3 (18.10.2013): 546–58. http://dx.doi.org/10.1093/icesjms/fst156.
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Abstract Egg production methods have been used successfully in the provision of advice for fisheries management. These methods need accurate and unbiased estimates of fecundity. We explore the reproductive strategy of horse mackerel and estimation of fecundity. Fecundity and fecundity regulation in relation to condition was investigated over a number of years. Fulton's K, lipid content, and hepatosomatic index increased after the start of spawning, though decreased again at the end of spawning. The increase in the gonadosomatic index, fecundity, and body condition after the onset of spawning suggests that horse mackerel utilizes food resources during the spawning season and might be an income breeder. However, the decline in K and lipid before the spawning season suggests that the first batch of oocytes is developed on stored energy. Fecundity varied between years and within a spawning season. Over latitude, variations in fecundity were small. K and lipid content are not reliable indices as proxy for fecundity. Batch fecundity appears to be heterogeneous across the spawning season but homogeneous across latitude. The homogeneity of batch fecundity over latitude could indicate that the daily egg production method is an appropriate approach for estimating the abundance of a wide ranging species, as horse mackerel.
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Kuipers, Matthew R., Gretta T. Pecl und Natalie A. Moltschaniwskyj. „Batch or trickle: understanding the multiple spawning strategy of southern calamary, Sepioteuthis australis (Mollusca : Cephalopoda)“. Marine and Freshwater Research 59, Nr. 11 (2008): 987. http://dx.doi.org/10.1071/mf07200.
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Many cephalopods are ‘multiple spawners’; however, we know little about the timing and dynamics of egg production. This has implications for the allocation of energy to reproduction, lifetime fecundity and subsequent recruitment. The current study aimed to determine if Sepioteuthis australis (Quoy and Gaimard, 1832), which spawns multiple times, produces mature oocytes for deposition in a continuous trickle or in larger discrete batches. Throughout a spawning season, developmental stages were assigned to the ovaries of each female by combining macroscopic and histological analyses of the oocytes. Half of the females (46%) showed a significant peak in oocytes at one of the maturation stages, indicating that females were developing eggs in batches. It was hypothesised that the remaining females were also batch spawning, given that the oviduct weights of the remaining females (54%) were high and the other measured biological characteristics were similar to those of the females showing a peak in oocyte stage. Average batch fecundity declined over the 3-month spawning season, but total egg numbers in the ovary increased, suggesting that females might have deposited small batches more often during December. As reproduction requires large allocations of energy, understanding how females distribute reproductive effort throughout their lives is crucial to understanding the behaviour of populations, individuals and their offspring.
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Hidayat, Thomas, Endah Febrianti und Yoke Hani Restiangsih. „POLA DAN MUSIM PEMIJAHAN IKAN TONGKOL KOMO (Euthynnus affinis Cantor, 1850) DI LAUT JAWA“. BAWAL Widya Riset Perikanan Tangkap 8, Nr. 2 (13.01.2017): 101. http://dx.doi.org/10.15578/bawal.8.2.2016.101-108.
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Ikan tongkol komo (Euthynnus affinis, Cantor 1850) merupakan salah satu jenis kelompok ikan pelagis besar yang banyak didaratkan oleh armada jarring insang dan pukat cincin di Tegal. Tersedianya data dan informasi tentang pola dan musim pemijahan merupakan bagian dari pengetahuan yang diperlukan untuk mengetahui status sumberdaya bagi upaya pengelolaanya. Penelitian ini ditujukan untuk mendapatkan pola dan musim pemijahan ikan tongkol komo di Laut Jawa khususnya di pantai Tegal dan sekitarnya. Penelitian dilakukan pada bulan Februari-Desember 2012 di tempat pendaratan ikan kota Tegal, Jawa Tengah. Pendugaan pola pemijahan berdasarkan pengamatan sebaran frekuensi diameter telur sedangkan pendugaan musim pemijahan menggunakan pendekatan Indeks Kematangan Gonad (IKG) atau Gonado somatic index (GSI) bulanan. Analisis data oseanografi khususnya suhu permukaan laut (SPL) dan konsentrasi klorofil-a berdasarkan citra satelit Aqua Modis digunakan sebagai data dukung musim pemijahan. Hasil penelitian menunjukkan pola pemijahan tongkol komo di Laut Jawa memiliki strategi reproduksi beberapa kali memijah (partial spawner). Fekunditas berkisar antara 225.760-2.601500 telur. Musim pemijahan terjadi pada Juni-Agustus dimana konsentrasi klorofil-a tinggi.Kawakawa (Euthynnus affinis, Cantor 1850) is one of large pelagic species group caught by drift gill nets and purse seine fisheries in the Java Sea. The information of spawning characteristics is crucial for fisheries management. This research aims to determine the spawning strategy of kawakawa in the Java Sea mainly in Tegal and adjacent waters. Observation has been conducted during February-December 2012 in Tegal, Central Java. The estimation the spawning season determined by using Gonad somatic index (GSI) and investigated with profiling oceanographic data on sea surface temperature (SST) and concentration of chlorophyll-a derived from Aqua Modis satellite imagery. The results showed the reproductive strategy of kawakawa in the Java Sea is partial spawner. Fecundity ranged between 225,760-2,601,500 eggs and the spawning season occurs in June-August where concentrations of chlorophyll-a high.
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Kaemingk, Mark A., Kristopher J. Stahr, Jeffrey C. Jolley, Richard S. Holland und David W. Willis. „Evidence for bluegill spawning plasticity obtained by disentangling complex factors related to recruitment“. Canadian Journal of Fisheries and Aquatic Sciences 71, Nr. 1 (Januar 2014): 93–105. http://dx.doi.org/10.1139/cjfas-2013-0282.
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Fishes can exhibit many forms of plasticity to maximize fitness. However, limited information exists on the ability of freshwater fish to adjust spawning behavior and characteristics (e.g., timing, duration, magnitude of spawning events) to minimize mortality of recruits and ultimately maximize fitness. We wanted to test the life history hypothesis for bluegill (Lepomis macrochirus) (i.e., opportunistic strategy) utilizing existing literature and results from our study to further evaluate the potential for spawning plasticity in this species. Our objective was to identify bluegill recruitment bottlenecks (i.e., periods of high mortality) and factors associated with these events in a single lake during 7 consecutive years. Bluegills exhibited shorter spawning durations and fewer spawning pulses (i.e., peaks in larval production) compared with bluegill in previous studies. Late-hatched (compared with early-hatched) bluegills consistently contributed the most to the fall juvenile population; these recruitment patterns were primarily attributed to biotic drivers. Our study suggests that bluegill could exhibit spawning plasticity and extends our current understanding of adaptations that are potentially capable of increasing fitness for a freshwater fish species under a wide range of environmental conditions and uncertainty.
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Penton, Paulette M., Craig T. McFarlane, Erin K. Spice, Margaret F. Docker und Gail K. Davoren. „Lack of genetic divergence in capelin (Mallotus villosus) spawning at beach versus subtidal habitats in coastal embayments of Newfoundland“. Canadian Journal of Zoology 92, Nr. 5 (Mai 2014): 377–82. http://dx.doi.org/10.1139/cjz-2013-0261.
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Capelin (Mallotus villosus (Müller, 1776)), a focal forage fish in the north Atlantic, spawn on both beach and demersal (deep-water) sites throughout their circumpolar distribution. Although these habitats rarely occur in close proximity, demersal spawning sites within 4 km of beach spawning sites (subtidal) have recently been discovered in two coastal embayments in Newfoundland, Canada. The physical environment differs considerably between beach and subtidal spawning sites, creating the potential for local adaptation and genetic divergence of capelin from the two habitats, but this has never been investigated on a fine spatial scale. We use eight microsatellite loci to test for genetic divergence between capelin spawning at beach and subtidal sites within these two coastal regions in Newfoundland. We found no genetic differentiation between fish spawning at beach and subtidal sites or between the two regions. The results from this fine-scale study are in agreement with the lack of habitat-based structure reported in other studies examining beach and demersal sites separated by a larger geographic area. We suggest that instead of showing site fidelity and local adaptation, the facultative use of alternate spawning habitats may be a more successful strategy in an unpredictable environment.
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Newton, GM. „Estuarine Ichthyoplankton Ecology in Relation to Hydrology and Zooplankton Dynamics in salt-wedge Estuary“. Marine and Freshwater Research 47, Nr. 2 (1996): 99. http://dx.doi.org/10.1071/mf9960099.
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The ichthyoplankton assemblage of the Hopkins River estuary, Victoria, was dominated by estuarine taxa that included demersal (goby, gudgeon) and pelagic (black bream, estuary perch, anchovy) species. The two seasonal peaks in fish larvae abundance were related to (1) the spring/summer zooplankton increase that occurred after flooding of the estuary and was comprised predominantly of copepod nauplii, thereby providing a good prey field for very young fish larvae, and (2) the autumn zooplankton maxima, which would provide a wide selection of copepod stages and meroplankton and promote dietary partitioning and flexibility among older larval stages. The two peaks in fish larvae abundance occurred well before and well after the attainment of maximum water temperature in the estuary. Goby, gudgeon, estuary perch and anchovy larvae were in the plankton over an extended period coinciding with the more stable conditions of salt-wedge presence and maximum zooplankton densities. The spawning of black bream and anchovies in the estuary was clearly related to physical conditions, such as salinity and water temperature, and habitat-although spawning of both species also occurred at times of high concentrations of potential prey organisms for their larvae. Adults of all the above fish species appear to have evolved spawning strategies that are adapted to the average hydrological and biological conditions in the estuary that would lead to the enhanced survival of their larvae. With the exception of the black bream, it appears that a ubiquitous and prolonged rather than a synchronous and confined spawning strategy is more widely used by estuarine-spawning fishes in the Hopkins River estuary. This type of spawning strategy, combined with the generally high density of food available to fish larvae in estuaries, suggests that the match-mismatch hypothesis of Cushing may be less relevant in the estuarine than in the marine environment.
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Folkvord, Arild, Christian Jørgensen, Knut Korsbrekke, Richard D. M. Nash, Trygve Nilsen und Jon Egil Skjæraasen. „Trade-offs between growth and reproduction in wild Atlantic cod“. Canadian Journal of Fisheries and Aquatic Sciences 71, Nr. 7 (Juli 2014): 1106–12. http://dx.doi.org/10.1139/cjfas-2013-0600.
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Animals partition and trade off their resources between competing needs such as growth, maintenance, and reproduction. Over a lifetime, allocation strategies should result in distinct trajectories for growth, survival, and reproduction, but such longitudinal individual data are difficult to reconstruct for wild animals and especially marine fish. We were able to reconstruct two of these trajectories in wild-caught Northeast Arctic cod (Gadus morhua) females: size-at-age was back-calculated from otolith growth increments, and recent spawning history was reconstructed from postovulatory follicles and present oocyte development. Our findings indicate distinct trade-offs between length growth and reproduction. Fish that sexually matured early had attained a larger size at age 3 than immatures, but onset of reproduction caused slower growth compared with immatures. We found that 6- and 7-year-old females skipping spawning grew significantly more in the year of missed spawning than females spawning for the second consecutive year. The latter tentatively supports the hypothesis that skipped spawning may occur as an adaptive life-history strategy, given the potential future fecundity gain with increased size.
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Li, Yang, James R. Bence und Travis O. Brenden. „Can spawning origin information of catch or a recruitment penalty improve assessment and fishery management performance for a spatially structured stock assessment model?“ Canadian Journal of Fisheries and Aquatic Sciences 75, Nr. 12 (Dezember 2018): 2136–48. http://dx.doi.org/10.1139/cjfas-2017-0523.
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We used simulations based on lake whitefish (Coregonus clupeaformis) populations to explore the benefits of using spawning origin information for parsing catch to spawning populations in stock assessments for intermixed fisheries exhibiting an overlapping movement strategy. We compared this origin-informed assessment model with a standard assessment model that did not parse catch. We additionally evaluated the influence of including annual recruitment penalties. For standard assessment models, spawning stock biomass estimates could be unstable and biased (sometimes by more than 50%), depending upon population mixing and productivity, and in some cases estimated near average zero recruitment in the terminal year. Incorporating information on population-specific harvest age composition improved spawning stock biomass estimation (e.g., by sometimes essentially removing 50% biases and improving accuracy). Assessments with recruitment penalties produced less biased terminal recruitment estimates (sometimes a 100% bias was removed). Under status quo target mortality rates, improvements in assessments did not necessarily translate to improved fishery management performance (e.g., avoiding depletion of spawning biomass), but such improvements, and overall better performance, were seen at lower target mortality rates.
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Berejikian, Barry A., Thom Johnson, Richard S. Endicott und Joy Lee-Waltermire. „Increases in steelhead (Oncorhynchus mykiss) redd abundance resulting from two conservation hatchery strategies in the Hamma Hamma River, Washington“. Canadian Journal of Fisheries and Aquatic Sciences 65, Nr. 4 (01.04.2008): 754–64. http://dx.doi.org/10.1139/f08-014.
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Conservation hatcheries for anadromous salmonids that aim to increase production and minimizing genetic, ecological, and demographic risks have not been experimentally tested for their ability to increase number of adults spawning in the natural environment. The conservation hatchery program for steelhead (i.e., sea-run rainbow trout, Oncorhynchus mykiss) evaluated in this study caused an increase in the number of redds in the supplemented Hamma Hamma River compared with the presupplementation period. Three control populations (nonsupplemented) either remained stable or declined over the same period. The increase in redds from hatchery-produced spawners did not reduce the redd production from natural-origin spawners. The strategy of rearing and releasing adult steelhead accounted for the greatest proportion of redd abundance increases. Environmentally induced differences in spawn timing between the adult release group and anadromous adults of hatchery and natural origin may explain why the adult release group and anadromous adults assortatively formed pairing combinations on the spawning grounds. Although captively reared adults produced the majority of redds in years they were released in substantial numbers, uncertainty regarding the relative reproductive success of this strategy suggests caution in recommending one strategy over the other. A demographic boost to the naturally spawning population was effected while managing to minimize negative ecological consequences.
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Jiang, Lei, Xin-Ming Lei, Sheng Liu und Hui Huang. „Fused embryos and pre-metamorphic conjoined larvae in a broadcast spawning reef coral“. F1000Research 4 (13.02.2015): 44. http://dx.doi.org/10.12688/f1000research.6136.1.
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Fusion of embryos or larvae prior to metamorphosis is rarely known to date in colonial marine organisms. Here, we observed for the first time the embryos of the broadcast spawning coral Platygyra daedalea could fuse during blastulation and further develop into conjoined larvae, and the settlement of conjoined larvae immediately resulted in inborn juvenile colonies. Considering the frequent record of synchronous spawning events and spawn slicks in the field, fusion of embryos might be a naturally occurring phenomenon, and act as an adaptive strategy to form pre-metamorphic united larvae and larger recruits, thereby promoting early survival. However, whether fusion of embryos is common in spawning corals and its implications deserve further investigation.
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Williams, Alan, Deborah Osterhage, Franziska Althaus, Timothy Ryan, Mark Green und John Pogonoski. „A Very Large Spawning Aggregation of a Deep-Sea Eel: Magnitude and Status“. Journal of Marine Science and Engineering 9, Nr. 7 (30.06.2021): 723. http://dx.doi.org/10.3390/jmse9070723.
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Multiple lines of evidence substantiate the existence of a very large aggregation of the basketwork eel, Diastobranchus capensis, on the small (3 km2) Patience Seamount off southeast Australia. The aggregation appears to be present year-round, but largest in the austral autumn when composed of spawning eels. Twenty eels caught in April 2015 (14 female, 6 male) were all in advanced stages of spawning condition. The eel’s abundance in the aggregation was very high as measured at seamount, local and regional scales. Hydroacoustic measurement of the spawning aggregation’s dimensions (~100 × 1000 m) and conservative counts of 100 s of eels along camera transects of ~1000–2000 m length indicate 10,000 s individual eels may have been present. The absence of other known spawning locations indicates the Patience Seamount is a regional-scale spatial anchor for spawning. The aggregation was protected in a marine park in 2007 following a decades-long impact from bottom trawling, indicating that the population can be expected to stabilise and recover. Monitoring the aggregation’s status, and validating seasonal spawning, provide important opportunities to examine conservation-led recovery in the deep sea as part of Australia’s new national strategy of Monitoring, Evaluation, Reporting and Improvement (MERI) for conservation values within marine parks.
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Kruse, Gordon H., Jie Zheng und Diana L. Stram. „Recovery of the Bristol Bay stock of red king crabs under a rebuilding plan“. ICES Journal of Marine Science 67, Nr. 9 (07.09.2010): 1866–74. http://dx.doi.org/10.1093/icesjms/fsq136.
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Abstract Kruse, G. H., Zheng, J., and Stram, D. L. 2010. Recovery of the Bristol Bay stock of red king crabs under a rebuilding plan. – ICES Journal of Marine Science, 67: 1866–1874. After peak landings in 1980, the red king crab fishery in Bristol Bay (Alaska) was closed in 1983 because of stock collapse. In the following decade, small commercial harvests and additional fishery closures (1994 and 1995) associated with depressed stock status prompted a reappraisal of the management strategy. A length-based population model was developed, which provided an improved stock assessment for setting annual catch quota. A management strategy evaluation revealed that a harvest strategy, which included a stair-stepped harvest rate of 10–15% of mature males and a threshold for effective spawning biomass below which no fishing is permitted, provides for relatively high long-term yield, greater stability in yield, fewer fishery closures, and higher effective spawning biomass. This strategy was adopted in 1996, in addition to crab bycatch caps and closed areas, to protect sensitive crab habitats implemented in the management of the groundfish trawl fishery. Since then, abundance of legal-sized males increased by 58%, that of mature males doubled, and mature female abundance and effective spawning biomass tripled through 2008. The stock has been considered rebuilt since 2003. Subsequently, a sharp reduction in fishing capacity improved profitability of the fishery, after implementation of an individual fishing quota programme in 2005.
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Huse, Geir. „Sex-specific life history strategies in capelin (Mallotus villosus)?“ Canadian Journal of Fisheries and Aquatic Sciences 55, Nr. 3 (01.03.1998): 631–38. http://dx.doi.org/10.1139/f97-275.
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The life history of capelin (Mallotus villosus) is presently suggested to be sex specific: while males follow a semelparous batch-spawning strategy, females are iteroparous. This hypothesis is based on predictions from a life history simulation model of Barents Sea capelin that shows that iteroparity is more profitable than semelparity for females, but for males, semelparity with several matings with females may be as profitable as iteroparity. These predictions are supported by (i) reports of males mating with several females during a spawning season, (ii) males having a lower gonadosomatic index than females and instead spending their energy on mating and somatic growth, and (iii) an observed higher mortality for males after spawning. The Darwinian fitness of female capelin is limited by the amount of eggs they can carry, and offspring production may only be increased by undertaking several spawning seasons with yearly intervals. Added together, these indices suggest that male and female capelin follow different life history strategies.
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Hamaguchi, Y. „Modeling spawning strategy for sex change under social control in haremic angelfishes“. Behavioral Ecology 13, Nr. 1 (01.01.2002): 75–82. http://dx.doi.org/10.1093/beheco/13.1.75.
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Nigmatullin, Chingis M., und Unai Markaida. „Oocyte development, fecundity and spawning strategy of large sized jumbo squid Dosidicus gigas (Oegopsida: Ommastrephinae)“. Journal of the Marine Biological Association of the United Kingdom 89, Nr. 4 (17.11.2008): 789–801. http://dx.doi.org/10.1017/s0025315408002853.
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Ovaries of 39 large jumbo squid Dosidicus gigas (415–875 mm mantle length (ML)) of different stages of maturity from the Gulf of California and Nicaragua were analysed. Oocyte development is asynchronous during female ontogenesis, with predominance (>85–90%) of small protoplasmic oocytes 0.1–0.2 mm in diameter for all stages of female maturity. Potential fecundity (PF) is determined at late immature stage II with average values around 18–21 million oocytes. The maximum PF estimated, 32 million oocytes, is so far the largest recorded for any cephalopod. PF is closely related to female size. Nicaraguan females, of smaller size (415–720 mm ML), show lower fecundity (5–15 million oocytes). Eggs were analysed in oviducts of mature females (540–875 mm ML), 7 from the Gulf of California and three females from Nicaragua. Eggs measured 0.9 × 1.1 mm in diameter and weighed 0.45 mg on average. The oviducts of the largest female (875 mm ML) held 1.2 million eggs, representing 4.6% of PF and no more than 14% of all vitelline oocyte stock of that squid. Variability in oviduct filling is very high and unrelated to ovary weight. However, a strong correlation was found between oviduct fullness and nidamental glands development. These observations suggest that spawning is extended and intermittent. A female spawns no less than half of the initial PF, and the minimal number of spawning activity events (egg batches) is roughly estimated at 8–12. During this terminal spawning stage females continue actively feeding and grow between egg-mass laying periods.
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Chaput, G., J. Allard, F. Caron, J. B. Dempson, C. C. Mullins und M. F. O'Connell. „River-specific target spawning requirements for Atlantic salmon (Salmo salar) based on a generalized smolt production model“. Canadian Journal of Fisheries and Aquatic Sciences 55, Nr. 1 (01.01.1998): 246–61. http://dx.doi.org/10.1139/f97-252.
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Atlantic salmon (Salmo salar) management in eastern Canada is based on ensuring that there is sufficient spawning escapement to meet an egg deposition target that maximizes the production of smolts. Using available egg deposition to smolt production data, we show that the present strategy of basing spawning targets on the presence-absence of lacustrine habitat for the rearing of juvenile salmon is a valid approach. We further show that a general smolt production model that accounts for this difference in available habitat when combined with the biological characteristics of the recruiting adults provides river-specific spawning targets. Targets corresponding to maximum yield tend to be less than half the target values currently used. A target representing the egg deposition for 90% of maximum yield serves as an example of a risk-averse strategy. The lower target values relative to those currently used are in large part determined by low sea survivals. The targets that we derived for four example rivers would correspond to the currently used target egg depositions if the long-term sea survivals were 2-3 times those observed in the last 6 years.
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ALNAHEDH, MISHARI, und SALEM ALSANOUSI. „ENTREPRENEURIAL SPAWNING IN THE INFORMAL ECONOMY“. Journal of Developmental Entrepreneurship 25, Nr. 02 (Juni 2020): 2050008. http://dx.doi.org/10.1142/s1084946720500089.
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What is the career background of formal and informal entrepreneurs and does this influence their formalization decision? We employ the theory of planned behavior, social identity theory and embedded career capital framework to develop hypotheses on how the new venture formalization decision is dependent on the entrepreneur’s career history. We find that employment in a family business and in the private sector is related positively to founding a formal new venture. Furthermore, our results show that a career in the same industry as the new venture increases the likelihood of formalizing the venture. These findings emphasize the role of the career background in the entrepreneur’s formalization decision through building embedded-career capital, influencing the social identity and determining the attitude toward starting a formal versus informal new venture.
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Ohshimo, Seiji, Takuya Sato, Yumi Okochi, Sho Tanaka, Taiki Ishihara, Hiroshi Ashida und Nobuaki Suzuki. „Evidence of spawning among Pacific bluefin tuna, Thunnus orientalis, in the Kuroshio and Kuroshio–Oyashio transition area“. Aquatic Living Resources 31 (2018): 33. http://dx.doi.org/10.1051/alr/2018022.
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Reproductive characteristics are one of the key factors for understanding population dynamics in fishes. This study describes the spawning habitat of Pacific bluefin tuna (Thunnus orientalis) in the Kuroshio and the Kuroshio–Oyashio transition area. A total of 551 adult fish (fork length > 120 cm) were collected during 1994–2007 (except in 2001 and 2003) and 2016. Based on a histological analysis of the gonads, we concluded that actively spawning females were mainly present in late May to early July. Relative batch fecundity was significantly lower than that reported in the Sea of Japan but was similar to that observed in the Nansei area. Whereas most spawning adults in the Sea of Japan are 3–6 years old and those in the Nansei area are over 10 years old, the majority of the specimens in this study ranged from 160 to 180 cm in length, which corresponds to 6–8 years of age. Our results indicate that Pacific bluefin tuna spawn in the study area and provide important data for understanding the spatiotemporal differences in spawning strategy with growth in this species.
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Smukall, Matthew J., Amy Shaw und Donald C. Behringer. „Effect of simulated catch-and-release angling on postrelease mortality and egg viability in sockeye salmon (Oncorhynchus nerka)“. Canadian Journal of Fisheries and Aquatic Sciences 76, Nr. 12 (Dezember 2019): 2390–95. http://dx.doi.org/10.1139/cjfas-2018-0426.
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Catch-and-release angling of salmonids is a widely implemented fisheries management strategy intended to provide recreational fishing opportunities while limiting harvest. Previous research has indicated mortality may be low, but the extent of sublethal impacts, including inability to reach spawning grounds or decreased spawning effectiveness, is relatively under-studied. Sockeye salmon (Oncorhynchus nerka) were subjected to simulated catch-and-release events, with a subset also enduring air exposure, to determine how physiological stress influences the ability of sockeye salmon to reach spawning grounds and the viability of eggs produced. Short-term postrelease mortality was highest for fish that were subjected to air exposure, but once recovered, neither simulated catch-and-release nor air exposure had a major impact on their ability to reach spawning grounds. Egg viability was similar between treatment groups, indicating physiological stress associated with the trials did not have a negative impact on reproduction. These results suggest that handling, especially air exposure, is the primary concern and substantially impacts the short-term postrelease mortality of sockeye salmon, which has important implications for management.
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Jordan, Alan R. „Reproductive biology, early life-history and settlement distribution of sand flathead (Platycephalus bassensis) in Tasmania“. Marine and Freshwater Research 52, Nr. 4 (2001): 589. http://dx.doi.org/10.1071/mf99155.
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The life-history ecology of P. bassensis was examined to determine the spatial and temporal patterns of spawning, larval transport and settlement distribution in coastal and continental shelf waters of southern and eastern Tasmania. Larval development is characterized by a large size at flexion and pelvic and dorsal fin formation, lightly pigmented trunk and tail and the absence of strong teeth on the roof of the mouth or lower jaw. The distribution of spawning fish and larvae and patterns of hydrography indicate that spawning occurs throughout estuaries, coastal embayments and inshore shelf waters of southern and eastern Tasmania. Larvae are concentrated in mid waters, which retain larvae inshore because cross-shelf subsurface currents are predominantly onshore. Spawning in P. bassensis occurred for up to six months between October and March. The broad range of lengths of 0+ fish in every month indicates that settlement occurred over an extended period, reflecting the protracted spawning period. Juveniles showed a preference for unvegetated habitats in nearshore waters, compared with beds of the seagrass Heterozostera tasmanica. Size compositions of 0+ fish indicate the presence of several cohorts in most months;this is discussed in terms of early life-history strategy and availability of settlement habitats.
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Mullon, Christian, Philippe Cury und Pierrick Penven. „Evolutionary individual-based model for the recruitment of anchovy (Engraulis capensis) in the southern Benguela“. Canadian Journal of Fisheries and Aquatic Sciences 59, Nr. 5 (01.05.2002): 910–22. http://dx.doi.org/10.1139/f02-064.
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Evolutionary simulations are developed to explore environmental constraints that select observed spatial and temporal spawning patterns for anchovy (Engraulis capensis) in the southern Benguela. They couple a realistic three-dimensional hydrodynamic model with an individual-based model in which an evolutionary-based reproductive strategy for adult fish and a passive transport for early life stages are implemented. The evolutionary success of spawning is quantified when patterns at the population level emerge after many generations from constraints at the individual level through a selective process. As a result, several self-sustaining populations are identified considering different sets of selective constraints. Simulated spawning patterns better match the observed mean spawning pattern when two selective environmental constraints are associated: a threshold temperature of 14°C, above which the development of early life stages is ensured, and the avoidance of offshore currents that constitute a loss of spawning products. Simulated recruitment patterns are more realistic when considering the constraint of reaching the nursery area. This modeling experience can help to identify, temporally and spatially, environmental factors important for fish recruitment and to establish a hierarchy of these factors. The probable coexistence in nature of several self-sustaining populations of pelagic fishes is shown to be important for recruitment studies.
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Langangen, Øystein, Geir Ottersen, Lorenzo Ciannelli, Frode B. Vikebø und Leif Christian Stige. „Reproductive strategy of a migratory fish stock: implications of spatial variations in natural mortality“. Canadian Journal of Fisheries and Aquatic Sciences 73, Nr. 12 (Dezember 2016): 1742–49. http://dx.doi.org/10.1139/cjfas-2015-0321.
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We investigate how the reproductive strategy in a migratory marine fish may be influenced by spatial variations in mortality in early life stages. In particular, we examine how spawning time and location affect offspring survival and growth. A drift model for early life stages (eggs to age 1) of the Barents Sea cod (Gadus morhua) is combined with empirical estimates of spatial variation in mortality at two different life stages. We examine seasonal and interannual differences in survival and growth in offspring originating from two spawning grounds, with the central site requiring higher migration distance, and hence cost, than the northern site. When accounting for spatially explicit mortality fields, central and northern spawned offspring have about equal survival, as do early and late spawned offspring. Furthermore, central spawned offspring grow faster and are likely to reach a larger size compared with northern spawned offspring. Our results indicate that the fitness benefit of southward migration in the Barents Sea cod is not mainly due to higher early survival of offspring, but rather due to effects of offspring acquiring a larger size.
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DEUDERO, S., A. GRAU, M. VÁZQUEZ-LUIS, E. ÁLVAREZ, C. ALOMAR und I. E. HENDRIKS. „Reproductive investment of the pen shell Pinna nobilis Linnaeus, 1758 in Cabrera National Park (Spain)“. Mediterranean Marine Science 18, Nr. 2 (18.07.2017): 271. http://dx.doi.org/10.12681/mms.1645.
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The spawning period can be a period of particular vulnerability for a species. In hermaphroditic species like the long-lived pen shell Pinna nobilis different costs could be associated with female, male or hermaphrodite stages. Here we evaluate gonad development in a population with few anthropogenic pressures and describe the timing and succession of developmental stages, determine the ratio of the sexes and the condition of the animals. We assess resource mobilisation and associated costs through the relationship between stable isotopes and condition indexes with reproductive parameters and evaluate the role of the adductor muscle as storage organ used in gonad maturation. In our study area only one spawning season is observed, starting in May and peaking in June-July. The onset of spawning coincides with water temperatures of 20 °C. Condition indexes drop during the spawning period and recover afterwards to reach pre-spawning values in November. Stable isotope signals are negatively related to the gonadal condition index, while the CN ratio shows a positive correlation with the same index. Additionally, the muscle condition index sharply decreases after the start of the spawning season, which suggests that P. nobilis uses the reserves stored in the adductor muscle for reproduction as in other Pinnidae species. Reproductive indices and stable isotopes ratios indicate ‘capital breeding’ as reproductive strategy of the pen shell. Decreased muscle force could mean a higher vulnerability during the summer period, coinciding with the peak in recreational activities involving poaching and anchoring.
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Domínguez-Petit, Rosario, Patrick Ouellet und Yvan Lambert. „Reproductive strategy, egg characteristics and embryonic development of Greenland halibut (Reinhardtius hippoglossoides)“. ICES Journal of Marine Science 70, Nr. 2 (29.11.2012): 342–51. http://dx.doi.org/10.1093/icesjms/fss180.
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Abstract Domínguez-Petit, R., Ouellet, P., and Lambert, Y. 2013. Reproductive strategy, egg characteristics and embryonic development of Greenland halibut (Reinhardtius hippoglossoides). – ICES Journal of Marine Science, 70: 342–351. Despite the commercial importance of Greenland halibut (GH), important gaps exist in our knowledge of the reproductive and early life stage biology for this species. The present study examined through laboratory experiments the spawning strategy, realized fecundity, egg characteristics, biochemical composition, and embryonic development of GH. The results confirmed the hypothesis that GH is a single-batch spawner producing large eggs, resulting in low realized fecundity. Embryonic development and hatching time are highly dependent on incubation temperature; 50% hatching occurred after 46, 30, and 24 days at 2, 4, and 6°C, respectively. Few changes in the biochemical composition of the eggs are observed during embryonic development. Newly hatched larvae are not well developed, having a large yolk sac, no pigmentation and incomplete development of the jaws. Egg specific density confirmed the mesopelagic distribution of the eggs at sea. However, important buoyancy changes occurring in the last 3–4 days before hatching indicate that larvae hatch higher in the water column. These results are important for understanding advection and dispersion processes of GH eggs and larvae and the connectivity between spawning grounds and nursery areas.
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Myers, Ransom A., Susanna D. Fuller und Daniel G. Kehler. „A fisheries management strategy robust to ignorance: rotational harvest in the presence of indirect fishing mortality“. Canadian Journal of Fisheries and Aquatic Sciences 57, Nr. 12 (01.12.2000): 2357–62. http://dx.doi.org/10.1139/f00-250.
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We develop a simple theoretical model of yield and spawning stock biomass per recruit for the American sea scallop (Placopecten magellanicus), which appears to have high indirect fishing mortality when harvested with dredges, i.e., mortality caused by the act of fishing that does not result in landings. The age at and degree to which individuals are affected by the indirect mortality are unknown, and it does not appear possible to develop a robust harvest strategy with yearly harvests unless indirect fishing mortality is well quantified. We show that there could be substantial benefits to a rotational harvest strategy for sessile species with high indirect fishing mortality. First, the strategy appears to be robust to ignorance about indirect fishing mortality and results in equal or better yields than a yearly harvest across a wide range of indirect fishing mortalities. Second, under most conditions, a higher spawning stock biomass is maintained. Third, rotational management is more easily enforced, as it does not require specifying a narrow range of fishing mortality in order to maximize yield.
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Rjeibi, Okbi, Okbi Rjeibi, Adel Gaamour und Hechmi Missaoui. „Kinetics of Oögenesis and Spawning Strategy of the Red Spiny Lobster Palinurus elephas“. Journal of Crustacean Biology 30, Nr. 3 (01.01.2010): 401–12. http://dx.doi.org/10.1651/09-3165.1.
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de Graaf, M., E. D. Nentwich, J. W. M. Osse und F. A. Sibbing. „Lacustrine spawning: is this a new reproductive strategy among 'large' African cyprinid fishes?“ Journal of Fish Biology 66, Nr. 5 (Mai 2005): 1214–36. http://dx.doi.org/10.1111/j.0022-1112.2005.00671.x.
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Esteve, Manu, Deborah A. McLennan und John M. Gunn. „Lake trout (Salvelinus namaycush) spawning behaviour: the evolution of a new female strategy“. Environmental Biology of Fishes 83, Nr. 1 (09.08.2007): 69–76. http://dx.doi.org/10.1007/s10641-007-9272-z.
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Walsh, Chris T., Charles A. Gray, Ron J. West und Lindsay F. G. Williams. „Reproductive biology and spawning strategy of the catadromous percichthyid, Macquaria colonorum (Günther, 1863)“. Environmental Biology of Fishes 91, Nr. 4 (20.04.2011): 471–86. http://dx.doi.org/10.1007/s10641-011-9807-1.
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Azrita, Azrita, Hafrijal Syandri und Netti Aryani. „Reproductive characteristics of the giant gurami sago strain (Osphronemus goramy Lacepède, 1801): basic knowledge for a future hatchery development strategy“. F1000Research 10 (15.09.2021): 922. http://dx.doi.org/10.12688/f1000research.53760.1.
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Background: The giant gourami sago strain (Osphronemus goramy Lacepède) has been approved in 2018 as a candidate for freshwater aquaculture in Indonesia. However, information on the species’ reproduction is minimal. This study analyzed the reproductive characteristics of the gourami sago strain broodfish to provide basic knowledge for a future hatchery development strategy. Methods: A total of 10 female and 10 male mature gourami sago strain broodfish were measured for body weight and length, and were evaluated for their reproductive characteristics. Breeding fish were spawned naturally in a 2×1×0.6 m concrete pond with a male-female sex ratio of 1:1. Egg weight and diameter were measured in 25 eggs per female using, respectively, ACIS AD- 600i scales with 0.01 g accuracy, and a microscope (Labo model L-711) using Canon Digital Camera Software 3 . Semen was collected using plastic syringes in 3 mL aliquots, then placed in an insulated ice-cooled container, and analyzed within two hours of collection. Results: Average weights of female and male broodfish before spawning were 2180±159.78 g and 3060±134.99 g, respectively. The relative fecundity and egg diameter were 1029±36 eggs kg-1 and 2.42±0.05 mm, respectively. The hatching rate and embryo survival to an eyed-egg stage were respectively 76.40±2.27% and 94.76±0.42%. Sperm characteristics showed that volume was 0.60±0.12 ml kg-1 and percentage of motile sperm was 70.04±2.27%. Female broodfish weight after spawning was strongly correlated with the weight before spawned (r2 = 0.999) and absolute fecundity was also strongly correlated with female broodfish weight before spawning (r2= 0.921). Sperm concentration was moderately correlated with sperm motility (r2 = 0.556) and duration of sperm motility (r2 = 0.502). Conclusions: The gourami sago strain broodfish has suitable reproductive characteristics for the development of hatcheries. Successful natural spawning should be followed by larval weaning and feeding technology to increase growth and survival.