Academic literature on the topic 'Sharks – Effect of fishing on – Australia'
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Journal articles on the topic "Sharks – Effect of fishing on – Australia"
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McAuley, Rory B., Colin A. Simpfendorfer, and Norm G. Hall. "A method for evaluating the impacts of fishing mortality and stochastic influences on the demography of two long-lived shark stocks." ICES Journal of Marine Science 64, no. 9 (September 20, 2007): 1710–22. http://dx.doi.org/10.1093/icesjms/fsm146.
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Abstract McAuley, R. B., Simpfendorfer, C. A., and Hall, N. G. 2007. A method for evaluating the impacts of fishing mortality and stochastic influences on the demography of two long-lived shark stocks. — ICES Journal of Marine Science, 64. Stochastic demographic models were developed for Carcharhinus obscurus and C. plumbeus populations off the west coast of Australia by resampling the input parameters for life tables from empirical biological data collected from commercial target fisheries and fishery-independent surveys. The models were used to examine the effects of multiple scenarios of age-specific survival, derived from the fishing mortality rates estimated from a tagging study on sharks and indirect estimates of natural mortality. In the absence of fishing, median estimates of the rates of intrinsic population increase (r) were 0.025 for both species. Inclusion of the age-specific fishing mortality rates estimated for C. obscurus recruits born in 1994 and 1995 resulted in the median estimates of r declining to 0.007 and 0.012, respectively, suggesting that recent harvest levels of mainly neonates by the target fishery were probably sustainable. However, the model also suggested that the population was more susceptible to exploitation of older sharks than was previously believed. The C. plumbeus model indicated that fishing mortality between 2001 and 2004 was probably unsustainable. The increasingly negative trend in median r estimates (from –0.032 to –0.049), and the population’s apparently limited capacity for density-dependent compensation through changes in fecundity, somatic growth and longevity, suggests that management intervention is necessary to prevent continued stock depletion.
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Drew, Michael, Paul Rogers, and Charlie Huveneers. "Slow life-history traits of a neritic predator, the bronze whaler (Carcharhinus brachyurus)." Marine and Freshwater Research 68, no. 3 (2017): 461. http://dx.doi.org/10.1071/mf15399.
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Intra-species plasticity in the life-history characteristics of sharks leads to the need for regional estimates to accurately determine resilience to anthropogenic effects. The present study provides the first length-at-age, growth and maturity estimates for the bronze whaler (Carcharhinus brachyurus) from southern Australia. Age estimates were obtained from vertebral sections of 466 individuals spanning 50–308-cm total length. Maximum estimates of age for males and females were 25 and 31 years respectively. The three-parameter logistic model for females (L∞=308cm LT, k=0.15, α=742) and for males (L∞=317cm LT, k=0.13, α=782) provided the best fit to the size at age data. Males matured at a similar age (16 years), but smaller size than females (224v. 270cm LT). Growth parameters and age-at-maturity estimates were similar to those for genetically isolated C. brachyurus populations, and the sympatric dusky shark (C. obscurus). The southern Australian C. brachyurus population is long-lived, slow growing and late maturing. These growth parameters are needed to undertake demographic analyses to assess the resilience of C. brachyurus to fishing, and provide an example of a wide-ranging elasmobranch with similar life-history characteristics across isolated populations.
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Moulton, PL, TI Walker, and SR Saddlier. "Age and growth studies of Gummy Shark, Mustelus antarcticus Gunther, and School Shark, Galeorhinus galeus (Linnaeus), from Souther Australian Waters." Marine and Freshwater Research 43, no. 5 (1992): 1241. http://dx.doi.org/10.1071/mf9921241.
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Age-length data were derived from counting stained bands on whole vertebral centra obtained from gummy shark, Mustelus antarcticus, captured by gill-nets during 1973-76 in Bass Strait and from gummy shark and school shark, Galeorhinus galeus, captured during 1986-87 in Bass Strait and waters off South Australia. The data were fitted to the von Bertalanffy growth equation after adopting the Francis reparametrization and correcting for sampling bias caused by the selectivity effects of the gill-nets of various mesh sizes used to capture the sharks. The von Bertalanffy growth curves of male and female gummy shark were significantly different, but the growth curves of male and female school shark were not. The growth curves suggest that growth rates of male and female gummy shark in Bass Strait were lower during 1986-87 than during 1973-76 and that the growth rates of male and female gummy shark and school shark in Bass Strait during 1986-87 were lower than those in South Australia at the same time. These apparent temporal and spatial differences in growth patterns of gummy shark are explained by the 'Phenomenon of Apparent Change in Growth Rate'. It is concluded that the growth curves determined for 1986-87 are distorted by the effects of a long history of high and length-selective fishing mortality and that actual growth patterns of gummy shark are better represented by the von Bertalanffy growth equation determined for shark caught in Bass Strait during 1973-76, when fishing mortality was much lower. Verification of age estimates was attempted by comparing von Bertalanffy growth curves derived from age-length data with those derived from tag release-recapture length-increment data, but these comparisons highlight the limitations of using tag data for this purpose. Although reasonable agreement was found between such growth curves for gummy shark, it appears that school shark older than 11 years cannot be aged accurately from stained whole or sectioned vertebrae. Sectioned vertebrae from a school shark recaptured 35.7 years after being tagged and released and calculated as having an age exceeding 45 years gave estimates of only 18-20 years of age.
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Zhou, Shijie, Ross M. Daley, Michael Fuller, Cathy M. Bulman, and Alistair J. Hobday. "A data-limited method for assessing cumulative fishing risk on bycatch." ICES Journal of Marine Science 76, no. 4 (January 28, 2019): 837–47. http://dx.doi.org/10.1093/icesjms/fsy206.
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Abstract To assess fishing effects on data-poor species, impact can be derived from spatial overlap between species distribution and fishing effort and gear catchability. Here, we enhance the existing sustainability assessment for fishing effect method by estimating gear efficiency and heterogeneous density from sporadic catch data. We apply the method to two chondrichthyan bycatch species, Bight Skate and Draughtboard Shark in Australia, to assess cumulative fishing mortality (Fcum) from multiple fisheries. Gear efficiency is estimated from a Bayesian mixture distribution model and fish density is predicted by a generalized additive model. These results, combined with actual fishing effort, allow estimation of fishing mortality in each sector and subsequently, the Fcum. Risk is quantified by comparing Fcum with reference points based on life history parameters. When only the point estimates were considered, our result indicates that for the period 2009 and 2010 Bight Skate caught in 14 fisheries was at high cumulative risk (Fcum ≥ Flim) while Draughtboard Shark caught by 19 fisheries was at low cumulative risk (Fcum ≤ Fmsy). Because of the high cost of conducting cumulative risk assessments, we recommend examining the distribution of fishing effort across fisheries before carrying out the assessments.
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Volep, E., A. R. Carroll, D. Strauss, J. O. Meynecke, and D. Kobashi. "Effect of environmental conditions on cetacean entanglements: a case study from the Gold Coast, Australia." Marine and Freshwater Research 68, no. 11 (2017): 1977. http://dx.doi.org/10.1071/mf16302.
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Entanglement of marine mammals in fishing gear is recognised worldwide and is a continuous management concern. Gill-net entanglement data from the Queensland Shark Control Program (QSCP) on the Gold Coast, Australia, from 1990 to 2012 were analysed in the present study. Environmental drivers that may affect entanglements of humpback whales (Megaptera novaeangliae) and common dolphins (Delphinus delphis) were selected. M. novaeangliae entanglements coincided with their annual migration, with the greatest occurrences in September. D. delphis were mostly entangled from March to November, with the greatest occurrences in June. For both species, entanglements primarily occurred when the wave height was between 0.5 and 1.25m, the wave power was between 0 and 5kWm–1 and the wind speed was between 12 and 19kmh–1. M. novaeangliae entanglements were significantly more likely to occur in low rainfall (<6mmh–1), and D. delphis entanglements were more likely to occur during spring tides. There was a correlation between entanglements and the position of the East Australian Current’s (EAC) maximum velocity, with 73% of M. novaeangliae entanglements and 79% of D. delphis entanglements occurring when the EAC’s maximum velocity was west (shoreward) of its average position at 154°E. The present study provides the first set of possible management intervention targets associated with environmental conditions.
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Bansemer, C. S., and M. B. Bennett. "Retained fishing gear and associated injuries in the east Australian grey nurse sharks (Carcharias taurus): implications for population recovery." Marine and Freshwater Research 61, no. 1 (2010): 97. http://dx.doi.org/10.1071/mf08362.
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Incidental hooking of Carcharias taurus is a threat to their populations’ recovery on the east coast of Australia. Photo-identification techniques were used to investigate the frequency of hooking at 25 aggregation sites along the east coast of Australia between 2006 and 2008. Of the 673 sharks identified, 113 sharks were identified with signs of 119 incidences of hooking. For sharks with both their left and right flank photographed during a single survey day, up to 29% of females and 52% of males were identified with retained fishing gear or an attributed jaw injury. The largest number of sharks identified (222) were from a year-round aggregation of immature and mature sharks at Fish Rock, New South Wales, Australia. Forty-eight per cent of all sharks identified with retained fishing gear were first identified at this site. Fish Rock, a designated critical habitat for C. taurus, allows most forms of line fishing except fishing with bait or wire trace while anchored or moored. As interactions with fishing gear can result in debilitating disease, morbidity and death, the high incidence of hooked individual C. taurus is considered a key threatening process that is likely to reduce this shark population’s ability to recover.
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Walker, TI. "Fishery simulation model for sharks applied to the Gummy Shark, Mustelus antarcticus Gunther, from Southern Australian waters." Marine and Freshwater Research 43, no. 1 (1992): 195. http://dx.doi.org/10.1071/mf9920195.
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A dynamic pool simulation model is derived and applied to the gummy shark stock of the southern shark fishery. Inputs to the model are fishing effort reported by fishers for hooks and for gill-nets with mesh sizes of 6 inches (152 mm), 7 inches (178 mm) and 8 inches (203 mm) along with estimates for growth, natural mortality, catchability, hook and gill-net mesh selectivity, size at maturity and fecundity of females, sex ratio at birth, and length-weight relationships. Growth is described by the von Bertalanffy equation; hook selectivity is constant with length for sharks recruited to the fishery; gill-net selectivity is based on the probability density distribution of the gamma function where selectivity varies with the mesh size of the gill-nets and the length of the sharks; number of births is related to the proportion of females mature at each length, and the relationship between number of births and maternal weight is linear; parturition is annual and time is standardized so that parturition occurs at the beginning of each year; sex ratio at birth is based on observations of a 1: 1 sex ratio of embryos; and allometric weight-length is based on the power curve. Natural mortality of recruits, catchability, reproduction and growth parameters are held constant, but density-dependent natural mortality of prerecruits is varied in proportion to stock abundance. The model is used to simulate effects of historical longline fishing effort and gill-net fishing effort for each mesh size on stock biomass, numbers of sharks in the stock, and numbers of births. The performance of the model is evaluated by comparing simulated annual catches and the simulated mean weight of sharks captured with annual catches reported by the fishers and the mean weight of sharks sampled in commercial landings. Uncertainties surrounding estimates of some of the parameters are discussed. Notwithstanding its shortcomings, the model indicates that the stock of gummy shark has been severely reduced and is in danger of further depletion unless immediate action is taken to reduce the commercial catch.
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Taylor, S. M., J. M. Braccini, B. D. Bruce, and R. B. McAuley. "Reconstructing Western Australian white shark (Carcharodon carcharias) catches based on interviews with fishers." Marine and Freshwater Research 69, no. 3 (2018): 366. http://dx.doi.org/10.1071/mf17140.
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The assessment of fisheries-related effects on protected species, such as white sharks (Carcharodon carcharias), is often hampered by a lack of historical catch information. In the present study, historical catch estimates derived from interviews with fishers operating in the Western Australian Temperate Demersal Gill-net and Demersal Longline Fisheries were matched with fishing effort data reported in statutory fishing returns. Catch estimates obtained from interviewed fishers were extrapolated to account for total catch in two different ways, resulting in mean (95% confidence intervals) estimates of 1232 (476–2245) and 1039 (505–2096) white sharks caught between 1988 and 2012. These estimates were then used to reconstruct catches over a 59-year period, from the start of commercial gillnetting in the mid-1950s. The reconstructed catch trend reflected the history of gill-net fishing effort, peaking in the late 1980s at a level approximately fourfold greater than the estimated catch of ~30 sharks year–1 in 2014. More than one-third of fishers interviewed expressed doubts about the accuracy of self-reported white shark catch data, a requirement of current legislation. Given the benefits of reporting data from protected species bycatch, efforts to accurately record this information should be continued and improved.
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Stevens, JD. "Blue and Mako Shark by-catch in the Japanese Longline Fishery off South-eastern Australia." Marine and Freshwater Research 43, no. 1 (1992): 227. http://dx.doi.org/10.1071/mf9920227.
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During the last 10 years, up to 70 Japanese longline vessels have fished Tasmanian waters of the Australian Fishing Zone each season, targeting bluefin tuna (Thunnus maccoyii). The average seasonal fishing effort in Tasmanian waters is about 3.3 million hooks, and data from observers suggests that, this results in a by-catch of some 34 000 blue sharks (Prionace glauca) each year, representing a weight of about 275 tonnes. In the last few years, fishing effort has increased as the catch rates of southern bluefin tuna have declined. The sharks are discarded after removal of the fins. The actual number of blue sharks hooked is much higher than 34000 because many are released by either shaking or cutting them off the line, although they are often damaged in the process. The majority of blue sharks caught are immature or adolescent females. Smaller numbers of shortfin mako sharks (Isurus oxyrinchus) are also caught and retained both for their fins and their meat. Tasmanian waters represent only one area of the Australian Fishing Zone fished by Japanese longliners.
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Diana, Farah, Hafinuddin Hafinuddin, and Muhajir Ansar. "PENGARUH JENIS UMPAN YANG BERBEDA TERHADAP HASIL TANGKAPAN KEPITING BAKAU (Scylla serrata) DENGAN MENGGUNAKAN ALAT TANGKAP BUBU." JURNAL PERIKANAN TROPIS 5, no. 2 (October 1, 2018): 119. http://dx.doi.org/10.35308/jpt.v5i2.1031.
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Mangrove crab (Scylla serrata) is one of the fishery commodities that have higheconomic value. In addition, mangrove crab is one of export commodities to several countries such as United States, Europe, Australia, Japan, Hongkong,Taiwan, Singapore and South Korea. In general, the fishing activities of mangrove crabs in the general waters of many fishermen use different baits,it's just not known which bait is best for catching mangrove crabs. The purpose ofthis study is to determine the effect of using different types of bait to the mangrove crab catch by using bubu and know the type of bait that is most effective against the catching of mangrove crab. This research method used Completely Randomized Design (RAL) with three treatments and three replications: P1 = shredded fish, P2 = Shark skin bark, and P3 = Chicken head bait. The parameters in this study are the number of catches, the feed response and the water quality parameters, the results of this study indicate the number of catches P1 = 55.55%, P2 = 22.22% and P3 = 33.33%. While feed response time in this research P1 = 1.61, P2 = 12.03, and P3 = 11.74. From the results of this study showed the use of different baits have a very significant effect on the number of mangrove crabs (scilla serata). While the feedback response also shows the results are very real (Fcal> Ftab).
Dissertations / Theses on the topic "Sharks – Effect of fishing on – Australia"
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Forrest, Robyn Elizabeth. "Simulation models for estimating productivity and trade-offs in the data-limited fisheries of New South Wales, Australia." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/3417.
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Recent shifts towards ecosystem based fisheries management (EBFM) around the world have necessitated consideration of effects of fishing on a larger range of species than previously. Non-selective multispecies fisheries are particularly problematic for EBFM, as they can contribute to erosion of ecosystem structure. The trade-off between catch of productive commercial species and abundance of low-productivity species is unavoidable in most multispecies fisheries. A first step in evaluation of this trade-off is estimation of productivity of different species but this is often hampered by poor data.
This thesis develops techniques for estimating productivity for data-limited species and aims to help clarify EBFM policy objectives for the fisheries of New South Wales (NSW), Australia. It begins with development of an age-structured model parameterised in terms of optimal harvest rate, UMSY. UMSY is a measure of productivity, comparable among species and easily communicated to managers. It also represents a valid threshold for prevention of overfishing. The model is used to derive UMSY for 54 Atlantic fish stocks for which recruitment parameters had previously been estimated. In most cases, UMSY was strongly limited by the age at which fish were first caught. However, for some species, UMSY was more strongly constrained by life history attributes. The model was then applied to twelve species of Australian deepwater dogshark (Order Squaliformes), known to have been severely depleted by fishing. Results showed that the range of possible values of UMSY for these species is very low indeed. These findings enabled a preliminary stock assessment for three dogsharks (Centrophorus spp.) currently being considered for threatened species listing. Preliminary results suggest they have been overfished and that overfishing continues. Finally, an Ecopath with Ecosim ecosystem model, representing the 1976 NSW continental slope, is used to illustrate trade-offs in implementation of fishing policies under alternative policy objectives. Results are compared with those of a biogeochemical ecosystem model (Atlantis) of the same system, built by scientists from CSIRO. While there were large differences in model predictions for individual species, they gave similar results when ranking alternative fishing policies, suggesting that ecosystem models may be useful for exploring broad-scale strategic management options.
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Westera, Mark B. "The effect of recreational fishing on targeted fishes and trophic structure, in a coral reef marine park." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2003. https://ro.ecu.edu.au/theses/1499.
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Recreational line fishing is highly targeted at predatory fishes, making them vulnerable to overfishing. These same fishes play a role in trophic structure by regulating prey species. Despite increasing numbers of fishers, few studies have investigated the potential effects of recreational fishing on fish populations and subsequent trophic effects. This project investigated whether there were differences in fishes and benthos between unfished and recreationally fished areas, and whether the removal of targeted fishes influenced trophic structure. The study was conducted at the Ningaloo Marine Park, Western Australia, which had Sanctuary (no-take) and Recreation {recreationally fished) Zones. Data were collected from three regions (Mandu, Osprey and Maud) and replicated over time. Fish assemblages, benthos and trophic interactions were compared between zones at each region. At Ningaloo the lethrinids (emperors) are a top-order predatory fish and the preferred target of recreational anglers. The algal-grazing urchin Echinometra mathaei comprised 51% of macro invertebrate abundances and was heavily preyed upon by lethrinids, being recorded in 50% of the guts of sampled fish. In nil regions, Sanctuary Zones had a greater biomass of lethrinids than Recreation Zones, but there were no differences in non-targeted fishes between zones. Despite the consistent effect on lethrinids, there were inconsistencies among regions in the predator-prey relationships. At Mandu, Echinometra mathaei abundances were inversely related to lethrinid biomass, suggesting a strong predator-prey interaction. In the Recreation Zone, the abundances of E. mathaei were four times greater, and macro-algal cover was half, that of the Sanctuary Zone. Furthermore, algal composition differed between zones, and this was driven by fucoid brown algae, which dominated the diets of E. mathaei. This was interpreted as evidence of a trophic cascade resulting from the removal of lethrinids at the Recreation Zone. At Maud, different results were recorded. Abundances of Echinometro mathaei and lethrinids were both higher in the Sanctuary Zone, than the adjacent Recreation Zone. E. mathaei reside in the crevices of rock, dead coral or Echinapora coral, which provided refuge from predation and this habitat was more available in the Sanctuary Zone. It is suggested that the availability of this habitat confounded the effects of predation. Macro- algal cover was lower in the Sanctuary Zone indicating a grazing effect from E. mathaei. At Osprey there was higher cover of E. mathaei habitat in the Sanctuary than the Recreation Zone. However, there were no differences in macro-algal cover, which was consistent with a lack of difference in E. mathaei abundances. The effect of E. mathaei grazing was unlikely to have been confounded by fishes that graze macro-algae, as they did not differ between zones at any region. These results indicate that recreational fishing reduced fish populations below that of adjacent protected areas at Ningaloo Marine Park, and in one region this resulted in a trophic cascade. This may be the first study that has recorded evidence of a trophic cascade where recreational line fishing is the only means of extraction. However, the results also show that this is not a consistent response to reduced fishing pressure; in other regions, changes in predatory fish abundance did not result in differences in the abundances of their prey, suggesting no trophic cascade. The studies have contributed towards an understanding of fish-habitat interactions and provide a baseline for future monitoring of the Ningaloo Marine Park. They also have important implications for marine park managers in terms of defining their expectations when implementing Sanctuary Zones. The results also show that Sanctuary Zones have the potential to be effective tools for fisheries management.
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Braccini, Juan Matías. "Assessment of ecological risks from effects of fishing to Piked Spurdog (Squalus megalops) in South-Eastern Australia." 2006. http://thesis.library.adelaide.edu.au/public/adt-SUA20060519.153928.
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Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2006."January 2006" Bibliography: pages 188-209. Also available in print form.
Books on the topic "Sharks – Effect of fishing on – Australia"
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Diop, Mika. 30 années d'exploitation des requins en Afrique de l'Ouest: Trajectoires des pêcheries, évolution des captures et état de conservation des requins dans les pays membres de Commission sous-régionale des pêches. Arles]: FIBA, 2011.
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Klippel, Sandro, and Carolus M. Vooren. Ações para a conservação de tubarões e raias no sul do Brasil. Edited by Projeto "Salvar Seláquios do Sul do Brasil." Porto Alegre: Igaré, 2005.
Find full textBook chapters on the topic "Sharks – Effect of fishing on – Australia"
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"Life in the Slow Lane: Ecology and Conservation of Long-Lived Marine Animals." In Life in the Slow Lane: Ecology and Conservation of Long-Lived Marine Animals, edited by Colin A. Simpfendorfer. American Fisheries Society, 1999. http://dx.doi.org/10.47886/9781888569155.ch11.
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<em>Abstract.</em> —An assessment of the dusky shark <em>Carcharhinus obscurus </em> fishery in southwestern Australia was undertaken using demographic techniques. Current annual catches of <em>C. obscurus </em> by the fishery are 500–700 metric tons (live weight), most of which are recently born individuals (age-0). The best estimates of life history parameters indicate that the annual rate of population increase is 4.3% when unfished and that the <EM>F</EM><sub> MSY</sub> is 0.021. Tests indicate that the results are most sensitive to changes in values of natural mortality and age at maturity. Changes to the values of average litter size, reproductive periodicity, and longevity had little effect on the results. The inclusion in the analysis of age-specific exploitation rates from a tagging study indicate that at current levels of fishing the <em>C. obscurus </em> population in southwestern Australia is most likely to be sustainable. However, it must be noted that there is some unquantified mortality of older year-classes due to fishing operations outside of the managed fishery. The results indicate that it is possible to exploit long-lived, late-maturing, slow-reproducing marine animals by targeting the youngest age-classes. The results are discussed in relation to the dusky shark fishery in southwestern Australia and the exploitation of other long-lived marine species.
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"Life in the Slow Lane: Ecology and Conservation of Long-Lived Marine Animals." In Life in the Slow Lane: Ecology and Conservation of Long-Lived Marine Animals, edited by John D. Stevens. American Fisheries Society, 1999. http://dx.doi.org/10.47886/9781888569155.ch2.
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<em> Abstract.</em>—Sharks have the reputation of being particularly vulnerable to fishing pressure, a fact attributed to their generally ‘<EM> K</EM>-selected’ life history strategies. The history of shark fisheries is not encouraging, and their poor record of sustainability is compounded by the fact that few countries have any form of management for these resources. The Australian Southern Shark Fishery provides an example of a well-studied shark fishery with a long history of exploitation that has been under a management plan for some ten years. This fishery is unique in that it exploits, under a similar fishing regime, two similar target shark species that show very different responses to fishing pressure. Stock assessments suggest that under current fishing effort the catch of one species is sustainable while the other species is overexploited. The vulnerability of the two species to the fishing gear is similar but their biological productivity is very different. The selective pressures that may have given rise to these different life history strategies are discussed.
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"Shark Nursery Grounds of the Gulf of Mexico and the East Coast Waters of the United States." In Shark Nursery Grounds of the Gulf of Mexico and the East Coast Waters of the United States, edited by JOHN K. CARLSON. American Fisheries Society, 2007. http://dx.doi.org/10.47886/9781888569810.ch18.
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<em>Abstract.</em>—A dynamic mass-balance ecosystem model (Ecopath with Ecosim) was used to investigate how relative changes in fishing mortality on sharks can affect the structure and function of Apalachicola Bay, Florida, a coastal marine ecosystem. Simulations were run for 25 years, wherein fishing mortality rates from recreational and trawl fisheries were doubled for 10 years and then decreased to initial levels. Effect of time/area closures on ecosystem components were also tested by eliminating recreational fishing mortality on juvenile blacktip sharks <em>Carcharhinus limbatus</em>. Simulations were run assuming mixed control and top-down control. In the mixed control, biomass of juvenile coastal sharks (finetooth shark <em>C. isodon</em>, spinner shark <em>C. brevipinna</em>, sandbar shark <em>C. plumbeus</em>), juvenile blacktip sharks, and bull sharks <em>C. leucas </em>declined up to 57% when recreational fishing mortality was doubled. Increases in biomass were also observed for the Atlantic sharpnose shark <em>Rhizoprionodon terraenovae </em>and, to a lesser extent, skates and rays. Increasing the fishing mortality imposed by trawl fisheries affected only a few elasmobranch groups, primarily skates and rays. Increases and decreases in biomass lasted only as long as fishing mortality was elevated, although a lag time was observed for some groups to recover to initial biomass. Simulating a time/ area closure for juvenile blacktip sharks caused increases in their biomass but decreases in juvenile coastal shark biomass, a competing multispecies assemblage that is the apparent competitor. Topdown control scenarios resulted in greater variation and magnitude of response than those elicited under mixed control, although the direction of the response was similar. In general, reduction of targeted sharks did not cause strong top-down cascades.