Science & Education

Shark Finning References and Abstracts

  1. Abercrombie, D.L., S.C. Clarke and M.S. Shivji. 2005. Global-scale genetic identification of hammerhead sharks: Application to assessment of the international fin trade and law enforcement. Conservation Genetics. 6: 775-788.

Anonymous. 2007. Mexican shark norm targets trade in fins – Mexico City, Mexico. EcoAmericas. 9 (5). http://www.ecoamericas.com/en/story.aspx?id=804

  1. Barnett, A., Braccini, J.M., Awruch, C.A., Ebert, D.A. An overview on the role of Hexanchiformes in marine ecosystems: biology, ecology and conservation status of a primitive order of modern sharks. J. of fish biol. 80: 966-990.

The large size, high trophic level and wide distribution of Hexanchiformes (cow and frilled sharks) should position this order as important apex predators in coastal and deep-water ecosystems. This review synthesizes available information on Hexanchiformes, including information not yet published, with the purpose of evaluating their conservation status and assessing their ecological roles in the dynamics of marine ecosystems. Comprising six species, this group has a wide global distribution, with members occurring from shallow coastal areas to depths of c. 2500 m. The limited information available on their reproductive biology suggests that they could be vulnerable to overexploitation (e.g. small litter sizes for most species and suspected long gestation periods). Most of the fishing pressure exerted on Hexanchiformes is in the form of commercial by-catch or recreational fishing. Comprehensive stock and impact assessments are unavailable for most species in most regions due to limited information on life history and catch and abundance time series. When hexanchiform species have been commercially harvested, however, they have been unable to sustain targeted fisheries for long periods. The potentially high vulnerability to intense fishing pressure warrants a conservative exploitation of this order until thorough quantitative assessments are conducted. At least some species have been shown to be significant apex predators in the systems they inhabit. Should Hexanchiformes be removed from coastal and deep-water systems, the lack of sympatric shark species that share the same resources suggests no other species would be capable of fulfilling their apex predator role in the short term. This has potential ecosystem consequences such as meso-predator release or trophic cascades. This review proposes some hypotheses on the ecology of Hexanchiformes and their role in ecosystem dynamics, highlighting the areas where critical information is required to stimulate research directions.

 

  1. Blanco, M., Perez-Martin, R.I., Sotelo, C.G. 2008. Identification of shark species in seafood products by forensically informative nucleotide sequencing (FINS). J. Agric. Food Chem, 56: 9868-9874.

The identification of commercial shark species is a relevant issue to ensure the correct labeling of seafood products, to maintain consumer confidence in seafood, and to enhance the knowledge of

the species and volumes that are at present being captured, thus improving the management of

shark fisheries. The polymerase chain reaction was employed to obtain a 423 bp amplicon from the

mitochondrial cytochrome b gene. The sequences from this fragment, belonging to 63 authentic

individuals of 23 species, were analyzed using a genetic distance method. Nine different samples of

commercial fresh, frozen, and convenience food were obtained in local and international markets to

validate the methodology. These samples were analyzed, and sequences were employed for species

identification, showing that forensically informative nucleotide sequencing (FINS) is a suitable techniquefor identification of processed seafood containing shark as an ingredient. The results also showed that incorrect labeling practices may occur regarding shark products, probably because of incorrect labeling at the production point.

 

  1. Bennett, M. 2005.The role of sharks in the ecosystem. Save our sharks newsletter, 1-6.
  2. Bromhead, D., Clarke, S., Hoyle, S., Muller, B., Sharples, P., Harley, S. Identification of factors influencing shark catch and mortality in the Marshall Islands tuna longline fishery and management implications. J. of fish biology, 80: 1870-1894.

Recent average annual catches of sharks by tuna longline vessels fishing in the Republic of the Marshall Islands (RMI) are estimated to be between 1583 and 2274 t. Although 22 shark species have been recorded by the observer programme for this fishery, 80% of the annual catch comprises only five species: blue shark Prionace glauca, silky shark Carcharhinus falciformis, bigeye thresher shark Alopias superciliosus, pelagic thresher shark Alopias pelagicus and oceanic whitetip shark Carcharhinus longimanus. Wire leaders (i.e. branch lines or traces) were also used by nearly all observed vessels. Generalized additive model (GAM)-based analyses of catch rates indicated that P. glauca and A. superciliosus are caught in higher numbers when vessels fish in relatively cooler waters, at night, close to the full moon, when the 27 degree C thermocline is close to the surface and during El Nino conditions. In contrast, C. falciformis, A. pelagicus and C. longimanus are caught in higher numbers when shark lines are used (all three species) or hooks are set at a shallow depth (A. pelagicus and C. longimanus and, also, P. glauca). These findings are generally consistent with current knowledge of these species’ habitat preferences, movement and distribution. The results of these analyses were combined with information pertaining to shark condition and fate upon capture to compare the likely effectiveness of a range of potential measures for reducing shark mortality in the longline fishery. Of the options considered, the most effective would be to combine measures that reduce the catch rate (e.g. restrictions on the use of wire leaders, shark baits and shark lines) with measures that increase survival rates after post-capture release (e.g. finning bans).

 

  1. Carlson, J.K. 2007. Modeling the role of sharks in the trophic dynamics of Apalachicola Bay, Florida.  American Fisheries Society Symposium. 50: 281-300.

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 Carcharhinus limbatus. Simulations were run assuming mixed control and top-down control. In the mixed control, biomass of juvenile coastal sharks (finetooth shark C. isodon, spinner shark C. brevipinna, sandbar shark C. plumbeus), juvenile blacktip sharks, and bull sharks C. leucas declined up to 57% when recreational fishing mortality was doubled. Increases in biomass were also observed for the Atlantic sharpnose shark Rhizoprionodon terraenovae 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. Top-down 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.

 

  1. Clarke, S. 2004. Understanding pressures on fishery resources through trade statistics: a pilot study of four products in the Chinese dried seafood market.  Fish and Fisheries, 5(1): 53-74.

 

  1. Clarke, S.C., Magnussen, J.E., Abercrombie, D.L., McAllister, M.K., Shivji, M.S. 2006 Identification of shark species composition and proportion in the hong kong shark fin market based on molecular genetics and trade records. Conservation biology, 20 (1): 201-211.

The burgeoning and largely unregulated trade in shark fins represents one of the most serious

threats to shark populations worldwide. In Hong Kong, the world’s largest shark fin market, fins are classified

by traders into Chinese-name categories on the basis of market value, but the relationship between market

category and shark species is unclear, preventing identification of species that are the most heavily traded. To delineate these relationships, we designed a sampling strategy for collecting statistically sufficient numbers of fins from traders and categories under conditions of limited market access because of heightened trader sensitivities. Based on information from traders and morphological inspection, we hypothesized matchesbetween market names and shark taxa for fins within 11 common trade categories. These hypotheseswere tested using DNA-based species identification techniques to determine the concordance between market category andspecies. Only 14 species made up approximately 40% of the auctioned fin weight. The proportion of samplesconfirming the hypothesized match, or concordance, varied from 0.64 to 1 across the market categories. We incorporated the concordance information and available market auction records for these categories into stochastic models to estimate the contribution of each taxon by weight to the fin trade. Auctioned fin weight was dominated by the blue shark ( Prionace glauca), which was 17% of the overall market. Other taxa, including the shortfin mako ( Isurus oxyrinchus), silky (Carcharhinus falciformis), sandbar (C. obscurus), bull (C. leucas), hammerhead (Sphyrna spp.), and thresher (Alopias spp.), were at least 2–6% of the trade. Our approach to marketplace monitoring of wildlife products is particularly applicable to situations in which quantitative data at the source of resource extraction are sparse and large-scale genetic testing is limited by budgetary or other market access constraints.

 

  1. Dulvy, N., Baum, J., Clarke, S., Compagno, L., Cortes, E., Domingo, A., Fordham, S., Fowler, S., Francis, M., Gibson, C., Martinez, J., Musick, J., Soldo, A., Stevens, J.,
  2. Field, I.C., Meekan, M.G., Buckworth, R.C., Bradshaw, C. J.A. 2009.Susceptibility of sharks, rays and chimaeras to global extinction. Advances in marine biology, 56: 275-363.

Marine biodiversity worldwide is under increasing threat, primarily as a result of over-harvesting, pollution and climate change. Chondrichthyan fishes (sharks, rays and chimaeras) have a perceived higher intrinsic risk of extinction compared to other fish. Direct fishing mortality has driven many declines, even though some smaller fisheries persist without associated declines. Mixed-species fisheries are of particular concern, as is illegal, unreported and unregulated (IUU) fishing. The lack of specific management and reporting mechanisms for the latter means that many chondrichthyans might already be susceptible to extinction from stochastic processes entirely unrelated to fishing pressure itself. Chondrichthyans might also suffer relatively more than other marine taxa from the effects of fishing and habitat loss and degradation given coastal habitat use for specific life stages. The effects of invasive species and pollution are as yet too poorly understood to predict their long-term role in affecting chondrichthyan population sizes. The spatial distribution of threatened chondrichthyan species under World Conservation Union (IUCN) Red List criteria are clustered mainly in (1) south-eastern South America; (2) western Europe and the Mediterranean; (3) western Africa; (4) South China Sea and Southeast Asia and (5) south-eastern Australia. To determine which ecological and life history traits predispose chondrichthyans to being IUCN Red-Listed, and to examine the role of particular human activities in exacerbating threat risk, we correlated extant marine species’ Red List categorisation with available ecological (habitat type, temperature preference), life history (body length, range size) and human-relationship (whether commercially or game-fished, considered dangerous to humans) variables. Threat risk correlations were constructed using generalised linear mixed-effect models to account for phylogenetic relatedness. We also contrasted results for chondrichthyans to marine teleosts to test explicitly whether the former group is intrinsically more susceptible to extinction than fishes in general. Around 52% of chondrichthyans have been Red-Listed compared to only 8% of all marine teleosts; however, listed teleosts were in general placed more frequently into the higher-risk categories relative to chondrichthyans. IUCN threat risk in both taxa was positively correlated with body size and negatively correlated albeit weakly, with geographic range size. Even after accounting for the positive influence of size, Red-Listed teleosts were still more likely than chondrichthyans to be classified as threatened. We suggest that while sharks might not have necessarily experienced the same magnitude of deterministic decline as Red-Listed teleosts, their larger size and lower fecundity (not included in the analysis) predispose chondrichthyans to a higher risk of extinction overall. Removal of these large predators can elicit trophic cascades and destabilise the relative abundance of smaller species. Predator depletions can lead to permanent shifts in marine communities and alternate equilibrium states. Climate change might influence the phenology and physiology of some species, with the most probable response being changes in the timing of migrations and shifts in distribution. The synergistic effects among harvesting, habitat changes and climate-induced forcings are greatest for coastal chondrichthyans with specific habitat requirements and these are currently the most likely candidates for extinction. Management of shark populations must take into account the rate at which drivers of decline affect specific species. Only through the detailed collection of data describing demographic rates, habitat affinities, trophic linkages and geographic ranges, and how environmental stressors modify these, can extinction risk be more precisely estimated and reduced. The estimation of minimum viable population sizes, below which rapid extinction is more likely due to stochastic processes, is an important component of this endeavour and should accompany many of the current approaches used in shark management worldwide.

 

  1. Hinke, J.T., Kaplan, I.C., Aydin, K., Watter, G.M., Olson, R.J. et al. Visualizing the food-web effects of fishing for tunas in the Pacific Ocean. Ecology and society, 9 (1): 10.

We use food-web models to develop visualizations to compare and evaluate the interactions of tuna fisheries with their supporting food webs in the eastern tropical Pacific (ETP) and the central north Pacific (CNP) Oceans. In the ETP and CNP models, individual fisheries use slightly different food webs that are defined by the assemblage of targeted tuna species. Distinct energy pathways are required to support different tuna species and, consequently, the specific fisheries that target different tuna assemblages. These simulations suggest that catches of tunas, sharks, and billfishes have lowered the biomass of the upper trophic levels in both systems, whereas increases in intermediate and lower trophic level animals have accompanied the decline of top predators. Trade-offs between fishing and predation mortality rates that occur when multiple fisheries interact with their respective food webs may lead to smaller changes in biomass than if only the effect of a single fishery is considered. Historical simulations and hypothetical management scenarios further demonstrate that the effects of longline and purse seine fisheries have been strongest in upper trophic levels, but that lower trophic levels may respond more strongly to purse-seine fisheries. The apex predator guild has responded most strongly to longlining. Simulations of alternative management strategies that attempt to rebuild shark and billfish populations in each ecosystem reveal that (1) changes in longlining more effectively recover top predator populations than do changes in purse seining and (2) restrictions on both shallow-set longline gear and shark finning may do more to recover top predators than do simple reductions in fishing effort.

 

  1. Kitchell, J.F. Essington, T.E., Boggs, C.H., Schindler, D.E., Walters, C.J. 2002. The role of sharks and longline fisheries in a pelagic ecosystem of the central Pacific. Ecosystems, 5: 202-216.

The increased exploitation of pelagic sharks by longline fisheries raised questions about changes in the food webs that include sharks as apex predators. We used a version of Ecopath/Ecosim models to evaluate changes in trophic interactions due to shark exploitation in the Central North Pacific. Fisheries targeted on blue sharks tend to produce compensatory responses that favor other shark species and billfishes, but they have only modest effects on the majority of food web components. Modest levels of intraguild predation (adult sharks that eat juvenile sharks) produce strong, nonlinear responses in shark populations. In general, analysis of the Central North Pacific model reveals that sharks are not keystone predators, but that increases in longline fisheries can have profound effects on the food webs that support sharks.

  1. Lucifora, L.O., Garcia, V.B., Worm, B. 2011. Shark hot spots and diversity. PLoS ONE, 6 (5): 1-7.

Sharks are one of the most threatened groups of marine animals, as high exploitation rates coupled with low resilience to fishing pressure have resulted in population declines worldwide. Designing conservation strategies for this group depends on basic knowledge of the geographic distribution and diversity of known species. So far, this information has been fragmented and incomplete. Here, we have synthesized the first global shark diversity pattern from a new database of published sources, including all 507 species described at present, and have identified hotspots of shark species richness, functional diversity and endemicity from these data. We have evaluated the congruence of these diversity measures and demonstrate their potential use in setting priority areas for shark conservation. Our results show that shark diversity across all species peaks on the continental shelves and at mid-latitudes (30–40 degrees N and S). Global hotspots of species richness, functional diversity and endemicity were found off Japan, Taiwan, the East and West coasts of Australia, Southeast Africa, Southeast Brazil and Southeast USA. Moreover, some areas with low to moderate species richness such as Southern Australia, Angola, North Chile and Western Continental Europe stood out as places of high functional diversity. Finally, species affected by shark finning showed different patterns of diversity, with peaks closer to the Equator and a more oceanic distribution overall. Our results show that the global pattern of shark diversity is uniquely different from land, and other well-studied marine taxa, and may provide guidance for spatial approaches to shark conservation. However, similar to terrestrial ecosystems, protected areas based on hotspots of diversity and endemism alone would provide insufficient means for safeguarding the diverse functional roles that sharks play in marine ecosystems.

  1. Magnussen, J.E., Pikitch, E.K., Clarke, S.C., Nicholson, C., Hoelzel, A.R., Shivji, M.S. 2007Genetic Tracking of Basking shark products in international trade. Animal conservation, 10: 199-207.

Mounting evidence that sharks are being over-fished to supply shark fin markets is causing widespread concern about the sustainability of these practices. The basking shark Cetorhinus maximus, whose fins command high market prices, has proven especially sensitive to exploitation. To prevent further population declines, this species is now protected in the territorial waters of several countries, and is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES) requiring monitoring of trade in its products by all parties to CITES. Tracking trade in basking shark products, however, is often hampered by difficulties in identifying shark products to species of origin. Here, we present the development and application of a streamlined genetic forensics assay that does not require DNA sequencing to identify basking shark products. The dual-primer, species-specific polymerase chain reaction strategy provides diagnostic redundancy  for robustness in legal venues. It is also effective for identifying basking shark products regardless of geographic origin, an important consideration, given the global distribution of the species and international sourcing of fins to the trade. Application of the assay confirmed the presence of basking shark fins in the Hong Kong and Japan markets, and indicated an apparent relationship between the Chinese fin trader category ‘Nu Wei Tian Jiu’ and fins from basking sharks. The assay was also used in a law enforcement investigation to document illegal trade in basking shark fins in the United States where this species is prohibited from harvest and trade. These trade detections suggest that the high market value of basking shark fins is continuing to drive the exploitation, surreptitious and otherwise, of this highly threatened species, underscoring the need for improved trade monitoring. The streamlined assay developed here can assist in monitoring and conservation on a worldwide scale.

 

Musick, J.A. Burgess, G., Cailliet, G., Camhi, M., Fordham, S. 2000. Management of sharks and their relatives (elasmobranchii). Fisheries, 25 (3): 9-13.

The American Fisheries Society (AFS) recommends that regulatory agencies give shark and ray management high priority because of the naturally slow population growth inherent to most sharks and rays, and their resulting vulnerability to overfishing and stock collapse. Fisheries managers should be particularly sensitive to the vulnerability of less productive species of sharks and rays taken as a bycatch in mixed-species fisheries. The AFS encourages the development and implementation of management plans for sharks and rays in North America. Management practices including regulations, international agreements and treaties should err on the side of the health of the resource rather than short-term economic gain. The AFS encourages the release of sharks and rays taken as bycatch in a survivable condition. Regulatory agencies should mandate full utilization of shark carcasses and prohibit the wasteful practice of finning. Multilateral agreements among fishing nations, or management through regional fisheries management organizations are sorely needed for effective management of wide ranging shark stocks. The AFS encourages its members to become involved by providing technical information needed for protection of sharks and rays to international, federal, state, and provincial policy makers so decisions are made on a scientific, rather than emotional or political, basis.

 

  1. Oceana 2010. The international trade of shark fins: endangering shark populations worldwide. Washington, D.C. 2 p.

 

  1. Clarke et al. 2006. Global estimates of shark catches using trade records from commercial markets. Ecology Letter, 9: 1115-1126.

Despite growing concerns about overexploitation of sharks, lack of accurate, speciesspecific

harvest data often hampers quantitative stock assessment. In such cases, trade studies can provide insights into exploitation unavailable from traditional monitoring. We applied Bayesian statistical methods to trade data in combination with genetic identification to estimate by species, the annual number of globally traded shark fins, the most commercially valuable product from a group of species often unrecorded in harvest statistics. Our results provide the first fishery-independent estimate of the scale of shark catches worldwide and indicate that shark biomass in the fin trade is three to four times higher than shark catch figures reported in the only global data base. Comparison of our estimates to approximated stock assessment reference points for one of the most commonly traded species, blue shark, suggests that current trade volumes in numbers of sharks are close to or possibly exceeding the maximum sustainable yield levels.

 

  1. Shivji, M., Clarke, S., Pank, M., Natanson, M., Kohler, N. et al. 2002. Genetic identification of pelagic shark body parts for conservation monitoring. Conservation biology, 16 (4): 1036-1047.

The conservation and management of sharks on a species-specific basis is a pressing need because of the escalating demand for shark fins and the recognition that individual shark species respond differently to exploitation. Difficulties with the identification of many commonly fished sharks and their body parts has resulted in a global dearth of catch and trade information, making reliable assessment of exploitation effects and conservation needs for individual species nearly impossible. We developed and tested a highly streamlined molecular genetic approach based on species-specific, polymerase-chain-reaction primers in an eight-primer multiplex format to discriminate simultaneously between body parts from six shark species common in worldwide pelagic fisheries. The species-specific primers are based on DNA sequence differences among species in the nuclear ribosomal internal transcribed spacer 2 locus. The primers and multiplex format accurately and sensitively distinguished samples from each of three lamnid ( Isurus oxyrinchus , Isurus paucus , and Lamna nasus ) and three carcharhinid ( Prionace glauca , Carcharhinus obscurus , and Carcharhinus falciformis ) species from all but one other shark species encountered in the North Atlantic fishery. Furthermore, the three lamnid primers were robust enough in their discriminatory power to be useful for species diagnosis on a global scale. Preliminary testing of dried fins from Asian and Mediterranean commercial markets suggests that our genetic approach will be useful for determining the species of origin of detached fins, thus allowing the monitoring of trade in shark fins for conservation assessment. Our approach will also facilitate detection of products from protected and other at-risk shark species and may prove useful as a model for development of the high-throughput, genetic, species-diagnosis methods typically required in conservation and management contexts.

 

  1. Shivji, M., Chapman, D., Pikitch, E., Raymond, P. 2005. Genetic profiling reveals illegal international trade in fins of the great white shark, Carcharodon carcharias. Conservation Genetics (2005) 6:1035-1039.

 

  1. Stade, K. 2011.  Fisheries Observers Told To Turn Blind Eye To Violations — Shark Finning, Pollution and Safety Complaints Trigger Reprisal, Not Enforcement.  Public Employees for Environmental Responsibility. Dec. 1, 2011. http://www.peer.org/news/news_id.php?row_id=1538.

 

  1. Stevens, J.D., Bonfill, R., Dulvy, N.K., Wakler, P.A. 2000. The effects on sharks, rays, and chimaeras (chondrichthyans), and the  implications for ecosystems. J. of Marine Science, 57: 476-494.

The impact of fishing on chondrichthyan stocks around the world is currently the focus of considerable international concern. Most chondrichthyan populations are of low productivity relative to teleost fishes, a consequence of their different life-history strategies. This is reflected in the poor record of sustainability of target shark fisheries. Most sharks and some batoids are predators at, or near, the top of marine food webs. The effects of fishing are examined at the single-species level and through trophic interactions. We summarize the status of chondrichthyan fisheries from around the world. Some 50% of the estimated global catch of chondrichthyans is taken as by-catch, does not appear in official fishery statistics, and is almost totally unmanaged. When taken as by-catch, they are often subjected to high fishing mortality directed at teleost target species. Consequently, some skates, sawfish, and deep-water dogfish have been virtually extirpated from large regions. Some chondrichthyans are more resilient to fishing and we examine predictions on the vulnerability of different species based on their life-history and population parameters. At the species level, fishing may alter size structure and population parameters in response to changes in species abundance. We review the evidence for such density-dependent change. Fishing can affect trophic interactions and we examine cases of apparent species replacement and shifts in community composition. Sharks and rays learn to associate trawlers with food and feeding on discards may increase their populations. Using ECOSIM, we make some predictions about the long-term response of ecosystems to fishing on sharks. Three different environments are analysed: a tropical shelf ecosystem in Venezuela, a Hawaiian coral reef ecosystem, and a North Pacific oceanic ecosystem.

 

  1. Valenti, S. 2008. You can swim but you can’t hide: the global status and conservation of oceanic pelagic sharks and rays. Aquatic Conservation: Marine and Freshwater Ecosystems

 

  1. Vannuccini, S.  1999.  Shark Utilization, Marketing and Trade.  FAO Fisheries Technical Paper 389, Rome, 470 pp.

 

  1. Verlecar, X. N., Desai, S.S.R., Dhargalker, V.K. 2007. Shark hunting – an indiscriminate trade endangering elasmobranchs to exctinction. Current science, 92 (8): 1078-1082.

Shark finning – chopping-off the fins and discarding the rest – is increasing worldwide to satisfy the demand of shark-fin soup. This massive requirement for shark fins and other shark-related products has created an industry motivated by high returns. Reaching figures of up to US$ 116/kg, shark fins have become one of the world’s most precious commodities. India has rich resources of elasmobranchs. Of this, annual shark production has been around 45,500 tonnes, obtained as a by-catch from a variety of gears. Shark-fin export in India reached its peak in 1995 with 303 tonnes, while a second peak was in 2001. Indian shark fins have been processed and marketed in many forms. Some of the shark-fin products have large market demand. Intricate techniques used for grading, processing and packaging of shark fin add to the product value. Overfishing due to increased demand has endangered many shark species. Mitigation measures are required to save the primitive species from becoming extinct. Identification of sharks based on fins, to track species being overfished has been a difficult task so far. However, recent developments on DNA-based forensic techniques have made the problem somewhat easy. This method of identifying sharks from the fins earmarked for export, could serve well to implement control measures to this unscrupulous trade and save the stocks under depletion.

References on Overfishing Sharks

  1. Myers, R.A., Baum, J.K., Shepherd, T., Powers, S.P. & Peterson, C.H. (2007). Cascading effects of the loss of apex predatory sharks from a coastal ocean. Science, 315, 1846–1850.
  2. MacKenzie B.R., Mosegaard H. & Rosenberg A.A. (2009). Impending collapse of bluefin tuna in the northeast Atlantic and Mediterranean. Conservation Letters, 2, 25-34.

IUCN Red List.

  1. Schindler, D.E., Essington, T.E., Kitchell, J.F., Boggs, C. & Hilborn, R. (2002). Sharks and tunas: fisheries impacts on predators with contrasting life histories. Ecological Applications, 12, 735–748.
  2. Compagno, L.J.V. (1990). Alternative life-history styles of cartilaginous fishes in time and space. Environmental Biology of Fishes, 28, 33–75.
  3. Bascompte, J., Melia´n, C.J. & Sala, E. (2005). Interaction strength combinations and the overfishing of a marine food web. Proceedings of the National Academy of Sciences U.S.A., 102, 5443–5447.
  4. Ferretti, F., Worm, B., Britten, G.L., Heithaus M.R. & Lotze H.K. (2010). Patterns and ecosystem consequences of shark declines in the ocean. Ecology Letters, 13, 1055-1071.
  5. Ripple, W.J. & Beschta, R.L. (2007). Restoring Yellowstone’s aspen with wolves. Biological Conservation, 138, 514–519.
  6. van der Elst, R.P. (1979). A proliferation of small sharks in the shore-based Natal sport fishery. Environmental Biology of Fishes, 4, 349–362.
  7. Dudley, S.F.J. & Cliff, G. (1993). Some effect of shark nets in the Natal nearshore environment. Environmental Biology of Fishes, 36, 243–255.
  8. Pradervand, P., Mann, B.Q. & Bellis, M.F. (2007). Long-term trends in the competitive shore fishery along the KwaZulu-Natal coast, South Africa. African Zoology, 42, 216–236.
  9. Heithaus, M.R., Frid, A., Wirsing, A.J. & Worm, B. (2008). Predicting ecological consequences of marine top predator declines. Trends in Ecology and Evolution., 4, 202–210.
  10. Frid, A., Dill, L.M., Thorne, R.E. & Blundell, G.M. (2007). Inferring prey perception of relative danger in large-scale marine systems. Evolutionary Ecology Research, 9, 635–649.
  11. Ellis, J.K. & Musick, J.A. (2007). Ontogenetic changes in the diet of the sandbar shark, Carcharhinus plumbeus, in lower Chesapeake Bay and Virginia (USA) coastal waters. Environironal Biology of Fishes, 80, 51–60.
  12. Kitchell, J.F., Essington, T.E., Boggs, C.H., Schindler, D.E. & Walters, C.J. (2002). The role of sharks and longline fisheries in a pelagic ecosystem of the Central Pacific. Ecosystems, 5, 202–216.