Transboundary movements, unmonitored fishing mortality, and ineffective international fisheries management pose risks for pelagic sharks in the Northwest Atlantic

2016 ◽  
Vol 73 (10) ◽  
pp. 1599-1607 ◽  
Author(s):  
Steven E. Campana
Keyword(s):  
Population Monitoring ◽  
Shark Species ◽  
Management Options ◽  
Blue Shark ◽  
Shortfin Mako ◽  
Large Numbers ◽  
Tuna Fishing ◽  
Fishing Fleets ◽  
National Boundaries ◽  
Satellite Tagging

The shortfin mako (Isurus oxyrinchus), porbeagle (Lamna nasus), and blue shark (Prionace glauca) are three frequently caught shark species in the northwestern Atlantic Ocean. Satellite tagging studies show that all three species range widely across many national boundaries but spend up to 92% of their time on the high seas, where they are largely unregulated and unmonitored. All are caught in large numbers by swordfish and tuna fishing fleets from a large number of nations, usually unintentionally, and all are unproductive by fish standards, which makes them particularly sensitive to fishing pressure. Landing statistics that grossly underrepresent actual catches, unreported discards that often exceed landings, and high discard mortality rates are threats to the populations and roadblocks to useful population monitoring. The influence of these threats is greatly magnified by inattention and ineffective management from the responsible management agency, the International Commission for the Conservation of Atlantic Tunas (ICCAT), whose prime focus is the more valuable swordfish and tuna stocks. Although practical management options are available, none will be possible if organizations like ICCAT continue to treat sharks like pests.

scholarly journals NEW RECORDS AND PRELIMINARY REPRODUCTIVE ASPECTS OF ELASMOBRANCHS OF THE TRINDADE-MARTIN VAZ INSULAR COMPLEX

2021 ◽  
Vol 25 (01) ◽  
pp. 159-165
Author(s):  
Thierry Salmon ◽  
Bianca de Sousa Rangel ◽  
Carlos Eduardo Malavasi-Bruno ◽  
José Roberto Kfoury-Jr
Keyword(s):  
Abundant Species ◽  
Shark Species ◽  
Tiger Shark ◽  
Blue Shark ◽  
Galeocerdo Cuvier ◽  
Shortfin Mako ◽  
New Information ◽  
Thresher Shark ◽  
Pelagic Fishing ◽  
First Time

Here we presented records of elasmobranchs obtained during a longline pelagic fishing monitoring around the Trindade-Martin Vaz insular complex, including one new record. New information on the reproductive aspects of the blue shark (Prionace glauca) and pelagic stingray (Pteroplatytrygon violacea) suggest the use of this area as mating and parturition ground for these species. The most abundant species was the P. glauca (N = 65), followed by shortfin mako shark Isurus oxyrinchus (N = 12). We also recorded for the first time the smooth hammerhead shark Sphyrna zygaena (N = 3) and the bigeye thresher shark Alopias superciliosus (N = 2), and other shark species previous reported for the insular complex, including the oceanic whitetip Carcharhinus longimanus (N = 2), and the tiger shark Galeocerdo cuvier (N = 1). Our findings highlight the importance of further studies at the Trindade-Martin Vaz insular complex considering the pelagic biodiversity and reproductive aspects of elasmobranchs.

Size, sex and reproductive biology of seven pelagic sharks in the eastern Arabian Sea

2016 ◽  
Vol 97 (1) ◽  
pp. 181-196 ◽  
Author(s):  
Sijo P. Varghese ◽  
N. Unnikrishnan ◽  
Deepak K. Gulati ◽  
A. E. Ayoob
Keyword(s):  
Reproductive Biology ◽  
Arabian Sea ◽  
Size Structure ◽  
Shark Species ◽  
Tiger Shark ◽  
Blue Shark ◽  
Substantial Impact ◽  
Shortfin Mako ◽  
Eastern Arabian Sea ◽  
Thresher Shark

Studies on reproduction in sharks are important for their management, since the attainment of sexual maturity has a substantial impact on their distribution, behaviour and biology. However, reproductive biology of large oceanic sharks is poorly studied in the Indian seas. In this study, the size structure, sex and maturity of pelagic thresher (Alopias pelagicus), bigeye thresher (A. superciliosus), oceanic whitetip shark (Carcharhinus longimanus), tiger shark (Galeocerdo cuvier), shortfin mako (Isurus oxyrinchus), longfin mako (I. paucus) and blue shark (Prionace glauca) in the eastern Arabian Sea are described based on 1449 specimens collected from gillnet-cum-longline landings at the Cochin fisheries harbour during 2013–2014. Sex ratios of sampled specimens were biased to males in pelagic thresher, bigeye thresher, tiger shark and blue shark, while females dominated in the specimens of oceanic whitetip shark. Females matured at greater lengths than males in all species except oceanic whitetip shark. Lengths at maturity for males were in the range of 189.05–286.56 cm, whereas those of females were in the range of 187.74–310.69 cm. Litter sizes of both the thresher shark species were always two, while in oceanic whitetip shark, litter size was 3–9 and 22–51 in tiger shark. Seasonal reproduction was noticed in oceanic whitetip shark and tiger shark. Pregnant females were not found in the blue shark, shortfin and longfin makos sampled during the study period. Reproductive aspects of pelagic thresher, bigeye thresher, oceanic whitetip shark, tiger shark, shortfin mako, longfin mako and blue sharks in the eastern Arabian Sea are generally consistent with earlier reports from other regions of the world's oceans. These preliminary findings should be useful to identify suitable management measures for the above shark species.

Connectionist Systems for Fishing Prediction

2006 ◽  
pp. 265-296 ◽  
Author(s):  
Alfonso Iglesias ◽  
Bernardino Arcay ◽  
José M. Cotos
Keyword(s):  
Fuzzy Logic ◽  
Support System ◽  
Digital Image ◽  
Shark Species ◽  
Blue Shark ◽  
Prionace Glauca ◽  
Remote Sensors ◽  
Fishing Boat ◽  
Fishing Resources ◽  
Pelagic Fisheries

This chapter explains the foundations of a new support system for fisheries, based on connectionist techniques, digital image treatment, and fuzzy logic. The purpose of our system is to increase the output of the pelagic fisheries without endangering the natural balance of the fishing resources. It uses data from various remote sensors and the logbook of a collaborating fishing boat to improve the catches of the Prionace Glauca, a pelagic shark species also known as the blue shark.

Cd, Mn, and Zn concentrations in vertebrae of blue shark and shortfin mako in Australian coastal waters

1990 ◽  
Vol 21 (4) ◽  
pp. 203-206 ◽  
Author(s):  
Philip Vas ◽  
John D. Stevens ◽  
Graham A. Bonwick ◽  
Omar A. Tizini
Keyword(s):  
Coastal Waters ◽  
Blue Shark ◽  
Shortfin Mako

scholarly journals Shark fisheries in the Southeast Pacific: A 61-year analysis from Peru

F1000Research ◽  
2014 ◽  
Vol 3 ◽  
pp. 164 ◽  
Author(s):  
Adriana Gonzalez-Pestana ◽  
Carlos Kouri J. ◽  
Ximena Velez-Zuazo
Keyword(s):  
Legal Framework ◽  
Species Level ◽  
Population Parameters ◽  
Blue Shark ◽  
Shortfin Mako ◽  
The Pacific ◽  
High Conservation ◽  
The Pacific Ocean ◽  
The Government ◽  
Level Identification

Peruvian waters exhibit high conservation value for sharks. This contrasts with a lag in initiatives for their management and a lack of studies about their biology, ecology and fishery. We investigated the dynamics of Peruvian shark fishery and its legal framework identifying information gaps for recommending actions to improve management. Further, we investigated the importance of the Peruvian shark fishery from a regional perspective. From 1950 to 2010, 372,015 tons of sharks were landed in Peru. From 1950 to 1969, we detected a significant increase in landings; but from 2000 to 2011 there was a significant decrease in landings, estimated at 3.5% per year. Six species represented 94% of landings: blue shark (Prionace glauca), shortfin mako (Isurus oxyrinchus), smooth hammerhead (Sphyrna zygaena), common thresher (Alopias vulpinus), smooth-hound (Mustelus whitneyi) and angel shark (Squatina californica). Of these, the angel shark exhibits a strong and significant decrease in landings: 18.9% per year from 2000 to 2010. Peru reports the highest accumulated historical landings in the Pacific Ocean; but its contribution to annual landings has decreased since 1968. Still, Peru is among the top 12 countries exporting shark fins to the Hong Kong market. Although the government collects total weight by species, the number of specimens landed as well as population parameters (e.g. sex, size and weight) are not reported. Further, for some genera, species-level identification is deficient and so overestimates the biomass landed by species and underestimates the species diversity. Recently, regional efforts to regulate shark fishery have been implemented to support the conservation of sharks but in Peru work remains to be done

scholarly journals Beyond Post-release Mortality: Inferences on Recovery Periods and Natural Mortality From Electronic Tagging Data for Discarded Lamnid Sharks

2021 ◽  
Vol 8 ◽  
Author(s):  
Heather D. Bowlby ◽  
Hugues P. Benoît ◽  
Warren Joyce ◽  
James Sulikowski ◽  
Rui Coelho ◽  
...  
Keyword(s):  
Survival Data ◽  
Recovery Period ◽  
Age Determination ◽  
Shark Species ◽  
Natural Mortality ◽  
The North ◽  
Covariate Effects ◽  
Shortfin Mako ◽  
Electronic Tagging ◽  
Key Parameter

Accurately characterizing the biology of a pelagic shark species is critical when assessing its status and resilience to fishing pressure. Natural mortality (M) is well known to be a key parameter determining productivity and resilience, but also one for which estimates are most uncertain. While M can be inferred from life history, validated direct estimates are extremely rare for sharks. Porbeagle (Lamna nasus) and shortfin mako (Isurus oxyrinchus) are presently overfished in the North Atlantic, but there are no directed fisheries and successful live release of bycatch is believed to have increased. Understanding M, post-release mortality (PRM), and variables that affect mortality are necessary for management and effective bycatch mitigation. From 177 deployments of archival satellite tags, we inferred mortality events, characterized physiological recovery periods following release, and applied survival mixture models to assess M and PRM. We also evaluated covariate effects on the duration of any recovery period and PRM to inform mitigation. Although large sample sizes involving extended monitoring periods (>90 days) would be optimal to directly estimate M from survival data, it was possible to constrain estimates and infer probable values for both species. Furthermore, the consistency of M estimates with values derived from longevity information suggests that age determination is relatively accurate for these species. Regarding bycatch mitigation, our analyses suggest that juvenile porbeagle are more susceptible to harm during capture and handling, that keeping lamnid sharks in the water during release is optimal, and that circle hooks are associated with longer recovery periods for shortfin mako.

International and National Problems in Fisheries Seabird By-Catch

2008 ◽  
Vol 3 (3) ◽  
pp. 187-195 ◽  
Author(s):  
Haruo Ogi ◽  
Keyword(s):  
Large Scale ◽  
Conservation Areas ◽  
The North ◽  
Common Murre ◽  
Large Numbers ◽  
By Catch ◽  
Fishing Fleets ◽  
Northern Territories ◽  
The Many ◽  
High Seas

Large-scale international fisheries have seen many developments, including the adoption of 200-mile fishing limits by many countries, including Japan, between 1976 and 1977. On the North Pacific high seas, the use of neon flying squid and large-mesh driftnets is expanding rapidly. The many kinds and large numbers of nontargeted species caught in such driftnets, however, influenced world public opinion and the United Nations to prohibit driftnet fishing on the high seas in 1991. The investigation on the consequences of such driftnets have been often failed to be conducted in Japan, because Japan’s fisheries have been downsized. Japan’s fishing industry has not addressed this problem appropriately, even though the authorities have recommended that fishing fleets minimize by-catch. Japan has no legislation designating sea surface conservation for sealife, and fisheries by-catch have dramatically reduced the number of breeding seabirds in isolated habitats. The Japanese murrelet (Synthliboramphus wumizusume) of Miyazaki Prefecture and the common murre (Uria aalge) and the tufted puffin (Lunda cirrhata) of Hokkaido face a serious situation. The number of the spectacled guillemot (Cepphus carbo) living along Tohoku-Hokkaido coast has rapidly decreased due to by-catch fishing. Russia has legislation designating breeding places for seabirds and animals and designating surroundings as conservation areas. The Northern Territory adjoining Hokkaido thus has extremely diverse sea species. Japan has no corresponding legislation to succeed the Russian conservation legislation if Russia should return the Northern Territories to Japan.

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