Shark bycatch in the experimental tuna longline fishery in Lakshadweep Sea, India

2015 ◽  
Vol 31 (2) ◽  
pp. 301-307 ◽  
Author(s):  
K. V. Aneesh Kumar ◽  
P. Pravin ◽  
B. Meenakumari ◽  
P. S. Khanolkar ◽  
M. V. Baiju
Keyword(s):  
Longline Fishery ◽  
Tuna Longline ◽  
Lakshadweep Sea

Reproductive biology of the pelagic stingray, Pteroplatytrygon violacea (Bonaparte, 1832), in the equatorial and south-western Atlantic Ocean

2014 ◽  
Vol 65 (11) ◽  
pp. 1035 ◽  
Author(s):  
D. P. Veras ◽  
F. H. V. Hazin ◽  
I. S. L. Branco ◽  
M. T. Tolotti ◽  
G. H. Burgess
Keyword(s):  
Sex Ratio ◽  
Atlantic Ocean ◽  
Reproductive Biology ◽  
Sexual Maturity ◽  
Pregnant Female ◽  
Longline Fishery ◽  
Western Atlantic ◽  
Pregnant Females ◽  
Size At Birth ◽  
Tuna Longline

From October 2005 to March 2010, a total of 480 pelagic stingray, Pteroplatytrygon violacea, specimens, 188 females and 292 males (0.64 female : 1 male), were taken in the equatorial and south-western Atlantic by the commercial tuna longline fishery and their reproductive biology was studied. Disc widths (DW) ranged from 28.0 to 66.0 cm for females and from 34.0 to 59.6 cm for males. Size at first sexual maturity was estimated at ~48.0 cm DW (first pregnant female) for females and ~41.0 cm DW for males. Ovarian fecundity, considering only follicles larger than 0.5 cm in diameter, ranged from 1 to 17 follicles per female, while the uterine fecundity of embryos in pregnant females in Stages 2 and 3 ranged from 1 to 5 embryos per female. The sex ratio between the embryos was almost equal (1.08 female : 1 male) and the size at birth was 19.0 cm DW.

scholarly journals Bycatch of sharks in Korean tuna longline fishery

2007 ◽  
Vol 43 (4) ◽  
pp. 329-338 ◽  
Author(s):  
Dae-Yeon Moon ◽  
Seon-Jae Hwang ◽  
Doo-Hae An ◽  
Soon-Song Kim
Keyword(s):  
Longline Fishery ◽  
Tuna Longline

Pelagic shark bycatch in the New Zealand tuna longline fishery

2001 ◽  
Vol 52 (2) ◽  
pp. 165 ◽  
Author(s):  
Malcolm P. Francis ◽  
Lynda H. Griggs ◽  
Susan Jane Baird
Keyword(s):  
New Zealand ◽  
Pacific Ocean ◽  
Temporal Trends ◽  
Longline Fishery ◽  
Catch Per Unit Effort ◽  
Prionace Glauca ◽  
Isurus Oxyrinchus ◽  
Males And Females ◽  
North And South ◽  
Tuna Longline

Tuna longline effort declined from 23—26 million hooks per year in 1979mdash;82 to 2mdash;4 million hooks per year in 1995mdash;98. Scientific observer coverage averaged 7.5%since 1988mdash;89, but increased in 1992mdash;93 (mean 23%). Observed catch per unit effort (CPUE) and the numbers of hooks set were used to estimate shark catches. Between 1988mdash;89 and 1997mdash;98,about 450 000 blue sharks (Prionace glauca), 65 000 porbeagles (Lamna nasus ) and 25 000 shortfin makos (Isurus oxyrinchus) were caught. In 1997mdash;98,about 45 000 blue sharks, 4000 porbeagles and 3000 makos were caught. Corresponding weight estimates were 1400 t, 150 t and 200 t. CPUE varied between foreign and domestic vessels, between north and south regions and among years, but there were no consistent temporal trends. Most males and females were immature, and most sharks were alive when recovered. Most sharks were processed, but usually only the fins were retained. The New Zealand tuna longline fishery is probably not seriously affecting pelagic shark stocks, but adequate assessment is not currently feasible. Accurate monitoring of Pacific Ocean catches is an important first step towards ensuring sustainability of their populations.

scholarly journals Distribution and trend in abundance of the porbeagle (Lamna nasus) in the southern hemisphere

2013 ◽  
Vol 64 (6) ◽  
pp. 518 ◽  
Author(s):  
Yasuko Semba ◽  
Kotaro Yokawa ◽  
Hiroaki Matsunaga ◽  
Hiroshi Shono
Keyword(s):  
Southern Hemisphere ◽  
Longline Fishery ◽  
Effective Management ◽  
Catch Per Unit Effort ◽  
Limited Region ◽  
Cape Of Good Hope ◽  
Tasman Sea ◽  
The Indian Ocean ◽  
By Catch ◽  
Tuna Longline

Knowledge of a species’ distribution is an important element in its effective management and conservation. The porbeagle (Lamna nasus) is a common by-catch shark in the tuna longline fishery in the southern hemisphere, but its distribution and abundance are largely unknown. The investigation of observer data from the tuna longline fishery and other fishery survey data has revealed that (1) porbeagles are distributed in the pelagic waters across the oceans of the southern hemisphere, (2) juveniles and adults are distributed in cooler environments than are neonates, (3) pregnant females occur in the pelagic waters of the Indian Ocean and the Tasman Sea, most being frequently recorded around the Cape of Good Hope between June and July and (4) the standardised catch per unit effort (CPUE) based on tuna longline fishery (1994–2011) and driftnet survey (1982–1990) data indicate no continuous decreasing trend in the abundance of the southern porbeagle, contrary to the declining trend reported in a limited region in the South Atlantic. Considering its circumglobal distribution, stock status of this population should be assessed using information from the areas of its major distribution, including pelagic waters, and international coordination across oceans is necessary for the effective management of this population.

scholarly journals Bycatch Estimates From a Pacific Tuna Longline Fishery Provide a Baseline for Understanding the Long-Term Benefits of a Large, Blue Water Marine Sanctuary

2021 ◽  
Vol 8 ◽  
Author(s):  
Vanessa Jaiteh ◽  
Tom Peatman ◽  
Steve Lindfield ◽  
Eric Gilman ◽  
Simon Nicol
Keyword(s):  
Electronic Monitoring ◽  
Retention Rate ◽  
Fishing Effort ◽  
Longline Fishery ◽  
Vulnerable Species ◽  
Fishing Mortality ◽  
Population Declines ◽  
Management Tools ◽  
Catch Rates ◽  
Tuna Longline

Bycatch on pelagic tuna longlines has contributed to population declines in several far-ranging, oceanic species and presents a conservation challenge that area-based management tools are increasingly promoted to address. In January 2020 the Republic of Palau, concerned about the impacts of longline fishing in its waters, closed 80% of its exclusive economic zone to all extractive activities, reserving the remaining 20% for a domestic fishing zone (DFZ). One of a growing number of very large marine protected areas, the Palau National Marine Sanctuary (PNMS) spans ∼500,000 km2 and was established inter alia to allow for the recovery of fish stocks adversely impacted by tuna longline fleets. Given that the main tuna stocks targeted in the western Pacific are not overexploited, the benefits of protection potentially afforded by the sanctuary are likely greater for vulnerable bycatch species. Evaluations of the sanctuary’s performance require, in part, a baseline of historical catch rates and effort distribution in the distant-water fleet (DWF) and locally based fleet (LBF) operating in Palau prior to sanctuary implementation. We describe the fishing effort, catch rates, catch estimates and fishing mortality in Palau’s longline fishery based on logbook, observer and electronic monitoring data. We defined bycatch as any species, retained or discarded, other than targeted tunas. Between 2010 and 2020, 104.8 million hooks were deployed, catching over 2 million individuals from 117 taxa at an overall target:bycatch ratio of 1:1, with a retention rate of ∼62%. Pronounced differences in fishing strategies and spatial distribution of effort between fleets were associated with large variations in catch rates and composition. The LBF had a larger effect on populations of at-risk species relative to the DWF, with higher catch rates and magnitudes for several vulnerable species and higher observable fishing mortality rates (64% vs 50% in the DWF). The sanctuary reshaped Palau’s longline fishery, contracting the fishery’s area and capacity. The relocation of the DFZ eliminated the LBF and constrained the DWF to an area where the fleet’s total catch rates and those of a number of vulnerable species were historically lower relative to former fishing grounds now closed by the sanctuary. Our results highlight the importance of consistent bycatch monitoring and emphasize the need for regional area-based approaches for managing longline fisheries.

Sign in / Sign up

Export Citation Format

Share Document