Size-selective catch by fishing operation technique in tropical tuna purse seine fishery in the Western Indian Ocean: Feasibility of free school operation for skippers

2016 ◽  
Vol 82 (3) ◽  
pp. 405-416
Author(s):  
Watcharapong Chumchuen ◽  
Tatsuro Matsuoka ◽  
Kazuhiko Anraku ◽  
Wilailux Premkit
Keyword(s):  
Indian Ocean ◽  
Western Indian Ocean ◽  
Purse Seine ◽  
Operation Technique ◽  
Free School ◽  
Tropical Tuna ◽  
Purse Seine Fishery

Size-selective catch in tropical tuna purse seine fishery in the Eastern Indian Ocean: Assessment on new selectivity model for purse seine net

2016 ◽  
Vol 82 (3) ◽  
pp. 391-404 ◽  
Author(s):  
Watcharapong Chumchuen ◽  
Tatsuro Matsuoka ◽  
Kazuhiko Anraku ◽  
Sukchai Arnupapboon
Keyword(s):  
Indian Ocean ◽  
Purse Seine ◽  
Eastern Indian Ocean ◽  
Selectivity Model ◽  
Tropical Tuna ◽  
Purse Seine Fishery

Monitoring of Spanish flagged purse seine fishery targeting tropical tuna in the Indian ocean: Timeline and history

Marine Policy ◽  
2020 ◽  
Vol 119 ◽  
pp. 104094
Author(s):  
José Carlos Báez ◽  
María Lourdes Ramos ◽  
Miguel Herrera ◽  
Hilario Murua ◽  
José Luis Cort ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Purse Seine ◽  
The Indian Ocean ◽  
Tropical Tuna ◽  
Purse Seine Fishery

scholarly journals Mortality rate of silky sharks (Carcharhinus falciformis) caught in the tropical tuna purse seine fishery in the Indian Ocean

2014 ◽  
Vol 71 (6) ◽  
pp. 795-798 ◽  
Author(s):  
François Poisson ◽  
John David Filmalter ◽  
Anne-Lise Vernet ◽  
Laurent Dagorn
Keyword(s):  
Mortality Rate ◽  
Indian Ocean ◽  
Purse Seine ◽  
The Indian Ocean ◽  
Carcharhinus Falciformis ◽  
Handling Practices ◽  
Tropical Tuna ◽  
Harsh Conditions ◽  
Purse Seine Fishery ◽  
Overall Mortality

Scientists aboard French purse seine vessels recorded the number and condition of silky sharks (Carcharhinus falciformis) caught during three fishing cruises in the Indian Ocean. A sample of 31 individuals that showed signs of life were tagged with satellite tags to investigate their postrelease mortality. The majority of individuals (95%) were brought on board using the brailer. Combining the proportion of sharks that were dead (72%) and the mortality rate of those released (48%), the overall mortality rate of brailed individuals was 85%. Few individuals (5%) were not brailed as they were entangled and landed during the hauling process. The survival rate of these individuals was high, with an overall mortality rate of meshed individuals of 18%. The combination of these two categories led to an overall mortality rate of 81%. This high value reflects the harsh conditions encountered by sharks during the purse seine fishing process. Consequently, methods that prevent sharks being brought on board are a priority for future investigations, but good handling practices should also be promoted as they could reduce mortality by at least 19%.

Behaviour and vulnerability of target and non-target species at drifting fish aggregating devices (FADs) in the tropical tuna purse seine fishery determined by acoustic telemetry

2015 ◽  
Vol 72 (9) ◽  
pp. 1398-1405 ◽  
Author(s):  
Fabien G. Forget ◽  
Manuela Capello ◽  
John D. Filmalter ◽  
Rodney Govinden ◽  
Marc Soria ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Acoustic Telemetry ◽  
Western Indian Ocean ◽  
Purse Seine ◽  
Management Approach ◽  
Target Species ◽  
Tropical Tuna ◽  
Fish Aggregating Devices ◽  
The Vertical Distribution ◽  
Purse Seine Fishery

Characterizing the vulnerability of both target and non-target (bycatch) species to a fishing gear is a key step towards an ecosystem-based fisheries management approach. This study addresses this issue for the tropical tuna purse seine fishery that uses fish aggregating devices (FADs). We used passive acoustic telemetry to characterize, on a 24 h scale, the associative patterns and the vertical distribution of skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), and bigeye tuna (Thunnus obesus) (target species), as well as silky shark (Carcharhinus falciformis), oceanic triggerfish (Canthidermis maculata), and rainbow runner (Elagatis bipinnulata) (major non-target species). Distinct diel associative patterns were observed; the tunas and the silky sharks were more closely associated with FADs during daytime, while the rainbow runner and the oceanic triggerfish were more closely associated during the night. Minor changes in bycatch to catch ratio of rainbow runner and oceanic triggerfish could possibly be achieved by fishing at FADs after sunrise. However, as silky sharks display a similar associative pattern as tunas, no specific change in fishing time could mitigate the vulnerability of this more sensitive species. For the vertical distribution, there was no particular time of the day when any species occurred beyond the depth of a typical purse seine net. While this study does not provide an immediate solution to reduce the bycatch to catch ratios of the FAD-based fishery in the western Indian Ocean, the method described here could be applied to other regions where similar fisheries exist so as to evaluate potential solutions to reducing fishing mortality of non-target species.

Catch and bycatch captured by tropical tuna purse-seine fishery in whale and whale shark associated sets: comparison with free school and FAD sets

2018 ◽  
Vol 28 (2) ◽  
pp. 467-499 ◽  
Author(s):  
Lauriane Escalle ◽  
Daniel Gaertner ◽  
Pierre Chavance ◽  
Hilario Murua ◽  
Monique Simier ◽  
...  
Keyword(s):  
Purse Seine ◽  
Whale Shark ◽  
Free School ◽  
Tropical Tuna ◽  
Purse Seine Fishery

scholarly journals Post-release survival of juvenile silky sharks captured in a tropical tuna purse seine fishery

2015 ◽  
Vol 521 ◽  
pp. 143-154 ◽  
Author(s):  
MR Hutchinson ◽  
DG Itano ◽  
JA Muir ◽  
KN Holland
Keyword(s):  
Purse Seine ◽  
Tropical Tuna ◽  
Purse Seine Fishery

scholarly journals Precision in bycatch estimates: the case of tuna purse-seine fisheries in the Indian Ocean

2012 ◽  
Vol 69 (8) ◽  
pp. 1501-1510 ◽  
Author(s):  
Monin J. Amandè ◽  
Emmanuel Chassot ◽  
Pierre Chavance ◽  
Hilario Murua ◽  
Alicia Delgado de Molina ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Linear Models ◽  
Purse Seine ◽  
Reliable Estimate ◽  
Routine Practice ◽  
Marine Animals ◽  
Trade Offs ◽  
The Indian Ocean ◽  
Current Sampling ◽  
Tropical Tuna

Abstract Amandè, M. J., Chassot, E., Chavance, P., Murua, H., Delgado de Molina, A., and Bez, N. 2012. Precision in bycatch estimates: the case of tuna purse-seine fisheries in the Indian Ocean. – ICES Journal of Marine Science, 69: . Estimating bycatch, i.e. the incidental catch of non-target marine animals and undersized individuals of target species, by raising observer data to the whole fishery is routine practice. The annual bycatch of the European tropical tuna purse-seine fishery over the period 2003–2009 was estimated at 11 590 t [95% confidence interval: (8165–15 818 t)], corresponding to 4.7% of the tuna landings. An analysis of the variability in the precision of this estimate, based on generalized linear models and Monte Carlo simulations, showed that the current sampling coverage of the tropical tuna fishery observer programme, which is 4.6% of the fishing trips, resulted in large uncertainties in bycatch estimates by species, i.e. none of the estimates have a relative root mean square error smaller than 50%. Although the overall magnitude of bycatch of the fishery appeared to be small, the current sampling coverage was insufficient to give any reliable estimate for low-occurring species, such as marine turtles, some oceanic pelagic sharks, and some billfishes. Increasing the sampling coverage would likely improve bycatch estimates. Simulation outputs were produced to help define (i) trade-offs between the priority species to be monitored, (ii) the estimation precision, (iii) expected accuracy, and (iv) the associated sampling costs.

scholarly journals High levels of halogenated natural products in large pelagic fish from the Western Indian Ocean

2021 ◽  
Author(s):  
Qiong Wu ◽  
Catherine Munschy ◽  
Yann Aminot ◽  
Nathalie Bodin ◽  
Walter Vetter
Keyword(s):  
Natural Products ◽  
Indian Ocean ◽  
Fish Species ◽  
Western Indian Ocean ◽  
Pelagic Fish ◽  
Negative Ion ◽  
Selected Ion Monitoring ◽  
Negative Ion Mass Spectrometry ◽  
Halogenated Natural Products ◽  
Tropical Tuna

AbstractConcentrations, profiles and muscle-liver distribution of halogenated natural products (HNPs) and anthropogenic persistent organic pollutants (POPs) were investigated in five large pelagic fish species and one smaller planktivore fish species from the Western Indian Ocean. Analysis of swordfish muscle from the Seychelles revealed the predominance of HNPs, with the highest concentrations found for 2′-methoxy-2,3′,4,5′- tetraBDE (2′-MeO-BDE 68 or BC-2), 6-methoxy-2,2′,4,4′- tetraBDE (6-MeO-BDE 47 or BC-3) and 2,3,3′,4,4′,5,5′-heptachloro-1′-methyl-1,2′-bipyrrole (Q1), along with varied contributions of further HNPs. The mean concentration of ∑HNPs (330 ng/g lw) was one or two orders of magnitude higher than ∑DDTs (60 ng/g lw) and ∑PCBs (6.8 ng/g lw). HNPs (BC-2, BC-3 and Q1) were also predominant in individual samples of three tropical tuna species from the Seychelles and from other regions of the Western Indian Ocean (Mozambique Channel, off Somalia and Chagos Archipelago). Non-targeted gas chromatography coupled with electron capture negative ion mass spectrometry operated in the selected ion monitoring mode (GC/ECNI-MS-SIM) analysis of one swordfish sample indicated low abundance of rarely reported HNPs (three hexachloro-1′-methyl-1,2′-bipyrrole (Cl6-MBP) isomers and pentabromo-1,1′-dimethyl-2,2′-bipyrroles (Br5-DBP)) but no further abundant unscreened polyhalogenated compounds.

scholarly journals Fish behaviour from fishers’ knowledge: the case study of tropical tuna around drifting fish aggregating devices (DFADs)

2007 ◽  
Vol 64 (11) ◽  
pp. 1517-1528 ◽  
Author(s):  
Gala Moreno ◽  
Laurent Dagorn ◽  
Gorka Sancho ◽  
David Itano
Keyword(s):  
Indian Ocean ◽  
Local Ecological Knowledge ◽  
Western Indian Ocean ◽  
Future Research ◽  
Ecological Knowledge ◽  
Fish Behaviour ◽  
Planning And Design ◽  
Tropical Tuna ◽  
Fish Aggregating Devices

Purse-seining for tropical tuna is one of the most technologically advanced fisheries in the world. The purpose of this study was to apply local ecological knowledge (LEK) to assist in the planning of future in situ studies of fish behaviour around drifting fish aggregating devices (DFADs) by prioritizing research topics, thereby reducing the number of potential hypotheses to explore. Interviews of fishing masters of the purse-seine fleets working in the western Indian Ocean provided an alternate, independent, and previously unexplored source of behavioural information, specifically on the attraction, retention, and departure behaviours of tuna schools in relation to DFADs. Most fishing masters agreed that the maximum attraction distance of a DFAD is approximately 10 km and generally agreed to the following statements. Tuna form distinct schools under FADs, commonly segregated by species and size. The main reasons for the departure of tuna aggregations from FADs are changes in currents or FAD movements and location in relation to physical or oceanographic features. The number of actively monitored DFADs at sea in the western Indian Ocean was estimated at approximately 2100. Incorporating fishers into the planning and design stages of future research projects will facilitate collaborative and integrated approaches.

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