Fuel consumption of free-swimming school versus FAD strategies in tropical tuna purse seine fishing

Abstract Numerous pelagic species are known to associate with floating objects (FOBs), including tropical tunas. Purse seiners use this behaviour to facilitate the capture of tropical tunas by deploying artificial drifting fish aggregating devices (dFADs). One major recent change has been the integration of echosounders in satellite-tracked GPS buoys attached to FOBs, allowing fishers to remotely estimate fishable biomass. Understanding the effects of this new technology on catch of the three main tuna species (yellowfin tuna, Thunnus albacares; bigeye tuna, Thunnus obesus; and skipjack tuna, Katsuwonus pelamis) is important to accurately correct for this change in catch-per-unit-effort (CPUE) indices used for stock assessments. We analysed catch data from the French purse seine fleet for the period 2010–2017 in the Indian Ocean to assess the impact of this fleet’s switch to echosounder buoys around 2012. Results indicate that echosounders do not increase the probability a set will be succesful, but they have a positive effect on catch per set, with catches on average increasing by ≈2−2.5 tonnes per set (≈10%) when made on the vessel's own dFADs equipped with an echosounder buoy. Increases were due to a decrease in sets below ≈25 tonnes and an increase in those greater than ≈25 tonnes, with a non-linear transition around this threshold. This increase explains the considerable investment of purse seiners in echosounder buoys, but also raises concerns about bias in stock size estimates based on CPUE if we do not correct for this fishing efficiency increase.

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Fishing on floating objects (FOBs): how French tropical tuna purse seiners split fishing effort between GPS-monitored and unmonitored FOBs

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2017-0152 ◽

2018 ◽

Vol 75 (11) ◽

pp. 1849-1858 ◽

Cited By ~ 2

Author(s):

Julia E. Snouck-Hurgronje ◽

David M. Kaplan ◽

Emmanuel Chassot ◽

Alexandra Maufroy ◽

Daniel Gaertner

Keyword(s):

Search Time ◽

Fishing Effort ◽

Purse Seine ◽

Trajectory Data ◽

Catch Per Unit Effort ◽

Position Information ◽

Foreign Objects ◽

Tropical Tuna ◽

Floating Objects ◽

Over Time

Fishing on floating objects (FOBs) dominates catch in tropical tuna purse seine fisheries. One frequently cited advantage of deploying GPS-monitored FOBs is that the position information can be used for directed fishing to reduce search time for tuna. However, purse seiners also fish on foreign objects for which position information is not available. It is critical to quantify the prevalence of fishing on GPS-monitored versus unmonitored FOBs to understand how they impact fishing effort and catch per unit effort. We analyzed French commercial, observer, and FOB trajectory data in the Atlantic and Indian oceans to determine how often purse seine vessels fish on GPS-monitored FOBs. Only 2.7%–20.4% of French FOB fishing sets over 2007–2013 in both oceans were made on GPS-monitored FOBs. Though increasing over time, the low percentage suggests that French vessels do not primarily use GPS-monitored FOBs to reduce search time for tuna. We hypothesize that fishery-wide FOB deployments have important collective consequences for overall fishing effort and recommend that future effort metrics should be based on fishery-wide FOB activities.

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Use of light-emitting diode (LED) lamps in combination with metal halide (MH) lamps reduce fuel consumption in the Vietnamese purse seine fishery

Aquaculture and Fisheries ◽

10.1016/j.aaf.2020.07.011 ◽

2020 ◽

Author(s):

Khanh Q. Nguyen ◽

Phu D. Tran ◽

Luong T. Nguyen ◽

Phuong V. To ◽

Corey J. Morris

Keyword(s):

Fuel Consumption ◽

Light Emitting Diode ◽

Metal Halide ◽

Purse Seine ◽

Reduce Fuel Consumption ◽

Light Emitting ◽

Purse Seine Fishery

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Targeting bigger schools can reduce ecosystem impacts of fisheries

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f2012-089 ◽

2012 ◽

Vol 69 (9) ◽

pp. 1463-1467 ◽

Cited By ~ 20

Author(s):

Laurent Dagorn ◽

John D. Filmalter ◽

Fabien Forget ◽

Monin Justin Amandè ◽

Martin A. Hall ◽

...

Keyword(s):

Total Yield ◽

Substantial Reduction ◽

Management Approach ◽

Resource Exploitation ◽

Free Swimming ◽

Ecosystem Impacts ◽

Set Size ◽

Living Resource ◽

Tropical Tuna ◽

Fish Aggregating Devices

Sustainability of living resource exploitation relies on an ecosystem management approach. Within tropical tuna purse seine fisheries using fish aggregating devices (FADs), such an approach incorporates the reduction of bycatch, in particular vulnerable species such as elasmobranchs. The levels of total bycatch (in mass) from fishing operations using FADs is known to be five times higher than when tuna are caught in free-swimming schools. We intend to find practical solutions to reduce bycatch in FAD sets through the investigation of the relationships between the ratio of bycatch to target catch across different set size classes in all oceans. Ratios were always highest when catches were small, with the smallest class of catches responsible for the highest total portion of bycatch (23%–43%) while only contributing negligibly to the total target catch (3%–10%). Reducing the number of fishing sets (a part of the total effort) while maintaining the same total yield could contribute to a substantial reduction in the impacts of human activities.

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Increasing the economic value of the eastern Pacific Ocean tropical tuna fishery: Tradeoffs between longline and purse-seine fishing

Deep Sea Research Part II Topical Studies in Oceanography ◽

10.1016/j.dsr2.2019.07.009 ◽

2019 ◽

Vol 169-170 ◽

pp. 104621 ◽

Cited By ~ 2

Author(s):

Chin-Hwa Sun (Jenny) ◽

Mark N. Maunder ◽

Minling Pan ◽

Alexandre Aires-da-Silva ◽

William H. Bayliff ◽

...

Keyword(s):

Pacific Ocean ◽

Economic Value ◽

Eastern Pacific ◽

Purse Seine ◽

Eastern Pacific Ocean ◽

Tropical Tuna ◽

Tuna Fishery

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

Marine Ecology Progress Series ◽

10.3354/meps11073 ◽

2015 ◽

Vol 521 ◽

pp. 143-154 ◽

Cited By ~ 40

Author(s):

MR Hutchinson ◽

DG Itano ◽

JA Muir ◽

KN Holland

Keyword(s):

Purse Seine ◽

Tropical Tuna ◽

Purse Seine Fishery

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Action Research in Tropical Tuna Purse Seine Fisheries: Thoughts and Perspectives

Collaborative Research in Fisheries - MARE Publication Series ◽

10.1007/978-3-030-26784-1_12 ◽

2020 ◽

pp. 193-212

Author(s):

Manon Airaud ◽

Laurent Tezenas ◽

Gala Moreno ◽

Laurent Dagorn ◽

Jefferson Murua

Keyword(s):

Action Research ◽

Purse Seine ◽

Tropical Tuna

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

ICES Journal of Marine Science ◽

10.1093/icesjms/fss106 ◽

2012 ◽

Vol 69 (8) ◽

pp. 1501-1510 ◽

Cited By ~ 33

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.

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