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Start Over Descriptor "Fish aggregating devices" Publisher elsevier bv
2 results on '"Fish aggregating devices"'

1. The Jelly-FAD: A paradigm shift in the design of biodegradable Fish Aggregating Devices

Author

Moreno, Gala, Salvador, Joaquín, Zudaire, Iker, Murua, Jefferson, Pelegrí, Josep Lluís, Uranga, Jon, Murua, Hilario, Grande, Maitane, Santiago, Josu, Restrepo, Víctor, Food and Agriculture Organization of the United Nations, and Agencia Estatal de Investigación (España)

Subjects
Tuna fisheries, Economics and Econometrics, FAD, Ecosystem impact, Marine Pollution, Management, Monitoring, Policy and Law, Aquatic Science, Ghost fishing, Fish Aggregating Devices, ALDFG, Biodegradable, Law, Responsible Consumption and Production, General Environmental Science
Abstract

Special issue Abandoned, Lost and Discarded Fishing Gear.-- 12 pages, 5 figrues, 2 tables.-- Data availability: The data that has been used is confidential, Fishers and scientists in the tropical Pacific, Atlantic and Indian Oceans are jointly designing biodegradable fish aggregating devices (bio-FADs) that are efficient for fishing. The tactic followed by most fishers to construct bio-FADs is to maintain the same conventional drifting FAD (dFAD) design (i.e., large, submerged net panels hanging from a floating raft) but replacing plastic ropes and netting with organic ropes and canvases. Results from these experiences show that the lifetime of bio-FADs made with conventional FAD designs is notably shorter than what fishers require, thus precluding their adoption. The short lifespan of these bio-FADs is due to the inefficient design of conventional dFADs, which results in major structural stress. Thus, to successfully replace plastic with organic materials and increase the lifespan of bio-FADs, a paradigm shift is needed. Bio-FAD structures should be re-designed to minimize structural stress in the water. The present study summarizes what we have learned from testing bio-FADs in the three tropical oceans, and it proposes a new concept in dFAD design, the jelly-FAD. Mirroring jellyfish, this new dFAD design will aim for quasi-neutral buoyancy, which should reduce (i) the structural stress of the FAD at sea and (ii) the need for additional plastic flotation. The jelly-FAD is not necessarily a fixed design; it is more of a change in the concept of conventional dFAD construction. Preliminary results show that jelly-FADs aggregate tuna as well as conventional FADs do, with lifespans greater than 6 months at sea. In addition, the jelly-FAD showed average drifting speeds similar to a conventional dFAD. To accelerate the adoption of bio-FADs worldwide, recommendations for jelly-FAD construction and tests are provided, Finally, this project would have not been possible without the funding of the FAO-GEF Common Oceans ABNJ Program and the Sarebio project from AZTI, With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

Published
2023

2. Machine learning for characterizing tropical tuna aggregations under Drifting Fish Aggregating Devices (DFADs) from commercial echosounder buoys data

Author

Baidai, Yannick, Dagorn, Laurent, Amande, M.j., Gaertner, Daniel, Capello, Manuela, Baidai, Yannick, Dagorn, Laurent, Amande, M.j., Gaertner, Daniel, and Capello, Manuela

Abstract

The use of echosounder buoys deployed in conjunction with Drifting Fish Aggregating Devices (DFADs) has progressively increased in the tropical tuna purse seine fishery since 2010 as a means of improving fishing efficiency. Given the broad distribution of DFADs, the acoustic data provided by echosounder buoys can provide an alternative to the conventional CPUE index for deriving trends on tropical tuna stocks. This study aims to derive reliable indices of presence of tunas (and abundance) using echosounder buoy data. A novel methodology is presented which utilizes random forest classification to translate the acoustic backscatter from the buoys into metrics of tuna presence and abundance. Training datasets were constructed by cross-referencing acoustic data with logbook and observer data which reported activities on DFADs (tuna catches, new deployments and visits of DFADs) in the Atlantic and Indian Oceans from 2013 to 2018. The analysis showed accuracies of 75 and 85 % for the recognition of the presence/absence of tuna aggregations under DFADs in the Atlantic and Indian Oceans, respectively. The acoustic data recorded at ocean-specific depths (6–45 m in the Atlantic and 30–150 m in the Indian Ocean) and periods (4 a.m.–4 p.m.) were identified by the algorithm as the most important explanatory variables for detecting the presence of tuna. The classification of size categories of tuna aggregations showed a global accuracy of nearly 50 % for both oceans. This study constitutes a milestone towards the use of echosounder buoys data for scientific purposes, including the development of promising fisheries-independent indices of abundance for tropical tunas.

Published
2020
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