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Limited mid-water scavenging of trawl discards

Published online by Cambridge University Press:  12 August 2003

Karim Erzini
Affiliation:
Centro de Ciências do Mar (CCMAR), Universidade do Algarve, 8000–117 Faro, Portugal
Pedro Monteiro
Affiliation:
Centro de Ciências do Mar (CCMAR), Universidade do Algarve, 8000–117 Faro, Portugal
Artur Araújo
Affiliation:
Centro de Ciências do Mar (CCMAR), Universidade do Algarve, 8000–117 Faro, Portugal
Margarida Castro
Affiliation:
Centro de Ciências do Mar (CCMAR), Universidade do Algarve, 8000–117 Faro, Portugal

Abstract

The consumption or scavenging of fish in the water column at depths from 75 to 275 m in Algarve (southern Portugal) trawl fishing grounds was evaluated. Longlines were used to suspend baits throughout the water column while electric fishing reels were used to simulate sinking discards. Eighteen species were caught, with higher catch rates near the surface than near the bottom. However, scavenging rates were generally highest near the bottom and lowest in the middle of the water column. At depths less than 100 m the majority or all the fish were scavenged throughout the water column, while at depths greater than 200 m most of the fish were untouched after periods of time greater than would be required for them to sink to the bottom. Since other studies have shown that most small fish discards are scavenged at the surface by sea birds and most of the discarded species that sink are either too large or not attractive to pelagic predators, these results suggest that mid-water scavenging of trawl discards in deep water is relatively unimportant.

Type
Research Article
Copyright
2003 Marine Biological Association of the United Kingdom

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