Ecosystem effects of fishing on the continental slope in the Central Mediterranean Sea

Fishing with demersal towed gears can have dramatic effects on the structure and functioning of marine ecosystems. We studied the ecosystem effects of the deep-sea red shrimpAristaeomorpha foliaceatrawl fishery (500 to 800 m) in the Strait of Sicily, at the population and community level by sampling...

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Bibliographic Details
Published in:Marine ecology. Progress series (Halstenbek) 2012-03, Vol.449, p.41-54
Main Authors: Dimech, Mark, Kaiser, Michel J., Ragonese, Sergio, Schembri, Patrick J.
Format: Article
Language:English
Subjects:
Animal communities
Aristaeomorpha foliacea
Biomass
Commercial fishing
Decapoda
Ecosystems
Etmopterus spinax
Fish trawling
Fisheries management
Galeus melastomus
Helicolenus dactylopterus dactylopterus
Marine
Marine ecosystems
Marine fishes
Nephrops norvegicus
Plesionika martia
Shrimp
Species
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Summary:Fishing with demersal towed gears can have dramatic effects on the structure and functioning of marine ecosystems. We studied the ecosystem effects of the deep-sea red shrimpAristaeomorpha foliaceatrawl fishery (500 to 800 m) in the Strait of Sicily, at the population and community level by sampling in trawled and non-trawled sites as determined by vessel monitoring system (VMS) fishing effort data. The study was conducted within the Maltese 25 nautical mile Fisheries Management Zone as part of the ongoing MEDITS trawl survey. Samples were collected using an experimental otter trawl net with a cod-end stretched mesh size of 20 mm, from 7 stations located in trawled sites (mean depth 616 ± 26 m) and from 7 stations in non-trawled sites (mean depth 556 ± 40 m). Population and community indicators were compared across the trawled and non-trawled sites. Populations ofA. foliaceaandEtmopterus spinaxdid not show any differences in biomass between the trawled and non-trawled sites, whereas the biomass ofPlesionika martia,Nephrops norvegicus,Helicolenus dactylopterus dactylopterusandGaleus melastomuswas 4 times, 16 times, 6 times and 2 times higher, respectively, at the non-trawled sites. Changes in length structure were also detected for all species except forE. spinax. At the community level, higher biomass, density and diversity indices were recorded at the non-trawled sites. Despite the clear evidence of ecosystem changes due to fishing, the main target species,A. foliaceaandP. martia, had a high resilience to trawling activities. Setting up trawling lanes as a management option would likely minimise negative impacts on species with slow growth rates and low resilience.
ISSN:0171-8630
1616-1599
DOI:10.3354/meps09475