Study

Steeper biomass spectra of demersal fish communities after trawler exclusion in Sicily

  • Published source details Sweeting C.J., Badalamenti F., D'Anna G., Pipitone C. & Polunin N.V.C. (2009) Steeper biomass spectra of demersal fish communities after trawler exclusion in Sicily. ICES Journal of Marine Science, 66, 195-202.

Actions

This study is summarised as evidence for the following.

Action Category

Cease or prohibit mobile fishing gears that catch bottom (demersal) species and are dragged across the seafloor

Action Link
Marine Fish Conservation
  1. Cease or prohibit mobile fishing gears that catch bottom (demersal) species and are dragged across the seafloor

    A replicated, site comparison study in 2004–2005 of three gulfs in the Mediterranean Sea, Sicily (Sweeting et al. 2009) found that 15 years after bottom-towed fishing gear (commercial trawling) was banned in an area, total fish biomass but not average fish weight was higher compared to gulfs where trawling was permitted. The total biomass of fish was higher in the non-trawled gulf than in the two trawled gulfs, and differences were greatest in smaller size classes (data reported as normalised biomass spectra analyses). Average fish weight was typically similar in non-trawled (61–89 g) and trawled gulfs (62–70 g), except for significantly greater average weight in spring. However, more than 70% of fish above 500 g were from the non-trawled gulf. A ban on trawl nets and all other bottom-towed fishing gear in a 200 km2 area was implemented in the Gulf of Castellammare, 200 km west of the trawled gulfs, in 1990. Fishing with static gears (trammel and gillnets) by artisanal vessels within the trawl exclusion area continued. All gulfs were subject to the existing country-wide ban on trawling in water <50 m. Fish surveys were carried out over four consecutive seasons in the trawl exclusion gulf from 2004 and in the two trawled gulfs in autumn 2004 and spring 2005. Bottom-dwelling fish were sampled with a benthic otter trawl. At each gulf, random sampling within several 2.25 nm2 areas, at three depths, was done and lengths and weights of all fish recorded.

    (Summarised by: Natasha Taylor)

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