Study

Factors affecting rule compliance with mesh size regulations in the Baltic cod trawl fishery

  • Published source details Suuronen P., Tschernij V., Jounela P., Valentinsson D. & Larsson P. (2007) Factors affecting rule compliance with mesh size regulations in the Baltic cod trawl fishery. ICES Journal of Marine Science, 64, 1603-1606.

Actions

This study is summarised as evidence for the following.

Action Category

Set a minimum landing size for commercially fished species

Action Link
Marine Fish Conservation

Fit mesh escape panels/windows to a trawl net

Action Link
Marine Fish Conservation
  1. Set a minimum landing size for commercially fished species

    A before-and-after study in 2002–2003 in a heavily fished area of seabed in the Baltic Sea, Northern Europe (Suuronen et al. 2007) found that an increase in minimum landing size did not reduce the amount of Atlantic cod Gadus morhua discarded by the trawl fishery for this species. This result was not tested for statistical significance. In the year following the minimum landing size increase in 2003 the discard rate of cod was 0.23 (rate by fish numbers) and 0.14 (rate by fish weight). In the year before the increase the discard rate was 0.18 by number and 0.09 by weight. The minimum landing size of Baltic cod was increased from 35 cm to 38 cm in January 2003. However, in April 2003, high discarding led to the temporary closure of the trawl fishery in Baltic European Union waters. Measures to improve selectivity of fishing gear in line with the increased minimum landing size were implemented in September 2003 (see paper for details). The typical trawl configuration in use at the time of the intervention was a 130 mm diamond-mesh codend. Discard data was collected from the Swedish cod fishing fleet by on-board observers.

    (Summarised by: Natasha Taylor)

  2. Fit mesh escape panels/windows to a trawl net

    A before-and-after study in 2003–2005 in a heavily fished area of seabed in the Baltic Sea, Northern Europe (Suuronen et al. 2007) reported that after a change in trawl net type was implemented, to a square mesh escape window codend from a standard diamond mesh codend, there was a short-term reduction in discarded undersized Atlantic cod Gadus morhua in the Baltic trawl fishery. Data were not statistically tested. Average cod discard rate (in numbers) was reduced to 0.11 in 2004, after the escape window codend was used, from 0.23 in mid-2003. In 2005, the discard rate increased to 0.31, despite the net control measure still being in place. In January 2003, the minimum landing size of cod was increased from 35 to 38 cm and resulted in large numbers of cod discarded because undersized fish were being caught. From September 2003, vessels participating in the Baltic cod trawl fishery were required to use nets fitted with a square-mesh escape window in the upper rear panel of the codend (a Bacoma window) with a minimum window mesh size of 110 mm. This replaced the 130 mm diamond mesh codend most vessels were using. Discard data was collected from the Swedish cod fishing fleet by on-board observers.

    (Summarised by: Natasha Taylor)

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