Study

Reduction of seal-induced catch and gear damage by modification of trap-net design: design principles for a seal-safe trap-net

  • Published source details Suuronen P., Siira A., Kauppinen T., Riikonen R., Lehtonen E. & Harjunpaa H. (2006) Reduction of seal-induced catch and gear damage by modification of trap-net design: design principles for a seal-safe trap-net. Fisheries Research, 79, 129-138.

Actions

This study is summarised as evidence for the following.

Action Category

Modify fishing pots and traps to exclude mammals

Action Link
Marine and Freshwater Mammal Conservation
  1. Modify fishing pots and traps to exclude mammals

    A replicated, controlled study in 2003–2004 of five pelagic areas in the Bothnian Sea, Finland (Suuronen et al. 2006) reported that five designs of modified trap-net with wire grids and strengthened netting had lower proportions of salmon Salmo salar damaged by seals than traditional trap-nets. One design of modified trap-net (a ‘pontoon’ trap) had a significantly lower average proportion of seal-damaged salmon/haul (1%) than two types of traditional trap-net (30%), and total catch rates were similar (modified trap-nets: 2.3 fish/haul; traditional trap-nets: 1.9–2.4 fish/haul). Four other designs of modified trap-net had lower proportions of seal-damaged salmon (4–27%) than traditional trap-nets, although statistical significance was either not assessed or not reported. Four commercial fishers each deployed modified trap-nets and two types of traditional trap-net (number of each not reported) at random locations within their fishing grounds. Four designs were tested for four weeks in June 2003 (‘pontoon’ trap, ‘pipe’ trap, ‘protection-net’ trap, ‘large-mesh’ trap). Two designs were tested for 19 days in June 2004 (‘pontoon’ trap, ‘folded-hoop’ trap). Modified trap-net designs had a wire-grid within the funnel and/or ‘seal-safe’ netting around the fish bag (see original paper for details). Each trap was hauled once/day. Researchers recorded fish catches and seal-damaged fish during each haul in 2003 and 2004.

    (Summarised by: Anna Berthinussen)

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