Marine mammal research at wild salmon fisheries: Annual Report for 2013

  • Published source details Harris R.N., Fowden D., Froude M. & Northridge S. (2014) Marine mammal research at wild salmon fisheries: Annual Report for 2013. Sea Mammal Research Unit (SMRU) report, Seal and Salmon Research Project: report to Scottish Government and Scottish National Heritage, 29pp.


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 controlled study in 2012 at a bay and harbour in the North Sea, Scotland, UK (Harris et al. 2014) found that fishing bag-nets with rigid steel bars, along with other modifications to prevent seal access, had greater catches of Atlantic salmon Salmo salar undamaged by seals than conventional bag-nets, but salmon took longer to pass through the modified net and a greater proportion escaped. Catch rates of undamaged salmon were almost twice as high in modified bag-nets than in conventional bag-nets (data reported as a catch rate index). However, salmon in the modified bag-net took longer to pass through the net (average 200 seconds) and a larger proportion swam back out of the net (65%) than in the conventional bag-net (average 44 seconds; 28%). A modified salmon bag-net and a conventional bag-net were deployed 250 m apart at a bay and a harbour. Modifications to the bag-net prevented seals from entering the inner chamber and trapping fish (e.g. rope-framed entrance replaced with rigid steel bars, heavier net material, a reduced mesh size in the net floor, tight corners inside the chamber closed off). Fishers reported fish catches and seal damage for modified and conventional bag-nets during a total of 130 hauls in July–August 2012.

    (Summarised by: Anna Berthinussen)

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