A voluntary logbook scheme as a method of monitoring the by-catch of seals in Swedish coastal fisheries

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Monitoring by-catches of marine mammals in fisheries is notoriously difficult. An alternative to observer programs or direct interviews with fishermen could be a detailed logbook system. In 1997 such a system was launched by the Swedish Fisheries Board, whereby fishermen were contracted to keep a detailed daily log of fish catches, seal disturbance (damage to gear and to fish and catch losses) and by-caught seals. In total, nearly 38,000 fishing records have been collected to date from a participating group of over 100 fishermen. The fishermen are compensated for their trouble with a small payment. To ensure that the information is properly recorded, all fishermen are contacted personally on a regular basis, and their entries are checked during site visits and by statistical means. In 2004, 22 grey seals, 4 ringed seals and 15 harbour seals were reported by-caught. The fishing effort represented by the participants in the logbook scheme is approximately 5 % of the total fishing effort in the Swedish coastal fisheries. These figures indicate that the total by-catch of seals in the Swedish fishing industry would be in the region of 900 animals annually. This figure tallies closely with the results from a telephone survey of 220 randomly selected fishermen in 2002. From that it was estimated that over 400 grey seals and harbour seals and 50 ringed seals were by-caught during the year 2001. By-catches as a relative proportion of the seal populations seem to be decreasing.