Abstract

Most of the harvested crayfish populations in Europe are managed through a combination of direct and indirect regulations. Of these the most important indirect regulations is control of the catching season. Lake Steinsfjorden is the most important crayfish locality in Norway accounting for some 25% of total harvest. Because the fishery is not licenced reductions in catching season is the principal method of regulation. We have studied exploitation, yield and stock structure of the heavily exploited noble crayfish Astacus astacus in Lake Steinsfjorden, S.E. Norway during 18 years. These data allow us to evaluate the effects of changes in the annual catching season. The study is based on catch statistics, mainly trap effort, and data from pre­and post- season test fishing in the period 1979-1996. In 1979, the length of the legal season ran from 7 August to 31 December. In 1981, the catching season was reduced from 6 August at 18.00 to 15 September in 1981. In 1989 the season was further reduced to two weeks and finally in 1995 to only 10 days. This short season regulation in combination with the national minimum size of 95 mm TL has proven successful in Lake Steinsfjorden. The short season is very easy to enforce. The management scheme allow females to spawn at least once before being caught. In addition females in the size interval 87-94 mm TL are allowed to molt and spawn in late August or early September without being exploited. Berried females are also protected. Males may molt twice between legal seasons and this implies a weight gain of approximately 35%. There is no need to limit number of fishermen or number of traps per fisherman. Yields have increased after the introduction of new regulations with a short season and may stabilize at approximately 2-2.5 kg ha^-1.

Supplemental Documents

• There are no supplementary documents for this article

Cited By

Citations: