Crayfish catch expected to surpass peak catches of previous years

According to the Game and Fisheries Research Institute of Finland, the crayfish catch this year will grow once again - up from the 2006 catch of nearly 7 million crayfish. Based on initial estimates of the stock, the 2008 crayfish season could yield a catch that is one-third larger. Catches of this kind were last seen over 100 years ago!

The significant growth is attributed to the flourishing of signal crayfish in waters that have been decimated of native noble crayfish by the crayfish plague. Fortunately, the noble crayfish stock is also growing, thanks to stepped-up management procedures.

Catch statistics compiled every second year by the Game and Fisheries Research Institute report that 5.2 million signal crayfish and 1.6 million noble crayfish were caught in 2006. Catches for both species were 2-2.5 times higher than in 2004. Professional fishermen working in signal crayfish waters have now taken to swapping their vendace trawls for crayfish traps during the crayfish season.

In 2007, crayfish fishers gathering statistics for the crayfish research programme reported a unit catch that was one-third greater than in the previous year, indicating continued crayfish stock growth. In some areas there was over-production of signal crayfish, forcing some crayfish fishers to abandon their efforts due to market saturation. The continued growth in catches has come as a surprise to the crayfish market.

Signal crayfish accrual during the crayfish season seems to deviate from that of the noble crayfish. According to statistics, the noble crayfish catch is at its peak at the beginning of the season, in late July / early August, with a slight delay in more northern waters. The signal crayfish, then, is at its peak in late August, continuing into September.

2008 crayfish season should yield sizable catches

Based on the catch and size distribution reported by gatherers of crayfish statistics in 2007, the noble crayfish stock should remain stable, although the catch is always affected by the early summer weather. In terms of signal crayfish, however, a great deal of them remained in the waterways after the 2007 crayfish season, especially those measuring 8-10 cm or larger. This means that after the early summer moulting, not only will there be larger catches, but the crayfish themselves will be larger.

Continued growth very likely

The last few years have been very favourable for crayfish breeding. Cool falls and winters mean that the noble crayfish, and even the more sensitive signal crayfish, have multiplied successfully. In the spring of 2007 and again this year, test catches carried out by the Institute in the southern waters of Päijänne in central Finland showed that signal crayfish had large quantities of roe. This signifies strong crayfish stocks for the next two to three years. Substantial noble crayfish stocking in different parts of the country in the 1990s are likely responsible for improved noble crayfish catches, as follow-up research deemed at least one-third of the noble crayfish stocking efforts successful. Challenges created by the growth are those of market demand, quality assessment and pricing: all of which are being addressed by the crayfish research programme of the Game and Fisheries Research Institute, based on research collected during the crayfish season.

Crayfish plague still affects stock

On average, ten crayfish plague epidemics are reported annually in Finland. 11 cases were reported in noble crayfish waters in 2007. Two different types of plague have been detected in this country, the so-called old crayfish plague and the new type carried by signal crayfish. A massive outbreak of crayfish plague struck signal crayfish in south Saimaa, located in eastern Finland. This is, however, a familiar phenomenon in newly founded stocks; they should recover to their previous numbers within a few years.

Text version