Occurrence of juvenile salmon, Salmo salar L., from natural spawning in the Słupia River (northern Poland) [SHORT COMMUNICATION]

Abstract

The native population of the salmon, Salmo salar L., in the Słupia River probably became extinct in the 1960s. The restoration of this species began in 1986, and is based on the population in the Daugava River. As indicated by historic data, salmon was decidedly less abundant than was sea trout, Salmo trutta L. This remains unchanged today. To date, it has been impossible to differentiate positively smolts of stocking origin from those of natural spawning. Since 2006, all salmon smolts released into the Słupia River have had their adipose fins clipped, which allows for easy identification. The aim of the current study was to present how many of the juvenile individuals caught in the Słupia River originate from natural spawning. During the 1999-2008 period, a total of 25 juveniles were caught that were classified as wild specimens. Although salmon spawning and redds were observed earlier, the catch of juvenile species is evidence of successful salmon spawning in the Słupia River.

CORRESPONDING AUTHOR:

R. Bernaś [+], P. Dębowski, R. Bartel, G. Radtke, M. Skóra
Department of Migratory Fish in Gdańsk
The Stanisław Sakowicz Inland Fisheries Institute in Olsztyn
Synów Pułku 37, 80-298 Gdańsk, Poland
Tel. +48 58 3057011; e-mail: rber@infish.com.pl
M. Miller
Lower Słupia Landscape Park, Poland