Occurrence of juvenile salmon, Salmo salar L., from natural spawning in the S³upia River (northern Poland)

• Main Authors: Rafa³ Bernaoe, Piotr Dêbowski, Ryszard Bartel, Grzegorz Radtke, Marcin Miller, Micha³ Skóra
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Salmo salar
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1071.1577; http://www.infish.com.pl/wydawnictwo/Archives/Fasc/work_pdf/Vol17Fasc4/Vol17-Fasc4-%20w14.pdf

Abstract. The native population of the salmon, Salmo salar L., in the S³upia 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 S³upia 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 S³upia 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 S³upia River.