Distribution, migrations, and growth of tagged sea trout released into the Vistula River [RESEARCH ARTICLE]

Abstract

The aim of the study was to determine the distribution, migrations, and growth of summer Vistula sea trout, Salmo trutta L., released as smolts into the lower Vistula River. During the 1972-1977 period, 16985 2+ smolts with external tags were released, and 1696 tag returns were obtained (10.0%), including 1412 returns from sea trout whitling (8.3%) and 284 (1.7%) from smolts and post-smolts. Almost immediately after being released into the Vistula River, the sea trout smolts descended to the sea and then migrated throughout the Baltic mainly toward the east reaching the Bothnian Bay and the Gulf of Finland. These fish were mainly caught in the southern Baltic, especially in the region of the Gdańsk Bay and the Vistula River mouth in the second year after stocking (65.7%). They were noted in the southern part of the Gdańsk Bay and the Vistula River mouth more frequently in the first year after stocking during the period from November to March, while in the second year after stocking more were noted during the period from July to March. Most of the tag returns were received from Polish fishers (80.7%). One year after stocking the sea trout had attained a mean body length of 57 cm and a mean weight of 1523.3 g. The mean lengths and weights two and three years after stocking were 69.6 cm and 4355.7 g and 78.7 cm and 6035.7 g, respectively.

CORRESPONDING AUTHOR:

R. Bartel [+], R. Bernaś
Department of Migratory Fish
The Stanisław Sakowicz Inland Fisheries Institute in Olsztyn
Synów Pułku 37, 80-298 Gdańsk, Poland
Tel./Fax.: 58 5507715; e-mail: gdansk@infish.com.pl
M. Pachur
Sea Fisheries Institute, Gdynia, Poland