KOMUNIKATY RYBACKIE

Nr 5 (118)/2010, 16-19

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BLACK CORMORANT, PHALACROCORAX CARBO SINENSIS (L., 1758), PRESSURE ON THE ICHTHYOFAUNA OF THE WŁOCŁAWSKI RESERVOIR AND COMMERCIAL AND RECREATION FISHERIES MANAGEMENT IN 2005-2009

Bogdan Wziątek, Andrzej Martyniak, Katarzyna Stańczak, Piotr Hliwa

ABSTRACT. The aim of the study was to determine the food preferences of the black cormorant and to assess fisheries losses in Włocławski Reservoir. Twenty fish species were identified in the cormorant diet. The dominant species were ruff and perch (29.4% and 24.4 % of the weight share, respectively). Roach (11.9%) and Prussian carp (10.9%) were also important components of the cormorant diet. The share of invasive species from Gobiidae family was negligible (0.2%). Among the fish species important to commercial and recreational fisheries management, the most numerous in the cormorant diet were: ide (10 t; 2.7% of the weight share), pikeperch (8.6 t; 2.3%), asp (6.3 t; 1.79%), and pike (4.9 t; 1.3%). The fish biomass consumed by cormorants was a mean of 372.8 t annually, which is 46.6 kg per ha (range of 44.6 to 49.6 kg per ha). The analysis of fisheries losses in 2009 was estimated at 980,000 PLN.

Keywords: rainbow trout, yersinosis, vaccination, immersion


Przyjęto po recenzji 1.10.2010 r.