Physiological impact of sea lice on swimming performance of Atlantic salmon
Abstract:Atlantic salmon Salmo salar were infected with two levels of sea lice Lepeophtheirus salmonis (0·13 ± 0·02 and 0·02 ± 0·00 sea lice g−1). Once sea lice became adults, the ventral aorta of each fish was fitted with a Doppler cuff to measure cardiac output (Q˙), heart rate (fH) and stroke volume (VS) during swimming. Critical swimming speeds (Ucrit) of fish with higher sea lice numbers [2·1 ± 0·1 BL (body lengths) s−1] were significantly lower (P < 0·05) than fish with lower numbers (2·4 ± 0·1 BL s−1) and controls (sham infected, 2·6 ± 0·1 BL s−1). After swimming, chloride levels in fish with higher sea lice numbers (184·4 ± 11·3 mmol l−1) increased significantly (54%) from levels at rest and were significantly higher than fish with fewer lice (142·0 ± 3·7 mmol l−1) or control fish (159·5 ± 3·5 mmol l−1). The fH of fish with more lice was 9% slower than the other two groups at Ucrit. This decrease resulted in Q˙ not increasing from resting levels. Sublethal infection by sea lice compromised the overall fitness of Atlantic salmon. The level of sea lice infection used in the present study was lower than has previously been reported to be detrimental to wild Atlantic salmon.
Document Type: Regular Paper
Affiliations: 1: Centre for Aquaculture and the Environment, Faculty of Agricultural Science, The University of British Columbia, 266 B-2357 Main Mall, Vancouver, BC, V6T 1Z4 Canada, 2: Norwegian Institute of Fisheries and Aquaculture, Breivika, N-9291 Tromsø, Norway and 3: Norwegian Institute for Nature Research, Tungasletta 2, N-7485 Trondheim, Norway
Publication date: May 1, 2003