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Egg production in the salmon louse [Lepeophtheirus salmonis (Krøyer)] in relation to origin and water temperature


P A Heuch, Fish Health Section, National Veterinary Institute, PO Box 8156 Dep., 0033 Oslo, Norway


Egg strings of salmon lice, Lepeophtheirus salmonis (Krøyer 1837), collected from farmed and wild Atlantic salmon had similar length and number of eggs string−1. Egg production was investigated at water temperatures from 7.1 °C to 12.2 °C. A regression model indicated that at low temperatures egg strings were longer and had more eggs. Mean length of single eggs was significantly smaller and the percentage of non-viable eggs in the strings was higher at 7.1 °C than at 12.2 °C. Adult females survived for up to 191 days at 7.2 °C, and during this period 11 pairs of egg strings were produced.