SS1.01 Assessing Potential Environmental Impacts of Aquaculture
Date: Thursday, June 13, 2002
Time: 12:00:00 PM
Location: Lecture Theatre
 
MortonAB, Raincoast Research, Simoom Sound, Canada, wildorca@island.net
 
HIGH NUMBERS OF LEPEOPHTHEIRUS SALMONIS ON JUVENILE PINK SALMON IN BRITISH COLUMBIA, CANADA
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Although historically an innocuous parasite, sea lice infections of wild salmon have become a critical issue in areas where wild and farm salmon share marine habitat. It is generally believed that farm salmon initially acquire sea lice (Lepeophtheirus salmonis) from adult wild salmon stocks returning from the sea to spawn. Under natural conditions, this species of sea louse dies when wild salmon enter freshwater to spawn, depriving this salmon-specific parasite of a host. Now it would appear salmon farms could offer sea lice artificial, inshore, over-wintering habitat. Widespread reports of Lepeophtheirus salmonis infestation of farm salmon suggests that sea lice respond favourably to the ideal parasitic conditions i.e. dense crowding, stationary hosts and 24-hour lighting, found on salmon farms. Sea louse egg-production peaks in spring just as wild salmon smolts encounter the farms on their out-migration, making infection possible. The number, age class, sex and species of lice were examined on 923 juvenile wild salmon caught from June 5 through August 15th, 2001 at 48 sites in the heavily salmon-farmed Broughton Archipelago. The data presented in this paper indicate the highest infection rates by early chalimus stage lice occurred at and immediately west of aquaculture pens containing adult Atlantic salmon.