Pink Salmon Action Plan

Findings to date

• Annual findings are outlined in the Pacific Region Pink Salmon Action Plan Bulletins

Sea lice are naturally-occurring parasites found in every ocean and on many species of fish around the world. They are very common on all Pacific salmon adults during their return migration in coastal waters of B.C.

Wild salmon can transfer sea lice to salmon farms and, if left untreated, farmed salmon can transfer sea lice back to the marine environment.
Sea lice were significantly more abundant on juvenile pink and chum salmon in 2004, compared to either 2003 or 2005. 2006 research indicates sea lice levels are the lowest ever among farmed and wild salmon

Specifics:

1. Two different species of sea lice, Caligus clemensi and Lepeophtheirus salmonis, have been found to commonly infect juvenile pink and chum in the Broughton.
    
2. Caligus clemensi was found to be the most abundant sea lice on juvenile pink and chum salmon in 2003, whereas Lepeophtheirus salmonis was most abundant in both 2004 and 2005.
    
3. 2006 research indicates sea lice levels are the lowest ever among farmed and wild salmon.
    
4. Several different developmental stages of both species of sea lice were found on juvenile pink and chum salmon. In all years the majority of the sea lice observed on juvenile pink and chum salmon were the early (non-motile) developmental stages.
    
5. Sea lice were significantly more abundant on juvenile pink and chum salmon in 2004, compared to either 2003 or 2005.
    
6. Sea lice were also observed to infect other fish species in the Broughton. In all three years (2003-2005), sea lice abundance was significantly greater on threespine stickleback (Gasterosteus aculeatus) than on juvenile pink or chum salmon. This research is the first reported case of L. salmonis infecting stickleback.
    
7. The abundance of later development stages of L. salmonis generally coincided with growth of pink salmon. Mature (motile) lice occurred more frequently on larger juvenile pink salmon. This pattern was less obvious during growth of chum salmon.
    
8. The total abundance of the sea lice L. salmonis on juvenile pink and chum salmon generally declined sharply as the salmon grew in size.
    
9. Significant variation in surface seawater salinity was observed in different areas of the Broughton.
    
10. The abundance of sea lice was minimal on juvenile pink and chum salmon and sticklebacks in areas with the lowest salinity.
     
11. Salmon species, size and location, as well as seawater salinity were all found to be significant predictors of the number of sea lice.