Cohen Aquaculture Daily – September 6, 2011
Transcript: September 6, 2011 Hearing Transcript
Summary: Today’s testimony involved varying perspectives on the potential impact of sea lice on the reduced productivity of Fraser River sockeye. The differences of opinion included the potential of the sea louse species Caligus clemensi having an impact on wild juvenile salmon and whether impacts can be managed. The panel of experts on sea lice included Dr. Craig Orr of Watershed Watch.
Questioning of the Sea Lice Panel included discussion about:
- Salmon sea lice (Lepeophtheirus salmonis) in the Pacific being genetically different from salmon sea lice in the Atlantic with Dr. Orr cautioning that this does not mean that there is a reduced ability of the Pacific sea lice to have an impact on juvenile salmon, as has been proven to be the case with sea lice in the Atlantic.
- The disagreement on whether sea lice are a major contributor to the reduced productivity and low 2009 return of Fraser River sockeye with Drs. Jones and Saksida stating that impacts from sea lice were unlikely.
- The sources of sea lice. There was disagreement by Drs. Saksida and Jones that the presence of open net-pen fish farms is the best predictor of sea lice on juvenile sockeye (included discussion of the findings of the papers by Price et al 2010 and 2011). Dr. Jones discussed sticklebacks as a source of sea lice.
- The impacts of the sea lice species Caligus clemensi (found to be the dominant louse species in juvenile sockeye) in contrast to Lepeophtheirus and that, while it was agreed that there appears to be less mechanical damage from Caligus, there was disagreement where Dr. Orr and Mike Price believe that Caligus impacts cannot only be seen in isolation but that the following much be considered:
- Sea lice as a disease vector (disagreement by Drs. Saksida and Jones who believed disease transmission is more likely via water);
- Sub-lethal effects of sea lice e.g. reduction in the swim performance of juvenile salmon;
- Behaviour impacts of sea lice that increase predation of juvenile wild salmon e.g. infected fish swim further away from the school, at the back of the school and/or that the fish flash more (found to significantly increase predation in juvenile Coho salmon with only 1 louse).
- Interaction of the two lice species Lepeophtheirus salmonis and Caligus clemensi; and
- Potential trophic transmission of sea lice (passing of sea lice up the food chain).
- The finding of Dr. Simon Jones that pink salmon are resistant to sea lice even when 0.7 gram. Discussion included concerns expressed by Dr. Orr of the validity of extrapolating such laboratory studies, which are based on only one exposure to sea lice, to what is happening in the wild where juvenile salmon have 2 to 3 orders of magnitude greater exposure to lice.
- Varying perspectives on the potential of the development of resistance to SLICE with Dr. Orr relating the experience of Europe and Eastern Canada proving how quickly resistance can develop.
- Contrasting the findings of two papers on the impacts of sea lice on “Effects of parasites from salmon farms on productivity of wild salmon” by Krkošek et al 2011 and “Relationship of farm salmon, sea lice, and wild salmon populations” by Marty, Saksida and Quinn 2010.
- The Consensus Statement from the Think Tank of Scientists “Adapting to Change” from December 9th, 2010 (not attended by DFO) which includes the need for “precautionary measures such as experimentally removing farmed salmon from sockeye migration routes” which is in contrast with the findings of Marty, Saksida and Quinn 2010: “We conclude that separating farm salmon from wild salmon—proposed through coordinated fallowing or closed containment—will not increase wild salmon productivity.”
- The importance of transparency in data in order to determine the impacts of varied management strategies.
- The need for research specifically on impacts of sea lice on juvenile sockeye and impacts of the Caligus sea louse species.
Witnesses – Aquaculture:
- Dr. Simon Jones – Research Scientist, DFO
- Dr. Craig Orr – Executive Director, Watershed Watch Salmon Society
- Mike Price – Biologist, Raincoast Conservation Foundation
- Dr. Sonja Saksida – Executive Director, Centre for Aquatic Health Sciences
See evidentiary documents page for a listing of key exhibits discussed at the hearings.
News Coverage resulting from September 6th Cohen hearings: List is updated as additional media is published.
- Globe and Mail; September 6, 2011; “Four scientists share view sea lice didn’t cause collapse of sockeye salmon stocks”