Hello Salmon Feedlot Industry supporters - care to comment??? Please tell us why you think this latest research is all wrong!
http://www.nrcresearchpress.com/doi/abs/10.1139/cjfas-2014-0284#.VUOpPdh0xuE
Sea lice, sockeye salmon, and foraging competition: lousy fish are lousy competitors
Sean C. Godwin, Lawrence M Dill, John D Reynolds, Martin Krkošek
Published on the web 27 March 2015.
Received June 19, 2014.
Canadian Journal of Fisheries and Aquatic Sciences, 10.1139/cjfas-2014-0284
Abstract
Pathogens threaten wildlife globally, but these impacts are not restricted to direct mortality from disease. For fish, which experience periods of extremely high mortality during their early life history, infections may primarily influence population dynamics and conservation through indirect effects on ecological processes such as competition and predation. We conducted a competitive foraging experiment using out-migrating juvenile Fraser River sockeye salmon (Oncorhynchus nerka) to determine whether fish with high abundances of parasitic sea lice (Caligus clemensi and Lepeophtheirus salmonis) have reduced competitive abilities when foraging. Highly infected sockeye were 20% less successful at consuming food, on average, than lightly infected fish. Competitive ability also increased with fish body size. Our results provide the first evidence that parasite exposure may have negative indirect effects on fitness of juvenile sockeye salmon, and suggest that indirect effects of pathogens may be of key importance for the conservation of marine fish
https://vimeo.com/86743042
https://vimeo.com/86743042/download?t=1430497516&v=227802512&
let's see if we can predict some of the arguments coming in the media from the PR firms and "Sustainability Officers" for the industry:
Misleading Comment: Lice have always been on fish/salmon
Rebuttal: Yes - but that answer purposely misleads and misses the point. The question is how big of a lice load is it (# lice per gram of fish), what stages are the lice at (subadult and adult lice cause much damage as they eat tissue), and how susceptible is that host stage to that lice damage (i.e. what additional mechanisms come into play).
Energy drain depends upon amount of damage, number of parasites and what stages they are at, and the size of the host. So having 12-20 lice on a returning 10KG Chinook may be of little significant effect. Having 1 motile louse on a 0.45g pink or chum juvie is a very different thing.
