Modeling sea lice dispersion and estimating encounter rates with juvenile Pacific salmon in the Broughton Archipelago and Discovery Islands
(Linked to PARR-2011-P-08)
Sea lice dispersion modeling, initiated by the Pacific Salmon Forum and Fisheries and Oceans Canada’s Program for Aquaculture Regulatory Research (PARR), is continuing in collaboration with the new Broughton Archipelago Management Plan (BAMP) project. The objective is to explore means for reducing the potential for sea lice from farmed salmon to infect juvenile pink and chum salmon during the outward migration season. Sea lice copepodid concentrations will be computed by coupled circulation and dispersion models for the Broughton Archipelago and used to estimate encounter rates with juveniles migrating seaward along pre-specified routes. The model grids have been improved to provide increased resolution around farms and coastlines, and various coastal boundary approximations will be tested to determine their effects on sea lice retention. A hindcast simulation for May 2008 will be compared with a similar run for March 2008 in order to estimate the impact of freshwater on sea lice mortality. A May 2010 run will also be compared with May 2008 to assess inter-annual variability. Methodologies to compare these concentrations and encounter rates with values arising from BAMP’s wild salmon monitoring program will also be investigated.In the second year of the project, model coverage will be extended to the Discovery Islands area utilizing the circulation component of a viral transmission model that is presently under development with Aquaculture Collaborative Research and Development Program (ACRDP) funding.
In an effort to provide validation data on larval sea lice abundance and distribution for the Foreman-Stucchi transport and dispersal model, the project was expanded to include a field sampling component. Sampling methods analysis of planktonic-stage sea lice distributions, will be applied in the Discovery Passage region. Compared to the Broughton Archipelago, tidal currents are stronger (probably leading to more rapid dilution of farm-origin sea lice). However, in light of uncertainties in the migratory paths of important Fraser River wild stocks through the Discovery Islands, the relative impact of individual farms remains to be determined.
2010 - 2012
Pacific: Vancouver Island West Coast
Institute of Ocean Sciences, PO Box 6000, Sidney, BC V8L 4B2
Tel.: (250) 363-6306
Dario Stucchi, retired DFO-Pacific region
Dareen Tuele, DFO-Pacific region
Moira Galbraith, DFO-Pacific region
Peter Chandler, DFO-Pacific region
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