Research Document - 2014/048
Oceanographic conditions of salmon farming areas with attention to those factors that may influence the biology and ecology of sea lice, Lepeophtherius salmonis and Caligus spp., and their control
By Kathy Brewer-Dalton (Editor), Fred H. Page, Peter Chandler, Andry Ratsimandresy
Abstract
This research document summarizes the oceanographic factors in Canada that influence sea lice distribution and their control. Particular attention is paid to the differences between the east and west coasts. Information related to the specific conditions, such as temperature, salinity and current trends, is provided.
On the Pacific Coast, aquaculture activities occur in several regions, including the inlets along the west coast of Vancouver Island, the Discovery Islands and the Broughton Archipelago. These areas experience sea surface temperatures that vary seasonally and by region, from just above freezing to 18°C, creating an environment that is suitable for all sea lice life stages. Salinity in this region varies seasonally and by location, due to influx of freshwater from direct precipitation and snowmelt. The vertical and horizontal movement of water is driven by the energy from tides, waves and winds, as well as density differences.
On the East Coast, the two main areas of aquaculture are on the south coast of Newfoundland and the Maritimes Region, primarily the Bay of Fundy. On the south coast of Newfoundland, the majority of aquaculture activities occur in Bay d’Espoir, Fortune Bay and Hermitage Bay. These areas have quite different oceanographic characteristics in terms of temperature, salinity and currents, which results in a varied environment for sea lice.
In the Bay of Fundy, oceanographic conditions vary within the bay, with temperatures ranging from -2.4 to 24.3°C, salinity is generally around 30 psu and current speeds range from almost zero to over 100 cm s-1. The duration of sea lice, nauplii and copepodid dispersal stages in this region range from about 1 to 10 days. Transport distances of pre-infective sea lice stages are on the order of 10-100 kilometers. This suggests that farms within bays or nearby bays may exchange sea lice, whereas farms in bays separated by distances greater than 100 km may have only limited sea lice exchange.
Additional oceanographic data are required to fully comprehend the potential influence of these factors on sea lice biology and ecology, as well as to further develop, test and validate physical/biological models for sea lice dynamics. Specifically, more information is needed on the influence of water velocities and sea lice behaviour on sea lice transport and dispersal. Consideration should also be given to the influence of other environmental factors, such as dissolved oxygen and pH, on sea lice biology.
This Research Document was presented and reviewed as part of the Canadian Science Advisory Secretariat (CSAS) National peer-review meeting, Sea Lice Monitoring and Non-Chemical Measures, held in Ottawa, Ontario, September 25-27, 2012. The objective of this peer-review meeting was to assess the state of knowledge and provide scientific advice on sea lice management measures, monitoring and interactions between cultured and wild fish.
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