Euphausiid

Euphausiid species, also known as krill, are fished under authority of a limited entry category "ZF" license. These animals are harvested commercially by fine meshed plankton trawl nets. About 23 species of euphausiids occur in B.C. waters, but biomass is dominated by five: Euphausia pacifica, Thysanoessa spinifera, T. inspinata, T. longipes and T. rashii. Euphausia pacifica typically dominates, accounting for about 70-100% of the euphausiid biomass in the Strait of Georgia where the commercial fishery occurs (Jamieson et al, 1990).

Stock Assessment

Current euphausiid research at both the Pacific Biological Station and the Institute of Ocean Sciences, focuses mainly on the ecological issues surrounding these creatures. The Canadian West Coast supports many fish, bird and mammal species that depend on krill as food:

• Reports indicate that euphausiids account for 84, 89 and 100% of the daily ration of pacific hake (Merluccius productus), spiny dogfish (Squalus acanthias) and pacific herring (Clupea pallasi) respectively, three dominant species of the pelagic fish biomass along the south-west coast of Vancouver Island.
• Distribution of euphausiids is known to influences movements of the pacific hake.
• Humpback whales (Megaptera novaeangliae), which rely heavily on krill, have shifted away form the south-west coast of Vancouver Island, which is coincident with the decline in euphausiid biomass of that area.

As one can see, euphausiids are a forage species upon which many other species depend and therefore, management of this species is taking a precautionary and conservative  approach.

The graph below shows the rationing trends of herring, dogfish, and hake related to the rationing of euphausiids of these three species. The segmented line represents the overall rationing of these species and the solid line represents the rationing consisting of euphausiids. As on can see, these two trends are almost identical. Please click on the graph to view larger version.

 

Contacts

For more information about ongoing research on euphausiids please contact:

Ronald Tanasichuk (Pacific Biological Station)

R. Ian Perry (Pacific Biological Station)
250-756-7137
Ian.Perry@dfo-mpo.gc.ca

Steve Romaine (Institute of Ocean Sciences)