Marine Biology: Rapid Assessment of Skeena Estuary Forage Fish

The area encompassed by the Skeena River estuary supports a prolific and diverse ecosystem. Mixing zones, areas where fresh water mix with the ocean, have a special function within the marine environment. The Skeena River is the second largest river in BC and one of the longest rivers in the world without a dam. Estuaries are some of the most productive habitats on earth and also quite rare with only 2.3% of the BC Coast supporting these special ecosystems.

The Skeena River is renowned internationally as one of the great salmon rivers but it also supports a thriving diversity of forage fish. Forage fish are a classification of fish that are primarily preyed on by other fish, seabirds and marine mammals. Generally the species are small and therefore cluster in schools. Forage fish, including other species such as shrimp, squid and tiny shrimp like creatures called krill, play an important role within the ecosystem as they mostly feed on a primary part of the food web – plankton. In turn the forage fish become food for the larger species.

Local Smithers biologist, John Kelson, performed a Rapid Assessment of Skeena Estuary Forage Fish to survey and identify species as well as calculating their approximate densities. Utilizing two custom built collection nets, a 2m diameter larval net, a 3m diameter larval net each with 15mm mesh, and a 0.5m diameter bongo net with 350micron mesh, tows were performed oblique to the shoreline to cross eddy lines, and sample a diagonal of depths from close to the bottom at 25m, to the surface. All samples were located with a GPS position, and temperatures and salinity recorded at 1m below the surface, then at 2m intervals for depths sampled. Specimens were preserved in alcohol and later cataloged at the Skeena Estuary Research Centre at the Cassiar Cannery.

The study identified a number of species, including the Long Fin Smelt which is endangered in San Francisco Bay.

To read the full report, please click on the PDF file below.

Skeena Estuary Ecology Report 2012

This study should occur much more frequently and is seeking sponsorship to continue to build the database of Skeena Estuary Forage Fish. Please contact us and we will direct you to the biologists.

Thank you to the Driftwood Foundation who funded this first assessment.