Fish

Fish play a vital role in all marine ecosystems, as both predator and prey. Within the GAP framework, research focused on each of these roles. From GAP’s inception through 2007, a number of projects were designed to specifically explore fish distribution, abundance, and availability. Through the years of GAP research, fish studies evolved to include other sources of prey, such as zooplankton, and to incorporate oceanography.

The backbone of “fish as prey” studies was a series of seasonal fish surveys designed to describe fish species composition, abundance, and distribution within the GAP study area. These surveys were essential to addressing questions of seasonal prey availability for the region's apex predators. Separate studies were conducted to assess the distribution, abundance, and diet of piscivorous fishes as predators and potential competitors to Steller sea lions.

Some species of focus

Links in this section are all to PDFs.

Predators

• Arrowtooth flounder (Knoth and Foy 2008)
• Spiny dogfish (Andrews 2010 [thesis])
• Sleeper sharks
• Pacific cod (Hanna 2006)
• Walleye pollock

Prey

• Zooplankton (krill and copepod species) (Wang 2007 [thesis])
• Walleye pollock (Guo 2010 [thesis])
• Capelin (Guo 2010 [thesis])
• Eulachon
• Pacific herring
• Pacific sand lance

Areas of research

• Surveys
  • Hydroacoustic and mid-water trawls
    • Repeated monitoring of Steller sea lion Long Island critical habitat
    • Portlock Bank
  • Nearshore beach seine
• Proximate composition
• Fatty acid composition
• Stomach contents
• Physiology and ecology

While directed prey (fish, zooplankton, and oceanographic) studies are no longer a specific component of GAP research, forage fish and zooplankton remain an important component of directed whale studies.