Fish and Seabirds Starve in Abnormal Ocean Conditions
Unusually warm ocean temperatures in 2005 along with altered current patterns drastically suppressed productivity of marine ecosystems off British Columbia's south coast. Continuing a trend since 2003, water temperatures were as much as 5 °C above averages in the early 1990s. As well, weak upwelling critically reduced the supply of nutrients to the ocean surface.
These conditions lowered the productivity of phytoplankton, the effects of which rippled further up the food chain. Zooplankton biomass was exceptionally low, affecting numerous seabirds and fish that feed on these. All seabirds breeding at Triangle Island off northern Vancouver Island had poor diets and fledged very few young. Extremely low numbers of herring and slow growth of juvenile salmon were other consequences observed from the scarcity of copepods and other zooplankton.
Exacerbating the dire conditions for zooplankton and fish was the stronger than usual fleet of predatory fish that moved into BC from southern waters. Several unusual species showed up, attracted by the atypically tepid temperatures. Notably, Humbolt squid arrived to voraciously consume herring and other important BC fish species. Scientists believe that if warm conditions continue over the next few years we'll see a marked altering of the northeast Pacific's ecology.
Pacific Scientific Advice Review Committee, Fisheries and Oceans Canada. 2006. State of the Pacific Ocean 2005. Ocean Status Report. 2006/001. Fisheries and Oceans Canada, Pacific Region. BC. Research Report