Pacific Sardine

Pacific Sardine (Sardinops sagax)


       The Pacific Sardine like the Chinook Salmon, play an essential role in the Pacific northwest marine ecosystem. In the 1950's however the Pacific Sardine population crashed. The population remained virtually non-existent until around 1990 when southern populations began migrating north till the population reemerged. With the increase of Pacific Sardine Populations, Salmonid runs in the Columbia river have too been increasing since around 1999. The reason for this most likely lies with the indirect effect they have with the Caspian Tern (Sterna caspia) and Pacific Harbor seal (Phoca vitulina). Both of those species predate on Chinook Salmon and Pacific Sardines, and with the addition of a more substantial Sardine population, pressure has now been taken off of the Chinook Salmon. Pacific Sardines may also provide adults with more calories, so that they can grow larger and produce larger eggs that have a greater chance of survival (Emmett et al. 2005).

Pacific Sardine. Web. 7 Mar. 2012. <http://www.sardineking.com/sardinespecs.html>.

      During the cold winters in the Pacific northwest, adults migrate to california and don't return until the sea surface temperature returns to approximately 12 degrees Celsius. The juvenile sardines do not have the strength yet to make this migration however, and instead remain in nearshore costal waters such as the Columbia River Estuary and Willapa Bay. These nearshore habitats are crucial to the survival of the juveniles and the future of the populations alike. If their habitat is to change even just a little it may possibly have detrimental effects on the juvenile populations. One example of this was observed in December 2004 by Paul J. Bentley. Bentley witnessed a significant juvenile die out in the Columbia river estuary that he hypothesized to most likely be due to high tides and high freshwater flows. The increase in freshwater lead to a change in salinity in the estuary and ultimately caused osmotic imbalance resulting in stress and death (Emmett et al. 2005).