The year-to-year circulation changes along the coast of the western U.S. can have significant impact on the transport of nutrients that affect fisheries. A 2021 article published in the journal Limnology and Oceanography described a study that used ocean currents derived from satellite altimetry to understand the trajectory of water masses from the southern coast of California to the Pacific Northwest. The results show that after a year, subtropical/tropical water masses can reach the Oregon coast from the Southern California Bight (30 °N), and in multiple years from even further south (~26 °N–27 °N) and west. During warmer than average years associated with El Niño Southern Oscillation (1997–1998, 2002–2003, 2004–2005, 2005–2006, 2009–2010, 2014–2015, 2015–2016, 2016–2017), these subtropical/tropical waters masses reached further north compared to other years – see Figure 2. This shift is due to the increase poleward wind stress observed in the California Current. The research team also showed that these tropical warm waters tend to transport “warm water” zooplankton species with a lower fat content. The shift in zooplankton species can impact the young salmon population, which prefer fatty cold-water zooplankton, entering the ocean off the Oregon coast.
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