STATE OF THE CALIFORNIA CURRENT 2018-19: A NOVEL ANCHOVY REGIME AND A NEW MARINE HEAT WAVE?

The California Current Ecosystem (CCE) has been in a primarily warm state since 2014, and this pattern largely continued into 2019. The CCE experienced a mild El Nino from late 2018 into 2019, and basin-scale indicators reflected this condition (elevated Oceanic Nitio Index and Pacific Decadal Oscillation; table 1). Despite the El Nino, spring upwelling was above average between southern California and Washington but below average in Baja California. Sea surface temperature (SST) was mostly near the long-term average between Washington and southern California, while surface chlorophyll a was above average in Oregon/Washington and slightly below average in most of California in spring/early summer 2019. SST changed dramatically by fall 2019, however, as a marine heat wave (MHW) that formed in May 2019 in the Gulf of Alaska impinged upon the West Coast of the United States. The expansion of the 2019 MHW followed a similar pattern to the 2014-15 MHW. Off Oregon, the zooplankton assemblage was in a mixed state as southern copepods were close to average while northern copepod abundances were positively anomalous in 2019. Off northern California, Euphausia pacifica body size was smaller than average. Euphausid abundances were well below average in both central and southern California in 2019. In the north, winter 2019 larval fish abundances were high and dominated by offshore taxa that are associated with warm conditions; spring larval and post-larval biomass were close to average; and spring surface trawls observed record-high market squid (Doryteuthis opalescens) abundances. The single most important finding in 2019 was that northern anchovy (Engraulis tnordax) adults and larvae were at record-high abundances in central and southern California. In central California, market squid and Pacific sardine (Sardinops sagax) were also abundant. In southern California warm-water mesopelagic fishes have been very abundant since 2014, and this trend continued into 2019. Indicators for future salmon returns were mixed in 2019. The abundance of northern copepods, which correlate positively with returns, was high. However, abundances of yearling Chinook salmon (Oncorhynchus tshawytscha) and coho salmon (O. kisutch), which also correlate positively with returns, were slightly below average. Winter ichthyoplankton was comprised mostly of southern or offshore taxa, which bodes poorly for future salmon returns. Seabird (common murre [Urfa aalge]; Brandt's cormorant [Phalacrocorax penidllatus]; and pelagic cormorant [Phalacrocorax pelagicus]) productivity off Oregon was the highest in years in both 2018 and 2019. In 2018, common murre chicks in Oregon consumed large amounts of young-of-the-year flatfish, a prey item known to be conducive to chick survival. Despite the prevalence of northern anchovy in central California, common murre and Brand's cormorant production was low in Southeast Farallon Island as these birds were unable to feed optimally on northern anchovy, and there was a scarcity of more appropriate prey such as young-of-the-year flat-fishes or rockfishes. California sea lions (Zalophus californianus), by contrast, benefitted greatly from the large northern anchovy forage base. In 2018, live pup count, weight, and growth rate were anomalously high, and northern anchovy remains occurred in >85% of scat samples. Humpback whale (Megaptera novaeangliae) sightings were also very high in 2019, likely because humpback whales congregated near shore to feed on northern anchovy.