State of the California Current 2014-15: Impacts of the warm-water "blob"

Citation:
Leising, AW, Schroeder ID, Bograd SJ, Abell J, Durazo R, Gaxiola-Castro G, Bjorkstedt EP, Field J, Sakuma K, Robertson RR, Goericke R, Peterson WT, Brodeur R, Barcelo C, Auth TD, Daly EA, Suryan RM, Gladics AJ, Porquez JM, McClatchie S, Weber ED, Watson W, Santora JA, Sydeman WJ, Melin SR, Chavez FP, Golightly RT, Schneider SR, Fisher J, Morgan C, Bradley R, Warybok P.  2015.  State of the California Current 2014-15: Impacts of the warm-water "blob". California Cooperative Oceanic Fisheries Investigations Reports. 56:31-68.

Date Published:

2015/01

Keywords:

abundance, california, community, current system, distributions, el-nino, marine predator, oceanographic conditions, pacific, pelagic juvenile rockfish, southern

Abstract:

In 2014, the California Current (similar to 28 degrees-48 degrees N) saw average, or below average, coastal upwelling and relatively low productivity in most locations, except from 38 degrees-43 degrees N during June and July. Chlorophyll-a levels were low throughout spring and summer at most locations, except in a small region around 39 degrees N. Catches of juvenile rockfish (an indicator of upwelling-related fish species) remained high throughout the area surveyed (32 degrees-43 degrees N). In the fall of 2014, as upwelling ceased, many locations saw an unprecedented increase in sea surface temperatures (anomalies as large as 4 degrees C), particularly at 45 degrees N due to the coastal intrusion of an extremely anomalous pool of warm water. This warm surface anomaly had been building offshore in the Gulf of Alaska since the fall of 2013, and has been referred to as the "blob." Values of the Pacific Decadal Oscillation index (PDO) continued to climb during 2014, indicative of the increase in warm coastal surface waters, whereas the North Pacific Gyre Oscillation index (NPGO) saw a slight rebound to more neutral values (indicative of average productivity levels) during 2014. During spring 2015, the upwelling index was slightly higher than average for locations in the central and northern region, but remained below average at latitudes south of 35 degrees N. Chlorophyll a levels were slightly higher than average in similar to 0.5 degrees latitude patches north of 35 degrees N, whereas productivity and phytoplankton biomass were low south of Pt. Conception. Catches of rockfish remained high along most of the coast, however, market squid remained high only within the central coast (36 degrees-38 degrees N), and euphausiid abundance decreased everywhere, as compared to the previous year. Sardine and anchovy were nearly absent from the southern portion of the California Current system (CCS), whereas their larvae were found off the coast of Oregon and Washington during winter for the first time in many years. Waters warmed dramatically in the southern California region due to a change in wind patterns similar to that giving rise to the blob in the broader northeast Pacific. For most of the coast, there were intrusions of species never found before or found at much higher abundances than usual, including fish, crustaceans, tunicates and other gelatinous zooplankton, along with other species often indicative of an El Nino. Thus species richness was high in many areas given the close juxtaposition of coastal upwelling-related species with the offshore warm-water intrusive or El Nino-typical taxa. Thus the California Current by 2015 appears to have transitioned to a very different state than previous observations.

Notes:

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