MEPS 538:221-227 (2015)  -  DOI: https://doi.org/10.3354/meps11444

ABSTRACT: The California Cooperative Oceanic Fisheries Investigations (CalCOFI) ichthyoplankton surveys and systematic sampling of southern California power plant cooling-water intakes (PPI) provide independent, complementary time series to assess fish communities off southern California from nearshore to oceanic environments. The PPI program has sampled the shallow nearshore fish community at 5 sites along the coast of southern California since 1972, while CalCOFI has sampled fish larvae along 6 transects at standard stations ranging from 35 m depth to more than 500 km offshore since 1951. Recently published analyses of these data sets led us to examine potential relationships between them. Although there was limited overlap in the taxa sampled by the 2 programs, key multivariate patterns were highly correlated between them. Both time series exhibited dramatic declines from the 1970s to the 2000s: 78% for fishes entrapped by the power plants and 72% for the overall abundance of larval fishes in the CalCOFI time series. These trends, which predominantly affected taxa with cool-water affinities, were shared by fishes across nearshore and oceanic habitats, and included several trophic guilds and many unfished or only lightly fished taxa. These declines were significantly correlated with declining zooplankton displacement volumes across the California Current System (CCS), which suggests the influence of large-scale climatic and oceanographic drivers. Over the past 4 decades, changing environmental conditions appear to have produced more losers than winners in the CCS.

KEY WORDS: Time series · Fish communities · Climate · California Current · Ichthyoplankton