Abstract
Miller, E. F., Pondella II, D. J., Beck, D. S., and Herbinson, K. T. 2011. Decadal-scale changes in southern California sciaenids under different levels of harvesting pressure. – ICES Journal of Marine Science, 68: 2123–2133. A unique 38-year time-series of power-plant entrapment data collected across ∼170 km of the southern California coastline was examined to describe the decadal-scale trends in common Southern California Bight sciaenid abundance in relation to oceanographic conditions. Adult catches for five of seven species declined at differing rates and severity. Declines of up to 94% were detected in historically common species such as Genyonemus lineatus, whereas historically less abundant species have increased dramatically, e.g. Umbrina roncador (2626%). Over time, the entrapped community became increasingly influenced by species with more southerly distributions, indicated by a significant decline in the average latitudinal midpoint of the community. This shift was significantly related to rising ocean temperature and took place in the early to mid-1980s. The observed species-specific abundance changes in all species except Atractoscion nobilis were significantly correlated with sea surface temperature, nearshore plankton volumetric biomass, G. lineatus or Seriphus politus nearshore larval density, or a combination of these. Patterns in A. nobilis abundance were the most isolated, likely reflecting its standing as an intensively fished species, unlike the other six species evaluated. The consistent relationship with environmental indices strongly supported the notion of a faunal shift driven by bottom-up forcing.
Decadal-scale changes in southern California sciaenids under different levels of harvesting pressure
