El Niño periods increase growth of juvenile white seabass (Atractoscion nobilis) in the Southern California Bight

Studies of the impact of El Niño periods on marine species have usually focused on negative, highly visible eVects, e.g., decreasing growth rates or increasing mortality due to a decline in primary productivity in typically nutrient rich upwelling zones; but positive eVects related to elevated water temperature are also known. This study examined how the growth rate of juvenile white seabass, Atractoscion nobilis, responded to changes in ocean temperature in an El Niño period (1997–1998) in the northern portion of the Southern California Bight, USA. Growth rates of juvenile white seabass during their Wrst 4 years of life were estimated as the slopes of linear relationships between body mass and age (from otoliths) of 800 Wsh collected at 11 stations throughout the bight. Growth rates diVered signiWcantly among cohorts hatched in 1996–2001. SpeciWcally, white seabass that hatched in 1996 and 1997 grew signiWcantly faster than those that hatched in 1998, 1999, and 2001. These diVerences in growth rates of cohorts appeared to be driven by variation in sea-surface temperature (SST). Growth rates averaged over the Wrst three or 4 years of life were signiWcantly positively correlated to average daily SST during the Wrst 1–4 years of life. Increased growth of juvenile white seabass during the warm El Niño period likely provided a number of beneWts to this warm-temperate species. This study demonstrated that some species will beneWt from these warm-water periods despite reduced system-wide primary production.