Latitudinal change in the distribution of luderick Girella tricuspidata (Pisces: Girellidae) associated with increasing coastal water temperature in eastern Australia

Abstract

During the past two decades there has been a major decline in the luderick (Girella tricuspidata) population and fishery in the coastal areas of southern Queensland, Australia. This region is the northern limit of the range of luderick. An analysis of annual time series information from the luderick fishery and from sea surface temperature records from 1976 to 2015 found a moderate and significant negative correlation (Pearson r=–0.39, P<0.05) between water temperature and population abundance in southern Queensland. Previous studies of juvenile and adult luderick indicate their sensitivity to elevated water temperature at the northern limit of their range, further supporting the hypothesis that declines in population abundance of luderick in southern Queensland are associated with increased water temperature. Other possible factors for the luderick population decline (overfishing and habitat loss) are discussed. Any future increases in coastal water temperatures in eastern Australia may result in further southward shifts of the luderick population, and may have similar effects on other fish species that have their northern range limits in southern Queensland.