GROWTH RATES OF LARVAL SARDINE, <i>SARDINOPS SAGAX</i>, IN UPWELLING AREAS OF THE EASTERN GREAT AUSTRALIAN BIGHT

The paper tests the hypothesis that the growth rates of sardine Sardinops sagax larvae off southern Australia are lower than those recorded off the coasts of southern Africa, theAmericas and Japan. We estimated growth rates in upwelling areas of the eastern Great Australian Bight (GAB) during summer and autumn using daily increments in sagittal otoliths and the Laird-Gompertz growth model. The maximum and mean growth rates of sardine larvae up to 30 days old were 0.82 and 0.58 + 0.24 mm day-1, respectively. These estimates are higher than the maximum and mean growth rates previously recorded for sardine larvae off southern Australia (0.62 and 0.48 mm day- 1, respectively). This may be because previous estimates for southern Australia were obtained from the unproductive waters of southern Western Australia and for South Australian waters outside the main upwelling and spawning period. The mean growth rate in upwelling areas of the eastern GAB is comparable to the worldwide mean growth rate range of 0.40 to 0.80 mm day -1 and to rates observed in the productive current systems offAfrica (0.59 mm day-1), America (0.65 mm day-1) and around Japan (0.85 mm day-1). The similarity between the growth rates of sardine larvae in the eastern GAB and these other systems may be because productivity is enhanced by seasonal upwelling in all of these locations. In contrast, no large scale predictable nutrient enrichment processes occur in other parts of southern Australia. These findings emphasize the importance of considering intra-regional variability when attempting to characterize the life history characteristics of pelagic fishes across regions as large and diverse as southern Australia.<p></p>