MEPS 364:157-167 (2008)  -  doi:10.3354/meps07480

Spawning, larval abundance and growth rate of Sardinops sagax off southwestern Australia: influence of an anomalous eastern boundary current

B. A. Muhling1, L. E. Beckley1,*, D. J. Gaughan2, C. M. Jones1, A. G. Miskiewicz3, S. A. Hesp4

1School of Environmental Science, and 4School of Biological Sciences, Murdoch University, 90 South St, Murdoch 6150,  Western Australia, Australia
2Department of Fisheries, Western Australia, PO Box 20, North Beach 6920, Western Australia, Australia
3Environment and Health Division, Wollongong City Council, 41 Burelli Street, Wollongong 2500, New South Wales, Australia
*Corresponding author. Email:

ABSTRACT:  The temporal and spatial distributions of sardine Sardinops sagax eggs and larvae off the oligotrophic southwestern coast of Australia were examined and related to gonadosomatic index, daily growth rates of larvae and regional biological oceanography. Seasonal environmental cycles were established from remotely sensed sea surface temperature and chlorophyll concentration, wind and sea surface height data. Sardine egg and larval distributions were determined from regular transect surveys and annual grid surveys. Sardine eggs and larvae were common across the continental shelf throughout the year between Two Rocks and Cape Naturaliste (~32 to 34°S), and gonadosomatic index data suggested a distinct winter peak in spawning activity. Surface chlorophyll concentrations were highest during winter, coincident with the seasonal peak in the southward flow of the Leeuwin Current along the continental shelf break. Retention conditions on the mid-outer shelf for pelagic eggs and larvae were therefore poor during this time. Egg and larval concentrations were lower than expected in winter and higher in summer when retention conditions were more favourable. Larval sardine growth rates were unexpectedly high, averaging 0.82 mm d–1. Fisheries for clupeiod species off southwestern Australia are insignificant compared to other eastern boundary current systems. Our data suggest that this may be due to a combination of low primary productivity caused by suppression of large-scale upwelling by the Leeuwin Current and the modest seasonal maximum in primary productivity occurring during the time least favourable for pelagic larval retention.


KEY WORDS: Biological oceanography · Sardinops sagax · Leeuwin Current · Fish larvae · Fish eggs


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Cite this article as: Muhling BA, Beckley LE, Gaughan DJ, Jones CM, Miskiewicz AG, Hesp SA (2008) Spawning, larval abundance and growth rate of Sardinops sagax off southwestern Australia: influence of an anomalous eastern boundary current. Mar Ecol Prog Ser 364:157-167

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