Fisheries Research Articles
Spawning, larval abundance and growth rate of Sardinops sagax off southwestern Australia: influence of an anomalous eastern boundary current
Document Type
Article
Publication Date
7-29-2008
Journal Title
Marine Ecology Progress Series (MEPS)
ISSN
Print: 0171-8630 Electronic: 1616-1599
Keywords
Biological oceanography, Sardinops sagax, Leeuwin Current, Fish larvae, Fish eggs
Disciplines
Aquaculture and Fisheries | Marine Biology
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.
Recommended Citation
Muhling, B A,
Beckley, L E,
Gaughan, D J,
Jones, C M,
Miskiewicz, A G,
and
Hesp, S A.
(2008), Spawning, larval abundance and growth rate of Sardinops sagax off southwestern Australia: influence of an anomalous eastern boundary current. Marine Ecology Progress Series (MEPS), 364, 157-167.
https://library.dpird.wa.gov.au/fr_fja/186
