Project number:
1993-050
Project Status:
Completed
Budget expenditure:
$15,630.00
Principal Investigator:
Peter Petrusevics
Organisation:
SARDI Food Safety and Innovation
Project start/end date:
29 Sep 1993
-
30 Jun 1995
Contact:
FRDC
1. To develop a method to systematically measure key environmental and oceanographic variables in the Cape Leeuwin region
2. To develop a leeuwin Environment Index (LEI) to predict Australian salmon recruitment levels along the southern ocean continental shelf
3. To establish an effective information transfer system where monthly LEI information is conveyed to fisheries managers and industry
4. To provide a framework to develop a LEI for pelagic species such as SBT crustaceans shellfish and freshwater species
Final report
Author:
P.PETRUSEVICS
Final Report
•
1995-12-01
•
2.69 MB
1993-050-DLD.pdf
This study investigated the relationships between recruitment of Australian salmon (western species Arripis truttaceus) in Barker Inlet, South Australia for the period 1981-1994 and environmental factors such as wind, mean sea level, Southern Oscillation Index (SOI) in spawning grounds Western Australia. Correlations between recruitment numbers in Barker Inlet and mean sea level in Albany, near the spawning grounds, for March, April, May and June for the period 1981-1993 were carried out. All the regressions except May were non-significant for mean level sea level. The correlation between the SOI and mean sea level for May in Albany is significant, while the numbers in Barker Inlet were non-significant. Three hourly wind data for Albany, Western Australia for the period 1981-1995 were resolved into northerly, southerly, easterly and westerly components. A consistent feature of these results was the presence of westerly winds which followed the time of spawning of the salmon (April-May). Duration of continuous westerly component winds ranged between 3 to 7 months during the period 1981-1994. NOAA/AVHRR sea surface temperature (SST) data of cross-shelf gradients in spawning grounds near Albany, Western Australia were examined. Published SST data of the Great Australian Eight (GAB) were examined and used to delineate major current systems of the region. Conductivity-temperature- depth (CTD) surveys were conducted which allowed differentiation of the various water masses present on and off the southern continental shelf. Acoustic Doppler Current Profile (ADCP) measurements along route confirmed the CTD survey results that the easterly limit of the Leeuwin Current was approximately 124 E and confirmed presence of increased shelf edge flow in the eastern portion of the GAB. The temperature of the Leeuwin Current appears as one of several factors which induce spawning. Afterwards the salmon eggs need to be favorably positioned within the mainstream of the Leeuwin Current to be advected to the east. This is affected by favorable winds which transport the larvae into the mainstream of the Leeuwin Current. Larval advection may be adversely affected by offshoots or cold-water intrusions which may transport salmon larvae well off the shelf.
