Project number:
1993-077
Project Status:
Completed
Budget expenditure:
$290,692.00
Principal Investigator:
Vincent Lyne
Organisation:
CSIRO Oceans and Atmosphere Hobart
Project start/end date:
22 Sep 1993
-
11 Jun 1999
Contact:
FRDC
1. To provide quantative interpretation incorporating environmental effect of SBT CPUE for the East Tasmanian fishery
2. To develop scientific support on targeting strategies for the Australian longline fleet
Final report
Author:
Vincent Lyne
Final Report
•
2011-11-24
•
2.54 MB
1993-077-DLD.pdf
An analysis of spatial and temporal variations in catch rates of Southern Bluefin Tuna (SBT) in relation to environmental factors was conducted for the region south of Tasmania up to 1he southern half of New South Wales. Substantial temporal and spatial variations were evident in catch-per-unit-effort (CPUE) as well as the size of SBT and attempts were made to relate these to environmental influences. Of these variations, spatial temperature variations in the study zone, in association with bathymetry, appear to influence the general spatial distribution of CPUE and size of SBT. Catch rates and size of SBT off eastern and southern Tasmania are significantly correlated with the Southern Oscillation Index (SOI), opening the possibility of predicting catch rates through forecasts of the SOI index. A wider study examining the downstream effects of the western surface fishery off WA and SA is recommended to examine the impacts of regional variations in fishing activities. There is a noticeable increase in the mean value of catch rates with full moon, particularly the waxing phase. Overall, the changes in mean catch rates with moon phase are small and reflect. A bias by outliers of large catch rates which are inferred as being due to enhanced aggregations during full moon. Observations of large SBT in the northern section of the fishing zone appear to be related to the unique energetic oceanic conditions off southern NSW. Temporal variation in CPUE from 1990-1995 do not appear to be significantly correlated with the chosen environmental factors although the variance of CPUE is correlated to the extent of warn/cold water masses. The consistency of CPUE, latter than CPUE itself, appears to be more strongly influenced by local environmental factors.
