Project number:
1995-016
Project Status:
Completed
Budget expenditure:
$85,164.00
Principal Investigator:
Neil Loneragan
Organisation:
CSIRO Oceans and Atmosphere Hobart
Project start/end date:
28 Jun 1995
-
30 Jun 1997
Contact:
FRDC
1. To contribute to maximise the economic yield of the red-legged banana prawn fishery in the Joseph Bonaparte Gulf by:
2. developing a model incorporating growth mortality and value at size parameters that can evaluate, under different fishing patterns, the economic returns to the fishery
3. evaluating the effects of different fishing patterns on the spawning capacity of the stock
Final report
Author:
Neil Loneragan and David Die
Final Report
•
1997-03-11
•
1.09 MB
1995-016-DLD.pdf
The fishery for red-legged banana prawns in the Joseph Bonaparte Gulf (JBG) developed in the early 1980s. Since then, fishing effort has varied from 700 to 2600 boat-days per year and catches range from 200 to 1000 tonnes per year. Initially the JBG fishery developed as an alternative to fishing in the Gulf of Carpentaria: during years of poor catches in the Gulf of Carpentaria, more fishing effort was applied in the JBG. In the early years most effort was concentrated at the end of the year. In recent years, however, in addition to being more heavily fished in years of poor catches elsewhere, JBG stocks are fished earlier in the season by a consistent number of boats, regardless of catches elsewhere in the NPF.
Although the red-legged banana prawn has been fished in the JBG since the early 1980s, we know little of its biology or population dynamics. Apart from a 12-month study by Northern Territory (NT) Fisheries in 1990, there has been no research on this species in Australia. The NT findings suggested that growth and mortality rates - important parameters for estimating the effects of changes in fishing effort on stocks - could not be estimated precisely by length frequency analysis of data from commercial catches. There was a need to develop a preliminary model for the red-legged banana prawn fishery in the JBG. This model would help to evaluate the impacts of changes in the pattern of fishing effort on the yield and spawning biomass of red-legged banana prawns. However, the estimates of growth and mortality used by the model would, unfortunately, be imprecise.
Therefore, a well-designed tag/release study would significantly improve the reliability of our estimates of growth and mortality for red-legged banana prawns in the JBG. However, prior to conducting a large-scale field tagging trial, the effect of tagging on the growth and mortality of red-legged banana prawns needed to be studied. For tag/release experiments to be successful, tagging should not affect the growth and survival of the prawns. An effective release-cage also needed to be designed for the deep waters of the JBG.
