27 results
Environment
Environment
PROJECT NUMBER • 1994-148
PROJECT STATUS:
COMPLETED

The age composition of ling catches

Ling (Genypterus blacodes) catches are an increasing component of the South East Fishery. There is increasing pressure to raise the trawl sector TAC for ling and there has been a substantial increase in catch by the non-trawl sector, particularly line, which is currently unregulated. Despite the...
ORGANISATION:
Agriculture Victoria
Environment
Environment

Age Composition of orange roughly in the eastern and southern management zones

Project number: 1995-032
Project Status:
Completed
Budget expenditure: $63,000.00
Principal Investigator: David Smith
Organisation: Agriculture Victoria
Project start/end date: 19 Jul 1995 - 2 Nov 1998
Contact:
FRDC

Objectives

1. To compare the age composition in the Eastern and Southern Management Zones and estimate mortality rates.
2. To assess degree of recuitment variability.
3. To examine stock structure using otolith morphometrics.

Final report

ISBN: 0-7311-4219-5
Author: David Smith
Final Report • 1998-10-22 • 522.07 KB
1995-032-DLD.pdf

Summary

Orange roughy is an important species in the South East Fishery (SEF).  The main areas in the SEF where orange roughy fishing has occurred are a major spawning aggregation off the east coast of Tasmania (the Eastern Management Zone) during winter and on non-spawning summer aggregations of the south coast of Tasmania (the Southern Management Zone).  Some data support separate stocks off eastern and southern Tasmania with an undetermined amount of mixing.  The current uncertainty in stock structure has important management implications, particularly on the size of the TAC that should be applied to the fishery.  The results of a previous study of orange roughy age composition in 1992/93 indicated that there were some differences in age composition between zones and there were indications of episodic recruitment. Analyses of otolith morphometrics indicated that there were significant differences between samples from the two areas.  However, because samples were taken during different seasons (i.e. winter and summer), interpretation of results was difficult.
 
This proposal was to repeat the earlier study and include samples from both areas during summer and winter.
 

Movement and Exploitation rates of blue and spotted warehou - a pilot study

Project number: 1994-023
Project Status:
Completed
Budget expenditure: $150,544.00
Principal Investigator: David Smith
Organisation: Agriculture Victoria
Project start/end date: 13 Dec 1994 - 30 Nov 1999
Contact:
FRDC

Objectives

1. To develop tagging methods for blue and spotted warehou including catching and handling techniques, and tag types
2. To determine tagging and handling mortality
3. To validate assigned ages
Environment
PROJECT NUMBER • 1995-165
PROJECT STATUS:
COMPLETED

Movement and re-aggregation of blacklip abalone in response to intensive fishing

Typically abalone are found clustered into aggregations of many individuals along gutters and ledges that dissect the surfaces of the reefs they inhabit. Commercial abalone divers take advantage of this clustering behaviour and specifically target aggregations to minimise the time spent searching...
ORGANISATION:
Agriculture Victoria

Port Phillip Bay and Bass Strait scallop research

Project number: 1983-032
Project Status:
Completed
Budget expenditure: $0.00
Organisation: Agriculture Victoria
Project start/end date: 28 Dec 1986 - 31 Dec 1986
Contact:
FRDC

Objectives

1. To define causes and extent of natural fluctuations in population numbers of scallops in Port Phillip Bay
2. determine effects of scallop dredging on aquatic biota of PP Bay
explore ways to optimise scallop yields from PP Bay

Final report

Author: D. Gwyther
Final Report • 1986-12-31 • 5.47 MB
1983-032-DLD.pdf

Summary

During the 3 years of the study, scallop spatfall was observed to occur over a short period (October-December) after the scallops had spawned in spring. Growth was rapid and scallops reached an acceptable harvestable size of 70mm within 16 months. Spatfall one year can therefore be related to recruitment during the next. Years of high and low spatfall were reflected in subsequent differences in recruitment. Though more years' data are required, indices of spatfall provide managers and fishermen with predictive information on likely recruitment strength one year in advance.

Each year the strength of recruitment and the residual stock size were estimated from the results of surveys by SCUBA divers. The results have shown that commercial viability of the fishery is primarily dependent upon recruitment each year. Residual stocks are normally insufficient to support the fishery in the event of poor recruitment.

Estimates of growth and mortality rates determined from tagging and data on seasonal changes in meat yield have been used to develop a mathematical model which can be used to determine number of scallops available each season and yields obtainable from different management strategies. Estimates from annual survey, of stock abundance and mean scallop size at the beginning of each year provide the data for the model.

As a result of the research program, the need to continue monitoring spatfall in Port Phillip Bay and to conduct surveys of recruitment strength each year has been identified. These data are necessary for fisheries managers to maintain the ability to manage the stocks by quota system.

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