313 results

Population dynamics workshop on banana prawns and scallops

Project number: 1975-008
Project Status:
Completed
Budget expenditure: $0.00
Organisation: CSIRO Oceans and Atmosphere Cleveland
Project start/end date: 28 Dec 1976 - 31 Dec 1976
Contact:
FRDC
TAGS
Workshop
Workforce
Population Dynamics
Fisheries Management

Objectives

1. Instruct fisheries officers in the use of population dynamics data for calculating yield and cost curves for banana prawns and scallops.
2. Illustrate the application of the principles of population dynamics to the management of the fisheries

Final report

Final Report • 137.22 KB
1975-008-DLD.pdf
Environment
Environment
PROJECT NUMBER • 2018-120
PROJECT STATUS:
COMPLETED

NCCP: Population dynamics and Carp biomass estimates

This study was undertaken by the Arthur Rylah Institute for the Department of Environment, Land, Water and Planning. Carp (Cyprinus carpio) is Australia’s most invasive pest fish. To facilitate more effective management, the Australian Government is considering release of a Carp herpesvirus...
ORGANISATION:
Department of Environment Land Water and Planning (DELWP)
TAGS
Reproduction
Population Dynamics
Modelling
Invasive Species
Habitat
SPECIES
European Carp

Population dynamics of southern rock lobster in SA waters

Project number: 1993-086
Project Status:
Completed
Budget expenditure: $333,640.53
Principal Investigator: Jim Prescott
Organisation: South Australian Rock Lobster Advisory Council (SARLAC)
Project start/end date: 8 Sep 1993 - 31 Dec 1996
Contact:
FRDC
TAGS
Wild Catch
Tagging
Reproduction
Population Dynamics
Mortality

Objectives

1. To obtain data (catch and effort, tagging, sampling) and analyse it to gain estimates of growth, mortality, catchability, female size at maturity, lenght-weight and movement
2. To develop an age structured population dynamics model of the fishery that will allow discrimination at the zone adn smaller spatial scale
3. To use the model to identify the most important biological parameters so as to give them highest priority
4. To use the model to estimate sustainable yields, predict outcomes of alternative management strategies and understand the interactions of the two management zones
5. To provide an accessible, secure data base of stock information, improved data validation and verification.
6. To provide a graphics interface for the models and ata to facilitate understanding by industry and management
7. To transfer results to industry and other user groups
8. To involve industry in research and educate them about the results and their consequences
9. To obtain preliminary habitat and oceanographic information to assist in determining critical habitats and physical processes controlling rock lobster distribution and abundance.

Final report

Authors: J. Prescott R. McGarvey G. Ferguson M. Lorkin
Final Report • 15.31 MB
1993-086-DLD.pdf

Summary

This study looks at the population dynamics and fishery biology of the southern rock lobster, Jasus edwasrdsii, in South Australian waters. The four distinct areas of investigation are biological research to describe key population parameters; development of a comprehensive database of biological and fisheries data; integration of biological and fisheries parameters and data in a computer simulation model of the lobster stock and fishery, and dissemination of the project results and assisting commercial fishers to use the simulation model and other information generated by the project. 

National Fisheries Technical Workshop Series " Population Dynamics for Fisheries Management"

Project number: 1993-209
Project Status:
Completed
Budget expenditure: $20,558.00
Principal Investigator: John Glaister
Organisation: Australian Society For Fish Biology Inc
Project start/end date: 14 Nov 1993 - 31 Dec 1994
Contact:
FRDC
TAGS
Workshop
Population Dynamics
Fisheries Management
Education
Distribution

Objectives

1. To promote the opportunity during the Australian Society for Fish Biology annual conference for the national fisheries research expertise to focus on a technical area or subject of current or percieved national or regional fisheries significance.
2. To promote the opportunity during the Australian Society for Fish Biology annual conference for the national fisheries research expertise to focus on a technical area or subject of current or percieved national or regional fisheries significance.
3. To assist in the publication of workshop proceedings as a benchmark document of current knowledge in the workshop subject area
4. As a result, to identify, and define research questions of national fisheries significance.
5. The proposed workshop - "Population Dynamics for Fisheries Management" - will focus on what are the processes leading to the development of management advice

Final report

Final Report • 2017-09-29 • 148.04 KB
1993-209-DLD.pdf

Population dynamics of southern rock lobster in SA waters

Project number: 1993-087
Project Status:
Completed
Budget expenditure: $803,696.50
Principal Investigator: John Keesing
Organisation: SARDI Food Safety and Innovation
Project start/end date: 25 Sep 1993 - 29 Jun 1998
Contact:
FRDC
TAGS
Population Dynamics

Objectives

1. Objectives as stated in B3 part B of the project Description forming part of this agreement

Final report

Authors: J. Prescott R. McGarvey G. Ferguson M. Lorkin
Final Report • 15.31 MB
1993-087-DLD.pdf

Summary

This study looks at the population dynamics and fishery biology of the southern rock lobster, Jasus edwasrdsii, in South Australian waters. The four distinct areas of investigation are biological research to describe key population parameters; development of a comprehensive database of biological and fisheries data; integration of biological and fisheries parameters and data in a computer simulation model of the lobster stock and fishery, and dissemination of the project results and assisting commercial fishers to use the simulation model and other information generated by the project. 
Environment

Population dynamics and management of spanner crabs in southern Queensland

Project number: 1995-022
Project Status:
Completed
Budget expenditure: $262,552.00
Principal Investigator: Ian Brown
Organisation: Department of Primary Industries (QLD)
Project start/end date: 18 Dec 1995 - 30 Jun 2000
Contact:
FRDC
TAGS
Yield
Wild Catch
Sustainability
Population Dynamics
Mortality

Objectives

1. To estimate the size of the south Queensland spanner crab stock.
2. Determine the appropriateness of existing spawning closure arrangements.
3. To determine whether catch size-distribution can be used to estimate population age-structure and growth rates.
4. To evaluate the impact of post-discard mortality amongst sub-legal crabs on yields, and promote the development (by industry) of less damaging apparatus.

Final report

Authors: Ian Brown John Kirkwood Shane Gaddes Cathy Dichmont & Jenny Ovenden
Final Report • 1999-09-01 • 13.01 MB
1995-022-DLD.pdf

Summary

Spanner crabs (Ranina ranina) represent a valuable resource to southern Queensland and northern NSW. The fishery became established in the late 1970s, and as a result of an almost exponential increase in fishing effort between 1992 and 1995 an output-controlled limited entry management arrangement was introduced. During that period catches increased from about 800 to over 3,000 t, as the fishery expanded northwards to previously unexploited grounds, and a profitable live-export market was developed in south-east Asia.
The Queensland fleet comprises some 240 vessels specifically licenced to take spanner crabs in Managed Area A, which is subject to a Total Allowable Commercial Catch (TACC), currently set at 2600 t. Another 310 vessels are licenced to fish only in Managed Area B (north of the main fishing grounds) where the TACC does not apply. At present the TACC is competitive, but in the near future an Individual Transferrable Quota (ITQ) system is to be introduced.
Trends in commercial fisheries catch-effort statistics indicate that the spanner crab stock in southern Queensland is currently being harvested at a sustainable level. However several questions remain with respect to the application of the commercial logbook data, possibly the most important of which is how well commercial catch-per-unit-effoti represents stock abundance. The spatial distribution of spanner crabs is patchy, and the fishery operates such that patches are located, targeted and fished down. This can potentially lead to a situation of hyperstability, where the stock is actually declining despite catch rates remaining constant. This highlights the expected value of the fishery-independent monitoring programme currently being planned by QDPI with (in the case of the spanner crab fishery) a significant level of cost-recovery from industry.
Previous attempts to estimate growth rate of spanner crabs resulted in little consensus, due in part to inadequate sample sizes (length-based methods) and uncertainty surrounding the effects of tagging on growth (tag-recapture methods). Our initial objective was to determine whether the length-based methods would work if the samples were very large.
 
Variability in the size-structure of even very large samples of adult crabs was so great that we could place little confidence in growth estimates obtained from this type of data. Because of this, we negotiated a change in research direction with FRDC, focussing on two alternative approaches to the question of growth rates. The first was to investigate growth in pre-recruits. The second was to quantify the likely effect of tagging on moulting and growth, and to determine the extent of growth rate differences between NSW and Queensland.
Very small spanner crabs are not taken by baited tangle nets, regardless of mesh size, so a different sampling arrangement was required. A two-track channel dredge was successful in capturing intact megalopae and early juvenile stages, which provided length frequency data of considerable value to estimating pre-recruit growth. However because of its small size only very limited samples were able to be collected. To increase the sampling volume we developed a substantially larger, hydraulically­assisted dredge. This device has been field-tested on several occasions, but it has not yet been developed and used to full effect.
Laboratory experiments demonstrated that tagging had an adverse effect on weight increase and survival of spanner crabs, suggesting that growth rate estimates based on mark-recapture techniques may be biased. Of the several different types tested, anchor tags were superior in terms of ease of application and visibility. Recognising that the results may be biased, we released 4,804 tagged crabs at sites throughout the fishing grounds, to determine whether growth of spanner crabs in Queensland waters is significantly different from that in NSW, reported in a previous study. Fourteen of the 221 crabs recaptured in 1998 had moulted, with growth male growth increments being greater than those offemales (X = 11.86 and 7.40 mm respectively). Recapture rates were significantly higher for males than females, and were also significantly greater for larger individuals of each sex. This suggests that tag mortality was greater in the smaller size-classes. Recaptured crabs had moved distances ranging from O to 45 km since release, but showed no tendency to move in any particular direction.
Our length-based assessment model has not yet been successful in producing useful estimates of the relevant stock performance indicators for use by management. This was due to the lack of contrast in the CPUE data, the relatively short data time-series, the extreme spatial and temporal variability in population size-structure and sex-ratio as represented in commercial catches and research samples, and the absence of definitive growth data.
Mitochondrial DNA analysis indicated that the east-coast spanner crab fishery comprises a single unit stock, and there thus appears to be no biological justification for separate management arrangements in different geographic areas.
 
Analysis of reproductive chronology indicates that the timing of the existing spawning closure is appropriate for minimising mortality amongst egg-bearing female spanner crabs across the entire fishery, and we recommend that the closure be retained in legislation.
 
Exploratory surveys for spanner crabs conducted in two areas outside the current fishing grounds did not reveal any significant quantity of crabs, although small numbers were captured at two sites amongst the Swain Reefs. From the available information it seems unlikely that there are any major unexploited populations of spanner crabs remaining in Queensland waters.
We have demonstrated that limb damage to undersized discarded spanner crabs has a major effect on their survival under natural conditions. Poor handling practices in the fishery result in considerable mortality amongst discarded small crabs, highlighting the need for continuing fisher education and ongoing investigation of alternative catching apparatus.
 
The two major issues for further research into the spanner crab fishery are (i) deriving a robust estimate of the species' growth rate, (ii) investigating the source of the extreme variability in size­frequency and sex-ratios in population samples.
Industry

Population dynamics and reproductive ecology of the southern calamari in Tasmania

Project number: 2000-121
Project Status:
Completed
Budget expenditure: $230,188.00
Principal Investigator: Natalie Moltschaniwskyj
Organisation: University of Tasmania (UTAS)
Project start/end date: 16 Oct 2000 - 7 Mar 2004
Contact:
FRDC
TAGS
Reproduction
Population Dynamics
Individual Transferable Quota
Fisheries Management
SPECIES
Southern Calamari

Need

Squid differ from fish in more than just short life span. They also have a relatively long juvenile phase, exponential growth, short spawning periods, spatial and temporal variability in population dynmaics and considerable inter-individual variability. Therefore, existing fish management strategies are unlikely to adequately address the spatial and temporal variability evident in squid populations. This project directly addresses the key areas of squid fisheries research, that is the need to clarify the variability in the life history characteristics in space and time. It will only be through the quantification of this information and the application of modelling techniques that we will be able to determine the appropriate management strategy for squid, eg closures vs limited access vs total allowable catch.

A need for research on Southern Calamari has arisen because the fishery targets sexually mature individuals on the spawning grounds while they are mating and laying eggs. This is a short-lived species (6-8 months) and populations are entirely dependent on successful production of young by each generation. Therefore, we need to determine the impacts of fishing upon adult populations and egg production, which may compromise future recruitment.

Fishers and managers in Tasmania have raised questions about the current status of Southern Calamari stocks, with suggestions that increasing exploitation may place the stocks at high risk of collapse. A number of factors such as the short lifespan, low fecundity, non-overlapping generations and high inter-annual recruitment variability of this species exacerbate the risk. Especially since managing a species with these biological characteristics cannot be based on previous catch history. We need to develop numerical models that can use biological indicators to manage stocks that are vulnerable to recruitment failure given that the primary target is spawning individuals.

The current state of biological and ecological knowledge about Southern Calamary does not allow management decisions to be made to allow this fishery to develop at sustainable levels. Consequently, there is an urgent need to quantify the productivity of Southern Calamari populations and determine which components of the population are fished by different gear types.

Objectives

1. Describe temporal and spatial variability in rates of growth, size and age distributions, and reproductive status of populations of Southern Calamari.
2. Describe the spatial and temporal patterns of spawning activities and quantify the reproductive output of Southern Calamari populations.
3. Determine the age, size, spawning condition, and sex composition of the Southern Calamari caught by commercial fishers using different fishing gear.
4. Develop performance indicators to be used with Southern Calamari populations and other short-lived marine species.

Final report

ISBN: 1-86295-104-7
Author: Natalie Moltschaniwskyj
Final Report • 2004-01-20 • 2.47 MB
2000-121-DLD.pdf
View Filter

Research

Category

Species

Organisation