3 results

Aquatic Animal Health Subprogram: pilchard herpesvirus infection in wild pilchards

Project number: 2002-044
Project Status:
Completed
Budget expenditure: $283,659.00
Principal Investigator: Brian Jones
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 30 Dec 2002 - 30 Jul 2006
Contact:
FRDC
TAGS
Disease
Diagnostic
Biosecurity
Animal Health
SPECIES
Sardines

Need

This proposal seeks to continue the work begun at AAHL and Department of Fisheries. There is a need to independently validate the available tools from Western Australia and AAHL and to put them to use in elucidating the biology of the virus, including a survey of wild pilchards for the virus. This is especially important as a number of modeling papers have made inferences about the latency and infectivity of the virus which need to be verified. There is also a need to continue the sequencing of the viral genome which has been carried out both at AAHL and in WA, in order to design more specific tools and also to compare the virus obtained in 1995 with that collected in 1998. This work was identified as a national priority in 1998 and the need has not diminished. It was also recognised by the JPSWG, from the outset, that progress would be slow.

Objectives

1. To improve the sensitive and specific diagnostic assays (polymerase chain reactions (PCRs) and in situ hybridization (ISH) which are based on current limited sequence data. This will include the generation of further sequence data from the available stocks of virus.
2. To independently establish the sensitivity and specificity of the PCRs and ISH at other laboratories, including AAHL.
3. To then investigate basic aspects of the virus and the disease eg. the tissue distribution of virus in infected fish, and the correlation between disease in fish and the presence of virus.
4. To survey wild pilchard populations to determine whether the virus is still currently detectable and causing disease.
5. To compare the herpesvirus strains from 1995 & 1998, and to compare, at the molecular level, this herpesvirus and this disease with two other similar herpesvirus fish diseases which have been reported elsewhere in the world.

Final report

ISBN: 1-877098-96-5
Author: Brian Jones
Final Report • 2008-11-25 • 1.34 MB
2002-044-DLD.pdf

Regrowth of pilchard (Sardinops sagax) stocks off southern WA following the mass mortality event of 1998/1999

Project number: 2000-135
Project Status:
Completed
Budget expenditure: $508,065.00
Principal Investigator: Dan Gaughan
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 9 Oct 2000 - 30 Jul 2008
Contact:
FRDC
TAGS
Stock Assessment
Social Science
Social Science
Mortality
Ecosystem
SPECIES
Sardines

Need

There is a need to assess the regrowth of pilchard stocks in southern Australia because of (1) the socioeconomic problems associated with fishery declines and the associated need to provide sufficiently detailed information so that management can proceed with the appropriate balance between sustaining the fishery and allowing recovery of the stocks, and (2) the potential for causes of wide ranging ecosystem affects to go unrecognized if there is no baseline data (i.e. abundance) for this key pelagic species.

In order to provide a time-series of the regrowth of S. sagax stocks in WA the biomass size of each adult assemblage needs to be assessed over the next few years. Because the ecosystem-based goal of this project is to provide a baseline of pilchard abundance which may relate to other species, the longer life spans, slower growth etc. typical of these higher trophic levels necessitates a long time series of surveys. Changes in biomass of the four pilchard assemblages should be assessed for a period of at least five years. Although this is a relatively short period of time over which to examine the recovery of a pelagic stock, such a routine will provide a solid basis for assessing the rebuild of pilchard abundance and thereby pro-actively collect data which could subsequently assist our understanding of other ecosystem affects of the Herpesvirus mortality event. This project will compliment the annual DEPM surveys intended for SA pilchard stock.

Collection of a continuous, albeit short-term, series of estimates of spawning biomass will permit the age structured simulation model being developed by Hall and Gaughan (in prep.) to be fitted to a likewise continuous series of these estimates. This should improve the fitting of the model, thereby making it more useful for predicting impacts of further mortality events involving S. sagax in southern Australia and facilitating the decision -making process in the ongoing management of pilchards in WA.

Objectives

1. Document changes in the biomass of the four exploited adult assemblages of S. sagax in WA during the six year period following the 1998/99 mass mortality event.
2. Integrate results of biomass surveys into the age structured model for each assemblage of pilchards. Further develop the age-structured simulation models for S. sagax and investigate ongoing behaviour of these under conditions of different levels of information
3. Determine if there is a measurable change in biological parameters of pilchards important to ongoing development of the simulation models, in particular growth rate, in response to the decrease in stock size.

Final report

ISBN: 1 921258 26 8
Author: Dr Daniel J Gaughan
Final Report • 2008-07-07
2000-135-DLD.pdf

Summary

This project produced time series of estimates of spawning biomass for pilchards in four purse seine management zones in Western Australia, three on the south coast and one on the west coast. The pilchard stocks in Western Australia have recovered strongly since the 1998/99 mass mortality.

This project has shown that the fishery independent and fishery dependent methods applied to Western Australia’s pilchard fisheries cannot provide precise estimates of the size of the pilchard spawning biomass in each management region. Although the trends indicated by the age-structured simulation model are reliable and provide good evidence for a strong recovery of pilchard stocks, the magnitude of changes in stock size from year-to-year are not known with sufficient certainty to allow high rates of exploitation.

The demonstrated increases in pilchard spawning biomass has lead to optimism for the future of the purse seine industry in southern WA, which in turn has encouraged this industry to be proactive in ensuring that exploitation rates were not set at levels that were too high to impede the recovery of the stock or put undue pressure on the long term viability of the stocks. Tracking the progress of estimating of pilchard biomass in each region over the duration of this project was a crucial factor that assisted industry members to better appreciate the need to examine factors additional to the point estimate of biomass generated in any one year.

The project also determined that the growth rates of pilchards in WA can be highly variable, sometimes changing markedly from year to year while at other times exhibiting more gradual changes over several years. The tendency for a negative relationship between annual growth rates and stock size suggests density dependence, which in turn supports the contention that that pilchard stocks in this region are limited in size by the biological and oceanographic characteristics of the continental shelf waters of southern WA. The magnitude and variability of pilchard biomass observed during this project builds on the knowledge obtained during the 1990s, providing a strong basis against which the purse seine industry can expect future quota levels to be set.

Keywords: pilchard (sardine), recruitment, age-structured model, spawning biomass, daily egg production method, stock recovery, fisheries management.

Pilchard (Sardinops sagax) nursery areas and recruitment process assessment between different regions in southern Western Australia

Project number: 1999-150
Project Status:
Completed
Budget expenditure: $124,503.76
Principal Investigator: Dan Gaughan
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 1 Aug 1999 - 11 Jun 2003
Contact:
FRDC
TAGS
Tagging
Stock Assessment
Reproduction
Fishing Gear
Ageing
SPECIES
Sardines

Need

There is an urgent need to determine the relationship between pre-recruit stages from the different stocks of adult pilchards amongst regions of southern WA. In particular, whether pre-recruits which originate in each region largely remain separate or mix together needs to be determined. Following this, knowledge on the rates of mixing of pre-recruits should be investigated so that the relative contribution from any one region to any other region can be estimated.

The key issues which need to be addressed are:
1. Do specific pilchard nursery areas exist?
2. Do recruits to each region come from a common pool of pre-recruits (e.g. one year olds)?
3. Is there significant eastward and or westward movements of pre-recruits between zones?
4. Does each zone of the fishery contribute similar numbers of recruits or is one zone (or two) more important than other(s)?

Because of the extent of the gap in our knowledge of pre-recruit pilchards this proposal is only for a 15 month pilot study. If results from the pilot study are encouraging, once the initial questions have been addressed a second research proposal will be developed to investigate mixing rates in greater detail through a combination of further otolith analyses and tagging. Also, continuing advances in methods to compare mitachondrial DNA may also permit this method to be used to examine the question of origin of recruits.

Objectives

1. Ascertain if pre-recruit pilchards can be caught on a regular (or even semi-regular) basis at each of the south coast regions or if a "major" nursery area exists for the entire stock.
2. Undertake an analysis of the oxygen and carbon stable isotope ratios for otoliths of pre-recruit and young post-recruit pilchards from each fishing zone to determine if separate groups of pre-recruits can be identified.
3. Undertake an analysis of the oxygen and carbon stable isotope ratios for the central region of otoliths from fully recruited pilchards at each region caught over the past 8 years to determine if separate groups of pre-recruits can be identified consistently over several years.
4. Attempt to tag large numbers of pre-recruit pilchards using tetracycline, calcein and possibly other 'dyes' to mark the otoliths and other calcium based structures such as fin rays to determine if this is a viable research tool for pilchards on the south coast of WA.
5. Assess whether there is a potential to develop a fishery independent index of recruitment.

Final report

ISBN: 0-7309-8463-X
Author: Dan Gaughan
Final Report • 2001-12-17 • 2.52 MB
1999-150-DLD.pdf
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