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Title:

Examining the relationship between fishery recruitment, essential benthic habitats and environmental drivers in Exmouth Gulf

Project Number:

2015-027

Organisation:

Department of Primary Industries and Regional Development (DPIRD) WA

Principal Investigator:

Scott Evans

Project Status:

Current

FRDC Expenditure:

$514,056.00

Program(s):

Environment

Need

Stock status in the EGPMF is assessed by monitoring fishery-independent and fishery-dependent catch rates (used as indices of recruitment and spawning stock levels) relative to specified reference points. However, in recent years factors other than the spawning stock index appear to be responsible for low levels of prawn recruitment. Given recent indications that the distribution and abundance of seagrass habitats may influence prawn recruitment there is a need to better understand the relationship between prawn recruitment, environmental conditions and habitats. Understanding these relationships is required to clarify the uncertainty around stock fluctuations and improve stock assessments. The information is also required so that management can be more cognisant of the impacts of environmental conditions on annual recruitment variability and implement adaptive management strategies, such as altering seasonal arrangements, to prevent overfishing. Similarly, the recent MSC assessment of the EGPMF fishery has highlighted the need to clarify the uncertainty in fishery independent surveys and stock assessments including the influence of environmental factors on indices, and collect environmental and habitat data to detect changes in risk to habitat due to fishing including ongoing monitoring of critical habitat types. Therefore, the development of broad scale fishery specific, cost effective monitoring techniques is essential to assess and monitor the association between critical fish habitats, environmental drivers and prawn recruitment. These techniques need to be developed at appropriate temporal and spatial scales to allow for early intervention of appropriate management measures, such as adjusting spatial and temporal closures, to ensure the long term sustainability of stocks and maintain MSC certification. Given that recruitment in a number of the State’s other invertebrate fisheries appears to be influenced by environmental drivers developing techniques to understand these relationships is a critical component of ensuring the management of WA’s fisheries resources is based on robust science.

Objectives

1. Collate and review historical, satellite, habitat and environmental data for the Exmouth Gulf and Shark Bay ecosystems to identify factors that may influence recruitment.

2. Assess the ability of different techniques, at various spatial and temporal scales, to identify, assess and monitor critical fish habitat and environmental conditions which may affect recruitment patterns of prawns into the Exmouth Gulf Prawn Managed Fishery

3. Collect local environmental and productivity data to assess the feasibility of collecting broad scale data remotely.

4. Develop a cost effective monitoring program for critical fish habitat and environmental drivers which allows the development of mitigation measures to assist in alleviating poor recruitment events.