The commercial scallop (Pecten fumatus) fisheries in south-eastern Australia have long been characterised as boom-and-bust (Tracey & Lyle 2010). While historic overfishing has contributed to this (Young 1989), unpredictable cycles of alternating abundance and large-scale die-off characterise the species, particularly in the eastern portion of the region. For instance, there have been five sudden die-offs on the eastern side of the Tasmanian fishery (TSF) and Commonwealth fishery (BSCZSF) combined since 2005. Whereas, since most recently being fished in 2014, the scallop beds in the King Island region of the BSCZSF have been harvested each year due to predictable and constant recruitment and scallop conditioning.
The relative difference in predictability between the regions likely lie with the changing nature of the EAC on the east coast bringing warm, nutrient-poor water to the east coast and the Leeuwin current bringing cold nutrient-rich water to the west coast, with these differences likely to be further exacerbated due to climate change. A case in point is the Tasmanian fishery, which after being closed for five years due to the stocks being depleted, opened in 2021 off Babel Island (east) only to find the bed had died-off only a few months post-preseason surveying. A sudden influx of warm water was likely the cause of the die-off, with beds in the eastern portion of both the BSCZSF and the Victorian scallop fishery (OSF) simultaneously suffering a significant loss of condition but not death (Semmens unpublished). In 2022, again a major die-off has impacted the TSF, with beds at White Rock (east) found to be dying off upon opening in late June. The unpredictability of these die-offs confounds management decisions, as a lack of understanding into the drivers of die-offs means that even if beds with commercially significant biomass are surveyed and opened, they may be lost before fishing begins. There is a clear need to understand these die-offs, determine if they can be predicted and adapt management such that it can be reactive and is tailored to the region in which the bed occurs (e.g., east vs west). Fitting management strategies to the fishing region also makes sense biologically, with the east and west portions of the species’ distribution displaying different life history features (e.g., spawning and settlement times, growth rates, etc; Semmens et al. 2019) and this may be a contributing factor to die-offs.
This project will use a collaborative industry/management/research approach to investigate the factors causing mass die-off of scallop beds, characterising the impacts of stressors including fishery practices, such as the use of tumblers, survey method (e.g., dredge vs video) and environmental factors, such as location of beds, sea temperatures (considering both absolute temperature and rate of change) and food availability, and assessing them in a framework that fits management practices to the relative risk of loss of fishable stock. Developing an understanding of the factors driving mortalities will also enable evaluation of existing data capture capabilities to identify whether potentially harmful conditions can be identified before beds are lost. Where deficiencies are identified, new data collection techniques will be evaluated, including video surveying of closed regions (both permanent, e.g., MPAs, and fishery closures) to allow more flexibility in decision making around when an area should be fished. The outcome of this research will provide the evidence needed to develop a decision-making framework that will enhance the rapid response capabilities of management of scallop fisheries in the future, but also ensure that they fit the changing environment and region within which the stocks sit, improving the sustainability of this vulnerable industry.
Project number:
2022-044
Project Status:
Current
Budget expenditure:
$373,032.00
Principal Investigator:
Ryan Day
Organisation:
Institute for Marine and Antarctic Studies (IMAS) Hobart
Project start/end date:
30 Jun 2023
-
29 Jun 2026
Contact:
FRDC
SPECIES
1. Identify intrinsic stressors (e.g., surveying techniques (e.g., video vs dredge) and timing, location (e.g., east vs west) and timing of fishing, the use of tumblers, size limits of scallops, etc.) and extrinsic stressors (e.g., temperature, food availability, etc.) commonly faced within the Pecten fumatus fishery that have the capacity to negatively impact scallop condition and cause mortality
2. Experimentally evaluate the effects of intrinsic, extrinsic and synergistic stressors on scallop physiology, condition, and mortality
3. Opportunistically video survey and collect scallops for sampling from scallop beds exposed to adverse conditions and/or experiencing die-offs to corroborate experimental results against real-world results
4. Develop recommendations to monitor for, and respond to, environmental conditions that may drive scallop bed die-offs
5. Work with industry and management to co-design decision frameworks for the sustainable management of Commercial scallop fisheries, including designing regional-specific approaches to optimising fishing opportunity and maximising continuity of stock, including obtaining video survey data from closed areas that may support recruitment
PROJECT NUMBER
•
2021-053
PROJECT STATUS:
CURRENT
Building capability in food safety in Australian shellfish
1. Understand the training needs to support the continued development of Australian shellfish industries covered by ASQAP
ORGANISATION:
University of Tasmania (UTAS)
PROJECT NUMBER
•
2021-010
PROJECT STATUS:
CURRENT
Wider investigation of the use of video survey techniques to determine commercial scallop abundance in inshore and offshore waters, closed areas and juvenile beds
1. Undertake a Commercial Scallop Fisheries review and a targeted desktop study examining current approaches used for video survey of scallop stocks
ORGANISATION:
University of Tasmania
PROJECT NUMBER
•
2019-120
PROJECT STATUS:
CURRENT
Building industry capacity to lead co-management initiatives within the Bass Strait Central Zone Scallop Fishery: Training industry to conduct biomass estimate surveys
1. Build industry capacity to lead and participate in fishery data collection projects
ORGANISATION:
Bass Strait Scallop Industry Association (BSSIA)