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Stock Status Overview
|Tasmania||Ansons Bay Vongole Fishery||ABVF||Environmentally limited||Biomass estimate, recruitment|
- Ansons Bay Vongole fishery (TAS)
Vongole (Katelysia spp.) is a species complex that inhabits coastal waters from Augusta in Western Australia to Port Jackson in New South Wales. They are found on sand banks in shallow bays and estuaries from the intertidal zone to a depth of 5 m1. Stock structure is unknown. However, given the short larval life span2, it is expected that Vongole in individual bays would constitute separate stocks.
Here, due to the potential for there to be a large number of stocks, assessment of stock status is presented at the management unit level—Western Australian Vongole Fishery, Ansons Bay Vongole Fishery (Tasmania), West Coast Cockle Fishing Zone (South Australia), Coffin Bay Cockle Fishing Zone (South Australia) and Port River Cockle Fishing Zone (South Australia).
Ansons Bay Vongole Fishery
The harvest strategy for Vongole in Tasmania in the Shellfish fishery policy document3 uses biomass and size-composition as performance indicators but does not define a limit reference point below which the stock would be classified as recruitment overfished. Biomass surveys of the Ansons Bay Vongole fishery are conducted every 2–3 years with total allowable commercial catches (TACCs) determined up to 10 per cent of the biomass estimate (at the 95 per cent confidence interval).
The 2015 estimate of biomass in the Ansons Bay Vongole fishery was 27.15 t (22.85–31.45 t). Exploitation rates were below the maximum of 10 per cent and minimum legal limits (32 mm shell length [SL]) are set at a size that enable the majority of Vongole to reproduce prior to being available for harvest. This level of fishing pressure is unlikely to cause the stock to become recruitment overfished.
Despite these measures, in 2015 there was no evidence of recent recruitment (no pre-recruits or juveniles identified) and the biomass estimate was the lowest on record. This low biomass estimate is likely attributable to a combination of mortality of Vongole as a result of extreme rainfall and flood events in the north-east of Tasmania in 2014, followed by recruitment failure in 20154. The above evidence indicates that spawning stock biomass is likely to have been reduced to the point where average recruitment levels are significantly reduced, primarily as a result of substantial environmental impacts (as in, the stock is not recruitment overfished).
The Ansons Bay Vongole Fishery (Tasmania) was closed to commercial fishing from 1 September 2015 on the basis of being an environmentally limited stock.
On the basis of the evidence provided above, the Ansons Bay Vongole Fishery (Tasmania) management unit is classified as an environmentally limited stock.
|Species||Longevity / Maximum Size||Maturity (50 per cent)|
|VONGOLES||29 years; 55 mm SL||4 years; 23–31 mm SL|
Distribution of reported commercial catch of Vongole
|Total allowable catch|
|1 in ABVF|
- Ansons Bay Vongole fishery (TAS)
a Active Vessels Vongole can be collected from beaches and bay on foot therefore, ‘vessels’ are not always used. Hence, numbers of licences and fishers are presented here instead of vessel numbers. Licences refer to the number of licence holders with an endorsement to take Vongole for sale.
Commercial catch of Vongoles - note confidential catch not shown
Effects of fishing on the marine environment
- The overall environmental impacts associated with the Vongole Fishery are considered to be low. The commercial Vongole catch represents a relatively small proportion of the biomass and, as such, there are unlikely to be significant impacts on the food chain from this fishery.
- Although the impact of cockle rakes on the benthic community is poorly understood, it is unlikely to be significant12. This is because only a small proportion of the available Vongole habitat is fished each year and communities in sand habitats, where the majority of fishing is concentrated, tend to be resilient to change. Bycatch can include juvenile prawns, juvenile crabs, juvenile fish and other molluscs. In the majority of cases, these animals are able to be released unharmed.
Environmental effects on VONGOLES
- Recruitment of Vongole is episodic6. The cause of this may be a result of an interaction between biological and environmental factors1 resulting in variable survival of the larvae in the planktonic stages, settlement, survival from settlement to recruitment. Above-average warm water and land heatwaves were inferred to have resulted in mortality of Vongole at Streaky Bay in 20148 and unseasonal severe flooding events in 2014 were implicated as the cause of mortality in the Ansons Bay Vongole Fishery (Tasmania)4. These events are expected to increase in severity and frequency under most climate change scenarios13.
- 1 Cantin, A 2010, Population biology of two sympatric mud cockles, Katelysia peronii and K. scalarina (Bivalvia: Veneridae), with implications for their management, PhD thesis, Flinders University, Adelaide.
Gluis, MR and Li, X 2014, Hatchery manual for larval rearing of Vongole Katelysia rhytiphora, Fisheries Research and Development Corporation Project 2009/208, South Australian Research and Development Institute (Aquatic Sciences), Adelaide.
Department of Primary Industries and Water 2007, Shellfish fishery policy document, Wild Fisheries Management Branch, DPIW, Hobart.
- 4 Tarbath, D and Gardner, C 2015, Small Bivalve Fishery assessment. Institute for Marine and Antarctic Studies Report, University of Tasmania, Hobart.
Primary Industries and Regions South Australia 2013, Management plan for the South Australian Commercial Marine Scalefish Fishery, South Australian Fisheries Management Series: Paper 59, PIRSA, Adelaide.
- 6 Dent, J, Mayfield, S and Carroll, J 2016, Harvestable biomass of Katelysia spp. in the South Australian commercial Mud Cockle Fishery, Report to Primary Industries and Regions South Australia, Fisheries and Aquaculture, SARDI Publication F2014/000191-2, SARDI Research Report Series 898, SARDI, Adelaide.
Dent, J, Mayfield, S, Burch, P, Gorman, D and Ward, TM 2012, Distribution, harvestable biomass and fisheries biology of Katelysia spp. in the South Australian commercial Mud-Cockle Fishery, Fishery assessment report for Primary Industries and Regions South Australia Fisheries and Aquaculture, SARDI Publication F2010/000263-2, SARDI Research Report Series 595, South Australian Research and Development Institute (Aquatic Sciences), Adelaide.
- 8 Dent, J, Mayfield, S, Ferguson, G, Carroll, J and Burch, P 2014, Harvestable biomass of Katelysia spp. in the South Australian commercial Mud Cockle Fishery, Fishery assessment report for Primary Industries and Regions South Australia Fisheries and Aquaculture, SARDI publication F2014/000191-1, SARDI research report series 766, South Australian Research and Development Institute (Aquatic Sciences), Adelaide.
Gorman, D, Mayfield, S, Burch, P and Ward, TM 2010, Distribution, harvestable biomass and fisheries biology of Katelysia spp. in the South Australian commercial mud cockle fishery, Fishery assessment report for PIRSA Fisheries, SARDI Publication F2010/000263-1, SARDI Research Report Series 442, South Australian Research and Development Institute (Aquatic Sciences), Adelaide.
- 10 Riley, SP, Green, RM, Zacharin, W and Maguire, GB 2005, Growth models and age determination for the intertidal venerid clam Katelysia scalarina (Lamarck 1818) from three sites in Tasmania, Australia, Fisheries Research and Development Corporation Project 93/232, in GB Maguire (ed) Enhancing Tasmanian clam resources, FRDC, Tasmania.
- 11 Giri, K and Hall, K 2015, South Australian recreational fishing survey 2013–14, Fisheries Victoria Internal Report Series No. 62, Victoria.
- 12 Primary Industries and Regions South Australia 2011, Ecologically sustainable development (ESD) risk assessment of the South Australian Marine Scalefish Fishery, Primary Industries and Regions South Australia, Adelaide.
Hobday, AJ, Poloczanska, ES and Matear, RJ (ed.s) 2008, Implications of climate change for Australian fisheries and aquaculture: a preliminary assessment, Report to the Australian Government Department of Climate Change, Canberra.