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Mussels
Mytilus edulis

General Information
Biology
Husbandry Information
Land and Water Requirement
Capital and Operating elements and costs
Licensing Information
Spat Information
Best practice environment guidelines
Papers

Additional Resources

 General Information

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Wild mussels tend to occur in bays and estuaries which have elevated levels of nutrients from land runoff, causing an increase in phytoplankton (microscopic plants) which is the main food for the filter-feeding mussels.  They attach to rocks, jetties and piers and sometimes form dense beds on sandy flat substrates.   They can be found from the low tide level to a depth of 10 metres, and they prefer sites with significant water movement. 

Blue mussels have a minor spawning period in June, followed by a second, extended spawning period from August to January.  Spawning occurs at water temperatures of 14°C.  Blue mussels are "broadcast spawners" releasing eggs and sperm simultaneously into the water with fertilisation taking place in open water.

The fertilised eggs are planktonic, averaging 0.07mm in diameter and develop into unshelled larvae within a day.

Larvae are free swimming and the planktonic stage can last from 2 weeks to several months, although most larvae settle 3-4 weeks after spawning.

Blue mussels are filter feeders, straining plankton from the water.  They are preyed on by crabs, starfish, leatherjackets, pufferfish and flat worms.

Blue mussels are an important commercial fishery.  There are only small sectors still harvesting wild mussels.  Most mussels are aquacultured, grown using long line methods, with sprat collected via natural settlement.  All farmed product is sold live and whole in the shell.

Some information on Cultured Mussels in Australia:
Mussels are one of the most nutritious, convenient and value-for-money seafood delicacies available.  Today, mussels are grown at 20 of the lease sites granted in Victoria's Port Phillip Bay.

The mussels are grown on ropes in clean, flowing ocean currents and harvested at their peak condition.  Unlike inferior dredged mussels dragged out of the mud at the bottom, Cultured Mussels are suspended metres above the seabed and are clean and free from sand and grit - so clean they need very little preparation.

The colour of the mussel meat varies slightly - the girls are pink and the boys are paler !!

MUSSELS are high in protein and minerals and low in calories and fat.

 Biology

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The blue mussel is a filter-feeder distributed widely throughout southern Australia. This and closely related species are also found throughout temperate waters of Northern and Southern hemispheres.

Mussels reproduce by releasing either eggs or sperm directly into the water in a process known as spawning. Hermaphrodite mussels (containing both sperm and eggs) are rare. Mussels first spawn when they are over 3 cm in length at approximately 11 months of age.  Mussels in spawning condition are ‘fat’ and can be recognised by eye at this stage. During spawning, a mussel may produce up to eight million eggs, each of which is 0.07 mm in diameter.

Once fertilisation has taken place, a free-swimming larva is formed. The larvae are ‘planktonic’ meaning they simply drift with the currents. Larvae usually spend a few days in this planktonic stage, however the length time depends upon environmental factors, such as temperature. After this time, the larvae will settle and attach onto a surface such as a jetty pylon with their byssal threads. Once mussels have settled they are no longer called larvae, but are now called ‘spat’.

 Husbandry Information

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Mussel farming is Victoria is based on natural settlement. Spawning occurs during the winter months depending on location (from the end of June to August).

Ongrowing to market size is undertaken on longlines. A 3ha farm could have between 10 and 15 longlines of 150m or more shorter lines. Blue mussels are available year-round in Victoria, from different growing locations. Farmers can harvest year-round excepting the month or so directly following spawning. Mussels can take up to 18 months to grow 25g. However, faster growth rates have been achieved; 12 months to 25g and 15 months to 40g.

Mussels are susceptible to predation by fish and growth can be slowed by competition for space with other organisms such as barnacles, tunicates, tube worms and bryozoans, which are also filter feeders and reduce the food available to mussels.

Mortality on long lines may result from a lack of food (phytoplankton), or mussels being physically removed from long lines by extreme wave action in more exposed locations.

 Land and Water Requirements

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Victoria has abundant clear, productive, marine water, and Port Phillip Bay is regarded as one of the finest spat collection basins and growout sites for blue mussels in the southern hemisphere. The Victorian Shellfish Quality Assurance and Water Quality Monitoring ensure that Victorian mussels achieve and maintain high standards. Victorian mussel growers have embraced the Australian Aquaculture Forum's Australian Aquaculture Code of Conduct. Victoria's aquaculture zones are located in water certified to meet the highest standard ('clear water') for shellfish culture under the Australian Shellfish Sanitation Program , which is internationally recognised.

The sites currently available for mussel farming in Victoria can be divided into three areas: approximately 500 hectares on the west coast of Port Phillip Bay (Clifton Springs and Grassy Point), 12 hectares on the east coast of Port Phillip Bay, and approximately 300 hectares at Flinders in Westernport Bay. Site depth ranges between 8 and 12 metres. Government proposals to establish 1000 hectares near Pinnace Channel may further expand shellfish aquaculture opportunities.

 Capital and Operating elements and costs

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Start-up capital expenses for a 6ha farm are around A$100,000. Annual operating costs are estimated at less than A$100,000. The expected lead time to commercial production is between 12 and 18 months, and estimated annual yield per ha once established is approximately 10 tonnes.

 Licensing Information

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Applicants for a new aquaculture licence should read through the following information. Licence application forms can be obtained from the Fisheries Victoria Aquaculture Unit head office or from regional NRE offices.

Click for the full article

Source: http://www.nre.vic.gov.au/fishing/aqua

 Spat Information

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Mussel spat have been produced by Tasmanian hatcheries, however the successful grow out of these spat has been limited by fish predation (Daintith et al. 1997). In other Australian states, most spat are supplied by natural collection on specially designed collection ropes.

As the mussels grow, overcrowding of spat may result in stunted growth and may also result in excess mortalities. For this reason, juveniles are generally removed from spat collectors when they are 12 mm in length and then transferred to long lines at lower densities

 Best practice environment guidelines

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No Information available at this time

 Papers

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No Information available at this time

 Additional Resources

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The West Australian Department of Fisheries website includes comprehensive information
http://www.wa.gov.au/westfish/aqua/broc/species/mussels/index.html

Publications

Bayne, B.L. (Ed.), 1991. The Biology and Cultivation of Mussels. Aquaculture (Special Issue), 94: 121-278.

Brown, D., Van Landeghem, K. and Schuele, M. 1997. Australian Aquaculture - Industry Profiles for Selected Species. ABARE Research Report, 97.3, 102pp.

Cole, N., 2000. Western Australian Aquaculture Production. Aquainfo 28 (the Department of Fisheries), 13pp.

Daintith, M. George, M. and Ryan, B., 1997. Shellfish Farm Attendant’s Manual. Fishing Industry Training Board of Tasmania (Inc.), Hobart, 268pp. [639.4 DAI]

the Department of Fisheries 1998. A Proposal for the Establishment of Mussel Farming at Two Locations in Cockburn Sound. Pearling and Aquaculture Program, the Department of Fisheries, 20pp.

Gosling, E., (Ed.) 1992. The Mussel Mytilus. Developments in Aquaculture and Fisheries 25, Elsevier, Amsterdam, 590pp.

Herriott, N. 1984. A Guide To Longline Mussel Cultivation. Aquaculture Technical Bulletin 9, (Ireland. Dublin National Board for Science and Technology), 97pp.

Jamieson, G., 1989. Mussel Culture. World Aquaculture (Special Issue), 20(3): 8-103.

Jeffs, A.G., Holland, R.C., Hooker, S.H., and Hayden, B.J. 1999. Overview and Bibliography of Research on the Greenshell Mussel, Perna canaliculus, from New Zealand Waters. Journal of Shellfish Research, 18 (2), 347-360.

Jenkins, R.J. 1985. Mussel cultivation in the Marlborough Sounds (New Zealand). New Zealand Fishing Industry Board, Wellington, 77pp.

Lawrence, C. 1995. Blue Mussels Mytilus edulis planulatus. Aquaculture WA No. 5, 4pp.

Lutz, R.A. (ed.) 1980. Mussel Culture and Harvest: A North American Perspective. Elsevier, Amsterdam, 350pp.

MacKenzie, C.L. Jr., Burrell, V.G. Jr., Rosenfield, A. and Hobart, W.L., (Eds.), 1997. The History, Present Condition, and Future of the Molluscan Fisheries of North and Central America and Europe. NOAA Technical Report NMFS 129, 240pp.

Pearce, A., Helleren, S. and Marinelli, M. 2000. Review of productivity levels of Western Australian coastal and estuarine waters for mariculture planning purposes. The Department of Fisheries Research Report (in press).

Saxby, S. Water Conditions and Food Availability at Bivalve Culture Sites. A review of literature concerning bivalve growth and condition, food availability and water conditions, at commercial growth sites. The Department of Fisheries Research Report (submitted).

Thorne, T.J. 1995. Fish Health for Fish Farmers. The WA Department of Fisheries, 40pp.

Treadwell, R., McKelvie, L. & Maguire, G.B. 1991. Profitability of selected aquaculture species. ABARE Discussion paper 91.11, 85pp.

Wilson, B.R. & Hodgkin, E.P. 1967. A comparative account of the reproductive cycles of five species of marine mussels (Bivalvia: Mytilidae) in the vicinity of Fremantle, Western Australia. Australian Journal of Marine and Freshwater Research, 18: 175-203.

 
 

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