Moving Mussels Offshore

24 September 2007

Trish Daly BIM

Killary Harbour

Rope mussel Production and value 1990-2006

12 000 10 000 8 000 6 000 4 000 2 000 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0 Volume (tonnes) Value ('000)

Licensed Areas in Kilmacillogue

Licensed Areas in Ardgroom

Licensed Areas V Hectarage in use 150 100 50 0 350 300 250 200 Licensed In use

Production areas

3000 Production V Floatation

Production versus floatation

3,000,000 2,500,000 2500 2000 1500 1000 500 0 2,000,000 1,500,000 1,000,000 500,000 0 Production Floatation

Production areas

Why Move Offshore

• Many established Bays are overcrowded • Growth rates have dropped off in some Bays • Risk of bacterial and viral pollution is reduced • Conflict with other Bay users is reduced • The nature of our coastline offers many opportunities • There is possible reduction in incidence of biotoxins

Offshore Mussel Trials in Ireland

• Semi submerged mussel longlines, single headrope lines • Submerged mussel longline, Seaflex mussel float • Longtube longlines, Smart Farm system

Semi-submerged longlines

• First trial 1990, Seal Harbour • Adopted and modified a system from IFREMER, France • Single headrope longline, 1-3m below surface • Purpose built Irish mussel floats • Floatation kept to a minimum

Seal Harbour

Outer Bantry Bay

Galway Bay

• Started in 2005, 7 longlines and 2 Smart lines • Maximum site depth is approx. 30m • Hard sandy bottom • Fully exposed to southwesterlies • Difficulties with droppers tangling • Collected on a new heavier Spanish rope, 400g/m • Preference for single anchor at either end • Site access limited

Submerged Mussel Longline

• “Seaflex mussel float • 2 x 20m x 300mm sandor hose • Moored at both ends and in the centre • Buoyancy in the water controlled through a hose connected at one end • Situated 5m below surface • Trial abandoned • No dedicated workboat

Longtube System Smart Farm

• Individual HDPE pipes, 126m x 250mm, wall thickness 7.7mm

• 2 – 2.8m deep collector made from square mesh, 8mm p/p, 250mm x 250mm square • 32mm headrope lashed to pipe • Stainless steel clamp • Pipes generally moored as grid system with prefabricated fan.

• Two machines available for husbandry & harvesting

Collector mesh & fan system

Thinning machine, Kenmare

Harvesting machine, Kenmare

Smart Farm in Ireland

• Three Bays selected: Lough Swilly, Bantry Bay, Kenmare River • Different focus for each trial site • Lough Swilly: strong currents, seed collection • Bantry Bay & Kenmare River: Varying degrees of exposure

Lough Swilly

Lough Swilly

• Max depth 20m • Strong current, up to 4 knots • Traditional system tried and failed, as did semi submerged lines • The lines yielded about 10 tonnes of seed each but a dive survey had estimated 14 – 16 tonnes.

• Brushes were not strong enough for removing the crop • Collector mesh offered great potential for seed collection and relaying

Smart Farm in Bantry Bay

• Three potential sites • Permission for two, licensed to Southward Ltd at Horse Island and Whiddy • Lines moored individually • Two lines damaged, clamp failed.

• Clamp design has since changed • Slippage at more exposed site

Kenmare Bay

Kenmare Trial Site

Kenmare Bay Site characteristics

• Maximum depth 40m • Seabed varies from hard sand to rocky • Fully exposed to prevailing southwesterlies • Over 12m swells recorded, current speed of about 2 knots • Highly productive site

Mooring point specification

Trial Results

• Disappointing • Pipes failed on all sites.

• Harvesting machine never operated to its full potential • Availability of workboat and machinery major limiting factor • Load cells attached to 2 westerly anchors, 2 anchor ropes and fan ring unreadable.

• Currently 32 lines on commercial site in Kenmare

Summary results

• Semi-submerged lines have been the most successful to date • A dedicated, purpose built workboat is essential. • Limited opportunities to manage and harvest lines • In all these systems the tidal range of 4m is always a major factor

Strengths

• Growth rates, shell quality and meat yield all improve • With advancements in reusable drop ropes and the natural flushing out associated with exposed sites the environmental impact of these farms is greatly reduced • Significant advances in husbandry technology in recent years make it more achievable on a practical level

Weaknesses

• Limited technical data available on sites • Workboat must be capable of operating in exposed conditions • Cost of setting up V market price of mussels • Weather windows limited from Autumn through to Spring • Results to date did not show an improved biotoxin profile for sites tested.

Opportunities for the Future

• Shellfish farming has a place offshore and Irish coastal waters offer huge potential for mussel production in exposed and semi-exposed sites.

• A detailed understanding of environmental parameters, including wave climate, topography, water exchange, current speed, temperature, salinity, oxygen and assessment of risk of harmful algal blooms is needed • Collaboration between the Agencies and between the sectors is essential