scallop (pecten maximus sea-ranching in norway lessons …

Scallop (Pecten maximus) sea-ranching in Norway

– lessons learned

Ellen Sofie Grefsrud, Tore Strohmeier

& Øivind Strand

Background - Sea ranching in Norway

• 1990-1997: Program to develop and encourage sea ranching (PUSH)

• Focus on four species • Atlantic salmon (Salmo salar)

• Atlantic cod (Gadus morhua)

• Arctic char (Salvelinus alpinus)

• European lobster (Homarus gammarus)

• Only lobster showed an economic potential

Grefsrud et. al, 6th ISSESR, 11-14 November, Sarasota FL, USA

Background - Scallop sea ranching

• 1980-90’s – a growing interest on scallop Pecten maximus cultivation in Norway

• Based on suspended culture (1980’s) – labour costs high

• European concensus that seeding on bottom was the most viable option

• First experimental releases i Norway in mid-1990’s


Photo: IMR Photo: IMR

Production model Pecten maximus

• Hatchery + nursery – larvae + 2-20 mm shell height

• Intermediate culture – 20-55 mm

• Grow-out on seabed – 55->100 mm

Three production steps to lower risk for investors and increase the profit in each step

Time aspect – four-five years from hatchery to market sized scallops


Photo: IMR

Hatchery + nursery

• Established a commercial hatchery, Scalpro

• Industry + research developed methodolgy for producing spat on a commercial scale

• Larvae phase • Antibiotics and probiotica to prevent bacterial outbreaks (early phase)

• Continous flow-through in larvae tank and increased volume

• No use of antibiotics in commercial production

• From hatching to spat in about three weeks


Photo: S. Andersen

Photo: IMR

Hatchery + nursery

• Transferred from hatchery to nursery in the sea at 2-4 mm

• Land based race-way system – 2-20 mm • Flow-through filtered sea water

• Reduced predation and fouling

• The commercial hatchery, Scalpro, covered both the hatchey and nursery phase


Photo: IMR

Photo: IMR

Intermediate culture

• Suspended culture or bottom cages

• Interaction between transport method and site selection

• Expected survival 75-90%

• Most scallops reach a size of 45-55 mm SH within a year

• Fouling challenges


Photo: IMR

Photo: IMR

Grow-out on sea bed

• Transport – stress impact recessing behaviour and mortality

• Site selection • Many areas considered suitable for scallop sea ranching

• Growing into commercial size (100 mm SL) within 3-4 years • Rotational system removing large scallops

• Majority of scallops should be harvested within a three-year period

• Predator control • Great loss to crab and starfish predation

• Need of predator control


Photo: IMR

Predator vs scallop

Two strategies

• Release large scallops (> 60 mm SH) • Negative effect of intermediate culture on viability

• Increased labor costs

• Develop predator control systems • Physical installations (fences)

• Release in areas with low predator density and/or when predator activity is low


Photo: Ø. Strand

Photo: IMR

• 1200 crabs caught outside fenced area and 4 crabs caught inside

• 89% survival within the fenced area, 5% in the site with no predator control

• Do not keep out seastars

Fence

Photo: IMR


Harvest at grow-out site

• Dredging not allowed in in-shore areas

• Diver based (reference level fishery: 200-300 kg/diver/day)

• ROV-technology – no success (less cost-effective compared to diving, 47 kg/hour)


Photo: Ø. Strand Photo: S. Mortensen

Later phase (mid 2000’s)

Idustry role • Technology

• Husbandry operations

• Predator control

• Product marketing

• Evaluation of site suitability

Government based research • Environmental impact on benthic

communities


Laws & regulations

• 2001 – The Act on Sea Ranching

• 2006 – became part of the Aquaculture Act • Restricted to sedentary species • Provides licence holders exclusive right to harvest released animals

within a defined area

• Licence holders resposibility • Ecological impact on biological diversity • Risk of disease transmission • Use of local broodstock for juvenile production • Document technical qualifications • Plan to remediate licence area



2006: 16 licences for scallop

sea ranching given under the

Aquaculture Act

2014: 9 licences, none in commercial operation

Commercialisation of scallop sea-ranching failed – but why?


Lessons learned

• Site selection • Research and industry trial generated knowledge

• But - farmers chose areas based on practical considerations, not necessarily based on best grow-out conditions

• Result - Production time exceeded due to slower than expected scallop growth rates

• Predator control • Labour intensive

• High costs


Lessons learned

• Conflicts with local interests • Municipality plans

• Sea ranching did not fit into any of the existing area-planning categories

• Resistance against structures on the sea bottom (fences)

• Fishing activity

• Recreational activity

• Environmental interests (protected areas)

• Lack of industry support from authorities to develop scallops as a new aquaculture specie (long production time and non-fish issues)


Future prospects

• More focus on biomass production lower in the food chain i.e. low throphic aquaculture

• More focus on sustainable production and harvesting • Hatchery + undersized scallops from wild fishery in holding

areas (put and take)

• Low density seeding strategy (stock enhancement)

• May be an opportunity for a renewed interest of scallop sea ranching – knowledge base is good, but governmental support and financial willingness is needed!


Photo: IMR

Photo: IMR

Photo: IMR

Photo: R. Olssøn

# BeMoreScallop

Production challenges Pecten maximus

• Hatchery + nursery • Survival and growth / bacterial control • Continuous larvae culture • Predation

• Intermediate culture • Transportation and handling stress • Optimize growth in cages

• Grow-out on seabed • Site selection • Predator control • Harvest


scallop (pecten maximus sea-ranching in norway lessons …

Documents