maximus) sea-ranching

Transcription

1 More than 20-year development of the King scallop (Pecten maximus) sea-ranching industry in the bay of Brest (France) P.G. Fleury, J.P. Carval, M.L. Muzellec, A. Gérard, J. Barret, J.C. Cochard, C. Lambert* & J.C. Dao Association Ecloserie Tinduff Crédit photos: Ifremer, CUB, Régis Lasbleiz

2 1. Background 2. The sea-ranching industry 3. Results and limits

3 King scallop production in Brest from 1950 bay of to 1990 Brest 2000 mt 1000 mt Engines Cold winter

4 2. The sea-ranching industry Funding Production techniques Fishing management

5 Funding (infrastructures and research) and : two contracts French state + Brittany region : Europe Bay contract for the bay of Brest (pilot program for scallop industry) + Concerted Action / scallop seeding

6 Three main rearing stages: Hatchery Intermediate culture at sea Production techniques On growing on sea bed

7 Hatchery: Le Tinduff 5/6 months: From larvae to 2 mm Conditioning hatchery nursery

8 Algal culture in batch Four main species Skeletonema costatum Chaetoceros calcitrans Isochrysis affinis galbana (T-iso) Pavlova lutheri. 2 and 10 liter flasks 300 L cylinders

9 Conditioning and spawning -Adults selected from the wild -2 to 3 month conditioning: maturation -Spawning induced by thermal shock

10 Larval stage ovocyte 21 to 30 days at 18 C Before metamorphosis 450 L cylinders

11 Nursery: from post-larvae to 2 mm Two months

12 Intermediate culture Bay of Morlaix Bay of Brest Bay of Saint-Brieuc Brittany 100 km

13 Intermediate Culture Intermediate culture, at sea (6-10 months) From 0.2 to 3 cm

14 On growing on sea-bed On growing on sea-bed (2-3 years)

15 Evolution of the program : Restocking On growing 5 years on sea-bed create an additional brood stock (+ 500 tons within 5 years) Since 1989: Sea ranching In fishing areas on growing 2 years on sea-bed (with wild stock) additional production for the fishery In restricted area (closed for 3 years) on growing 3 years on sea-bed (till opening of the restricted area) give production when fishing yields decrease

16 Fishing management > Licenses: 60 to 70 x 4500 > Minimum Shell size : 10.5 cm > fishing period: - from October 1st to May 15th - Duration of fishing decided before each new period > Max engine power: 150KW > Max size of the boat: 11 m

17 3. Results and limits

18 Seeding production 83/84 84/85 85/86 86/87 87/88 88/89 89/90 90/91 91/92 92/93 93/94 94/95 95/96 96/97 97/98 98/99 99/00 00/01 01/02 02/03 03/04 Seeding / bed Seeding / restricted area Wild Metric Tonnes tons Year Années ± 300 tons /year Seeding: from 1/3 to 2/3 fished scallops

19 Technique Limits (Among others) Algae production (quantity, quality ) Larval rearing prophylaxis Stress due to the transfer of juveniles when seeded Environment Competitors: Crepidula Predators : starfish, whelks, crabs, polydora... Vermin Gymnodinium, Pseudo-nitzschia (ASP amnesic shellfish poison )

20 Conclusion Use of aquaculture appeared successful to partially restore the scallop fishing in the bay of Brest and to develop new integrated management tools however the scallop network appeared still fragile due to technical problems but above all to new and/or uncontrolled environmental hazards.

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