Final Report Summary - BLUE SEED (Technology development for a reliable supply of high quality seed in blue mussel farming)
The existing blue mussel culture has two technical limitations. The first is the unpredictability in seed supply. Techniques for seed supply are dredging wild seed beds, scraping mussel seed from rocks and collecting seed by natural settlement on, ropes or other substrates. Success of any of these methods depends on environmental conditions, which fluctuate. The amounts of wild seed available are therefore extremely variable from year to year. Producing seed under controlled conditions in a hatchery will disconnect its production from environmental factors and provide a reliable supply of seed. The second technical limitation is a lower meat quality during and after the spawning season Preventing maturation of market-size mussels during spawning season, is a major challenge to all European blue mussel farmers. Production of triploid mussels will secure a year round high meat content.
The use of hatchery-produced seed and sterile triploids could contribute to the solution of these two pan-Atlantic challenges. To reach these goals, the appropriate hatchery and nursery technology needs to be developed. In addition, any future program aiming to strengthen mussel quality through genetic improvement techniques will require well-tuned hatchery and nursery procedures for seed production.
The long-term goals of the BLUE SEED project were to secure a reliable supply of hatchery produced seed and to develop techniques allowing farmers to sell high quality blue mussels all year round. To achieve the long term goals a number of scientific and technical project objectives were formulated:
1. Develop hatchery technology for a reliable blue mussel seed production, by focussing on (a) broodstock conditioning, (b) larval rearing and (c) seed production.
2. Develop a viable production method for (a) sterile triploid mussel seed and (b) tetraploid broodstock that will enable year-round marketing of high quality mussels.
3. Compare, in each of the project partner countries, the economic feasibility of producing blue mussel seed based on hatchery-produced larvae with the benefits of blue mussel seed collection methods presently in use.
The BLUE SEED project optimised existing hatchery and nursery technologies for commercial blue mussel seed production. Important achievements were made in optimising the production and use of hatchery-produced mussel spat and seed.
Within the BLUE SEED project the hold and cold method has been optimised and the heat and treat method has been developed for blue mussels.
The BLUE SEED project showed that the larvae of the different mussel species require different algal species for optimal growth. In addition, optimal egg density, concentration of foods and size and shape of the rearing vessels were determined.
Within the BLUE SEED project the parameters were determined in the laboratory for Mytilus edulis. Other work in BLUE SEED suggests that the addition of Epinephrine (Adrenaline) speeds up settlement when added at the end of larval rearing. Furthermore, the relative recruitment of Mytilus galloprovincialis seed obtained from larval cultures carried out under different experimental conditions showed a density-dependent effect of recruitment on growth rate of spat. This suggest a possible effect of the moment of the season when induction of spawning or / and larval culture are carried out, on the recruitment of spat.
The BLUE SEED project produced tetraploid spat by direct induction from diploids. Because normal (diploid) blue mussel meat contains gonads, their absence could influence taste, texture and palatability. However, for the oyster Crassostrea gigas it was established that consumers and experts favoured the firmer meat of triploids over the softer meat of diploids, and market-sized diploid and triploid Saccostrea commercialis were also given equivalent scores. The evaluation to compare the sensory properties of diploid and triploid mussels at the end of the BLUE SEED project showed both types of mussels had a good acceptance by the panellists.
The minimum price at which the hatchery production method for blue mussel seed will be economically profitable was determined. In general, hatchery seed is used in areas where other sources of seed are scarce. In the BLUE SEED project a comparison with fishing for seed was made. This showed that hatchery seed is economically 17 interesting only when added value is present, or when other sources become less available.
The use of hatchery-produced seed and sterile triploids could contribute to the solution of these two pan-Atlantic challenges. To reach these goals, the appropriate hatchery and nursery technology needs to be developed. In addition, any future program aiming to strengthen mussel quality through genetic improvement techniques will require well-tuned hatchery and nursery procedures for seed production.
The long-term goals of the BLUE SEED project were to secure a reliable supply of hatchery produced seed and to develop techniques allowing farmers to sell high quality blue mussels all year round. To achieve the long term goals a number of scientific and technical project objectives were formulated:
1. Develop hatchery technology for a reliable blue mussel seed production, by focussing on (a) broodstock conditioning, (b) larval rearing and (c) seed production.
2. Develop a viable production method for (a) sterile triploid mussel seed and (b) tetraploid broodstock that will enable year-round marketing of high quality mussels.
3. Compare, in each of the project partner countries, the economic feasibility of producing blue mussel seed based on hatchery-produced larvae with the benefits of blue mussel seed collection methods presently in use.
The BLUE SEED project optimised existing hatchery and nursery technologies for commercial blue mussel seed production. Important achievements were made in optimising the production and use of hatchery-produced mussel spat and seed.
Within the BLUE SEED project the hold and cold method has been optimised and the heat and treat method has been developed for blue mussels.
The BLUE SEED project showed that the larvae of the different mussel species require different algal species for optimal growth. In addition, optimal egg density, concentration of foods and size and shape of the rearing vessels were determined.
Within the BLUE SEED project the parameters were determined in the laboratory for Mytilus edulis. Other work in BLUE SEED suggests that the addition of Epinephrine (Adrenaline) speeds up settlement when added at the end of larval rearing. Furthermore, the relative recruitment of Mytilus galloprovincialis seed obtained from larval cultures carried out under different experimental conditions showed a density-dependent effect of recruitment on growth rate of spat. This suggest a possible effect of the moment of the season when induction of spawning or / and larval culture are carried out, on the recruitment of spat.
The BLUE SEED project produced tetraploid spat by direct induction from diploids. Because normal (diploid) blue mussel meat contains gonads, their absence could influence taste, texture and palatability. However, for the oyster Crassostrea gigas it was established that consumers and experts favoured the firmer meat of triploids over the softer meat of diploids, and market-sized diploid and triploid Saccostrea commercialis were also given equivalent scores. The evaluation to compare the sensory properties of diploid and triploid mussels at the end of the BLUE SEED project showed both types of mussels had a good acceptance by the panellists.
The minimum price at which the hatchery production method for blue mussel seed will be economically profitable was determined. In general, hatchery seed is used in areas where other sources of seed are scarce. In the BLUE SEED project a comparison with fishing for seed was made. This showed that hatchery seed is economically 17 interesting only when added value is present, or when other sources become less available.
