Blue Seed

 
Technology development for a reliable supply of high quality seed in blue mussel farming
 

Acronym

BLUE SEED

Start & end date

1 Nov 2005 until 1 Nov 2007

Funding & funded by

EU Craft  - Co-operative Research

Objectives

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 to the benefits of blue mussel seed collection methods presently in use.

Summary

Broodstock
The best success in obtaining good larvae from spawnings was during the first 6 months of the year. Cold temperature conditioning worked well for both species (Mytilus edulis and M. galloprovincialis) with larvae still being obtained during August. Warm water conditioning was carried out successfully with M. galloprovincialis and tests are presently being carried out with M. edulis.

Larvae
At all locations involved in larval rearing, larvae were reared up to the ready to settle stage (see Fig. 1). A protocol for the different tests was developed and several tests were carried out. Parameters include temperature, larval density, algal food species and combinations, container shape, aeration, broodstock origin and water quality. All institutions produced ready to settle diploid larvae.



Fig. 1: Ready-to-settle diploid M. edulis larvae

Triploids (3n) and tetraploids (4n)
Trials have been performed using two chemical (CB and 6-DMAP) and one physical 3n induction method.  The chemical inductions have shown good 3n yield percentages in the larval stage but poor larval survival, usually inferior to 2n controls. Heat shock induction of 3n showed a definite partial induction of 3n though its proportion declined over larval rearing and was low after settlement.  Settled 3n mussels are therefore few in number and methods not yet commercially viable. Viable tetraploid mussels have not yet been produced. One method of 4n induction was investigated, but was found not functioning as expected and highly toxic. Another method of direct induction was sought. More information has been gathered about the mechanism of the technique and possible future strategies.

Seed
A protocol for tests with spat was formulated and experiments were carried out. The effect of type of settlement rope, algal species diet, amount of food and culture density on spat settlement and growth rate were tested The quantities and quality of spat were insufficient to allow large scale experimental studies of settlement or on-growing, or the comparison between triploid and diploid seed. However, grow-out in the field was successful (see Fig. 2).

Fig. 2. Rope collectors with hatchery produced diploid Mytilus galloprovincialis seed when retrieved from a raft.




Production costs
The first accounting data on production costs for hatchery seed were collected. Areas where economies can be made to bring production costs more into line with potential sale value of mussel seed are: (1) Use low tech algal culture, (2) Restrict activities to natural season, (3) Scale up volumes of culture during restricted period of activity.
 

Staff involved

Pauline Kamermans, Ainhoa Blanco, Emiel Brummelhuis, Johan Jol, Marnix Poelman, Jeanet Allewijn

Position

Coordinator

Cooperation Partners

Five mussel farmers/sellers Grainocean (France), Neeltje Jans and Roem van Yerseke (The Netherlands), OPMEGA (Spain) and Deepdock (Wales), AquaTT an Irish based network for training and technology transfer, and three research institutes University of Wales at Bangor, CIMA (Spain), IFREMER (France).