Yields of great scallop, Pecten maximus, larvae in a commercial flow-through rearing system in Norway

Abstract

Survival, growth and yield of competent great scallop (Pecten maximus) larvae were investigated during a full production season in a commercial hatchery in western Norway. Broodstock were collected from natural scallop beds and 12 groups were induced to spawn during the period December 2002 to July 2003. Larvae were reared on a large scale in 36 flow-through tanks (3500 l) at 17±1°C and continuously fed a mixture of five algal species produced in an indoor continuous-flow system. Large variations in larval performance between spawning groups and tanks were observed, but the results were as good as earlier results using the batch system and prophylactic addition of chloramphenicol. Growth from days 3-24 averaged 4.8 lm day )1 ±0.8 (sd) and survival 22.4%±21.8 (sd). Mean yield of day 3 larvae was 7.1%±10.0 (sd) and 26.6%±25.9 (sd) for those surviving to day 24. Yield was significantly correlated to larval survival. Larval success was related to initial larval density, algal concentration and season. It was found that the best production regime had an initial larval density lower than 6 ml )1 and algal concentration of less than 12 ll )1 regardless of season. Seventeen tanks met these criteria and produced a mean yield of 0.5 larvae ml )1 to settlement. Flow-through systems are currently regarded as the only feasible method for viable hatchery production of P. maximus larvae in Norway.

Does a large-scale continuous algal production system provide a stable supply of fatty acids to bivalve hatcheries?

“…Although the results showed that many FAs varied between replicates and over time, the production of the essential PUFAs increased. Considering the total microalgal production of the essential PUFAs in this experiment, a stable supply of all the essential PUFAs to the scallop larvae and spat was secured at a ratio of 1:1:1 of Isochrysis sp., P. lutheri and C. muelleri, similar to combinations used in scallop hatchery by Magnesen et al (2006). Improvements to be considered in order to increase PUFA production further are lower pH and increase light penetration, particularly in the Isochrysis sp.…”

“…Three species, Isochrysis sp., P. lutheri and C. muelleri, widely used as feed in bivalve hatcheries because of their nutritional profile, were grown in commercial scale (e.g. Magnesen et al 2006). The variation of FAs in the algal production system were analysed between replicate bags over time.…”

Impacts of rearing techniques on growth, survival and bacterial microbiota of carpet shell clam (Ruditapes decussatus) larvae

“…However, the overuse of antibiotics in treatment of mollusk aquaculture may contribute to an increase in the level of antimicrobial resistance (Mechri et al 2013(Mechri et al , 2015. The introduction of a flowthrough system instead of closed-circuit water system in larval rearing tanks eliminated the use of antibiotics by improving water quality (Southgate and Ito 1998;Magnesen et al 2006).…”

“…These authors also revealed that the use of FTS with constant flows of highquality water and a daily cleaning of the sieve clogs facilitated the circulation in the rearing tank and removal of metabolic waste products providing favorable conditions for larval development. Several studies suggested an association between the stocking density and the water exchange rate (Magnesen et al 2006;Rico-Villa et al 2008). Furthermore, Andersen et al (2000) and Sarkis et al (2006) reported a reduction in growth performance at high stocking density when they reared scallop (Pecten maximus) and oyster (C. gigas) larvae in FTS.…”

Hatchery-scale trials using cryopreserved spermatozoa of black-lip pearl oyster,Pinctada margaritifera

“…Twentyfour hours later, the incubator tank was drained onto a 35 µm sieve and D-shaped larvae were concentrated in a 5 L graduated cylinder. D-shaped larvae were counted (3 × 20 µl) and then reared in a through-flow culture system (Magnesen et al 2006;Rico-Villa et al 2008;Sarkis et al 2006) in 4 replicates. D-shaped larvae were fed using three tropical species of micro-algae: Isochrysis clone T-Iso, Chaetoceros minus and Chaetoceros gracilis.…”