Ragnheidur I. Thorarinsdottir*, Soffia K. Magnusdottir, Halldor P. Halldorsson, Asbjorn Drengstig and Ann-Lisbeth Agnalt
University of Iceland, VR-2, Hjardarhaga 2-6, 107 Reykjavik (Iceland)
E-mail: rith@hi.is
Introduction
European lobster is a high value species where catches are low and commercial farming has yet to be established. Thus, the consumer demand and market price is high in all market segments around the globe. Hence, the European lobster could be one of the most promising potential aquaculture species, due to very high prospected profit margins.
The progress in aquaculture with e.g. recirculation of seawater and low-cost industrial automation technology has made it possible to meet the particular demands of lobster farming (Nicosia & Lavalli 1999, Kristiansen et al. 2004). On this ground the European Lobster Center of Excellence was established last year and now a project joining partners from Iceland, Denmark, Norway and UK aims to estimate the viability of implementing landbased farming of European lobster using geothermal energy in Iceland.
Materials and methods
The lobsters were received from the National lobster hatchery in Padstow UK and the Institute of Marine Research in Bergen, Norway, respectively. All lobsters are kept in single cages. The oxygen concentration, temperature, salinity and food consumption is monitored daily and the molting and survival is registered.
Growth trials of the UK lobsters are performed in semi-RAS and flow-through systems. The temperature is 18°C and the salinity is 32±1 psu in both systems. Growth trials of the lobsters from Norway are performed in the flow-through system at 10°C and 18°C. The day/night cyclus is 16h/8h and the lobsters are fed 5 days a week. The growth is followed by measuring total length of all lobsters and the carapace length and weight is also measured for lobsters larger than 35 mm in total length. The feed used is commercially available Arctic charr feed - Bleikja Natur - 3 mm from Fodurblandan in Iceland.
The metabolic rates in lobsters are measured under basic metabolism and during peaks under feeding. For respiration measurements the animals are placed in closed 100-300 ml plastic vials filled with air-saturated seawater. The decline in oxygen is measured using calibrated Strathkelvin 1302 microcathode oxygen electrodes and a multichannel Strathkelvin 98 system.
The lobsters were kept in two different types of cages and growth of individuals compared between those types.
Results
The growth rate and survival rate were relatively high compared to earlier studies. Difference in temperature affected growth rate significantly. Family information was available on the Norwegian lobsters and growth was compared between families. This information was not available on the UK lobsters. Lobsters were held in two different types of compartments which did not affect growth rate in a significant way. The commercially available Arctic charr feed - Bleikja Natur - 3 mm pellets were very well received by the lobsters. The composition of the pellets are quite similar to the lobster feed developed earlier by Norwegian Lobster Farm. The pellets contain astaxanthin and this results in a natural dark blue color of the lobsters making it suitable for market.
Information are given on oxygen consumption and ammonia excretion from standard tests at different growth stages and at different temperatures. The results will be used for dimensioning of intensive recirculating aquaculture systems (RAS) for commercial production of lobster.
Discussion and conclusion
Land-based farming of European lobster is possible and could become one of new stepping stone in land-based aquaculture. However, due to growth variations and high losses from cannibalism and injuries when kept communally, the cultured lobsters have to be kept in individual containers. This provides huge challenges for culture system design. The system needs to be relatively inexpensive to construct and operate, simple to maintain and based on automatic feeding and self-cleaning. The water quality conditions need to be maintained to obtain high survival and the system should allow easy access to the livestock for inspection and control.
The future work aims to provide solutions to these challenges, other biological questions, as well as the overall economy of the system design so further steps towards commercialization can be taken.
References
Kristiansen, T.S., Drengstig, A. Bergheim, A., Drengstig, T., Kollsgård, I., Svendsen, R., Nøstvold, E., Farestveit, E., Aardal, L. (2004): Development of methods for intensive farming of European lobster in recirculated seawater. Results from experiments conducted at Kvitsøy lobster hatchery from 2000 to 2004. Fisken og Havet, no. 6 -2004. 52 p.
Nicosia, F. & K. Lavalli. 1999. Homarid lobster hatcheries: their history and role in research, management and aquaculture. Marine Fisheries Review, 61(1), 1-57.