Introduction
The European lobster (Homarus gammarus) has been the subject of aquaculture research for the last 150 years, due to both the wild fishery and cultural value of the species. Since the middle of the 20th century, increasing anthropogenic pressure has led to a severe decline in wild fish and shellfish stocks, including H. gammarus, with some fisheries yet to recover. H. gammarus is amongst the most exclusive shellfish products worldwide, and whilst management measures have been implemented to safeguard stocks, H. gammarus aquaculture is an increasingly credible approach to help to secure sustainable lobster supply. Historically, this has been achieved by relatively small-scale release of hatchery reared juveniles. Until recently, commercial attempts at farming have not been viable, mainly due to cost prohibitive technical challenges. At present, there are several promising approaches to overcome bottlenecks hampering commercialisation of lobster aquaculture. This talk will summarise the new husbandry and nutritional advancements in H. gammarus culture from experiments performed at Swedens fiest pilot scale lobster hatchery over the last 5 years. Additionally, likely directions for both sectors in the coming decades are summarised, knowledge gaps identified, and the societal support required to achieve further potential will be highlighted.
Material and methods
This presentation will summarize data taken from a series of juvenile lobster exoeriments that took place between 2017-2022 at Kristineberg research station, Sweden. In general, gravid female lobsters were donated from commercial fishermen operating in Gullmarsfjorden, Sweden, and delivered directly to the Sven Lovén Centre, Kristineberg, Sweden during September- October 2015 and September-October 2016. During preparation for experimental periods, lobsters were individually maintained in opaque 40 L perforated boxes with a 8:16 L:D photoperiod, immersed in a flow-through system, incorporating “deep” water pumped to shore and originating from ca. 33 m depth. Temperature fluctuated with season but with a minimum and maximum 6-16°C. For hatching, up to three ripe adults were removed and placed in an experimental facility for preparation of the experiments. Hatching systems were matched to ambient water conditions, and temperature was gradually increased and temperature was gradually increased. For the experiment 1 larvae were fed a wet feed, dry feed and conspecific treatment in communal and individual reared cells to ascertain the degree and importance of larval cannibalism in lobster nutrition. In experiment II, Pandalus borealis, was used as a reference diet, with four additional diets: isocalorific and isonitrogenous commercial fishmeal, experimental shrimp meal, herring meal ± supplements, or mussel based feeds based on the nutritional profile of larvae from experiment I, in order to test the potential of alternative protein sources and added supplements in juvenile on growth diets.
Results and discussion
Experiment 1 underlines the impact of cannibalism on survival and nutrition in H. gammarus larviculture.Analysed H. gammarus zoea 1 composition, identified deficiencies in ash and carbohydrate in lobster feeds. This suggests a need for a species-specific, formulated dry feed for H. gammarus larviculture. This experiment represents the first investigation of H. gammarus larval composition and dietary requirements and highlights decreased growth potential associated with providing nutrition solely from generic commercial feed. In experiment II, the high survival and growth, low incidence of moulting problems and high availability of waste shrimp material, suggest that non‐heat‐treated shrimp products are a promising feed ingredient for post‐larval European lobsters.
In conclusion, this presentation has highlighted the technical, nutritional and practical innovations that have taken place over the last two decades that have allowed European lobster hatcheries to proliferate throughout Europe. However to reach a sustainably produced plate sized product that can contribute towards a local nutritious food production systems, further innovations revolving around improved feeds for all life stages, technical and ecological scale ups, systemic support and regulations and improving welfare practices are needed.