Lobster Grower 2 (LG2 – www.lobstergrower.co.uk) is a multifaceted, collaborative project assessing the potential for sea-based rearing of European lobsters in containers situated in the wild environment. The LG2 project represents a fantastic opportunity to deliver a cheap, effective and natural way of on-growing hatchery-reared lobsters before they are released into the wild. The project also presents the chance to develop a novel and sustainable component of the UK’s growing aquaculture sector. Whether via the improvement of hatchery stocking’s effectiveness or the realisation of commercially viable marine aquaculture (mariculture), LG2 could provide a large step towards the solutions required to address concerns about food security and wildlife conservation which currently surround European lobster capture fisheries.

The potential of sea-based container culture became clear to us when we first saw the striking development of our hatchery juveniles following their on-growing in Ireland several years ago. After a few years of trialling container-based mariculture ourselves via independent and student-placement research, the Hatchery attained funding from Innovate UK and BBSRC for LG1, an early-stage catalyst project which enabled the design and development of a marine container system specifically suited to on-growing juvenile lobsters, and put in place a marine licence for establishing a pilot-scale site at an existing offshore mussel farm.

Follow-on funding was secured to launch LG2 in 2016, and the Hatchery now front a highly skilled collaborative partnership featuring the University of Exeter, Westcountry Mussels of Fowey, CEFAS and Falmouth University. We are really enjoying working alongside these organisations as we attempt to understand and advance methods for rearing lobsters at sea over the next few years. Not only could LG2 yield outcomes potentially applicable to purposes of commercial aquaculture, with the absence of supplemental feed ensuring high sustainability credentials, but it offers enormous scope to improve the ecological conditioning of lobsters destined for release as part of stocking initiatives.

Container development

Halswell P, Daniels CL, Hardwick, J., Johanning L. (In Press) Evaluation framework for external and internal parameters associated with Sea Based Container Culture (SBCC): Towards understanding rearing success in European lobsters (Homarus gammarus). Submitted to Aquaculture in November 2017.
Abstract

Sea Based Container Culture (SBCC), a low carbon form of mariculture, has been trialled for on-growing European lobsters (Homarus gammarus) through post larval stages. Trials have established: 1) low energy costs, 2) zero feed costs, 3) almost fixed unit cost of production and 4) good short term rearing success. This form of aquaculture relies on the natural oceanic environment to provide and sustain suitable rearing conditions for lobster on-growing. SBCC shows potential for (i) cost-effective and ecologically-conditioned on-growing to improve stocking efforts and enhance capture fisheries, and (ii) the advent of sustainable aquaculture of this prized seafood species which could help alleviate the increasing demand for protein, complementing the supply through the natural fishery. As with any organism, lobsters require specific environmental conditions for rearing success including (but not limited to): dissolved oxygen (DO) concentration, food availability, and suitable flow velocities. All of which, to varying extents, are driven by external environmental parameters including: current velocities, turbulent fluctuations and wave orbital velocities. This paper utilises a novel evaluation framework to assess the relationship between external and internal environmental parameters and aims to aid predictions of rearing success in SBCC systems. Rearing limitations were selected from available literature for DO concentration and, foraging and mobility behaviours to evaluate the rearing success. Current, wave and turbulent velocities were temporally and spatially described to define an External Velocity Profile (EVP) around SBCC containers. Transfer functions were used to predict the Internal Velocity Profile (IVP) within SBCC containers as a result of the EVP, based on a hydrodynamic study of SBCC containers by Halswell et al. (2016). Thus, rearing success has been statistically quantified by comparing the temporal and spatial IVP to rearing limitation. This paper uses a case study to demonstrate framework methodology based on field data obtained within Cornish waters. The framework demonstrated that in situ measurements of current, wave and turbulence (EVP) could be used to predict IVP of SBCC containers, which in turn can be used to predict theoretical rearing success based on rearing limitation. The framework provides a suitable tool to optimise the SBCC design for spatial and temporal conditions related to a geographical location or (vice versa) identify suitable aquaculture sites based on SBCC design and environmental conditions. Additionally, the framework can optimise the vertical position of the SBCC in the water column and identify, from parameters considered, those which are most likely to affect rearing success.

Halswell P, Daniels CL, Johanning L. (2016) Sea-based container culture (SBCC) hydrodynamic design assessment for European lobsters (Homarus gammarus). Aquacultural Engineering. 74; 157-173.
Full text      Abstract

The presented work describes the hydrodynamic assessment studies of a much needed technical innovation of Sea-Based Container Culture (SBCC) as part of a semi-intensive, passive aquaculture culture system for farming the European lobster (Homarus gammarus). Factors that are known to influence growth and survival rates were obtained from previous literature, including flow rate, wave energy and motion characteristics; these factors defined performance criteria for SBCC containers. The internal flow velocities and external flow patterns for different SBCC container designs were measured and used to inform design decisions. Suitable graphical representations have been developed to assess SBCC containers on specific performance criteria. Oyster SBCC containers were found to provide stable motion characteristics but perform poorly against the lower velocity limit, indicating insufficient supply of Dissolved Oxygen (DO) to allow for optimal growth of European lobsters. Internal flow velocities were also measured on unfouled and fouled SBCC containers; results showed SBCC 2 would not provide enough DO with 66% biofouling coverage (66% biofouling replicates one year deployment) and triggered a redesign. SBCC 1 at 90° yaw angle of attack demonstrated all round good performance against upper and lower velocity limits and motion characteristics; thus showed greatest promise for cultivation of European lobster.

Daniels CL, Wills B, Ruiz-Perez M, Miles E, Wilson RW, Boothroyd D. (2015) Development of sea based container culture for rearing European lobster (Homarus gammarus) around South West England. Aquaculture. 448; 186-195.
Full text      Abstract

This three year field investigation consisted of three discrete experiments, examining six potential sites for rearing the European lobster (Homarus gammarus) around the Cornish coast (U.K.). Sea-based container culture (SBCC) systems were deployed, varying site, year, depth, shelter and pre-fouling, to test effects on growth and survival of juvenile H. gammarus. Site and depth were examined between May–August 2011 at two sites off the South coast. One estuarine (River Fal: RF) and one sea-based (St. Austell Bay: SA) site were assessed with containers suspended at either 2 or 8 m depth. Greatest survival was found at the SA site (56%) compared to RF (25%), with the greatest growth (specific growth rate: SGR 3%, live weight gain: LWG 0.4 g and carapace length gain: CLG 4.5 mm) also achieved at SA. Depth did not affect juvenile development. Between May and August 2012, one estuarine (Fowey: F) and two sea-based (SA and St. Mawes: SM) sites on the south coast were selected to assess the effect of site and shelter. SM showed the highest survival (93%). Growth and survival were not affected by the presence of a shelter. From August to December 2013, three sites off the north and south coasts were selected to assess the effect of site, depth, pre-fouling and feed availability. Sea-based (Port Quin Bay: PQ, Wave Hub: WH and SA) sites were assessed, with containers submerged at either 3 or 10 m above the sea bed (PQ 7–14 m, WH 42–49 m depth at chart datum). Survival did not significantly differ between sites (61–86%), but growth at the PQ site (LWG 0.7 g; carapace length gain: CLG 6.1 mm) was significantly greater than at all other sites (LWG 0.3–0.4 g; CLG 2.5–3.6 mm). Depth did not affect juvenile development. Pre-fouling reduced growth at all sites. Feed availability varied between sites with PQ showing the greatest taxonomical units. Variations between years were also shown between 2011 and 2013 at the SA site. SBCC systems show potential for culturing H. gammarus juveniles compared to hatchery controls (survival ≤ 46%), acting as a transition step between hatchery rearing and release for stocking purposes. The importance of site selection and between year variations is highlighted as important factors to consider for larger scale assessment of aquaculture potential.

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