Emerging species for sea cucumber aquaculture

The project, Emerging species for sea cucumber aquaculture works toward the closing of the life cycle of new sea cucumber species for aquaculture. Project partners are Møreforsking (MF) in Norway, and the University of KwaZulu-Natal (UKZN) in Durban in collaboration with the Department of Forestry, Fisheries and the Environment (DFFE) in Cape Town in South Africa. Funding is through the bilateral program SANOCEAN 2018-2023 (South Africa-Norway Co-operation on Ocean research, including blue economy, climate change, the environment and sustainable energy), which aims to strengthen research cooperation between South Africa and Norway in sustainable use of ocean resources. Both countries have a long history as fisheries and seafood nations, and in recent decades have developed considerable expertise in aquaculture. Aquaculture is suggested as an alternative to commercial fishing to meet a growing Asian market demand for sea cucumbers, and at the same time reduce the fishing pressure on vulnerable wild local stocks. New knowledge on biology and farming of native sea cucumber species will be obtained and provide valuable input to knowledge-based policies for management and conservation of this high-value marine resource. The project is organised in six work packages (WPs) covering the different scientific tasks (WP1-WP4) as well as knowledge exchange, networking, dissemination (WP5) and project management (WP6). The research is designed around the steps of a cultivation protocol for sea cucumber and comprises studies of the species Parastichopus tremulus, a potential candidate for aquaculture in Norway, and four species from South Africa, Pentacta doliolum, Thyone aurea, Pseudocnella sykion and Holothuria cinerascens, for which aquaculture potential is unknown. The work includes studies on broodstock collected from the wild, rearing technology and growth conditions for the early life stages, the suitability as deposit feeders in integrated multitrophic aquaculture systems (IMTA), and effects of marine pollution on sea cucumbers. The project period is four years (2019-2023) and joint research activities was planned to take place alternately in South Africa and in Norway. Methods related to gonad development and microplastics detection were exchanged during the first joint workshop at UKZN in South Africa in March 2019. In 2020-2022 the visits to and from South Africa were hindered by the Covid-19 situation, thus limiting the results obtained during this period. A close communication has still been ensured through monthly video meetings. Studies on reproduction of P. tremulus have been carried out in Norway during the natural spawning season each year. The animals were obtained from by-catch of commercial trawl and pot fisheries and spawning induced in the laboratory. A specially designed larval rearing system was developed for the second season. Repeated egg batches were successfully fertilized during the successive spawning seasons and larval development followed. Broodstock held in captivity under different feeding regimes gave lower spawning success than broodstock caught from the wild close to the natural spawning season. Attempts to re-develop gonads under laboratory conditions from one year to another has thus far not been successful. Larval development in the lab has reached the late auricularia stage but failed in settlement and metamorphosis. Studies on oocyte maturation and fecundity (number of eggs) for the evaluation of reproductive potential has progressed during the last reporting periods. Results from feeding trials on adults are used to explain the digestibility and effect of different compositions on feeding behaviour in the lab. A growth trial on small specimen was performed in flow-through facilities over 1.5 years. The fed groups increased in weight during the first months, but later levelled out and towards the end had similar weight to the unfed group. The project was presented at the launch conference for the SANOCEAN program in South Africa in March 2019 and through the NORA network HOLOSUSTAIN project in 2020 and 2022. Results were presented at Aquaculture Europe20 and 22, and at a special sea cucumber workshop at the Concarneau marine station in France in 2022 and in scientific journals. Information about the project has been made publicly available through a press release in July 2019 and a follow up about larval rearing in 2020 on the Møreforsking web pages. The status of P. tremulus has been published in the specific sea cucumber Beche-de-mer Information Bulletin in 2021, 2022 and 2023, and a chapter will be included in the book The World of Sea Cucumbers, to be published by Elsevier in June 2023. The final project meeting included a seminar presentation on the SANOCEAN's potential contributions to the UN Decade of Ocean Science for Sustainable Development which took place on board the sailing ship Statsraad Lehmkuhl visiting Cape Town on its One Ocean Expedition.

The project has contributed to the development of aquaculture of low trophic species by studying sea cucumbers. New knowledge on selected local sea cucumbers in Norway and South Africa anticipated to have market potential has been generated, thus levelling up the competency of researchers and students within marine sciences. Closing the life cycle under controlled conditions is key to developing an aquaculture industry, and the project results increased the biological understanding related to reproduction, feeding and rearing conditions. The knowledge on the Norwegian red sea cucumber Parastichopus tremulus has advanced, thus giving opportunities to explore the possibilities of the species as a resource both for fisheries and aquaculture. Methods for spawning and pelagic larval development have been developed in parallel to studies on reproductive potential. So far, the production of spat has not succeeded. Based on feeding trials on adults given different feed mixes, the suitability of P. tremulus as deposit feeders in integrated multitrophic aquaculture systems (IMTA) was suggested. It was documented that dried salmon freshwater sludge, an underutilised resource, could be a future ingredient in sustainable feeds for P. tremulus. The project has been a steppingstone for the establishing of new international research networks and collaborations in project proposals targeting sea cucumber aquaculture. The species P. tremulus has potential for aquaculture in Norway. There is an overall lack of biological information of the different sea cucumber species, which is crucial for a sustainable and proper management of wild stocks as well as for developing a viable aquaculture industry. To feed the world’s growing population, marine food sources will in the future have to contribute significantly more to the world’s food supply. Globally, wild sea cucumber stocks are under pressure from overfishing, pollution and climate change, and aquaculture thus represents a solution for seafood production and job creation in the marine sector. The success will depend on whether economically viable growth and survival rates during the different life stages are achieved. The inclusion of deposit feeders in IMTA systems has the potential to decrease the sediment and nutrient loads to the environment, thus contributing to healthy waters. The sea cucumber P. tremulus can fill this role. Diversified production can improve robustness of aquaculture businesses, and adaptation of already existing infrastructure is expected to have a minimal additional impact on the environmental footprint of the industry. Continuous multi- and interdisciplinary research effort is needed to further develop aquaculture of new sea cucumber species leading to innovations and societal changes. In addition to support and advice for entrepreneurs and industry stakeholders, the results of this project are valuable as input to knowledge-based sustainable management of this high-value marine resource.

Aquaculture is suggested as an alternative for producing sea cucumber to fulfil the market demand and reduce the fishing pressure on vulnerable wild local stocks. University of KwaZulu-Natal (UKZN) in South Africa and Møreforsking Ålesund (MFAA) in Norway will through the project “Emerging species for sea cucumber aquaculture” create new knowledge on biology and aquaculture of native species and provide valuable input to knowledge-based policies for management and conservation of this high-value marine resource. The two countries have a history of collaboration within marine sciences and this project will strengthen the exchange of expertise and joint research efforts. The research comprises studies of the species Parastichopus tremulus (Gunnerus, 1767), a potential candidate for sea ranching and integrated aquaculture in Norway, and three species from South Africa, Pentacta doliolum (Pallas), Thyone auriata (Q. & G.) and Holothuria cinerascens (Brandt), for which their potential in aquaculture is unknown. Existing knowledge on the biology and key life history parameters of the species is incomplete, and the project will obtain background information as to their occurrence, abundance and fishing methods, development of early life stages, growth in land-based cultivation systems, suitability as deposit feeders in integrated aquaculture systems (i.e. IMTA) and effects of marine pollution. Special attention will be given the effects of microplastics on sea cucumber behaviour and quality. The project is organised in six work packages covering the different scientific tasks as well as knowledge exchange, networking, dissemination and project management. The output is expected to benefit researchers and students at the partner institutions and their national and international network including industry stakeholders and management bodies.