This is a repository copy of Wild seaweed harvesting as a diversification opportunity for fishermen. White Rose Research Online URL for this paper: https://eprints.whiterose.ac.uk/137123/ Version: Published Version Monograph: Burrows, M, Fox, C, Moore, P et al. (3 more authors) (2018) Wild seaweed harvesting as a diversification opportunity for fishermen. Research Report. Reuse This article is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs (CC BY-NC-ND) licence. This licence only allows you to download this work and share it with others as long as you credit the authors, but you can’t change the article in any way or use it commercially. More information and the full terms of the licence here: https://creativecommons.org/licenses/ Takedown If you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing [email protected] including the URL of the record and the reason for the withdrawal request. [email protected] https://eprints.whiterose.ac.uk/ WILD SEAWEED HARVESTING AS A DIVERSIFICATION OPPORTUNITY FOR FISHERMEN April 2018 Highlands & Islands Enterprise SAMS Research Services Ltd. Registered Office: Lismore Suite, Malin House, The European Marine Science Park, Oban, Argyll PA37 1SZ T: +44 (0) 1631 559470 F: +44 (0) 1631 559001 E: [email protected] W: http://www.srsl.com Vat Registration No GB 828 9579 61 Company Registered in Scotland No. SC224404 ACKNOWLEDGEMENTS SAMS Research Services Ltd. (SRSL) was supported in the delivery of this project by several subcontractors, who are detailed below with a summary of their contributions. Mike Burrows from SAMS used elements of research funded by the UK Natural Environment Research Council (NE/L003058/1, “MERP: Integrated Macroecology and Modelling to Elucidate Regulation of Services from Ecosystems”) and the Engineering and Physical Sciences Research Council (EP/K012851/1, “ECOWATT2050: Impacts of Very Large Scale Arrays and their Regulation”). Dan Smale from MBA and Pippa Moore from Aberystwyth University worked along divers from the National Facility for Scientific Diving (NFSD) based at SAMS to undertake diving surveys of kelp beds. They processed the survey data and provided additional expertise and knowledge on kelp habitats for the mapping elements of the project. Alison Benson and Ian Sotheran from Envision Mapping Ltd. undertook the vessel based acoustic surveys and drop down camera work of kelp beds, and processed the associated data, which also fed into the predictive mapping part of kelp habitats. Andrew Parker and Emily Thompson from Imani Development undertook economic feasibility analysis of seaweed harvesting, including conducting interviews with various stakeholders and business operators. A project Steering Group led by HIE provided support, guidance and comments throughout the duration of this project. The group included representatives from SNH, Marine Scotland, the Scottish Seaweed Industry Association and Crown Estate Scotland. The authors would like to acknowledge the help and advice of MacDuff Shipyards in relation to fishing vessel design and to the Maritime and Coastguard Agency in relation to fishing vessel and workboat licencing. This report should be cited as: Burrows M.T., Fox, C.J., Moore, P., Smale, D., Sotheran, I., Benson, A., Greenhill, L., Martino, S., Parker, A., Thompson, E., Allen, C.J. (2018) Wild Seaweed Harvesting as a Diversification Opportunity for Fishermen. A report by SRSL for HIE, pp. 171 Wild Seaweed Harvesting as a Diversification Opportunity for Fishermen ii EXECUTIVE SUMMARY The seaweed industry in Scotland is still in its infancy, but has the potential to thrive and develop to support a range of business that have identified uses for seaweed products. Wild seaweed harvesting can potentially present a unique opportunity for fishermen to diversity their work activities, relieving pressure from fish stocks and providing alternative seasonal income. Although small scale wild harvesting of seaweed occurs around the Scottish coast, the economics and feasibility of large scale wild seaweed harvesting has yet to be examined, with knowledge gaps for sustainability of harvests, environmental impacts and the costs of Marine Licensing. Scottish waters are considered to have large stocks of Laminaria, and it is believed that they may be harvested with tolerable impacts to the natural environment. Laminaria hyperborea is not presently cultivated in Scotland, and although experiments are being undertaken in this area, cultivation cannot at present be regarded as an alternative replacement to wild harvesting with respect to providing stocks of kelp to support large scale industry. Highlands and Islands Enterprise (HIE) contracted SRSL to investigate the potential of wild seaweed harvesting as a diversification opportunity for fishermen. The aim of the project is to deliver a report that covers three areas: (i) Guidance on the mapping and location of seaweed for harvesting (ii) Guidance on the harvesting of seaweed (iii) Marine Licence scoping and economic feasibility of seaweed harvesting This report is concerned with the potential for medium to large-scale harvesting of kelps in Scotland using mechanical harvesting techniques. Mapping Kelp Location & Quantities in Scotland Habitat suitability models were developed for the two major kelp species in Scotland, Laminaria hyperborea and Saccharina latissima, as well as for two less abundant species Saccorhiza polyschides and Laminaria digitata. Around the Scottish coast, these models predicted a total biomass of 20 Mt for L. hyperborea, 2.5 Mt for Saccharina latissima, 188000t (0.19Mt) for Saccorhiza polyschides and 161000t (0.16Mt) for Laminaria digitata. A total of 6.5 Mt of L. hyperborea was predicted for harvestable areas, where biomass per unit area may exceed 5 kg/m2. Over 75% of predicted biomass of L. hyperborea was in three Marine Scotland Atlas regions: West of the Outer Hebrides, the Minch and Inner Hebrides, and the north coast and Orkney. Model predictions of kelp biomass compared with actual quantities of kelp at surveyed localities show that while the general patterns of abundance are captured, the model over predicts when no suitable bed type is present. This does not mean the model is wrong, but that the underlying seabed data is insufficiently spatially resolved. Suitable baseline surveys of the resource quantities and quality in proposed harvest locations would be required to improve resolution. Wild Seaweed Harvesting as a Diversification Opportunity for Fishermen iii From quantities predicted by models it is recommended that any potential harvesting industry for Laminaria hyperborea should prioritise areas in (1) the Minch and Inner Hebrides with 35% of the biomass in areas >5 kg/m2, (2) the west coast of the Outer Hebrides (21%), (3) the North Coast and Orkney (20%), and (4) the combined east and west coasts of Shetland (10%). The predictive kelp habitat layer provides one element of locational guidance for harvesters. However, this is based solely on where kelp may be found. Other environmental factors may make these areas unfavourable to harvest. A full constraints analysis should be completed for any potential harvesting area to ensure that no protected conservation features are compromised by the planned activity, and that the harvesting does not unduly interfere with existing use of the environment for other purposes. Such analysis is a normal part of conducting an Environmental Impact Assessment (EIA) and it is recommended that this approach be broadly followed even if a full EIA is not required by the appropriate licencing authority for a kelp harvesting proposal. Sustainable Harvesting of Kelp Habitats Kelp habitats support high biodiversity, contribute to marine foodwebs through the production of detritus and provide nursery habitats for invertebrates and fish, including commercially important species. Whilst kelp are vulnerable to a variety of natural factors including grazing by urchins, disease, parasites and storm damage, mature kelp beds are generally thought to be resilient and can persist over many years. Lessons regarding the impacts of harvesting of kelp are drawn mainly from studies in Norway and France. Harvesting temporarily removes the kelp habitat and results in measurable reductions in associated biota. The kelp itself recolonises and regrows within a few years, but harvesting leads to a more restricted size and age range in the recovering stands compared with unharvested areas. Re-colonisation of the harvested areas is possible, providing there are sufficient source populations nearby. However, full recovery may not be seen within the inter-harvest periods typically applied in Norway. Impacts of harvesting kelp on commercial fish populations are currently difficult to evaluate. Designing a sustainable harvesting regime is complex and needs to take account of many factors such as the spatial and temporal variability in the resource, the present and future quantities required by processors, the accessibility of sites taking into account typical weather patterns etc. Possible conflicts with other stakeholders including fisheries, tourism, fish farms, and marine renewables also need to be considered. Most present commercial fishing activities are unlikely to be directly affected as mobile gears are not normally deployed in kelp beds, but potting could be affected in some locations targeted for kelp harvesting. Harvesting plans will also need to have contingencies