Assessing the role of kelp for small-scale fisheries by combining fishers' knowledge of spawning locations with modelled kelp distribution

Abstract

Kelp forests are found on rocky shores from polar to temperate coasts, where they provide important ecosystem services to humans. For coastal communities, kelp forests are particularly important as spawning and nursery grounds for small-scale fisheries. Despite their value, surprisingly few studies have assessed how fished species relate to kelp during early life stages. Fishers' knowledge could contribute to filling some of the gaps in our understanding by identifying where many of these species are usually spawning. We aimed to (i) assess to what extent multiple fished species (N = 29) are spawning nearby/in areas where kelp is present, indicating the importance of kelp to small-scale fisheries and (ii) demonstrate the value of combining the mapping of fishers' knowledge with scientific information to better understand large-scale spatial patterns relevant to fisheries' management. Since the 1980s, fishers have identified more than thousand spawning areas along the Norwegian coastline. Based on this extensive spatial information and the kelp distribution model, we found that the number of spawning areas decreases as the distance from kelp increases, with some species appearing more attached to kelp than others (21% located between 0 and 100 m and 81% located between 0 and 1000 m). Synthesis and applications. The co-occurrence of spawning areas and the presence of tangle kelp (Laminaria hyperborea) indicate that this kelp species might play a significant role for early life stages of multiple fished species. We substantiated our findings by using fishers' knowledge to identify the spatial patterns of spawning at a scale that would otherwise be very costly to map using ordinary fish surveys. Our results could inform management efforts to preserve and restore coastal habitats important for safeguarding the viability of the small-scale fisheries over time. Read the free Plain Language Summary for this article on the Journal blog.