REVIEW: Potential effects of kelp species on local fisheries

Abstract

Summary Kelp species are ecosystem engineers in temperate coasts, where they provide valuable services to humans. Evidence of the declines of kelp forests exists from several regions, but their effects on fisheries still need to be elucidated. More effective management strategies for sustainable fisheries require a synthesis of research findings and an assessment of how research could be improved to fill current gaps. This review aimed to: (i) summarize the available evidence on the influence of changes in kelp density and/or area on the abundance and diversity of associated fisheries and (ii) examine how research on kelp–fisheries interactions could better support effective management. Most studies (67%) reported data ascribable, directly or indirectly, to a positive relationship between kelp and fishery‐relevant variables, 11% provided evidence of a negative relationship, 15% indicated species‐specific findings and the remaining found unclear or ‘neutral’ relationships. Important shortcomings were identified, including the paucity of experimental studies suitable to test for unequivocal cause–effect relationships, the disproportion between North America, which is well‐studied, and other regions and between the large number of fish‐based investigations and the small number of those focusing on other commercially important organisms, and the general lack of studies carried out over spatial and temporal scales comparable to those of global processes driving patterns of distribution of both kelps and fisheries. Synthesis and applications. The consistency of most studies in showing a positive kelp–fishery relationship supports the protection of kelp habitats stated by current environmental directives. However, achieving their goals requires that the limitations we detect are addressed through better connections between research, management practice and policy. This would require the following: (i) researchers to combine multiple approaches (large‐scale experimental studies and modelling) for the analysis of kelp–fisheries relationships; (ii) funding agencies to provide resources needed to fill the existing gaps; and (iii) researchers and institutions from less studied regions to strengthen collaborations with those from regions where there have been more investigations into kelp–fishery systems. This is essential under present and predicted environmental changes, with the ultimate aim of conserving and allowing the sustainable use of critically important habitats and of fishery resources relying on these.