Galicia Stalked Barnacle Fishery (Spain)
The stalked barnacle is a marine crustacean that inhabits exposed rocky shores in the northeast Atlantic. Galicia in NW Spain sustains the largest fishery for the resource through a co-management system based on the use of Territorial User Rights for Fishing (TURFs). Under climate change, warming and upwelling relaxation are expected to bring positive (productivity increases by ways of higher reproductive output and recruitment) and negative (reductions in the quality of the resource and in larval dispersal) effects to the system, which might synergistically interact with other stressors (e.g., overfishing). Resilience in the fishery is provided by the use of adaptive spatial management with nested scales at a regional, local (TURFs, 10-60 km) and patch/rock (2-10 km) level. This detailed spatial scale is only possible thanks to the close collaboration between fishers associations and managers. Ecologically, the high plasticity, genetic diversity and larval connectivity of the species contribute to resilience. The learning capacity and the consideration of ongoing change in management are key aspects of the fishery in preparation for climate change. However, the adaptive capacity of the system could be improved by a higher level of cooperation and knowledge exchange between TURFs.
The stalked barnacle (Pollicipes pollicipes) is a warm-temperate species that supports several small-scale fisheries that are commercially oriented across the Atlantic Rim from Brittany to southern Portugal (Aguión et al. 2022), as well in some Northwest African countries like Morocco. However, a strong market demand for the resource only exists in Spain and Portugal where stalked barnacles are considered a delicacy and reach first sale market prices of EUR 200 per kg in the high season. In Galicia, 325 tons of stalked barnacles were harvested by 1,308 fishers yielding a profit of EUR 7.6 million between 2013 and 2016 (Aguión et al. 2022).
Future climate scenarios in Galicia predict decreases in coastal upwelling and increases in seawater temperature (Sousa et al. 2020) that have been already noted in the region (Gómez-Gesteira et al. 2011). Although the impacts of these changing trends are still not well studied for the species, productivity increases are expected in the fishery considering the positive relationship described between landings and upwelling relaxation (Molares et al. 2009). This prediction is supported by ecological studies that associate warming and/or decreases in upwelling with a longer and more intense recruitment season (Fernandes et al. 2021), a faster embryo development time and an increase in the number of broods (Macho 2006; Román et al. 2022). But despite this potential positive effect, climatic stressors might also be behind the increasing number of elongated barnacles with low commercial value (Molares et al. 2009) and potential reductions in resource quality (Bode et al. 2009) due to changes in the texture of the meat. A lower larval dispersal capacity is also expected due to a reduced duration of the larval pelagic time caused by seawater warming (Nolasco et al. 2022), potentially reducing the connectivity between populations.
Apart from climate-related stressors, the fishery has navigated through shocks like overfishing (1990s), oil spill pollution (2002) and a conflict with mussel seed harvesters (since the 2010s) maintaining a fairly stable trend in landings and revenues (Consellería do Mar 2020) on account of the stock ecological resilience and the governance system in place. On one hand, the important levels of larval dispersal (Nolasco et al. 2022), plasticity and genetic diversity (Parrondo et al. 2022) of the species support the capacity of the populations to adapt and recover from stressors. On the other hand, the implementation of TURFs where only licensed members are allowed access to the resource creates a sense of ownership and stewardship that fosters place attachment in the fishery. The fact that TURFs have been designed considering historical social and political aspects facilitates the creation of social capital and participation. This results in an adaptive and responsive system where fishers usually lead daily decisions such as reducing the daily quota or stop fishing if resource status or maker price are not good enough (Aguión et al. 2022). The technical assistant (biologist) present in most TURFs is a key figure in the fishery, providing management advice to fishers and facilitating communication between fishers, managers, scientists and other stakeholders (cross-scale integration) (Macho et al. 2013).
Considering the heterogeneous vulnerability of TURFs to climate change due to their differences in size, resource dependency, management strategies, etc. (Ruiz-Díaz et al. 2020), the development of a regional plan to tackle climate change that identifies 1) effective management responses implemented in some TURFs that could be extended to others and 2) promotes a higher level of cooperation and information exchange between TURFs, is likely to increase the resilience of the system. A good starting point for this is the organization of workshops where fishers, managers and technical assistants exchange knowledge to enable mutual learning and provide basic principles to overcome the common challenges that the fishery is increasingly facing.
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Acknowledgements: Thanks to Dr. Gonzalo Macho for his comments.
Photo: Harvesting stalked barnacles in Spain. Credit: Alba Aguión