According to a four-year study involving Professor Elsa Vázquez and Researcher Salvador Román from the CIM, which was supported by the fishing communities of Baiona, Cangas and A Coruña
Researchers from CIM-UVigo, Professor Elsa Vázquez and Researcher Salvador Román, have played a key role in an international study focused on the recovery of barnacle (Pollicipes pollicipes) populations along the southwest coast of Europe. The study, which also highlights key Galician areas of study and involved collaboration with the fishing communities of Baiona, Cangas, and A Coruña, was conducted over a four-year period. Led by Víctor Gómez and José Luis Acuña from the Marine Observatory of Asturias at the University of Oviedo, the research underscores the importance of adult barnacles left on rocks as nuclei for recruitment and regeneration. Published in Reviews in Fish Biology and Fisheries, the findings offer hope for the recovery of barnacle populations in areas closed due to resource depletion, showcasing the critical role of local expertise and resources in advancing marine conservation.
The quantitative importance of the process
Over four years, the study, which followed the recovery of more than 500 barren surfaces left on the rocks after barnacle harvesting, revealed that recovery is slower than expected. Half of the surfaces showed no signs of recolonisation after three and a half years, while 50% that did show some recovery took more than two and a half years to fully recolonise, and 21.5% took over six years. Additionally, recovery largely depended on the presence of adults, as more than 90% of the voids left on the rocks by barnacle collectors started recovering in less than six months if some adults were left on their perimeter.
“These adults serve as initiators of recruitment. In contrast, 40% of the voids without adults didn’t even begin recovery within the four-year conservation period”, state the authors of the article, who add that once recovery began, the rate was 0.5 cm²/month in the absence of adults, but up to 2.54 cm²/month when the exploited voids were in contact with many adults.
The study confirms that the removal of all adult barnacles from the rocks, as well as other barnacles, mussels, and coralline algae, critically delays the recovery of their populations, with a negative impact on the fishery. “This is exactly what happens when the entire surface of the rocks is exploited to obtain seed for the mussel farming industry in Galicia. If the removal of mussel seed is repeated over successive years, this will inevitably lead to a repeated reset of the colonisation process and a chronic reduction in barnacle populations”, detail the authors of the study.
Use of more selective and narrower tools
The research also highlights that for the barnacle fishery to be sustainable, adults should be left dispersed on the rocks to facilitate population recovery, and that more selective and narrower tools (rakes) should be used. “In this publication, a tool width of less than 3.5 cm is recommended to minimise the capture of individuals below the commercial size. This selective harvesting method with narrow rakes has traditionally been successfully applied by some fishing communities in Galicia”, explain the authors of the study.
The PERCEBES project (Tools for spatial management of coastal resources: the barnacle fishery in southwest Europe) was promoted by the EU Eranet Biodiversa, in coordination with the national scientific funding agencies from Spain, France, and Portugal. It was coordinated by the University of Oviedo (Spain), with the participation of Sorbonne University (France), the University of Vigo (Spain), University of Aveiro and University of Évora (Portugal), and the ENSTA Bretagne engineering school (France).
Source: DUVI