The razor clam is a bivalve shellfish that, although in the past it had little value, has now become a resource of high commercial value. Of all the exploitation areas, the Ría de Vigo is the most productive, contributing 133 tonnes in 2016 and an income of 1.5 million euros. In Galicia, the banks are exploited manually by diving in a highly selective way. However, in recent years they have suffered a high exploitation rate, although their maximum sustainable yield is still unknown. The razor clam fishery also faces a problem during the winter months since a high percentage of individuals break at the foot when being captured due to the development of the gonad inside the foot during the maturity period, being discarded as not being marketable. In order to avoid this problem or reduce it as much as possible, exploitation is generally stopped at the initiative of the collectors for one or two months during the winter. However, prior knowledge of the gonadal state by both collectors and the Administration would help reduce discards and streamline the administrative procedures necessary for rotation between banks.
With this objective and continuing with the studies already initiated in the Ría de Pontevedra by the Coastal Ecology group, led by Elsa Vázquez, a research project will start in the Ría de Vigo, hand in hand with the University and the Ministry of the Sea. The rector, Salustiano Mato, and the minister, Rosa Quintana, signed a collaboration agreement this Monday that will allow the scientific community to work together with the sector and the administration. The objective of this project is to provide biological and technological support to the management of the razorfish fishery, studying spatial heterogeneity in reproduction and improving the methods of studying and visualizing the gonadal state of the banks already initiated in previous studies. In addition, studies will be carried out on the distribution of the stock and the possible application of models for estimating the state of the stocks based on limited data will be evaluated. The purpose is to promote an exploitation based on biological information obtained continuously that will be collected in a computer application and that will allow for the reduction of closure periods and the discarding of specimens.
Information collected and available in real time
The research, with a budget of 166,000 euros and valid until August 2020, will study the variability of the reproductive cycle and size of the first spawn of razorfish in the Vigo estuary, from the innermost banks such as Rande to the outermost ones, in the Cíes Islands. “The biological information will be collected by divers and by the technical assistance of the brotherhoods, who will be responsible for entering this data into the application”, as detailed by Alba Hernández, technician at the Marine Research Center of the University of Vigo and responsible for the studies already carried out in the Ría de Pontevedra. Thus, there will be real-time knowledge that allows, as the minister explained, “greater agility in decision-making for the management of this resource”. The rector of the University highlighted the importance of this agreement because “it allows the University’s scientific staff to work hand in hand with the administration and bring their knowledge to the real world” and highlighted the role of both the Campus do Mar, the Marine Research Center and the Singular Center for Research in Telecommunications Technologies atlanTTic, which will be the participating organizations of our University, together with the Marine Research Center (CIMA) of the General Directorate of Fisheries Development. All of them will work hand in hand with the brotherhoods that are exploiting razor clams in the Vigo estuary, which bring together 52 vessels and 78 divers.
The design of the computer tool will be carried out by experts from atlanTTic. As Francisco Javier González Castaño, director of the Information Technologies Group, explains, they will take the results of the Ecimat and the field experience of the Marine Research Center (CIMA) to “convert their results into a mobile data analysis application that allows shellfish gatherers to identify the best time to carry out their work”. Through this tool, which can be used both from phones and from desktop computers, workers will be able to know the state of the resource in the different shellfish beds and reduce the periods of closure of razor clam beds and the discarding of specimens. In this sense, the rector explained that “it is important not to extract razor clams during the rupture period, the most important period of their life cycle, that of gonadal maturity, on the one hand, because it is a critical period for the species and, on the other, because these ruptures reduce the commercial value of the catches”.
Previous study in the estuary of Pontevedra
Alba Hernández explained at the press conference that this project stems from a previous scientific study carried out in the Pontevedra estuary with the Bueu brotherhood, in which it was found that “there is a shift in the gonadal cycle between the internal and external parts of the bank, since the razorfish matures earlier inside than outside the estuary”. With this updated information, which they would obtain from the computer application, the divers “could move around the banks according to the state of maturity of the species” avoiding the capture of specimens during the rupture period. This will allow for the reduction or avoidance of closures and total closures of the estuary and, in fact, in this previous study “we managed to reduce the closure from two months to one month”.
Methodologies with limited data
Another part of the project will be coordinated by the scientist Gonzalo Macho, from the Coastal Ecology group, who will be in charge of assessing the state of the resource using different methodologies appropriate for fisheries with limited data, such as traditional fisheries. Methods based on life cycle parameters, catches or catch sizes will be tested. These models use proven scientific theories and require little data to know the state of the stock, abundance, dynamics over the years, etc. This is a model, as Hernández added, “that is being used in the FAO and other world organizations, but which has never been introduced in Galicia, so its efficiency will be tested in the razorfish sector and the possibility of applying it to other species will be evaluated”.
