AZTI, the Technology Center Expert in Marine and Food Research has studied the causes of the shortage of albacore in the Bay of Biscay and already has several conclusions.
The Albacore campaign of the Basque fleet has declined considerably this year. It has gone down by more than 40% compared to last year. Moreover, the scarcity of the species in the Bay of Biscay has forced the tuna vessels to travel hundreds of miles to the northwest. This means a consequent increase in costs, which in turn has been reflected in the final price of this product in the fisheries.
This situation is not new, since in recent years, albacore has been scarce in the waters of the Bay of Biscay and has moved into the northern Atlantic, for reasons that scientists have been analyzing. The research center AZTI Gipuzkoa, included in the Tecnalia technology corporation, explained the results of several studies to try to understand why that change in Albacore tuna’s behavior. AZTI’s field analysis and laboratory work shows that there are several reasons why this species is no longer entering the Gulf of Biscay.
According to Haritz Arrizabalaga, principal investigator of the Tuna Resource Management at AZTI, in first instance they toyed with the hypothesis that Albacore tuna was entering the Bay of Biscay but had not been detected by the fishing vessels because it was at deeper levels than usual. Studies have shown that in the Cantabrian sea, where water reaches a depth of thousands of meters, Albacore tuna usually moves in very shallow waters, between 30 meters and the surface, a vertical distance which the sonar of fishing vessels can easily detect. Scientists, therefore, have ruled out this hypothesis.
Another possibility, the most plausible for AZTI, is that fish stocks have not come into the Bay of Biscay because of alterations in the environment due to climate change, which generate temperature anomalies in the water. This species usually moves in waters between 17 and 18 degrees in the Atlantic, Arrizabalaga explains, pointing out that there is a group of white tuna thattravel to areas with temperatures of up to 20 degrees. The investigation center indicates that, the fact that catches this year have occurred further north in waters closer to Ireland, may indicate that Albacore tuna is “looking for its optimum temperature" in more cooler water. In any case, whatever the time of the year the Albacore tuna may move within the Bay of Biscay -summer and part of autumn- there has been practically no temperature changes in recent years. Therefore, the speculation about a direct influence in the behavior of the species because of the temperature does not convince scientists.
However, it is possible that this factor has affected other species which Albacore tuna feeds from. The Albacore specimens that are coming into Cantabrian waters are juvenile and are targeting food to continue their growth. AZTI has also studied the diet of this fish, which have different habits when inside or outside the Bay of Biscay. It is quite “opportunistic,†said Arrizabalaga, adding that “if they find food on their way, they will stay there.†In waters of the Cantabrian, Albacore tuna normally feeds from anchovies, if available, and also from perlite, whereas outside they eat fish from deeper water.
The AZTI researcher recalls that when there were poor coastal anchovy catches or when anchovy catches were banned by Brussels for their resource recovery, changes were detected in the feeding habits of Albacore tuna. However, in the last two years the anchovy stocks have recovered and the tuna is still not coming.
Stockreduction
Arrizabalaga states that the absence of Albacore tuna resources in the Bay of Biscay in the last two-three years may be due not only to those unusual movements but also to a decline in stock . That is why representatives of all countries fishing for Albacore in the Atlantic are gathering in Madrid to discuss the issue.
The scientific committee of the International Commission for the Conservation of Atlantic Tunas (ICCAT) are discussing the state of the fishery and submitting any recommendations for actions to be taken. There is already an international research proposal that was previously not accepted by the ICCAT. The AZTI expert says that the need to carry out such studies will be discussed again this year and he expects the commission will agreed the funding.
The center of the Tecnalia corporation has spent decades studying albacore behavior with increasingly sophisticated methods. For the past ten years it has been tagging specimens (most recently electronically) through a kind of chip that is implanted in the fish, which gives valuable information about the migrations of the groups.
AZTI scientists are confident that the albacore’s current “disregard†for showing up at the Bay of Biscay is just a timely issue and that the species will return to these waters.
