New research identifies “blue lanes” for highly migratory fish.

Pacific bluefin tuna. Credit: Photo by OpenCage, Wikimedia Commons

New research has identified four high-traffic locations in the Pacific Ocean that should be given high priority if conservation efforts for large pelagic fishes such as tuna, blue marlin, and swordfish are to be effective.

By studying the tendency of fish to return to their place of birth to reproduce — a phenomenon known as philopatry that is commonly, and incorrectly, attributed to salmon species — and combining this information with catch distribution maps and tagging and genetic sequencing studies, researchers at UBC’s Sea Around Us initiative identified the tentative migration routes of 11 tuna and other large pelagic fish in the Pacific Ocean and determined that certain areas should be conserved.

“We applied the idea of philopatry to the movements retrieved from tagging studies of species such as the near-threatened Pacific bluefin tuna and the highly fished yellowfin tuna, and we integrated this information with the linkages between populations inferred from genetic research. This allowed us to tentatively identify annual migration patterns “These findings are presented by Veronica Relano, a Sea Around Us doctorate candidate and the study’s principal author.

“When we compared our proposed migration routes with the plotted catch data from 1950 to 2016 published on the Sea Around Us website, we observed numerous coincidences. Clearly, considering philopatry improves the correctness of these routes, but they are still uncertain “She stated.

After evaluating the seasonal migration patterns of each of the 11 fish species separately, the researchers superimposed them and discovered that several species and populations of these huge pelagic fishes utilise the same migration pathways.

“These high-traffic areas, two of which are in the northeastern and central sections of the Pacific Ocean and two in the southwestern and central sections, should become part of blue corridors,” said Dr. Daniel Pauly, co-author of the study a.

“Before establishing a protected area to aid in the recovery of depleted fish populations, it is essential to consider the full body of knowledge on the migrations and movements of different species. This was the objective of this investigation. As indicated in our title, the closed migration cycles we propose are speculative; therefore, it would be beneficial if additional researchers tested their validity “He stated.

Sustainability published the article “Philopatry as a technique to establish tentative closed migration cycles and conservation areas for giant pelagic fishes in the Pacific.”

Further information: Veronica Relano et al, Philopatry as a Tool to Define Tentative Closed Migration Cycles and Conservation Areas for Large Pelagic Fishes in the Pacific, Sustainability (2022). DOI: 10.3390/su14095577

Source: University of British Columbia