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New research reveals potential shifts in blue marlin habitat

- BRUCE POHLOT

Blue marlin are a cosmopolitan and globally distributed species, and are often the focus of offshore anglers' dreams. However, new research utilizing electronic tags is showing that this migratory predator's habitat might be shifting, and where you target these fish in the future may shift as well.

Over the years, tagging studies using both satellite and conventional methods have taught us that oceanic predators such as billfish and tuna are capable of extensive migrations that span ocean basins, international boundaries, and tens of thousands of miles. From these studies, we know some basic biological and ecological information about billfish, but the physical drivers of their movements are still relatively unknown.

FISH RESPONSE

All billfish migrate to find optimal waters for spawning and feeding, as most fish do, but we know very little about their spawning requirements. In order to better conserve and manage all billfish species, we have more work to do.

Blue marlin are known as epipelagic fish, meaning they live predominantly at the sunlit zone that exists from the surface to a depth of 200 meters. Here, they are top predators with only occasional dives into the deeper twilight zone. They play a critical role in maintaining the health and function of the open-ocean ecosystem, therefore characterizing their distribution and habitat use is vital for effective fisheries management. This is especially true as the oceans change on a global scale. How fish respond to such environmental changes likely varies from one species to another, so understanding the habitat preferences of different fish species, and the factors that shape those preferences, provides a more informed understanding of the management and conservation actions necessary to ensure a healthy population in the face of Earth's changing climate.

A NEW STUDY