New insights to behaviour of North Atlantic albacore tuna (Thunnus alalunga) observed with pop-up satellite archival tags

• Pop-up archival satellite tags were successfully deployed in albacore tuna.
• Shallow nocturnal and variable diurnal depth preferences were exhibited.
• Deep diving behaviour was adapted to deal with cold water.
• Environmental factors significantly affected vertical depth preferences.

Pop-up archival satellite tags were deployed on North Atlantic albacore tuna (Thunnus alalunga) in the first experiment using this technique on this species. New information on movement, habitat use and fish behaviour is presented. Data from five successful tag deployments for periods of up to 106 days revealed consistently shallow nocturnal depth preferences and progressively deeper diurnal depth preferences as seasons unfolded. In situ environmental variables such as chlorophyll-a and mixed layer depth significantly affected vertical depth preferences. Adapted deep diving behaviour to colder water below the mixed layer was also exhibited in the first record of repetitive bounce diving in albacore tuna.