Habitat Utilization of Blackfin Tuna, Thunnus atlanticus, in the North-Central Gulf of Mexico

Short-duration (9.5–, 18-, and 28.5-day) deployments of pop-up satellite archival tags (PSATs) on blackfin tuna, Thunnus atlanticus Lesson 1831, were used to evaluate the applicability of external electronic tags on small tunas. Ten tunas (71.1-86.4 cm FL) were tagged in the northern Gulf of Mexico in April 2012 after being caught on typical recreational fishing gear. PSATs recorded point measurements of temperature, pressure (depth), and light level every 90 s ( n  = 2 tags, deployment duration 9.5 days), 180 s ( n  = 4, duration 19 days), or 270 s ( n  = 4, duration 28.5 days). Nine fish survived for their respective full deployment periods; one fish died after only 5 h following release. Depths ranged from 0–217 m with a mean of 28 m (SD = 8.38 m) and temperatures ranged from 13.9–32.9 °C with a mean of 23.8 °C (SD = 1.3 °C) for all nine archived records. The nine blackfin spent 90 % of their time in depths from 0–57 m and 89 % of their time in temperatures from 21.9–26.6 °C. Over 87 % of the movements in the water column, either ascending or descending, were less than 12 m differences in depth between sequential short-duration data sampling. With appropriate concern regarding the matching of fish and PSAT sizes, these results suggest that external tags with fishery-independent reporting capabilities are an available option for smaller tuna species.