Blue marlin and sailfish post-release recovery periods revealed via high-resolution biologging

High catch rates of istiophorid billfishes in the eastern tropical Pacific (ETP) have led to substantial economic benefit for the countries in the region via eco-tourism, prompting many countries to mandate catch-and-release practices for recreational anglers. Using a high-resolution biologging tag, we evaluated the post-release behavior and recovery period of blue marlin (Makaira nigricans; n = 9) and sailfish (Istiophorus platypterus; n = 9) caught in a typical recreational fishery off the Pacific coast of Panama for periods of 6–70 h after release. Angling times ranged from 4–90 min (mean: 45 ± 30 and 8 ± 3 min for blue marlin and sailfish, respectively). Post-release behavior is similar to previous studies, but limited to much shallower water due to the shallow thermocline and oxycline present in the ETP. Using 40 metrics derived from acceleration (i.e., tailbeat period, amplitude, ODBA) and physical parameters (i.e., depth, speed, temperature, oxygen saturation) to quantify a recovery period, results suggest blue marlin and sailfish recover 9 ± 3.2 and 4.9 ± 2.8 h after release, respectively. This is the first study to use tailbeat activity to estimate the post-release recovery period of billfish, and suggests that these fish are capable of rapid physiological recovery after stressful events, and that catch-and-release can be an effective practice to conserve and sustain billfish populations in the Eastern Tropical Pacific