Using Remotely Transmitted Accelerometer Data Collected from Pop-Up Satellite Archival Tags to Predict Spawning in Wild Mahi-Mahi (Coryphaena hippurus)

Mahi-mahi (Coryphaena hippurus) is a highly migratory ecologically and commercially important pelagic fish species that inhabit tropical and sub-tropical waters around the world. The ecology of mahi-mahi is tied to their vertical dives and migrations; however, these remain understudied. Further, almost nothing is known about the frequency, timing, or location of spawning of wild mahi-mahi despite the importance of this information for successful management. To better understand the habitat use and reproductive ecology of wild mahi-mahi, we used Wildlife Computers pop-up satellite archival tags (PSATs) to measure acceleration, depth, temperature, and light levels for geo-location modeling. To predict spawning in wild fish we first tagged three sets of wild-caught captive mahi-mahi male and female pairs with PSATs and observed them in a 30,000 L tank over a cumulative five-week period in which we noted 32 spawning events. Known spawning times were used with summary acceleration data collected from PSATs to build models to estimate spawning in wild fish. We followed the captive-based tagging experiments with the deployment of 19 PSATs on wild mahi-mahi in the Florida straits (n=17) and the Gulf of Mexico (n=2). Wild mahi-mahi tagged in the Florida straits generally migrated north and eastward moving up to 100 km per day, while mahi-mahi in the Gulf of Mexico remained in the Gulf for the tagging period. Mahi-mahi had larger and more frequent vertical excursions when sea surface temperatures were warmer, at nighttime, and when the moon was less than half full. Our predictive spawning model was applied to PSAT data from wild mahi-mahi and the depths, temperatures, and locations associated with the potential spawning and non-spawning events were assessed. These data are the first to predict spawning of a wild marine teleost from accelerometry data and add critical information about the vertical and horizontal migrations to our understanding of the ecology of mahi-mahi.