Fisheries Ecology Research

The Dauphin Island Sea Lab employs acoustic and satellite tagging to understand more about the ecology and movements of marine life in Mobile Bay, Mississippi Sound, and the northern Gulf of Mexico.

One way DISL scientists deploy tags each year is by teaming with the Alabama Deep Sea Fishing Rodeo held on Dauphin Island each year. Read more. 

Acoustic and Satellite Telemetry to Track Movements of Alabama’s State Saltwater Fish

Background: The recent collapse of many estuarine and marine fisheries has been widely recognized and is particularly acute for fishes that are long lived, slow growing, and reach sexual maturity at a late age. Several of these fishes have life histories that include ontogenetic movements across estuarine habitats and knowing how much area an individual uses during their residency in a marine habitat is vital to understanding the life history of a species; however, shifts in habitat with ontogeny can make evaluating habitat utilization and seasonal distribution difficult to assess. Atlantic tarpon are a highly migratory and highly prized sport fish throughout the Gulf of Mexico (GOM). Tarpon make seasonal and regional migrations along the GOM as part of their complex life history and exemplify the life history characteristics that exacerbate population declines. Given the paucity of information on tarpon ecology, there is a clear need to investigate and understand movement patterns and habitat use of this large fish.  

Objectives: The objective of this study is to apply advanced telemetry to adult tarpon in Mobile Bay and the surrounding coastal waters of Alabama to investigate fine-scale (acoustic telemetry) and large-scale (satellite telemetry) movement patterns.    

Approach: Telemetry is a valuable tool used to collect data from mobile marine organisms. Acoustic telemetry allows for fine-scale movement patterns to be assessed when a tagged fish is within range of an acoustic receiver array while satellite telemetry (specifically, pop-off archival transmitting (PAT) tags) allows for large-scale movement patterns to be assessed. Both acoustic and PAT tags were applied to tarpon in this study to track their movements around the coastal waters of Alabama.    

Results to Date: Three satellite and PAT tags were successfully deployed on adult tarpon in the summer of 2014. We received data from the satellite tags and preliminary data show tarpon movements along the coastal waters of Orange Beach, AL where they then move into Mobile Bay, AL before making long-distance movements offshore towards Louisiana!    

Funding Sources: This project is funded through the Mississippi-Alabama Sea Grant Consortium with additional funding from the Coastal Conservation Association of Alabama and from NFWF Wildlife and Sport Fish Restoration. 

Coastal Alabama Acoustic Monitoring Program

There is an array of 40 listening stations with hydrophones strategically placed around Mobile Bay and Mississippi Sound.

“The hydrophones were placed around the bay to cover the entry and exit points of fish, and in this instance, we’re talking about a red drum or speckled trout,” Dr. Sean Powers explained. “We have all the rivers covered in the (Mobile/Tensaw) Delta. We have a string of them along the Causeway, at Fowl River and Dog River. We also have them in Mississippi Sound.

The hydrophones are designed to pick up acoustic signals with unique codes that identify individual fish. The acoustic tag sends a series of sound pulses in a few seconds. The hydrophone interprets that signal and identifies the fish. If it was a fish from Alabama, the identification of the fish gives researchers data on where the fish was tagged and where it was located when the signal was picked up at different times. If the hydrophone identifies an unknown code, the other states involved in the program are notified.

Each fish in the study is caught by researchers or other anglers and the small tag is attached.

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