by austin heil, fsucml graduate student
In the Gulf of Mexico, the Sheepshead are famous (or infamous) for their human-like teeth. Their teeth produce a smile matched by no other fish species. Tourists and land-dwellers often marvel at the Sheepshead’s teeth when they first encounter them. Despite what their outward appearance may imply, Sheepshead are a tasty fish, frequently sought after by recreational fishers in the Gulf of Mexico. Unfortunately, Sheepshead are almost exclusively targeted during their spawning season. This could result in a potential problem. The fishing spawning populations has resulted in declines of other fisheries species. Although I must admit that Sheepshead teeth are quite a spectacle, I personally find their biology more fascinating and important.
The first part of my research examined the reproduction and movement patterns of Sheepshead in the NE Gulf of Mexico. The first step was to determine where Sheepshead were spawning. I used data collected from a previous study in our area, along with communication from the local fishing community, to choose my study sites. I ended up choosing three artificial reefs for my study near Dog Island, FL. I used a Go-Pro mounted drop camera system to monitor monthly Sheepshead abundance on these reefs from August 2015 to August 2016. I found Sheepshead were basically absent from these reefs during summer and fall. However, in January, hundreds of Sheepshead showed up on these artificial reefs. This was exciting! A healthy population of Sheepshead remained on these reefs until April, after which they completely disappeared.
Now, I needed to determine if Sheepshead were indeed spawning on my study sites. To do this, I sampled from each reef population from January-April. Using histology, a nifty technique that allows you to observe tissue in detail, I found presence of hydrated eggs and post-ovulatory follicles. These indicated a presence of actively spawning individuals on all three reefs. I found evidence of Sheepshead spawning aggregations!
In the past couple of months, I have been presented with an exciting opportunity to further investigate the movement patterns of Sheepshead. Dr. Chip Cotton of the FSUCML received a grant to deploy a number of acoustic receivers array in Apalachicola Bay. The receivers will be strategically deployed to block off any exit from the Bay to the Gulf of Mexico. This allows you to capture movement offshore. Luckily for me, Sheepshead spend the majority of their life cycle in estuaries (like Apalachicola Bay).
Starting in late November 2016, I will be tagging 15 Sheepshead with an acoustic tag in Apalachicola Bay. These acoustic tags will transmit to the receivers and track the movement of each fish inside the Bay. Ultimately, I want to capture when Sheepshead start their migration out of the estuary to offshore habitats. By tracking their movement, I will be able to determine the triggers (e.g. tides, water temperature, etc.) that initiate their migration offshore.
You can help fund Austin’s Sheepshead research, by donating here!