Permit, Sharks and Fishing in the Lower Keys: A Reel Dilemma

The project initially started at one of their most hallowed spawning grounds, Western Dry Rocks, a 1 square mile area of high relief contiguous reef around ~10 miles southwest of Key West. The project started small, with the goal of characterizing fishing pressure and depredation mortality of permit at Western Dry Rocks specifically. Since 2018, the project has grown to sites in the middle Keys and now includes the 7 Mile Bridge Rubble, the Thunderbolt, and an unmarked artificial reef. The goals have expanded as well, and now they are working towards comparing aggregation sizes at artificial and natural reefs, estimating fishing effort between the regions, and determining how shark depredation varies through the Keys. The goals were simple, but the technology used to answer most of these questions was anything but! The researchers gathered fisheries independent and dependent data, applied sonar technology (echosounders and multibeam imaging sonar) to map the seafloor, estimate aggregation size, and even document the interactions between permit and their predators.

A Day in the Life of a Fisheries Scientist

I’ve been fortunate enough to support the team of scientists in their field efforts through the years, which mainly consisted of long days under the beating sun and lugging around bulky sonar equipment and fishing gear. After a 30-60 minute run to the site, the fun begins! All hands on deck – or better yet, eyes are laser focused on the horizon in search of those silvery green ghosts rolling inches below the surface. Once spotted, the research vessel creeps in the direction of the flashes to cast an arsenal of fishing lines that present their favorite dish, the swimming crab! If you think this sounds a lot like fishing, well it is, but for scientific purposes! Once the crab is gobbled up and the hook is set, another researcher deploys the sonar pod to determine the fate of the hooked permit and maybe capture the interaction between the school and any sharks in the area. Simultaneously, a third team member is actively recording catch rates of other anglers on the aggregation site and keeping track of the school for the next cast. Once a fish is landed, its length is recorded, pictures are taken to document their condition (and because these scientists love what they do), and the fish is promptly returned to the water with a smile and wave. This entire process is repeated over and over again until near sunset, weather permitting. At the end of the day, tired, salty, and satisfied, researchers return home to the National Save The Sea Turtle Foundation’s R/V Hawksbill I to break down and clean up sampling gear. Before a well earned night’s rest the team hunts down a slice of key lime pie, and then it’s lights out before they hit the water the following morning! While bad weather days, a shortage of live crabs, and a few delays due to the worldwide pandemic halted the project for a season, the FIU team charges onward to aid in permit conservation efforts throughout the Keys. What the Data Have Told Us (continued) Over three years, FIU researchers angled nearly 200 permit and reported highly variable rates of depredation. Between March and May of 2021, variation occurred between sites, but also month to month at the same location, ranging from 0-37% of all angled fish between March and May of 2021. Interestingly, aggregation size was comparable across the season and between sites, and there were no apparent changes in conditions, but they reported a half dozen Caribbean reef sharks (Carcharhinus perezi) and the occasional great hammerhead (Sphyrna mokarran) following the boat day after day while conducting fisheries independent surveys. Sharks in high numbers like this aren’t exceptionally common “to just see” in their work, but once the sharks have it figured out, they can’t get a permit to the boat! Due to this variability they have planned to continue their work in 2022 and 2023 and plan to deploy environmental sensors to capture the seasonal change in conditions. They’re also expanding their data collection effort at each site to begin explaining the stark changes in shark abundance and activity levels through the season.