Ready to set the longlines
Long-line fishing, while commonly done by commercial fisherman, is also an effective tool when studying sharks. The BBFS has been long-lining since its inception, and sets the lines once a month. Long-lining allows us to survey the populations of larger sharks and their movement, migrations & growth around Bimini.
Once per month, 5 long-lines are set around Bimini for a 24 hour time period. Four lines run North to South down the East side of the Main Lagoon. The fifth, "Wild Card" line, is a "roaming" line that is laid in a new location each setting.
Baiting the hooks
Each long-line is over ¼ mile long, anchored on each end, and adorned with alternating white Styrofoam floats and baited gangions. Circle hooks are used on the gangions to prevent sharks from swallowing the hooks, and to decrease by-catch.
In the years that Dr. Gruber has been long-lining around Bimini, he has recorded 13 species of sharks caught on the lines. See the Sharks of Bimini for a list of the sharks caught on the Sharklab's long-lines
In order to be sure that any sharks that are caught are not harmed, the long-lines are checked every 3-5 hours. This ensures that anything that is caught on a hook, is not left on the line too long.
Every shark that is caught on the lines is pulled to the boat to check its condition, and then "worked-up". The data collected from each shark includes: species, sex, pre-caudal length measurement (PCL), fork length measurement (FL), and total length measurement(TL). The sharks are then tagged. Every shark over 140 cm (TL) is tagged with a Casey dart tag from the National Marine Fisheries Service. Lemon sharks are additionally tagged with a Passive Integrated Transponder (PIT) tag, and a DNA sample is taken for genetic analysis. Any additional comments about the shark, or the conditions of which is was caught are also logged in our database. The shark is then de-hooked and released.
Blacktip Shark ready for the work-up
Each tagged shark that is recaptured provides us with information on that sharks growth, movements, migration, and habits.