Tarpon Genetic Recapture Study FAQ

Find answers about this completed study, a joint project of the FWC's Fish and Wildlife Research Institute and Mote Marine Laboratory.

The Tarpon Genetic Recapture Study ended in 2015. Thank you to all anglers who participated in this research project.

What is the Tarpon Genetic Recapture Study?
The Florida Fish and Wildlife Conservation Commission (FWC), in collaboration with Mote Marine Laboratory, encourages anglers throughout the state to genetically sample tarpon, regardless of size, before releasing them. A small sample of skin cells collected from the outer jaw provides enough DNA for identification purposes. The FWC's Fish and Wildlife Research Institute (FWRI) will evaluate the genetic samples over time to estimate recapture rates. The study also may help determine how tarpon travel between Florida's estuaries and offshore areas.

Why identify an individual fish?
Tagging and marking a fish is a common tool in fishery science that has provided much information about fish species and their movements, migrations, speed, homing tendencies, spawning habitat, reproductive biology, survival rates, growth rates, site fidelity (tending to return repeatedly to a specific place), stock identification, abundance, and more. There are many ways to "mark" an individual fish for various purposes: internal, external, chemical, physical, and biological. This study uses DNA "fingerprinting" techniques to determine migration, movement, and recapture rates. DNA is a permanent biological "marker" of an individual tarpon.

Why is FWRI asking anglers to scrape the tarpon's jaw for skin cells instead of fin-clipping?
While fin-clipping is a common, relatively harmless method of obtaining DNA samples from fish, a series of trials during the 2006 tarpon season revealed a simpler method. The jaw scrape technique helps overcome challenges created by the size, demeanor, and strength of some tarpon, large or small. This technique, implemented in 2007, requires less handling of the fish and in most cases can be performed by one person while the tarpon is still in the water. While one hand controls the fish by holding the leader or lower jaw, the free hand can scrape the outer jaw of the tarpon with an abrasive pad to gather a small sample of skin cells. This method is not a typical approach with other species, but it is especially useful when dealing with such large, powerful fish. Fin clips from tarpon will still be accepted.

Is fin-clipping fish common in fishery science?
Fin-clipping fish has long been used in fisheries research as a simple and quick way to mark a fish externally. Scientific literature by Wydoski and Emery (1983) shows that partial clips of dorsal fins can be used as short-term marks without adverse effects on survival or metabolism; the fins will grow back. However, permanent loss or injury can occur if a fin is removed to the point where it attaches to the bone. For tarpon, the elongated dorsal threadfin or dorsal filament is an ideal tissue to sample by taking only a half-inch of the tip of the fin. In reality, any fin of the tarpon would work.

Does fin-clipping the threadfin hurt the fish?
Clipping the tip of the threadfin is like clipping a fingernail. The fin will regenerate itself.

Is removing a tarpon scale better than fin-clipping for DNA samples?
No. Tarpon often lose scales during an angling event, but the FWC does not advise pulling off scales. Scale removal has the potential to be much worse than removing a small area of superficial skin. If you must take a scale, take care to use a wet hand to rub the slime back over the area where the scale was removed. The slime coat of a fish protects against disease. Removing it exposes tissue to bacterial infection. Scales can be used for DNA analysis, but for various reasons, FWC biologists prefer the skin cell sample for tarpon DNA analysis.

FWC Facts:
It is common for closely related species such as bluegill (bream) and redear sunfish (shellcracker) to hybridize or spawn with each other.

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