Identification Tags

Tagging is a valuable technique for investigating the behavior of sharks. Oceanic and deep-water sharks are difficult to study, and most shallow water species are either large, active predators not easily observed for any length of time, or are species that are rarely seen and in small numbers. Sharks in general are particularly suited to tagging studies because of their extensive movements, schooling behavior, and relatively large size which allow them to carry most tags successfully. Tagging studies provide valuable information on a wide variety of aspects of elasmobranch biology, including life history parameters, stock status, behavioural and distribution patterns, and migration patterns. See below for description of tags used in Bimini:
NMFS M-Type Dart Tags
Photo Credit: CJ Crooks
 
These tags are supplied by the National Marine Fisheries Service (NMFS) Cooperative Shark Tagging Program as part of continuing research on the biology of large Atlantic sharks. They comprise of a stainless-steel dart that anchors into the musculature at the base of the first dorsal fin, a piece of trailing monofilament and a plexiglass capsule at the end that contains a unique identification number and return instructions. Each tag has an accompanying data card that is completed by the tagger and returned to NMFS. In the event of recapture, fishers remove the note from the capsule and follow instructions.  This tag and recapture data give vital information on migration patterns and growth rates for a range of species.
 
At the sharklab

Any shark (> 1.3 m total length) captured in or around Bimini by BBFS is fitted with a M-type dart tag including tiger, blacktip and lemon sharks through our shallow water longlines and bull and hammerhead sharks captured using poly-ball and free-diving techniques respectively. 

Passive Integrated Transponder (Destron Fearing, PIT Tag)
 
PIT tags, also known as ‘microchips’, allow researchers to safely mark animals internally without altering external appearance. In almost all cases the tag will stay with the animal for it’s entire life cycle. The small size of PIT tags virtually eliminates negative impact on animals with little or no influence on growth-rate, behavior, health or predator susceptibility.
 
At the sharklab
 
All lemon sharks captured in or around the Bimini islands are individually marked through a PIT tag. After capture sharks are restrained and implanted with this unique alpha-numeric tag using a hypodermic needle through the skin, at the base of the first dorsal fin. If a shark is recaptured a PIT tag reader can then be used to scan it and identify the shark. This allows for easy long-term identification of individuals, effectively giving each shark an ID which we can add and update morphometric data for throughout its life.
 
We also use PIT tags to identify Bimini boas.  This is so we can monitor their growth and population numbers around the islands.
These are external markers that are used to identify individual sharks both in the wild and during captive experiments. They are small T-bar tags of various colors (mono, bi or tri) and sizes that are punctured through the first or second dorsal fin. 
 
At the sharklab

Dr Tristan Guttridge used these tags extensively during his PhD to monitor juvenile lemon shark social behavior. Currently all three PhD students use them in a variety of behavioural experiments. They are relatively non-invasive, cheap and easy to attach. 

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