The National Marine Fisheries Service (NMFS) Cooperative Shark Tagging Program (CSTP) is part of continuing research directed to the study of the biology of large Atlantic Sharks. The CSTP was initiated in 1962 with an initial group of less than 100 volunteers. The program has expanded in subsequent years and currently includes over 6,500 volunteers distributed along the Atlantic and Gulf coast of North America and Europe. The tagging methods used in the CSTP have been essentially unchanged during the past thirty years. The two principal tags that are in use are a fin tag (Jumbo Rototag) and a dart tag ("M" tag).
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Rototag showing tag number and address. |
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"M" tag displaying tagging needle (top) and legend (bottom). |
Numbered tags are sent to volunteer participants on self-addressed return post cards for recording tagging information (date, location, gear, size and sex of shark), along with a tagging needle, tagging instructions, an Anglers Guide to Sharks of the Northeastern United States, and current management information. Tagging studies have been mostly single release events in which recoveries are made opportunistically by recreational and commercial fishermen. When a previously tagged shark is re-caught, information similar to that obtained at tagging is requested from the recapturer. Initially, a five dollar reward was sent as an incentive for returning tags; since 1988, a hat with an embroidered logo has been used.
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Between 1962-2001, more than 171,000 sharks of 52 species have been tagged and more than 10,000 sharks of 33 species have been recaptured, as a result of the CSTP. Eighty-seven percent of the tags are represented by eight species: blue shark Prionace glauca, sandbar shark Carcharhinus plumbeus, tiger shark Galeocerdo cuvier, dusky shark C. obscurus, shortfin mako Isurus oxyrinchus , blacktip shark C. limbatus, Atlantic sharpnose shark Rhizoprionodon terrraenovae and scalloped hammerhead Sphyrna lewini. The number of sharks tagged varies from 1 for the scoophead (S. media) to 93,494 for the blue shark.
Numbers of recaptures by species range from 1 for the Greenland shark (Somniosus microcephalus) to 5,808 for the blue shark. Eighty-eight percent of the recaptures are made up of seven species: blue shark; sandbar shark; tiger shark; shortfin mako; lemon shark, Negaprion brevirostris; blacktip shark; and dusky shark. The rate of recapture ranges from 1.3% for the oceanic whitetip shark (C. longimanus) to 11.3% for the shortfin mako.
Anglers using rod and reel accomplish the majority of the tagging for all species combined. Biologists, NMFS fisheries observers, and commercial fishermen using primarily longlines, handlines, and nets (gill, trawl) account for the remainder. Conversely, commercial fishermen using longlines and net gear, and rod and reel anglers are responsible for the majority of the recaptures.
Distances traveled for the 33 species ranged from no movement to 3,740 nautical miles (nmi). In total, 2 species, the blue shark and tiger shark, traveled distances over 3,000 nmi, 4 species traveled distances between 2,000-3,000 nmi (shortfin mako, sandbar shark, bigeye thresher and dusky shark), 7 species between 1,000-2,000 nmi (longfin mako, I. paucus; bignose shark, C. altimus; Galapagos shark, C. galapagensis; oceanic whitetip shark; night shark, C. signatus; silky shark; and porbeagle Lamna nasus) and 8 species traveled distances between 500-1,000 nmi (spiny dogfish, Squalus acanthias; scalloped hammerhead; spinner shark, C. brevipinna; blacktip shark; sand tiger, Carcharias taurus; great hammerhead, S. mokarran; Atlantic sharpnose shark; and white shark Carcharodon carcharias).
The longest time at liberty for any shark in the CSTP is 27.8 years. Overall, one species of shark, the sandbar shark, has been at liberty over 20 years, 6 species have been at liberty between 10-20 years (dusky shark, night shark, spiny dogfish, shortfin mako, tiger shark, and bignose shark), and 15 have been at liberty between 5-10 years (scalloped hammerhead; bigeye thresher; blacknose shark; porbeagle; Caribbean reef shark; blue shark; silky shark; thresher A. vulpinus; nurse shark; blacktip shark; Atlantic sharpnose shark; Galapagos shark; bull shark; longfin mako; and lemon shark).
Data from tagging programs, such as the NMFS CSTP, provide valuable information on migration and the extent of fish movements. The need for international cooperation in such work is underscored by the fact that many shark species have wide ranging distributions, frequently traverse national boundaries, and are exploited by multinational fisheries. The CSTP is also an important means to increase our biological understanding of sharks and to obtain information for rational resource management. The tagging of sharks (and other aquatic animals) provides information on stock identity, movements and migration (including rates and routes), abundance, age and growth (including verification/validation of age-determination methods), mortality, and behavior.
For more information on the NMFS Cooperative Shark Tagging Program, please contact: