The IUCN/SSC Shark Specialist Group
Shark News 7: June 1996
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NMFS Cooperative Shark Tagging Program
Nancy Kohler, National Marine Fisheries Service, USA
A juvenile tiger shark Galeocerdo cuvier, tagged by scientists in the Bahamas,
about to be released. Photo: Jeremy Stafford-Deitsch.
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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 30 years.
The two principal tags that are in use are a fin
tag (Jumbo Rototag) and a dart tag ("M" tag).
The rototag is a two piece, plastic cattle ear tag
which is inserted through the first dorsal fin.
These tags were primarily used by NMFS
biologists on small sharks during the first few
years of the CSTP. As the Program expanded to
include thousands of volunteer fishermen, the
dart tag was developed to be easily and safely
applied to sharks in the water. The "M" tag is
composed of a stainless steel dart head,
monofilament line, and a plexiglas capsule
containing a vinyl plastic legend with return
instructions printed in English, Spanish, French,
Japanese and Norwegian. These dart tags, in
use since 1965, are implanted in the back
musculature near the base of the first dorsal fin.
More recently, a Hallprint tag has been used on
a limited basis for use on small sharks in the
nursery areas.
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 a current Shark Tagger newsletter.
This newsletter is an annual summary of the previous year's tag
and recapture data and biological studies on sharks which is sent
to all participants in the CSTP. 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.
Between 1962 and 1995, more than 128,000 sharks of 40 species
have been tagged and more than 6,000 sharks of 32 species have been
recaptured, as a result of the CSTP. Eighty-six per cent of the tags are
represented by eight species: blue shark Prionace glauca, sandbar
shark Carcharhinus plumbeus, dusky shark C. obscurus, tiger shark Galeocerdo cuvier, shortfin mako Isurus oxyrinchus, blacktip shark C. limbatus, scalloped hammerhead Sphyrna lewini and Atlantic
sharpnose shark Rhizoprionodon terrraenovae. The number of sharks
tagged varies from two for the smalleye hammerhead Sphyrna tudes
to 70,303 for the blue shark.
Numbers of recaptures by species range from one for the Greenland
shark Somniosus microcephalus to 3,098 for the blue shark. Eighty-six
per cent of the recaptures are made up of seven species: blue shark,
sandbar shark, tigershark, shortfin mako, lemon shark Negaprion
brevirostris, dusky shark, and nurse shark Ginglymostomatum cirratum.
The rate of recapture ranges from 1.4% for the Atlantic sharpnose
shark to 10.6% for the nurse shark.
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.
A juvenile tiger shark Galeocerdo cuvier, tagged by scientists in the Bahamas,
about to be released. Photo: Jeremy Stafford-Deitsch.
Distances travelled for the 32 species ranged from no movement
to 3,740 nautical miles (nmi). In total, one species, the blue shark,
travelled distances over 3,000 nmi, three species travelled distances
between 2,000 and 3,000 nmi (shortfin mako, dusky and sandbar
shark), eight species between 1,000 and 2,000 nmi (tiger, bignose
C. altimus, galapagos C. galapagensis, bigeye thresher Alopias
superciliosus, night C. signatus, oceanic whitetip C. longimanus,
blacktip, and porbeagle shark Lamna nasus) and seven species
travelled distances between 500 and 1,000 nmi (scalloped
hammerhead, spinner C. brevipinna, longfin mako I. paucus, silky
C. falciformis, sand tiger Odontaspis taurus, Atlantic sharpnose 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, three species have been at liberty between 10 and 20
years (dusky, night and tiger shark), and 13 have been at liberty
between 5 and 10 years (scalloped hammerhead, shortfin mako,
blacknose C. acronotus, bignose, porbeagle, blue, thresher A. vulpinus,
nurse, Atlantic sharpnose, blacktip, silky, bull C. leucas, and bigeye
thresher shark).
Data from tagging programmes, such as the NMFS CSTP, provide
valuable information on migration. The need for international
cooperation 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 behaviour.
For more information on the NMFS Cooperative Shark Tagging
Program, please contact:
Apex Predator Investigation
NOAA/NMFS/NEFSC
28 Tarzwell Drive
Narragansett, RI 02882 USA
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