The IUCN/SSC Shark Specialist Group
Shark News 7: June 1996
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Catch/tag-and-release:
the conservation option for
recreational shark fishermen
Dr Robert E. Hueter, Center for Shark Research, Mote Marine
Laboratory
More and more, sport fishermen around the world are choosing to
practice catch-and-release of sharks, often tagging their catch for
science. What has turned anglers away from the old attitudes of catch-and-
kill of sharks, leading to the demise of many of the traditional shark
kill tournaments? At least three factors have been involved. First, the
conservation movement in sport fishing has slowly changed the ethic
in recreational shark fisheries by educating fishermen about the value
of all marine resources, including sharks. Second, the proliferation of
shark-tagging programmes has given anglers a satisfying alternative to
killing or just releasing their catches. And third, and perhaps the most
profound reason, the alarming depletion of large sharks in many coastal
regions has sharply reduced the number of sharks available to sport
fishermen. As depletions have been documented, a number of
jurisdictions have instituted management measures, setting restrictions
on shark landings by recreational fishermen. So whether it is by choice
or by rule, anglers are electing for live release of a greater proportion of
their shark catch.
This attitude shift has benefited tagging programmes around the
world. Prominent among these has been the US National Marine
Fisheries Service's Cooperative Shark Tagging Program (see page 1),
which began in 1963 and currently involves about 6,000 volunteer
fishermen (Casey et al. 1995). Although there are many pluses to the
growing interest in tagging by fishermen, there are minuses as well, and
both should be considered when assessing the value of angler shark-tagging
programmes.
The pluses
Obviously, catch-and-release, with or without tagging, can decrease
recreational fishing mortality on shark stocks, a desirable objective in
this era of shark overexploitation. The embracing of catch-and-release
and tagging by recreational shark fishermen can be a powerful
conservation tool. This is because the inherent conservation message is
disseminated among the fishing community and out to resource managers
and the public. The results are an impression on management that the
recreational sector is 'doing its part', increased pressure on the
commercial sector to follow suit, and a more enlightened public
concerning the resource value of sharks. An example of this effect has
been seen in Florida with the annual Gulf Coast Shark Census, a 100%
catch-and-release sport tournament for shark research coordinated by
Mote Marine Laboratory. Over the eight years of this tournament, nearly
1,000 anglers - many of them formerly shark killers - have caught,
collected data on, and released over 4,500 sharks, 530 of them with tags
applied by Mote biologists. Media coverage of this tournament has
magnified its message, helping to accelerate the fall of shark kill
tournaments in Florida (Hueter 1991a, b).
Proper tagging of the shark catch can provide basic biological
information on shark migration, age and growth, natural mortality,
behaviour and habitats, as well as applied information for shark fishery
managers (Casey and Taniuchi 1990). Volunteer taggers can cover a
much broader geographic range, at a greatly reduced cost, than can
fishery-independent scientific tagging programmes. The over 113,000
sharks tagged in the NMFS programme from 1963 to 1993 (Casey et al.
1995), for example, would no doubt be far less if it had depended
solely on federally funded boats and personnel. This participation
has important educational value in that fishermen become active
partners in the search for scientific truth, benefiting all involved.
The minuses
Despite these benefits, there are pitfalls to angler catch/tag-and-release
of sharks. The most obvious is post-release mortality. As sport fishermen
like to say, a shark has a much better chance of surviving if it is released
than if it is lying on the boat's deck. But if the stress of capture is mortally
damaging the sharks, catch-and-release is not accomplishing what the
fishermen may think it is. There have been a number of studies on post-release
mortality of hook-and-line-caught fish (see pages 8-9). In
general, sharks caught-and-released on recreational tackle have a
much better chance of surviving than on most commercial gear.
However, if the allure of tagging is attracting significant numbers of new
shark anglers, rather than simply altering the behaviour of those already
in the fishery, then post-release mortality becomes more important.
Closely related, but subtly different, is tagging mortality and other,
sublethal effects of tagging on the sharks. Fishermen, as well as biologists,
require training to apply tags properly. Tags improperly applied or placed
in the wrong types of sharks can fall out, kill the animals, or affect their
growth. Bad tagging technique or poor choice of tag type, then, can be far
worse for the shark than simple release. These problems can also affect the
scientific objectives of tagging: tag retention can go down, affecting
quantitative measures of population parameters; tags can affect sharks'
behaviour, altering normal migratory patterns; and tags can stunt growth,
seriously biasing estimates of age and growth in these species.
Scientists can address these issues by conducting rigorous studies of
tag design and technique before deploying tags in either a fishery-independent
or cooperative angler programme. The specific size and style
of tag can be matched to the shark being caught-and-released. For
example, young or small adult sharks cannot accommodate tags designed
for larger, tougher animals (Manire and Gruber 1991). To reduce mortality
from large tags, the juvenile shark-tagging programme at Mote Marine
Laboratory uses biologists to tag the sharks with appropriate tags and
concentrates on recreational fishermen to recapture them.
Finally, the quality of the data - shark species, sex, size etc. - is lower
in a cooperative angler programme. This can be accounted for in data
analysis, but it can never be corrected. In other words, the data collected
in an angler tagging programme must always be weighted differently than
the data collected by the biologists themselves. But as with the other
pitfalls, this drawback can be outweighed by the many practical and
conservation-oriented benefits of tagging. Properly implemented, the
tagging of sharks by sport fishermen provides a wealth of new information
and immeasurably adds to global efforts to conserve shark species.
References
Casey, J.G., Kohler, N.E., Stillwell, C.E., Turner, P.A., Briggs, R., Pratt,
H.W., and Natanson, L.J. 1995. A summary of shark tag-recapture
data from the NMFS Cooperative Shark Tagging Program (1963-
1993). Amer. Fish. Soc. 125th annual meeting abstracts: 126.
Casey, J.G. and Taniuchi, T. 1990. Recommendations for future shark
tagging programs. In: Elasmobranchs as Living Resources: Advances
in the Biology, Ecology, Systematics, and the Status of the Fisheries.
Eds. H.L. Pratt Jr., S.H. Gruber, and T. Taniuchi.) Pp. 511-512. US
Dept. Comm., NOAA Tech. Rep. NMFS 90.
Hueter, R.E. 1991a. The rise and fall of recreational "kill" tournaments
for sharks in Florida: historical trends, research potential, and the
conservation movement. J. Aust. Mar. and Fresh. Res., Sharks Down
Under Conference meeting abstracts, Sydney, Australia.
Hueter, R.E. 1991b. Survey of the Florida recreational shark fishery
utilising shark tournament and selected longline data. Mote Marine
Laboratory Tech. Rep. 232A (Final report to Florida DNR, Project
6627): 94 pp.
Manire, C.A. and S.H. Gruber. 1991. The effect of M-type dart tags
on field growth of juvenile lemon sharks. Trans. of the Amer. Fish.
Soc. 120(6): 776-780.
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