The S.C. Department of Natural Resources’ Dolphin
Tagging Study will step into a new dimension of high-tech
monitoring this summer. This phase will employ archival
satellite pop-off tags similar to those used on billfish and
bluefin tuna.
The high-tech tags to be utilized are the PTT-100 HR
Archival Satellite pop-off tags manufactured by Microwave
Telemetry. They provide one of the first opportunities to
study the dolphin’s vertical movements in the water column
and to document their water temperature preference. These
miniature computers record water pressure, temperature, and
time of day every few minutes, generating a detailed portrait
of the dolphin’s use of the water column and the temperature
selection throughout each day for a 30-day period.
The most unique advantage the satellite tags offer is that the
dolphin do not have to be recovered in order for us to learn
information. The tags are designed to release, or pop off from
the fish automatically. At a preprogrammed time, the
microcomputers will release from the fish, float to the surface
and download information via satellite back to the tag
manufacturer. The data is then forwarded to a computer at the
S.C. Department of Natural Resources.
The cost of the tags at over $4,000 each limited the project
to purchasing only seven tags. Additionally, the large size of
the tag requires that only dolphin of 40 pounds or more be
tagged. Such a large size requirement limits the study to
using these tags on only the largest of the species, which may
not be representative of the entire population.
The satellite pop-off tag weighs about two ounces, and
features a main body that is just over 13 inches in length and
0.8 to 1.6 inches in diameter. It carries an eight-inch nylon
coated stainless steel antenna.
This effort to use the satellite tags this summer will likely
be the first attempt in the U.S. to document the vertical
movement behavior and water temperature preference of
dolphin. Fishermen have frequently reported catching dolphin
on downriggers and planners. This study will hopefully
gather information on how deep dolphin dive, how much time
they spend in deeper water, and what temperatures they
prefer.
Current plans in this pilot study call for two satellite tags to
be deployed in the Florida Strait in May of 2005. Three tags
are allotted for use off the South Carolina coast in June and
July. The two remaining tags are designated for use in the
Mid-Atlantic Bight in August. The project will be seeking
assistance from fishermen in each area who are
knowledgeable in catching big dolphin and who are willing to
tag and release a trophy bull for science.
Fishermen Needed
Entering its fourth year in 2005, the dolphin study is in
serious need of experienced offshore boat owners who are
concerned enough about the future of dolphin to tag and
release their smaller catches for science. Boat owners who
fish in the Mid-Atlantic Bight, Gulf of Mexico and eastern
Bahamas are needed to tag dolphin to help answer questions
about the movement of dolphin from their regions.
This project offers offshore fishermen the chance to
actively participate in scientific research. Anglers often voice
their concerns that no research is being done on popular
gamefish in their area. Well here is the opportunity! Anglers
who want to know more about dolphin in their area should
sign up to participating in this project. The more dolphin
tagged in an area, the greater the opportunity there will be to
learn about the fish in that area.
Anglers interested in participating in this study can register
at http://dolphintagging.homestead.com or should contact the
project leader listed at the end of the newsletter.