Processes involved in Shark Tagging
equipment is used to catch
sharks. When conducting
research, scientists choose gear
and procedures in order to help
limit possible damage to sharks
that could occur as the sharks
are captured. The scientist's goal
is to capture the shark, collect
data, tag the shark, and return it
to the ocean to live a healthy life.
The most common gear used by
scientists are gill nets which are
400 feet long (122m) and 10 feet
(3.04m) high. The size of the
mesh is selected according to the
size of the sharks being caught.
Smaller mesh is better for
catching smaller sharks. When
using gill nets, scientists are
extremely careful to remove the
sharks immediately, quickly
collecting data and tagging the
sharks, and returning them to the
ocean. For tagging very large
sharks, it is not possible to bring
them out of the water, so they are
tagged from the boat using a
pole. Scientists at Mote Marine
Laboratory have a special permit
to use gill nets and are required
by law to follow procedures that
limit damage to sharks. Gill nets,
if not used with special care, can
cause damage to sharks or may
that will not harm the shark or
affect its movements. In recent
years, fishermen have joined the
efforts to collect data about
sharks by tagging g sharks when
they catch them, rather than
killing or releasing them without
tags. The fishermen who
participate in these tag and
release programs also need to be
trained to use tags correctly.
Tags improperly applied or
placed in the wrong types of
sharks can fall off, affecting stunt
growth, creating inaccurate age
and growth estimates.
Improperly applied tags can
even cause death. To prevent
this, scientists have studied
different types of tag design and
technique in order to determine
the best type of tag to use. The
specific style and size of a tag
can be matched to the shark
being caught and released. For
example, young or small adult
sharks cannot handle tags
designed for larger, tougher
fin. The most frequently used tag
for sharks is the Dart tag which
has a small dart connected to a
cord about 8 inches long.
Contact information and
instructions for the person who
recaptures the shark are printed
on the cord. Sonic or radio tags
are sometimes used as a way to
track sharks continuously by
sound, but these are expensive
and only used in special studies.
Casey tags are similar to dart
tags except that they have a
larger barb at the end. These
tags are used less frequently
than dart tags, and only for very
large sharks. Very large sharks
that cannot be brought on board
a boat are tagged using a pole,
which attaches the tag to the
sharks first dorsal fin. Roto tags
are an older design, less
effective than dart tags and used
rarely, since they are more
awkward and bulky than dart
The net is kept ready for use.
The net is fed out the back of the boat.
Letting the net
Once the shark has been encircled, the net is hauled in
Raising the shark into the boat once it's in the net is a tricky process.
The shark is placed on a board to begin measuring and weighing
The shark is bundled in a smaller net to make handling easier.
The shark is hung in the net from a scale.
The shark must be carefully handled to prevent it from thrashing around the boat.
The length is measured
Spans between fins are measured.
The various weights and measures are recorded.
A durable tag is inserted into the dorsal fin that will identify this shark uniquely.
Insertion of the barbed tag in the cartiledge of the dorsal fin.
The sharks are released as quickly as possible to insure their well being.
Next: Try to predict where sharks will be and try to tag one.