“Sharkology” 225
relative to length of different parts), head shape, mouth width, lateral-line
pore distribution (especially in chimaeras), coloration, scale roughness and
distribution (especially in skates), eye diameter and color and pupil shape,
number of gills, and barb characteristics (in stingrays) are also helpful. In-
formation about geographic location is absolutely essential, but such “lo-
cale data” are sometimes lost in the case of preserved museum specimens.
A researcher may also dissect the animal and look at the size, number,
shape, and distribution of various internal organs. Increasingly, biochemi-
cal characteristics, including molecular genetics (i.e., DNA fingerprinting),
are often used in combination with one or more of the anatomical traits to
finalize an identification.
By making use of these characteristics, we can tell what species a shark
may be or whether it is unknown to science. In addition, molecular tech-
niques have been used increasingly in forensic investigations to determine
if shark meat or fins being sold are in fact from the species advertised.
These techniques have allowed researchers to ascertain when parts of rare,
protected species are being passed off illegally as being from abundant, un-
protected species.
How do scientists study the movements of large sharks?
One of the big questions in elasmobranch biology has been and remains
how much sharks travel and where they go. This critical piece of informa-
tion is essential for conserving sharks because many move long distances.
This means protection in one place may be ineffective if the same animal
moves to an area where it isn’t protected.
For a long time, the only way we could gain such information was to tag
a shark by placing an individually recognizable tag on its fin or in its back,
and hope someone would catch (and probably kill) it somewhere else and
report the tag number to the address listed on the tag, hopefully with size
and capture locale information included. Moving needles and giant hay-
stacks.
Slowly, we’ve learned that certain species—White Sharks, Whale
Sharks, Blacktip Reef Sharks, Whitetip Reef Sharks, Zebra Sharks, manta
rays and Spotted Eagle Rays—have individually distinctive markings.
These markings sometimes make photo-identification possible, whether a
researcher is underwater looking at color patterns, or above water in a boat
looking at the dorsal fin shape and scarring of White Sharks (see “Can
sharks tell one another apart?” in chapter 4).
As technologies have grown more sophisticated and complex electronic
equipment has been miniaturized, researchers have developed “packages”
that can be surgically implanted, attached to the dorsal fin, glued on the