|Blue & Mako Sharks|
|The face of a predator, the shortfin mako (Isurus oxyrinchus) reaches
lengths of nearly 14 feet long and 1500 pounds. it represents the cutting
edge of selachian predatory development. the mako preys upon tunas
swordfish and other sharks. A close relative of the white shark (C.
carcharias) and the salmon shark (L.ditropis), the mako is a warm blooded
endo-therm capable of tremendous bursts of speed and power. Shortfin makos
have a more obscure relative called longfin or big-eye mako (Isurus paucus)
that dwells in the deep waters of the tropics.|
Fritz-Cope/PSRF Aug 1997
|A large blue shark surfaces to consume an injured mackerel. Blue sharks
have large well-developed eyes that are suitable for surface or deep-water
situations. Blue sharks can reach a maximum length of nearly 13 feet long
and several hundred pounds, although a 9 footer is considered a large
adult. Blue sharks are opportunistic predators that will not hesitate to
scavenge off of dead whales or harry an injured porpoise. Typically blue
sharks are strictly piscivores (fish eating) feeding on mackerels, squid
and other schooling fishes.|
Fritz-Cope/PSRF July 1997.
|The blue shark, Prionace glauca represents the archetypal pelagic shark.
Built for long-range gliding the blue shark is perfectly suited for
crossing vast ocean basins.|
|Blue sharks are very bold and determined
foragers with keen eyesight as
well as a well-developed sense of smell.|
|The blue shark's snout is packed with sensitive
electrical field detection
equipment that enables it to track and zero in on a prey item. Blue
are known to be able to exert bursts of speed although they are designed
cruise over great distances with minimum energy expenditure. Blue sharks
hunt everything from squid to tuna, they are opportunistic foragers that
will not hesitate to consume densely packed krill, scavenge off of a
whale or pursue an injured porpoise. They have been known to consume
and injured sailors and pilots during air/sea war disasters.|
|A blue shark biting on a piece salmon is pulled to the side of the boat for measuring and tagging.
|Ventral view of Blue Shark.
|Removal of hook from tagged blue
|PSRF Director Sean Van Sommeran executes a carefully timed tail grab on
small blue shark.
The blue shark was lured close to the boat with a piece of salmon on a
As the shark comes within reach, it can be carefully grabbed and/or
netted. The shark can then be brought briefly aboard to be measured,
sampled, tagged and released. Grabbing a blue shark should be done with
extreme caution, they are able to flex and twist all the way around and
bite their own tail or an offending hand.|
|PSRF staff technician Tushar Atre restrains a small blue shark while
demonstrating its indigo blue dorsal surface for which the shark is
The shark is kept out of the water for no longer than 3 minutes as it is
measured, gendered, tagged and released. These sharks are often sampled
for blood and tissues.|
Van Sommeran/PSRF July 1997
|A drugged blue shark is lifted from the "Pelagic 1" holding basin, prior
to the shark's revival and release.
MS 222 is a commonly used tranquilizer, which renders the sharks
temporarily groggy and limp. The blue sharks are collected with a
scoop-net and set into a basin of seawater laced with MS 222. After a few
minutes, the shark becomes limber and can be quickly measured, blood sampled and
tagged. The shark is then held over the side of the boat until it
revives and swims away.|
Casper/PSRF summer 1995
|PSRF Director Sean Van Sommeran puts a blue shark into tonic immobility
rolling it over on its back.
By rolling a small shark over and suspending them in an inverted
the shark will sometimes go into what is called tonic immobility where
can be more easily measured and sampled. This state of immobilization
should never be taken for granted and does not always last very long.|
|Dr Dave Casper draws a blood sample from a blue shark from the deck of the
"Pelagic II", a 23-foot Wilson Custom Hull, and sister ship to "Pelagic I".
The blood samples collected are archived for analysis of pollutant loads.
PCB's, Metals, Trace organo-chlorines and other pollutants are carried in
the sharks blood. The samples collected from open ocean blue sharks can be
compared with samples taken from benthic sharks and estuarine sharks to
analyze differences in the levels of contamination.|
Van Sommeran/PSRF July 1997.
|PSRF staff photographer Callaghan Fritz-Cope releases a small blue shark
after it has been tagged and sampled. With sharks less than 5 feet long
scoop net or a carefully timed tail grab is used to collect and
restrain them for sampling. This method is much less likely to injure
shark than hook and line capture.|