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Guy Harvey

The captain was backing down hard on the blue marlin that was swimming away from the boat, the angler keeping the line tight, and the expectant mate was leaning over the transom reaching for the leader. The marlin was just below the surface, and in a few seconds would qualify for a technical release in the annual tournament in Port Antonio in Jamaica, and would then be set free.
 
All the crew saw next was a bolt of electric blue rocketing up from beneath the surface and slam into the two hundred pound marlin chopping its tail clean off, cutting through the leader at the same time. The marlin struggled at the surface, its propeller missing. The predator attacked again taking off another huge chunk of the body. We watched in amazement as the big shark swam down out of sight following the sinking head of the marlin.

A mako shark we estimated at 800 pounds had just demolished half of a blue marlin and was taking its time with the rest. What an amazing animal. I related the story to some captains in Florida, and some had seen the same behaviour exhibited by mako sharks working on swordfish. Apparently this was their preferred method of attacking large and equally fast, dangerous prey. They execute a surprise attack rocketing up from beneath, and cutting the tail of the swordfish off, immobilizing it, and then returning to bite their face off, removing the blade like bill and a source of serious harm for the predator. The shark then feeds on the body at leisure.

This marvellous fish was made famous by authors like Zane Grey and Ernest Hemingway, who hunted the spectacular jumping gamefish in the Gulf Stream. In The Old Man and the Sea, Hemingway made it the shark species that began the destruction of the huge marlin The Old Man had just vanquished. Hemingway got it right;
 
“He was a very big mako shark built to swim fast as the fastest fish in the sea and everything about him was beautiful except his jaws. He was built as a swordfish except for him huge jaws which were tight shut now as he swam fast, just under the surface with his high dorsal fin knifing through the water, unwavering. Inside the closed double lips of his jaws all of his eight rows of teeth were slanted inwards.
 
They were not the ordinary pyramid-shaped teeth of most sharks. They were shaped like a man’s fingers when they are crisped like claws. They were nearly as long as the fingers of the old man and they had razor sharp cutting edges on both sides. This was a fish built to feed on all the fishes in the sea, that were so fast and strong and well armed that they had no other enemy.”

“When the old man saw him coming he knew this was a shark that had no fear at all and would do exactly as he wished. He called him dentuso.” You know what happened next.

The mako has escaped much of the media disinformation about sharks, primarily because it lives far from human population, unlike bulls, tigers and hammerheads.

The mako shark comes in two distinct species, the long fin and the more common short fin variety. They belong to a family of sharks, the Lamnidae, that include the white shark, the porbeagle and the salmon shark. All are characterised by a large size, pointed snout, robust body, and fast swimming speed.

Their tails are lunate, with lobes of equal length unlike all other shark species in which the upper lobe is typically longer than the lower lobe. Their mouth is armed with a spectacular set of long, sharp teeth adapted to grabbing fish. Their eyes are large, and gill slits are long, with the ventilation of their gill rakers dependent on their forward motion, ramming water over their gills, as seen with billfish and tunas. The makos are found in all tropical and subtropical waters, usually in deep water, but occasionally venturing into shallow water.

In addition to being the fastest of oceanic predators, having the ability to attack swordfish, billfish and tunas, their physiology is unique for sharks. The members of this family can maintain a body temperature higher than that of the surrounding sea water. This is achieved using a counter-current heat exchanger in the red muscle which is used for swimming, so they can regulate their body temperature much the same way as tunas do. This adaptation allows them to swim faster in deep cool water, or to migrate to cooler latitudes where food is more abundant and still be effective apex predators.

Mako sharks grow more rapidly than most other shark species but only reach first maturity at a length of ten feet. So it takes many years for them to mature, as do most sharks. They are incapable of replacing themselves at the rate of current extraction by directed commercial shark fisheries worldwide, hence their predicament. There are industrial long lining operations throughout the Atlantic Ocean targeting tuna and swordfish that also catch many mako sharks. Their flesh is reported to be the best of all shark species, resembling swordfish in taste and texture. Their fins and jaws are also in great demand.

As with most other predators in the epi-pelagic zone of the open ocean, mako sharks travel great distances in a short time. Constantly moving, they shadow their prey schools of tunas, squid, billfish and other large fish near seamounts and drop-offs, consuming amberjacks and other species of sharks.

My research institute, the Guy Harvey Research Institute, has done a lot of research work on different shark species during the last decade and has recently embarked on a study of the migrations of blue sharks and mako sharks in the North Atlantic Ocean. In the northern summer, these species are found in the same areas, the blue sharks feeding mostly on squid, whereas the makos feed on swordfish and on blue sharks. When the water temperature falls in the late summer, these fish migrate south and spend the winter in the Caribbean and in the Bahamas.

There are few mako shark sightings reported from the Cayman Islands, but they do migrate through our waters, and one may have a rare encounter while doing a decompression stop off the coral walls around the island, or while chumming for tuna at Twelve Mile Bank.

Dive safely, fish responsibly.
Guy Harvey PhD.
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