Have you ever eaten shark? Perhaps you have, unwittingly, if you’ve tried rock salmon or huss, because they are names given by fishmongers and chippies to various species of small sharks; few people in these islands would eat them otherwise. In many parts of the world, however, shark meat is commonly consumed; in China, shark-fin soup is a delicacy.
Back in 1970, my father was one of the founders of the Courtmacsherry Sea Angling Centre. I am ashamed now to think of all the blue sharks pulled out of the water just for fun, clubbed to death and brought ashore to be weighed and photographed. But what sad pictures – those magnificent animals, their beautiful blue backs turning grey, their entrails hanging out, blood and slime dripping onto the pier. And next day, piles of them in the dock, covered in feasting crabs.
In those days, people didn’t worry about conservation, or cruelty to fish, but my father did think it a waste of food. So he sent me and my sister, then aged twelve and ten, from door to door in the village with a bucket of shark steaks. They looked very appetising: round, white cutlets with just a central cartilaginous spine. But no one was interested in trying them, mostly because of the sharks’ fearful reputation. Also, fresh shark meat has an unpleasant smell, due to their method of osmoregulation.
Osmosis, as you will remember from school, is the movement of water from areas of low solute concentration, across a semi-permeable membrane, to areas of high solute concentration. Fresh-water fish, more concentrated than the surrounding water, are constantly being flooded, and without very efficient kidneys which excrete copious amounts of dilute urine, their cells would expand and burst. Saltwater fish, conversely, are in danger of dehydration – their body tissues are less concentrated than sea water, so they lose water all the time. They have to keep drinking water and excrete excess salt.
Nearly all sharks are marine, but instead of drinking sea water, they maintain an osmotic balance (i.e. they keep their cells as salty as the sea) by retaining urea in their blood, not excreting it. After death, the urea breaks down into ammonia, among other things, which explains the pungent odour.
The Greenland shark, a gigantic fish that can live for up to 400 years, has a particularly high urea content and is poisonous to eat fresh. But in Iceland its flesh, buried for three months then dried, is called hákarl, and is the country’s most infamous dish (considered by many to be revolting).
We found that after a few days in the freezer, the ammonia had dissipated and the shark steaks were perfectly good to eat. But we never really enjoyed them.
Thankfully, in Ireland anyway, sharks are not killed for sport anymore. In 1974, the Inland Fisheries Trust started a tagging programme, and from then on, most sharks caught by anglers were tagged and released. That produced interesting results: for example, nearly all the blue sharks caught in Irish waters are female; on the other side of the Atlantic, they are nearly all male. They meet up in the middle of the ocean.
Many tagged sharks were recaptured by anglers, but by the 1990s, most were being caught by commercial fishermen, particularly off the Azores. These fish would have had their fins sliced off (for sale to China) then been thrown back alive but unable to swim, condemned to sink to the bottom and die horribly. As a result of this, between 1986 and 2000, blue shark populations in the North Atlantic declined by over 60 per cent. Sharks are especially vulnerable to overfishing because they grow slowly and have few young; worldwide, many species are in serious trouble.
Sharks belong to the class Chondrichthyes – fish with simple skeletons made of cartilage, not bone. This class is divided into two: the elasmobranchs (sharks, skates and rays) and the holocephalans (the chimaeras). There are over 500 species of sharks in the world, ranging in size from the 20 centimetre dwarf lantern shark, to the whale shark, which can grow to 18 metres. About nine species of sharks live in, or regularly visit, Irish coastal waters: basking, blue, porbeagle, tope, lesser and greater spotted dogfish, starry smooth hound, spurdog and the now critically endangered angel shark. There are a few records of common thresher and short-finned mako sharks, while many other species are found in deeper water.
Nearly all sharks are predators with very sharp teeth, so even small ones can give a serious bite (I have the scars to prove it). But only a few species are definitely man-eaters: the great white, the tiger, the bull, and the oceanic white-tipped shark, which was probably the species responsible for eating hundreds of sailors from the torpedoed USS ‘Indianapolis’ in 1945 (a story recounted by Quint in the film Jaws).
Three of the largest sharks are harmless and eat only plankton. The beautiful whale shark, the largest of all fish, is found only in the tropics; the ugly megamouth, which was not discovered until 1976, lives in deep water. But the basking shark, the second largest fish, is a common visitor to our shores.
In late spring and early summer, increased temperatures in coastal waters produce plankton blooms, which bring the basking sharks in from the deep sea, where they spend the winters. The basking shark’s Latin name is Cetorhinus maximus: ‘ketos’ is the Greek for monster (‘cetacean’ has the same origin); ‘rhinus’ means nose. So the basking shark can be called “greatest monster nose”. They swim through clouds of plankton with their cavernous mouths wide open, and often their great big noses stick out above the water. Tiny planktonic animals, and any other things in the water, get trapped by gill rakers on the inside of their gill arches and are swallowed. The water, carrying oxygen, flows over the gills and out of their gill slits.
Basking sharks were once hunted in Ireland, most famously from Achill Island. They were killed for their meat, their leather-like skin and, most especially, for their oil, which was used for lighting lamps. Sharks have enormous oily livers which help with their buoyancy (unlike most fish, they have no swim bladders). The liver of a basking shark can make up a quarter of its total weight. Fortunately, that fishery ended in the 1960s.
Basking sharks were often entangled in salmon drift nets; that danger is gone too, and since 2022 they have been protected by law in Irish waters. But in the rest of the world they are still endangered. Their huge fins make a lot of soup, their cartilage is used for spurious Chinese medicine, and they suffer badly because of all the rubbish dumped in the sea.
Over six million tons of fishing gear is lost each year, entangling and killing millions of sharks of many species, as well as whales, dolphins, turtles and birds. Some of that loss is unavoidable, but much is not – I was recently sent photographs of short lengths of rope that have been appearing in unusually large amounts on beaches in West Cork, allegedly discarded by careless mussel farmers.
Then there is all the plastic – an estimated 14 million tons – dumped into the sea every year. A study in the Mediterranean calculated that basking sharks there were swallowing 540 pieces of plastic per hour. This will result in malnourishment, blockage or serious injury. Whale sharks in Japan and Thailand have died from internal damage caused by ingesting plastic. And plastics can contain toxins that leach out into the shark’s tissues, which might already be poisoned by heavy metals.
Last May, there were hundreds of basking sharks in Courtmacsherry Bay, easily sighted from the land. One day, I spotted three, close inside Broadstrand. I pointed them out to a holidaymaker staring at his phone; he hadn’t seen them. On the other side of the strand, several people were swimming. They didn’t see them either. Twenty-foot monsters with tall black fins cutting through the water close to shore, unnoticed. Is it any wonder nature is in trouble?
I should have shouted “Shark!” They would have noticed them then.
