KEY POINTS:
Sharks are the most feared of sea creatures, yet there are only about 25 fatalities recorded worldwide each year.
New Zealand's last fatal shark attack, at Te Kaha in the Bay of Plenty in 1976, holds special significance as I was spearfishing in the same bay on the morning of the attack. The unfortunate spearfisherman had been carrying dead fish and was bitten as the shark, probably a bronze whaler, attempted to seize his catch. Most of us towed our fish on a float five metres behind us in case a shark wanted to share our fish.
Shark scares were commonplace in the 1970s as New Zealand had experienced several fatal attacks in the decade before the one at Te Kaha. The movie Jaws came out around the same time and accentuated the fear and paranoia that still surrounds sharks.
This summer sharks have been seen off many popular beaches, leading to more sightings as people forego a swim in the ocean and sit on the beach watching for anything that resembles a shark fin.
An attack on an inflatable boat off Omaha Beach seemed unusual until it was reported that the boat had run over the shark while trying to drive it away from the beach. Naturally the shark retaliated, tearing the fabric on the boat's hull, but the report was still headed "shark attack".
Perhaps it is the warmer water around the coast of northern New Zealand this summer that has led to the increase in shark sightings. Sharks and their relatives, stingrays and eagle rays, move into shallow water to give birth to their young each summer. The sharks feed on the schools of smaller fish just offshore and swimmers are not part of their normal diet.
Stingrays and eagle rays, which also increase in numbers on the coast at this time of year, are not usually aggressive towards humans. The unfortunate death of TV personality Steve Irwin put them in the same category as sharks.
Injuries caused by rays usually occur when someone stands on one or attempts to remove it from a net or off a fishing line. Rays do not attack but are very capable of defending themselves with their tail and venomous spines.
New Zealand's only recorded stingray fatality was on the Thames coast in 1938 when a young woman wading in shallow water stepped on a stingray and was spined in her thigh. She must have fallen on the ray as the barb at the base of its tail pierced her chest and she died before reaching hospital.
Estuaries and harbours such as the Waitemata, Manukau and Kaipara have large numbers of sharks and rays. Smaller harbours and bays around the Hauraki Gulf also experience a shark population increase over summer, although numbers vary greatly from year to year. This leads to more shark sightings, including some from passing air traffic.
In recent years, non-fatal shark attacks have occurred at Stewart Island, the Chatham Islands and Campbell Island. Around mainland New Zealand a few surfers have returned to shore with bite marks on surfboards.
Rather than a major increase in shark numbers around New Zealand and the world, sharks are in decline.
Thirty years ago, any boat trip across the Hauraki Gulf on a calm day was rewarded with the sight of sharks lolling on the surface. If approached by boats the sharks would vanish.
Of the 100 or so exploited shark species worldwide, 20 per cent are considered vulnerable, endangered or critically endangered. Kawau Bay, north of Auckland, was once the target of a large school shark fishery, first by Maori and later Europeans. The fishery died out in the 1940s when the sharks disappeared. The shark populations never re-established in the same numbers. Overseas fisheries targeting the same shark species also ended when the sharks vanished.
Goat Island, part of the Cape Rodney to Okakari Point Marine Reserve north of Auckland, has large numbers of fish and is well known to the thousands who flock there to swim, dive or snorkel. Yet virtually no shark sightings have been recorded in the marine reserve.
One reason may be because there is plenty of natural food in the deeper water outside Goat Island. Perhaps a lack of fish offal from dumped fish bodies and no struggling fish at the end of a fishing line means sharks aren't attracted close to the beach at the reserve.
Many boaties visit the marine reserve after fishing to snorkel or dive with the fish. Fish scraps are often tossed into the water to attract the resident snapper for those on board to see. They may be inadvertently attracting much bigger fish than they planned. The practice, not permitted in marine reserves, hopefully won't cause a sudden increase of shark sightings there.
Three species of ray, the long-tailed, short-tailed and eagle ray, are all common in the reserve. In spite of their numbers, snorkellers, divers and rays have shared the reserve's waters without incident.
The sharks sighted in Omaha Bay, not far south of Goat Island, have been reported as being attracted by bait used in commercial crab pots. Each day over summer dozens of boats leave Omaha to fish locally or around the offshore islands.
Many fishermen leave a trail of fish bodies as they clean or fillet their fish when returning to the boat ramp. This practice would attract as many sharks as the pots.
There has been an increase in free divers, who don't use scuba gear, spearfishing around northern New Zealand in recent years. Spearfishermen often see sharks that come in to investigate their catch. A tug on the line to the float where the fish are secured is often the first indication that their catch is about to be shared with a shark. That large gap between the spearfisherman and their catch and a good knowledge of the behaviour of sharks is probably why the divers are not attacked.
A trend among a minority of scuba divers to carry spear guns and shoot fish underwater is far less safe. Two instances of a shark, probably a bronze whaler, taking a catch bag carried by a diver in Omaha Bay have been reported. Luckily the sharks came in on the side of the bag rather than inadvertently biting the diver while attempting to get his fish.
Anyone entering the sea to dive, swim, snorkel or surf is entering the domain of sharks and rays. Few of those enjoying the sea will ever encounter a shark, although a greater number will see stingrays and eagle rays. The number of people injured by marine life will always be far less than those killed in traffic accidents or even lightning strikes.
Sharks and rays may not be everyone's favourite fish but they have a part to play in the well-being of our oceans. If we decide to enter that environment, then we must share it with the creatures that live there.
* Tony and Jenny Enderby are freelance authors and photographers who have written extensively on marine ecology subjects.
