KEY POINTS:
Snapper, blue maomao and parore swarm near the rocks as a hundred visitors stand and watch. In the shadows of the kelp behind them, much larger snapper lurk.
Stories from several generations ago told of all the coast being like this, but today only the coastal waters of the Cape Rodney to Okakari Point Marine Reserve - best known as Goat Island - have fish schools like this.
Thirty years ago, the rock platforms from low tide down to 6 metres depth were grazed barren by sea urchins. The lack of their major predators, snapper and crayfish, allowed the urchins to feed on the kelp forest and eventually almost completely remove it. It was thought that this was normal for the Northland open coast.
In 1965, University of Auckland marine laboratory staff wanted to protect the reefs and sand flats adjacent to the laboratory so that students and scientists could study marine life without people catching, collecting or damaging what they were studying.
Any form of marine protection was unheard of then, and there was no empowering legislation. Professors Val Chapman and John Morton, aided by Dr Bill Ballantine, battled through red tape and opposition and in May 1977, New Zealand's first marine reserve, surrounding Goat Island, was officially opened.
The benefits of marine reserve protection are now obvious to visitors. On busy summer days more than 3000 people squeeze on to the beach. Yet when the reserve was created, no one thought people would come to a beach where they couldn't fish or collect seafood.
Some children who come to the reserve with their school, to snorkel or walk the reefs at low tide, encourage their parents to bring them backagain.
Many visitors have never seen a live marine fish, apart from a dying specimen on the end of a fishing line. Some do not venture into the water but prefer to stay dry and watch the fish from the rocks or from the glass-bottom boat.
Many visitors enjoy fishing and collecting seafood outside the protected area but also want places like the marine reserve where they can just look and enjoy the marine life.
While Goat Island's marine reserve was created for scientific purposes, tourism and education benefits sprang up, including a glass-bottom boat business, marine education centre, dive shop, restaurants and accommodation.
The impact is huge for an area of only 5 sq km.
Snapper and crayfish numbers increased fairly quickly. Sea urchin numbers gradually decreased through predation by snapper and crayfish, and the kelp forest began to grow back. Fish and invertebrates that live on or around the kelp returned. Without the reserve, none of this would have been possible.
We have dived and monitored Goat Island's marine life since the 1970s and gradually witnessed an increase in fish numbers. Species like red moki and butterfish were previously comparatively rare, but have now re-established in numbers far greater than along the surrounding coast.
Silver drummer schools were almost gone from the coast before the reserve was set up. These fish have taken longer to come back and just 10 years ago they were small and flighty. Now schools of large drummer move over the shallow rocky reefs at high tide to feed on seaweed. Parore, a similar kelp-eating fish, also abound in the shallows.
Other unusual species, such as giant boarfish, have been seen in 3m or 4m of water in the past few years. Previously they were seen by divers only below 20m. Maybe they once lived in the shallows around the coast and are returning to their original habitat.
Northern New Zealand's premier food fish, the snapper, were always present but not in the numbers now found here. Recent scientific data using baited underwater video shows their numbers average more than 14 times the numbers found in similar habitats outside the reserve.
The average size of the snapper in the reserve is much greater, too. Some large snapper, first seen in the mid-1990s, are still there today apart from forays outside the reserve during breeding.
Research suggests the breeding snapper in the 5km length of the marine reserve produce eggs equivalent to 90km of unprotected coast. At dive sites outside marine reserves, snapper are not easily approachable, but at Goat Island they follow divers, looking for anything uncovered in the sand.
Some reefs now harbour hundreds of crayfish, the largest over 5kg. Many of the large ones live in the same area for several years. They are mainly red crayfish, but in recent years small numbers of green or packhorse crayfish have reappeared.
Red crayfish have been studied at length, and while numbers vary from year to year, their numbers within the marine reserve are between 12 and 23 times greater than outside. Large male crayfish actively seek out large female crayfish to mate with, and studies show that very large crayfish produce a far higher number of eggs than smaller crayfish, proportionate to their size.
The marine reserve's crayfish stocks and their habit of wandering outside the boundaries are known to local crayfishers, and the boundaries of the marine reserve are dotted with commercial crayfish pots.
Studies involved the tagging of crayfish within the reserve and along the boundaries to learn about seasonal movement. In one study, of 429 crayfish tagged at a site, 106 were not seen again but 21 per cent were resighted there a year later.
Snapper studies involving tagged fish were also carried out over a period of years. Of those studied, around a third left the reserve and were not seen again, a third left the reserve and reappeared at a later date and the remainder stayed within the reserve boundaries, usually foraging over a relatively small area.
Studies of snapper numbers have compared Goat Island with the Tawharanui Marine Park, 10km to the south, and the Cathedral Cove Marine Reserve on the eastern side of the Coromandel Peninsula.
These studies showed higher numbers of snapper at Goat Island than the other two sites, but all three showed much higher densities of larger fish within the boundaries than on similar habitat zones outside.
Thirty years after its opening, the Goat Island marine reserve is still changing as resident marine life populations fluctuate. While numbers of crayfish and snapper are recorded by scientists, other species are noted by divers and snorkellers who dive the marine reserve regularly.
New Zealand's first marine reserve is educating people in the benefits that protecting a section of the coastline can provide.This increased awareness will see future generations enjoy marine life in numbers not thought possible only a few years ago.
