Diving on Harbour Riches

Forest and Bird, Issue 291, 1 February 1999, Page 26

Diving on Harbour Riches

WADE DOAK

WADE DOAK

dives in

waters ‘in some ways more densely populated than the Poor Knights’

tumbled rock walls of a small island just within the entrance to Whangarei Harbour and found an underwater world in some ways more densely populated with marine life than the Poor Knights Islands. Known variously as Aubrey, Passage, or Motukaroro, this island is only about the size of a large cruise ship but much beamier: 200 metres by 100 metres. It lies 18 kilometres downstream from a city, and but 300 metres from a major oil refinery and supertanker port. Twelve hundred hectares of mangroves and vast expanses of mud flat and channels drain their nutrient riches past the island, and through a deep, narrow throat beneath the crags of a mythic volcanic mountain. Around me in the half-light, ghostly white, cardboard-thin John Dory, squadrons of them, stalk their quarry. Jack-in-a-box jaws flash open and shut. I cannot see their prey in the gloom. I glimpse a school of silvery snapper at the edge of vision. I have hip-hopped down 10 storeys from the pohutukawa trees overhanging the calm water’s edge, where herons and gulls in the glow of the late sun are waiting out the high tide before returning to their intertidal feeding zone. I'd stepped from our inflatable onto a knee-deep flat rock. Jan passed the video camera and I slid in — it’s surprisingly warm, even for late autumn. The water is quite turbid with a high load of visible particles. A hazy five metres of vision. Initially I felt a little disappointed. Nowhere near as clear as my beloved Matapouri mangrove creek, nor Whangateau’s blue channel. But I wanted to check out this location as perhaps the acme of mangrove productivity. Kelp fronds on short stems are coated with silt. Here is richly encrusted rock. Weed-eating parore, drummer and butterdescended 30 metres down the

fish dart among the canopy. Myriad juvenile spotties with bright yellow markings nip at sealife on the kelp leaves. Then comes a swarm of oblique-swimming blennies, plankton feeders from the open sea. And demoiselles nipping at the current, flitting about with their scissor-tails like undersea swallows. Even small blue maomao — I never dreamt of seeing such oceanic fishes within a harbour. At 10 metres an abrupt transition: the kelp forest stops and encrusting life expands, along with a dramatic increase in reef fish, both in variety and substance. The profile is steep but not vertical: big volcanic rocks with sandy terraces. These rocks often have flat faces and over them jewel anemones spread in sheets of opulence, each colony its own colour: mauve, wine red, apricot, green, lolly pink — exquisite, vibrant hues that seem to fluoresce as the

light diminishes. I feel I am on a coral reef. At 15 metres I just stop and stare in amazement. The density of fishes is unbelievable. Above me the sun is dimmed by a cyclone of jack mackerel that weave around me in a living cylinder. Like sharks, massive bullet-shaped bodies whirl out of the gloom to scrutinize me: they are large kingfish in squads of five to eight, bigger than I have seen for some years. Among the rocks, in hollows and near ledges the reef fish are busy. I do a video run, trying to compress the diversity of species into a brief time frame. A butterfly perch and a triggerfish cross my screen, giving way to a skittish, lumbering marblefish, then a weaving group of large spotties and scarlet wrasses. A big male banded wrasse dashes to and fro in a rocky alcove. I veer to the left: a red moki rests beneath a ledge. It exits and I follow

close to its broad tail as several triggerfish and wrasses cross my path towards an overhang where slender roughies and big eye — night-plankton feeders — dart around in the gloom, awaiting dusk. My sequence finishes on a mottled blenny resting on a rock like an owl. Then, beneath the ledge I notice a longlegged red rock crab; its ornate carapace reminds me of the Cockney pearly kings who decorate their clothes with shiny buttons. While crabs often flee the camera, this one is big and shows no fear. I watch its elaborate mouth parts flicking as it combs the water for plankton. Then it reaches up, grasps the rock ceiling and swings up so its tail is towards me. Upside down it rotates to face the camera and resumes feeding in a topsy-turvy pose. Nearby a pair of ghost shrimps waft like sporty helicopters.

Amidst the anemone colonies nudibranchs crawl, and blennies pounce and roost: mottled blennies, masked ones, lined, banded, crested, yellow-black — a variety to equal any offshore island scene. A pair of mimic blennies hover sinuously, trying to bite the sides of a spotty which may be deceived into thinking these pirates are just harmless oblique-swim-ming blennies. In a sandy mall I meet a herd of goatfish more numerous than I have ever seen before and the adults are huge. This sand must be rich in the micro-fauna that goatfish dabble and delve for with their tastebud bearing barbels. uddy diver, Glen Edney, who has down a slope nearby, is taking still photos with slow, quiet precision. We keep clear of each other to avoid problems but his signal attracts me. He has found an octopus. He holds out his hand, palm uppermost. Its head flushes a variety of colours. Then it extends a tentacle and palps Glen’s palm gently. We’ve been accepted by the local intelligentsia. But there are even bigger brains in these waters. One day, while concentrating on the viewing prism of his Hasselblad camera, veteran photographer Warren Farrelly heard a weird sound. After taking a shot of a paddle crab amidst vivid jewel anemones he had two frames left to shoot. He was waiting for the twin strobe lights on either side of his camera to recycle with their shrill electronic whirr. But the sound he heard seemed to be somewhere else. Was it his ears squealing because he had not equalized properly? He continued taking pictures until his film ran out. Then he began to worry about the sound in his ears. It would rise as the strobes recharged and reduce as they reached a full charge. It seemed to be mimicking the sound-pattern strobes make, but where was it coming from? He felt no pain in his ears. He was kneeling on the bottom so there were no pressure changes. Slowly he realized it was behind him. ‘On turning round, I was eyeball to eyeball with four nosy, motionless orca whales. The middle pair I could have touched. In the gloom a white patch along their sides initially caught my notice. Then my focus shifted closer in, to their eyes and mouths. The blackness of their heads disguised their faces in poor light. I just gawked. With no electronic flashes recharging to challenge their powers of mimicry, they may have become bored. They departed. Those huge creatures turned away and powered off, hardly moving their tails. They didn’t seem

to disturb the water in the least. For some time I continued to hear their sonar squeals out in the harbour. Then silence. I left the water feeling incredibly clumsy but touched by magic. Orca (or killer whales), regularly visit this harbour to hunt the stingrays that feed on molluscs over the flats. In the deep zone the encrusting sponges become erect and impressive, like yellow stalagmites; long finger sponges, organpipes and orange spheres. Pale feathery plumes of a hydroid colony look like an elaborate hat. A gnarled Solanderia hydroid tree is like a Chinese bonsai miniature. With the outgoing current gaining force I surface near dusk. Shortly this spot will become a maelstrom, water piling up against the island as on a tanker’s bow. I take stock of the thriving world below my fins. In terms of biomass and species diversity the reef fish population around this tiny island would equal most locations in

New Zealand’s richest waters, the Poor Knights Islands, but not their overall diversity. The fishes are an indicator of the diversity of the encrusting life. Aubrey Island, with its powerful currents but lack of violent waves, and the enormous nutrient riches of the adjacent mangrove forests, must be one of New Zealand’s hot spots for reef fish life — a regular Sky City Casino. A more detailed survey of the fish life, greatly assisted by local diver/photographer Warren Farrelly, gives a fish count of some 50 species for the area, extraordinary for an enclosed harbour site and a tribute to the immense power of mangrove productivity. No wonder that Warren and his pupils at the nearby Kamo High School are fighting to make this island a marine reserve, along with an area of mangroves, and an expanse of intertidal mud flats up the harbour.

is the author of many books

of diving adventures and life in the oceans.

Protection Needed

‘1 am concerned about the proposed Northland Port Corporation development at Whangarei Harbour entrance. ‘It is close to extremely rich waters surrounding Aubrey, or Passage Island, which is subject to a proposed Marine Reserve application by pupils at Kamo High School. ‘| believe that the proposed excavation of a turning basin for log ships close by will seriously endanger a unique treasure of great value both educationally and ecologically. ‘1 am advised by the head of Transit New Zealand that all the log traffic from Northland could be railed to Mount Maunganui, a method which | believe is currently underused. Most road users would endorse this!’

— Wade Doak