From Wreck to Reef in 200 Days


October/November, 2008

by Alison Perkins

In a flash of pyrotechnics on 3 November 2007, the ex-HMNZS Canterbury slipped swiftly below the sea, taking up residence in Deep Water Cove in the Bay of Islands on the North Island of New Zealand. She was destined to take on a new life as a designated divers’ playground and artificial reef for marine life. Six months have passed since the sinking, so how has she fared?

wreck-reef2Seven days after the sinking, I descended on the new wreck. I didn’t know quite what to expect. Would there be fish on it? A dozen divers tumbled down on the hulk, and immediately vanished inside, like damselfish darting under the cover of coral when a menacing shadow passes overhead, leaving my buddy Cameron and I with the wreck to ourselves. A nonchalant observer might have thought they were diving a ghost ship. But I observed a leatherjacket, female Sandager’s wrasse and snapper on the outer decks. Two blue cod were cruising the bottom, marching up and down the length of the ship as if patrolling their new-found territory, only pausing to perch on their pelvic fins and peer warily at the newcomers. Under the conning tower a school of small silvery fish, Koheru or Jack mackerel, flitted about using the tower as shelter from larger predatory fish.
wreck-reef3By Christmas, the accumulated gathering of fish on the Canterbury was like a disparate annual family reunion. Spottys, trevally, common and variable triplefins had joined a growing number of leatherjackets. Algae had covered the exterior surfaces of the ship, providing plenty of grazing material for baby leatherjackets loitering like leopard-spotted pancakes in the safety of the walls of steel. Barnacles, athecate hydroids and the meandering lines of tube worms had encrusted the decks. Clouds of oblique-swimming triplefins darted in and out of openings in the ship.
wreck-reef4In January, the water was a pleasant 20°C and the list of fish species found on the wreck now included tarakihi, sweep, leatherjackets, hiwihiwi, banded wrasse, porae, goatfish, trevally, snapper and blue cod. Of the triplefins there were oblique-swimming, blue-dot, variable and common. Around 40 small squid hovered over the top deck like strange underwater UFOs. Sadly, some divers had seen fit to deface the wreck by writing their names in the algae, but the growth was unstoppable and in weeks the ‘graffiti’ had disappeared.
A school of koheru and a female scarlet wrasse were new inhabitants of the burgeoning reef in February. A conger eel was spotted in the bridge but it found the crowd of divers too much and swam away in fright. By March common anemones were spotted and the ecklonia kelp growth could be measured in centimetres. Empty barnacles were now houses for crested blennys. But the real thrill came in April. Rolling backwards off the boat, I stuck my head in the water to look down. Thousands of Jack mackerel were schooling up and down the ship with five good sized kingfish on their tail. The next day the number of kingfish had swelled to 11 and the sight of them hunting the Jack mackerel made my decompression stop pass quickly. Jewel anemones were starting to colonise the railings, adding a bright splash of purple to the otherwise dull-coloured wreck.
wreck-reef8Each dive on the Canterbury I spotted something new: scorpionfish, a male Sandager’s wrasse and red moki. Not only were there new species arriving, but their numbers were increasing too. Finally, the long awaited red crayfish arrived. Settling on the sand on the starboard side, I swept a gap under the ship with my torch, startling five red crayfish, who scuttled backwards, far from reach. I looked for them again the following day but they had gone, and I hoped this was a sign of the crustacean’s roaming nature, rather than the hand of man.
I have been keen to report my sightings of new species on the Canterbury, so that other divers can share my joy at seeing new life develop on the wreck. Being a site designated for divers, it is a voluntary no take zone, and I hope fishermen, spearfishers and crayfish hunters can respect that. There are kilometres of coastline in the area on which they can fish, but only one wreck for divers to play on and the marine life on it adds to the diver experience.
wreck-reef5Comfortably relaxing back at the Cowshed Backpackers, some divers were poring over maps of the Canterbury, looking at what rooms they’d wandered through, and where to explore next. I’m generally disinterested in the interior of the wreck. Maybe when the ship fills with bigeyes and other fish, I’ll be drawn in too. Instead, I pondered an article I had read during the week about New York, where they had dumped 44 subway cars into the Atlantic Ocean to create an artificial reef to attract fish for the lucrative sport-fishing industry. Is it too much? You can definitely argue that the ocean is no place for man to dump its unwanted refuse. You can also argue that the fish that are flocking to the Canterbury reef each week don’t seem to mind the new addition to their backyard. What will set the Canterbury wreck apart from its sister wrecks, the Wellington in Wellington and the Tui and Waikato in Tutukaka will be its longevity and consistently ideal location for diving. In 15 dives on the Canterbury in a wide range of conditions, I’ve never experienced more than a barely perceptible current and even after torrential downpours, the visibility has been around eight metres. Now we just need to wait for the marine life to catch up, and fortunately, we shouldn’t have to wait too long. I look forward to seeing what new additions the next six months will bring.
wreck-reef9In a world where daily news articles report the increasing devastation of fish stocks in our oceans, watching the fish life grow on the Canterbury has provided me some relief from the depressing reports. I was surprised in June, to see a scallop growing on the top deck. On the upper railings sheltered some tiny fish that were unfamiliar. Malcolm Francis identified them as juvenile moon wrasse (Thalassoma lunare); a tropical species rarely recorded around mainland New Zealand. If they manage to survive the winter they’ll grow into extremely colourful adults. There were as many small snapper on the young reef as I’ve ever seen in one site before and some larger ones had started to appear. As divers swam over the wreck, the snapper rose up and after the divers had passed they descended back down to the deck, like the red curtain falling at the end of a very good show.

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