FIORDLAND PROTECTING THE UNDERSEA WORLD

Forest and Bird, Volume 22, Issue 3, 1 August 1991, Page 34

FIORDLAND PROTECTING THE UNDERSEA WORLD

Forest and Bird

researcher

Barry Weeber,

The waters around Fiordland National Park currently have no protection. They continue to be exploited for crayfish, blue cod, sea cucumbers and, potentially, kina. Department of Conservation marine scientist Anita Pillai explains why the fiords are a unique and vulnerable marine environment deserving of protection.

O MOST PEOPLE Fiordland appears a vast, remote and unspoilt area. At more than 12,500 square kilometres, Fiordland National Park is the country's largest national park. Near a park this size, you would think it would be easy to catch a fish, especially a blue cod. Yet during Easter last year, 42 keen fishermen, using 12 boats, took part in a three-day fishing competition in Doubtful Sound. They caught only two blue cod. Yet photos and archives held at the Deep Cove Hostel show that in the past school children regularly caught cod. This puzzled Dr Ken Grange, a DSIR scientist, and author of a recent report "Unique Marine Habitats in the New Zealand Fiords". He recognised that strong flows of fresh water down the fiords limited the entry of ocean water and blue cod larvae, but doubted this was enough to cause the collapse of the fishery. It was not until Dr Grange started calculating the amount of habitat available to most marine life in the fiords that the reasons for the poor catch became evident.

Mountain wall

In Fiordland the mountains form a wall which forces the warm wet westerly air to rise up into cold alpine air. It then condenses to form rain. Up to seven metres is fed into the fiords every year by thousands of creeks and rivers. As the rain filters down through the forest, it picks up tannic acid from decaying vegetation and turns the colour of strong tea or beer. This stained freshwater layer floats on top of the seawater in a permanent three-to-four-metre deep layer, and like a blanket spread

across the fiord it soaks up the sunlight. As light cannot penetrate very deep, many species usually found at much greater depths live within the first 40m. Below 40m, light levels drop quickly and life thins out. Dr Grange proposed that if the top 40m band contained the majority of life on the fiord rock walls, then a habitat area for the fiords could be calculated. Since the coastline of the fiords covers 948 kilometres and the gradient of these walls averages 45 degrees (it is often between 60 and 80 degrees), then, using simple maths, the habitat of the area is about 46 square kilometres. This is smaller than Wellington Harbour (87 km2) or Manukau Harbour (145 km2). Many rare, unknown and protected species about which little is known live in this small area. The largest black coral population in the world occurs in Fiordland (7.5 million colonies) and is accessible to scuba divers studying these fascinating organisms. Red corals, gorgonian fans, brachiopods, feather stars and sea pens can also be seen in this 40m band.

Species-rich area

The area supports more than 60 fish species and contains representatives from warm

water, cold water and deep water habitats. However, apart from their existence and basic biology, little is known about these creatures, their ecological relationship with other animals and their role in the marine environment. Some species have been studied elsewhere but, because the fiord environment is unique, comparisons with populations of different areas is very difficult. One species which has been extensively studied is black coral (Antipathes fiordensis). Dr Grange, who has studied the animal over many years, found that limited water exchange with the open coast and weak currents caused low levels of food supply and growth rates. An average growth rate of 2.5cm a year suggests some black coral trees could be older than 200 years. It is not unreasonable to assume that limited food supply will similarly affect other organisms of the fiord rock wall community. Considering the habitat size, it is easy to see that fiords are extremely vulnerable to fishing pressure and why in Easter last year only two blue cod were caught in Doubtful Sound. While the effects of single species extraction are obvious, there are also indirect effects on the environment caused by the removal of one species from the food chain and the complex web of species interactions. Fishermen working the open coast of Fiordland are noticing changes which may have been caused by the crayfishing boom of the 1970s. Some scientists believe the depletion of crayfish stocks caused a massive increase in kina, which are predated by crayfish. The large numbers of kina have munched their way through long-established seaweed beds, destroying the habitat for small fishes. Small fishes feed big fishes, so the effect of the extraction of one species may have had a dramatic effect on the whole coastal ecosystem. The latest commercial venture in the fiords the extraction of sea cucumbers has begun in the absence of knowledge about the animals’ lifestyle and role in the ecosystem. Fortunately last summer's operation ceased a quarter of the way through its permit to extract 73 tonnes of sea cucumbers.

These slug-like creatures, known to scientists as Stichopus mollis, are widespread throughout Fiordland, lying both on the mud and sandy sediments at the head of the fiords and clinging to the sheer rock walls. Their similarity to cucumbers is in their shape; in colour they range from greyish brown to black, providing excellent camouflage from potential predators. The cucumber’s mouth is surrounded by special sticky tentacles, which collect sediment lying on the rock walls and sea floor, and pass it into the mouth. As in our society, the cleaners while often underrated play an extremely important role. Many organisms which inhabit the fiords rely on a clean environment, with low levels of sedimentation.

Long-lasting effect

The extraction of this seemingly insignificant animal could have an important and longlasting effect on other animals of the fiords. While the cucumber's shape suggests that it remains lying in one place all day, closer observations have revealed that these creatures can often be found partially raised off the surface gently swaying back and forth in the current. The reason for such behaviour is unknown. Divers have also observed sea cucumbers practise a defence mechanism, known as auto-evisceration. This involves the organism "throwing up" its entire stomach, complete with sticky threads, in an attempt to put off any would-be attacker. Large sea cucumbers are common in many places but it is difficult to find many animals which are 8cm or less. Whether they are hiding in rock crevices or perhaps spend part of their lifecycle in another marine habitat, is also unknown. Sea cucumbers occur around the New Zealand coast, so given the special conditions of Fiordland, it needs to be asked whether this is an appropriate location for extraction. Kina appears to be the next species to be targetted in the sheltered waters of the fiords. The importance of the fiords’ 40m band goes beyond commercial extraction. This is an internationally recognised area which over the years has attracted many notable visitors, including Jacques Cousteau, National Geographic and Television New Zealand's Wild South.

Fiordland’s Underwater world...

Although the unique features and beauty of Fiordland’s underwater world are not as visible to tourists as Mitre Peak and Sutherland Falls, they are no less worthy of protection. TVNZ's Wild South fittingly called the fiords a "mirror world" of the region's forests, mountains and wildlife. The National Cancer Institute plans to research the potential of anti-cancer compounds contained in the marine organisms. As with rainforests, many of the organisms within the fiords may contain as-yet-undis-covered substances of use to medicine. The Department of Conservation believes that, like the land of Fiordland, the marine environment of the region is also worthy of protection. Fiordland is a great natural asset and one of the world’s special places. It deserves the greatest respect and protection. #&

Permissive conduct

A HE FIORDLAND SEA CUCUMBER case raises important questions about the role of special fishing permits. The Fisheries Act and the Marine Farming Act both have provisions for special permits.Originally special permits were designed to allow an applicant to Carry out research into fishing or farming specified species of fish or marine vegetation. Among the large number of permits issued to date have been some for paua harvesting at the Bounties and Antipodes Islands, seaweed cultivation in Northland, on the West Coast and at Kaikoura, and salmon farming in Big Glory Bay, Stewart Island and Akaroa Harbour. The latest to cause concern is a proposal to harvest the giant southern spider crab on the Pukaki Rise in subantarctic waters. The crustacean, with a span of about 2m, was fished by the Japanese 20 years ago but has not been touched since. Fisheries scientists are concerned that it would be very easy to overfish this species in a short period of time. So what are the concerns about special permits? @ There is.no requirement for an environmental impact assessment before the activity starts or approval is given. @ There is no opportunity for the public to have a say, in the same way they are invited to comment on ordinary marine farm licences, for example. © The permit can be issued in an area where certain fishing practices are banned under regulations or fisheries management plans. The Royal Forest and Bird Protection Society believes MAF are taking an irresponsible approach to the question of special permits. This is illustrated by the sea cucumber example. Any assessment of the sea cucumber fishery is likely to be highly speculative. A figure based simply on counting and measuring cucumbers from randomly selected sites at one time of the year will not take into account growth rate, breeding potential or seasonality. It certainly will not take into account the effect of the removal of this species on the rest of the fiord ecology. Another danger with special permits is that an entrepreneur may invest large sums in a venture, even though it may be environmentally unsound. It then becomes extremely difficult to prevent the practice when the proponent applies for a full licence. This area of fisheries is likely to come under intense debate in the coming review of the Fisheries Act. The fishing industry will want to widen the provisions for exploratory fishing or marine farming without public debate.