Fiordland’s Long Sound

By-Tony and Jenny Enderby

The dull green fresh water layer seems incredibly deep. My depth gauge, distorted by the oily effect of the fresh water, shows I am below eight metres. Somewhere down there it must be clearer. Then as if someone has lifted a curtain, I drop into the clearer and warmer salt water beneath the fresh water.

At 12 metres on the bottom I have my first surprise – dozens of really big scallops. They sit in grains of granite rock rather than sand. A blue cod arrives and for a moment attracts me away from the scallops. It sits and swivels its eyes, no doubt contemplating whether I have anything slightly edible amongst the gauges and straps hanging off me.

I ignore the blue cod and return to the scallops. The grains of rock they sit in average the size of a ten cent coin and don’t seem to be the right habitat for scallops.

A rocky reef appears out of the granite sea floor. It is covered in red corals. Their branches spread out like tiny sculptures and our lights bring out the brilliant red.

A little deeper, the orange fronds of a sea pen extend vertically from the gravel sea floor. It looks like the Victorian quill pen it was named for, apart from the colour. I become aware that it is not an orphan as there are dozens more sea pens spread out around it. They vary in height between 15 and 35 cm. At 15 metres depth they are the dominant organism on the bottom.

Our dive is in the Te Tapuwae O Hua Marine Reserve in Long Sound, Fiordland. The marine reserve is almost new, having been established in 2005, protecting the unique marine life for future generations. If any large scale dredging had taken place here the sea pens would have been long gone.

Most new marine reserves are created in areas where human interference has changed the marine ecosystems. This reserve is almost pristine, and at 3672 ha, is the largest in Fiordland. A group known as the Guardians of Fiordland was instrumental in increasing the number of marine reserves in Fiordland from two to 10. The group comprised of recreational and commercial fishermen, charter boat operators, Ngai Tahu who hold customary rights, community, environmental and marine science interests. Support also came from Environment Southland, the Ministry of Fisheries, the Department of Conservation and the Ministry for the Environment

The group looked at and improved the fisheries regulations covering unprotected parts of Fiordland. As well as marine reserves, some other special areas were identified as China Shops, having an abundance or diversity of animals or plants or an abundance of a particular species. To date 23 areas have been identified as significant and protected. Anchoring, cray potting, diver harvesting and dredging are all prohibited activities in the designated China Shops.

Fiordland’s underwater world was largely unknown until the 1970s. Divers working on the Manapouri Power Station tailrace in Doubtful Sound were the first to discover what lay beneath the discoloured surface water. Their stories of Fiordland’s underwater life began to draw other scuba divers.

The almost pristine habitats of Long Sound exist because of the fresh water layer from the huge rainfall that cascades into the fiords throughout Fiordland. The layer, created by fresh water stained by tannins from rotting vegetation, washes into the fiords and filters sunlight, darkening the world beneath. Known as deep-water emergence, this allows light-shunning creatures to live in comparatively shallow water. The layer of fresh water runs like a river across the warmer and denser salt water below it. The two layers remain separate until near the fiord entrances where wind, waves and ocean swells begin to mix the fresh and salt water.

A tug on a loose strap on my BCD is from the first of a few inquisitive blue cod that have turned up and begin to follow us. Why are fish more aggressive in marine reserves? It is hardly the thanks due to preserving their habitat. Some of the blue cod are big and aren’t scared at all. Their activity is attracting more fish, hopefully just to look.

Our dive plan in the Te Tapuwae O Hua Marine Reserve doesn’t include a feeding frenzy of blue cod. There are now dozens of them around us and schools of tarakihi and butterfly perch hover in the open. Above in the green fresh water layer, schools of telescope fish swirl about. Another rock looms covered with a wealth of invertebrate life including even more red corals. Several tiny black corals also sit on the walls of the rock and a white sea anemone glows on the side. Ascidians and sponges grow around the corals. Grazing tiger shells sit on the sponges and a huge trumpet shell sits in a crack.

The blue cod continue their harassment but for a little variety they have a nibble at some of the growth on the rocks.

On the other side of the rock a forest of tube worms extend their feather-like fronds. A small triplefin darts across and half the tube worms close instantly. My shadow must have crossed the other half as they have now closed too.

We move over the gravel again. Small movements as we pass are the scallops closing. There are hundreds of them. I place my hand with outstretched fingers across the shell of one. The scallop extends a centimetre or so out each side making it around 20 cm across. As soon as I move off, the first blue cod gives the scallop the once over, ensuring that the shells will stay shut for a little longer.

Our ascent is back through the fresh water. Somewhere in there are beds of strawberry ascidians, unique to this site. We are probably not going to see them due to the fresh water layer but rather than disappointment I’m surfacing elated at the amount of marine life I have seen. And of course the knowledge that hopefully once in the fresh water I will be safe from the blue cod.

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