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Great Barrier Island Marine Reserve - One Step Closer

The large marine reserve proposed for the northeast side of Great Barrier Island came one step closer to reality on 16 June with the announcement that the Minister of Conservation, Chris Carter, has put his stamp of approval on the application.

Now we await concurrence from the Minister of Fisheries, David Benson-Pope, and the long process of recovery of the marine life in the area can begin. Once gazetted, this marine reserve will be the third largest in New Zealand, and at 49,500 hectares will be by far the largest close to the mainland.

Near the middle of the proposed reserve, Whangapoua Estuary and an area off Whangapoua Beach have been left out of the reserve. This is in recognition of the importance of the estuary as a shellfish harvesting site for the local people. The area off the beach is also excluded as an important sustenance fishing area for local residents.

It is intended, however, that a local community fisheries plan of some sort, yet to be decided, will be established to control fishing in this area. Afterall, within a few years the fishing in this area would become extremely good, and without further control unfortunately could act as a "sink" from which fish are removed at the expense of the surrounding marine reserve. That is what happened at the Poor Knights Islands for many years, where recreational fishing around much of the Poor Knights prevented full recovery of the fish stocks in the totally protected parts of the reserve. This situation was finally corrected when all fishing was stopped at the Poor Knights in 1998, after which snapper populations exploded spectacularly, and the rest of the marine life could progress towards "naturalness".

The site of the Great Barrier (Aotea) Marine Reserve is relatively close to Auckland, and within a few years time will provide a spectacular example of the positive results of timely and sensible marine conservation.

Because the proposed reserve is so large, it will show us a lot of surprises - things which have not happened in smaller marine reserves around NZ. I am particularly looking forward to seeing any increase in packhorse crayfish and hapuku. Those two species in my view need a complete rest from fishing - their quota generally should be set at zero. But the Aotea Marine Reserve may be big enough and in the right place to make a difference, at least locally, for these two seriously depleted species. The habitat for both is ideal, and historically they were common in the area. If a marine reserve is ever going to make a difference to these species, this reserve will be the one.

I think we can confidently predict that red crayfish, snapper, and probably kingfish numbers will increase spectacularly in the Aotea Marine Reserve. And of course there will be many less-spectacular but nevertheless important gains for marine biodiversity in the area. Deep reefs offshore, for example, support large old black coral "trees" and massive deepwater glass sponges hundreds of years old. Fishing has already been shown to cause damage to these deep reef communities, and the "no fishing" policy in the marine reserve will prevent long lines, drop lines, nets and pots from further damaging the rich life of these reefs.

New Zealand has a history of commercial and recreational fishing which has left no stone unturned. There is nowhere in our seas that has not been affected by fishing. In SNA1, which is the snapper fishery from North Cape to East Cape, with Great Barrier Island near the middle, the snapper population has been reduced to only 16% of its original biomass. Marine reserves allow the marine life in a few areas to bounce back from many decades of industrial-scale fishing, and gradually become closer to what was natural before humans came here.

Marine Reserves are equivalent to National Parks on land, where native fauna and flora have somewhere safe to live their lives without serious interference from humans. They are sanctuaries in the sea where all fishing, dumping, dredging, and building of structures is prohibited. Without such interference, the fish and other life can go about their business and recover to their natural abundance and population structure, and thereafter maintain a healthy natural balance, with numerous large individuals which are the best breeders and probably have important social roles within the population. Only with total protection do they get a chance to grow old and big - pretty logical really when you think about it.

None of this is possible outside no-take sanctuaries, because Government fisheries policy and fishing management practices have deliberately exterminated about 80% of the population of each commercially important fish. Furthermore, fisheries policy dictates that the populations will not be allowed to recover to more than 20% of their original size. If this happened, commercial quotas would be raised to take advantage of what would be considered excess capacity in the fishery. That is how the Quota Management System (QMS) works in order to achieve maximum sustainable yield (MSY).

You don't need to be a scientist to understand that if you take 80% of the top predators out of the system then that will have serious consequences on the rest of the food chain and ecology. Although the concept of MSY may seem to work for single species management, it takes no account of its "sustainability" in terms of impacts on the rest of the ecology. So even "legitimate" fishing has serious impacts on the rest of the ocean system.

According to Ministry of Fisheries figures, currently red crayfish numbers are very low in the greater Hauraki Gulf area (specifically CRA1 and CRA2), and the total allowable commercial catches are not being landed. They have effectively been "overfished", and quota cuts are needed to try to encourage the population to climb back up to the target biomass (BMSY). This could take several years.

Within the first five years after establishment of the no-take marine reserve at Great Barrier Island, we can expect to see a massive increase in red crayfish numbers, despite their present serious depletion. This has occurred at most other marine reserves where crayfish habitat is available.

Not only crayfish numbers, but also their sizes, will increase for many years, and will result in the release of huge numbers of crayfish larvae from the large population of big crayfish which will establish there. These larvae will have the potential to boost crayfish numbers in other areas where crayfish have been depleted.

No doubt some fishermen will not be happy about the Minister's decision on this marine reserve. A national target of 10% of the territorial sea has been proposed to effectively protect marine biodiversity. The exact figure is not important, but I fail to see how fishermen can justify fishing in nearly ALL of NZ's ocean.

Surely the marine life has rights too. They need somewhere to live in peace, re-establish their natural behaviour and population structure which has been knocked to bits, and exist without prospect of being untimely ripped from their ocean home.

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1. Outline map of the proposed Great Barrier (Aotea) Marine Reserve, recently approved by the Minister of Conservation. Note area excluded at Whangapoua Beach and Estuary.

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2. The Whangapoua Estuary was excluded from the marine reserve because of its importance as a shellfish harvesting area for the local people.

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3. Beds of pipis in the estuary channel, and extensive cockle beds on the sand flats, are the only good shellfish resources on the island.

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4. Hapuku used to be common on deep reefs within the proposed marine reserve. The Aotea Marine Reserve has a good chance to foster a recovery of this seriously depleted species.

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5. Large old black coral trees are common on deep reefs in the proposed marine reserve.

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6. Large deepwater glass sponges, some hundreds of years old, are found on reefs over 70 metres deep in the proposed marine reserve.

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7. In northeastern New Zealand the snapper population has been reduced to only 16% of its original biomass. Within the marine reserve snapper will recover from many decades of industrial-scale fishing, eventually reaching a population density and size structure close to that of the original population.

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8. Surely the fish have rights too. They need somewhere safe to live. Marine reserves provide that opportunity.

 

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