Keeping within environmental limits

Children born in 2006 will be starting to plan for their future by 2020. What kind of world will they inherit? Globally, the omens do not look good. Everywhere, there are signs of the environment's limits being stretched. The global fish catch has now reached the limits of ocean productivity. At the same time, some marine ecosystems and habitats are damaged or destroyed by fishing and pollution.

Our oceans and their ecosystems are hugely complex, and we struggle to understand a tiny fraction of them. So it is understandable for the government to be cautious when it sets catch limits for fisheries.

Caution is also needed when dealing with the effects of fishing on threatened seabirds and marine mammals, or on habitats and ecosystems.

To get better at managing such things, we must learn more about the marine life in our seas. We need to know more about how these ecosystems function, and also what effects fishing, pollution from the land, or changes in ocean and weather patterns have on them.

When setting limits around the effects of fishing, three questions are asked: Can the environment handle the effects? What does society think about the effects? And what are we leaving for future generations? To answer the first question, the Ministry of Fisheries' science group draws mainly on the work of scientists from research agencies like the National Institute for Water and Atmospheric Research (NIWA).

Answering the other questions involves a wider range of people, including government agencies like the Department of Conservation, tangata whenua, environmental interest groups, recreational fishers, and fishing companies. Together, we are making progress in many areas.

The government and industry are working to reduce seabird deaths in our fisheries. As a result, we have seen huge drops in seabird deaths in the joint-venture tuna and ling auto-line fisheries. We expect to soon see a drop in seabird deaths in our squid and hoki fisheries, as a result of recent government/industry initiatives to keep seabirds away from the sterns of trawlers, where their trawl warps enter the water.

Recent laws have also closed parts of the North Island's west coast to set netting, in places where the endangered Maui's dolphin is found. The government is now working to stop deaths of its South Island relative - Hector's dolphin - in fisheries there.

Recently there has been growing concern about the effects of bottom fishing on seafloor habitats. Fragile bryozoan beds on the sea floor in Tasman Bay and Spirits Bay have already been closed to bottom fishing, as have 19 deep-water seamounts. The government is now looking at the effects of bottom fishing on other habitat types.

Many other types of human activities can potentially damage the marine environment. One of the greatest threats to near-shore fisheries is runoff from the land. This includes sediment and nutrients being carried down rivers from farmland, forestry and other land development. In some coastal areas, these effects may be greater than the effects of fishing.

Another potential threat to our marine environment is the introduction and spread of marine pests, like the seaweed undaria and the clubbed tunicate sea squirt.