Managing our catch

Setting catch levels

It's almost 20 years since New Zealand bought in a quota system for managing its commercial fisheries.

Almost all the major commercial species are now included in this system.

They are managed in a way that lets us catch the greatest weight of fish, year after year, in a sustainable way. This is called managing for Maximum Sustainable Yield (MSY).

Managing for MSY means finding the delicate balance between taking what we"d like now, and leaving enough in the water to grow and breed for the future.

However, we need a lot of information to get this balance right. Ideally, we need to know what proportion of each fish stock is being caught each year. Knowing how quickly different species grow and reproduce, and how long they live, helps us work out sustainable catch levels. These levels are then adjusted, as more information on catches and abundance is gathered.

Commercial fishers must report their catches to the Ministry of Fisheries. This information can be used to work out trends in catch rates, and in some cases gives an idea of abundance. When there are more fish around, people usually find it easier to catch the same amount of fish from one year to the next.

When there are fewer fish, it is usually harder to catch that same amount.

Knowing the catch rates and the size and age of fish caught is often enough to tell us how sustainable a particular catch level is. So in most important fisheries, we also gather information about length and age of fish caught. Some of this comes from Ministry of Fisheries" observers on board fishing vessels; some is gathered by the industry's own research programmes.

Where even more detailed information is needed, this can be collected through surveys by research vessels or tagging studies. However, these methods tend to be used only in our more valuable fisheries.

Where we have little information, it is hard to gauge how close a fish stock is to our target level. In these cases, the government must act cautiously, and set the catch at what it thinks is a safe level.

However, sometimes when we have little information the government may arrange to raise commercial catch levels slightly for a time, if quota owners agree to gather extra catch/effort data. Once this is analysed, the government decides whether to keep catches at the new level, increase them further, or reduce them.

Recreational fishers sometimes want different things from a fishery than commercial fishers. Particularly, they often want to be able to catch larger fish more easily. This may mean reducing catches to below the MSY level, so that more fish can grow larger. However, lowering catch limits simply for the sake of catching bigger fish might not be what commercial fishers want.

When catch levels need adjusting, the government seeks advice from Ministry of Fisheries" scientists and managers, as well as from commercial and non-commercial fishers, environmental interests, and the wider public.

Fisheries management in New Zealand is certainly not perfect. Some of our fish stocks have been over- fished. With only four million people, and the fourth largest exclusive economic zone in the world, we simply can't afford the science needed to manage all fisheries exactly at their Maximum Sustainable Yield.

The government must be cautious whenever it sets catch limits for fisheries, so that New Zealand's fisheries will continue to provide food and jobs for future generations.