Nearly all New Zealand’s fisheries are managed through a system of catch limits and quotas that lets us fish, year after year, in a sustainable way.
The Government sets target levels for each management grouping of a particular fish species. These groupings are called fish ‘stocks’. And the targets are set at a point where the stock should produce its greatest weight of fish, year after year, in a sustainable way.
Because we can never count all the fish in the ocean, this theoretical point of ‘Maximum Sustainable Yield’ must be estimated for each stock. The estimate is based around how quickly a species grows and reproduces, and how long it lives.
It is fine for a fishery to fluctuate around its target level. However, the government has set limits around how far things can go before a fishery must be rebuilt, or the Government considers closing it. These are set out in the Harvest Strategy Standard.
To manage a fishery around a specified target like this, you need a lot of good information. Scientists use this information to work out how a fish stock is performing relative to its target.
In the past some of our fish stocks have been over-fished. With only four million people, and the fourth largest EEZ in the world, New Zealand simply can’t afford the science needed to manage all fisheries exactly at their target level.
So the government prioritises spending on fisheries data collection, monitoring and stock assessment to focus on stocks with the highest landings or greatest importance, or those considered most at risk of being unsustainable.
Where there is little information, it is hard to gauge how close a stock is to its target level. So the Government must act cautiously, and set the catch at what it thinks is a safe level. Fisheries managers advise the Government, based on the results of Science and Monitoring programmes.
In 2008, New Zealand had enough information to know the status of a stock relative to its target level for 101 of the 629 fish stocks in the Quota Management System. These 101 stocks account for around 90% of the total allowable catch in any fishing year.