Species Focus - Kahawai (Arripis trutta and A. xylabion)
Kahawai is a particularly important fishery to recreational and Maori customary fishers; it is also caught by commercial fishers. Kahawai is part of a suite of fish that make up the "catch plans" of purse seine vessels in New Zealand waters.
Most kahawai caught by non-commercial fishers are taken using set nets or lines. Most kahawai caught commercially is taken using purse-seine nets, with smaller amounts being caught in commercial trawl and set net fisheries.
Commercial fishers began targeting kahawai in the 1980s. Commercial catches peaked in 1987-88 at around 9600 tonnes. In 1991, commercial catch limits were set for kahawai targeted using purse seine nets.
Management of kahawai fisheries is causing some controversy. Recreational fishers say the numbers and size of kahawai they are catching have declined markedly, as a result of commercial purse seine fishing.
Commercial fishers say that recent catches are at sustainable levels.
Status of the stocks
Stock assessment work done in the mid-1990s suggested that kahawai stocks then were above a level that would support Maximum Sustainable Yield (MSY). Though these estimates are uncertain and depend on key assumptions, they are thought to be conservative. However, we have no more recent stock assessment than this.
Because of this uncertainty over stock size, catch limits and allowances were set cautiously - at around 7600 tonnes (around 15 percent less than recent catches had been) - when kahawai was brought into the quota system in 2004.
Kahawai catch levels were reviewed in 2005. It was assumed that the kahawai stocks would increase in size under the catch and allocation levels set in 2004. However, the government wanted to be more certain that stock size would increase, so it reduced the catch levels and allowances by a further 10 percent.
We need more information on kahawai stocks, and recreational catches of this fish. The current research programme for kahawai should provide a new stock assessment in 2007.
Until then, there remains uncertainty as to where current kahawai catch levels are in relation to the level that would support MSY. So we do not know whether the current catch limits and allowances are sustainable
Current management issues
A key issue at the moment is how to manage the fishery in a way that takes the needs of non-commercial and commercial fishers into account.
Commercial fishers want kahawai stocks managed at the level of MSY, so they can catch the greatest amount of fish, year after year in a way that is sustainable.
However, recreational fishers want kahawai to be more abundant, and for bigger fish to be easier to catch.
One way to do this would be to leave more fish in the sea. However this could mean that less fish could be taken each year.
Kahawai catch limits and allowances
The catch limits and allowances for kahawai have been set at 6,834 tonnes for the 2005/06 fishing year.
Of this, the government has allowed 3,984 tonnes to cover the combined recreational and customary catch. It has also allowed 135 tonnes to cover things like accidental wastage during fishing. Commercial fishers have been allocated 2,728 tonnes.
At present there is no minimum legal size limit for kahawai taken recreationally. Up to 20 kahawai per day can be taken by recreational fishers within the mixed bag limit of 20 fish per person per day (except in the Southern Fishery Management Areas, where the daily limit is 15).
A range of commercial rules apply to kahawai, including catch limits and a voluntary fishing season. There are also voluntary commercial purse-seine fishing closures across a range of inshore areas from Northland to Kaikoura, including the Hauraki Gulf.