Species Focus - Southern Blue Whiting (Micromesistius australis)

Approximately one third of the southern blue whiting catch is made into surimi (a processed fish product that imitates other seafood, particularly crab), while the remaining two thirds is processed into higher value fillet.

Approximately 20,000 to 30,000 tonnes of southern blue whiting is caught each year and it is an important catch for the middle depths trawl fleet.

Vessels target southern blue whiting in late winter to early spring, when the fish group together, or aggregate to spawn. There are four distinct spawning areas in New Zealand’s sub-Antarctic waters: the Auckland Islands, the Bounty Islands, Campbell Island and the Pukaki Rise. Each is managed as a separate stock.

Southern blue whiting are fast growing and typically spawn for the first time when they are three to four years old. Varying numbers of young southern blue whiting join the spawning aggregations each year. Stock size can change quickly if a large number of young fish reach adulthood in the same year.

To manage the southern blue whiting fishery well biological data from the fishery, and acoustic surveys to measure stock size, are important. This information is used to determine how much fish can be caught without threatening the sustainability of each of the stocks.

Southern blue whiting distribution and management areas.
(SBW6A – Auckland Islands, SBW6I – Campbell Island, SBW6B – Bounty Island, SBW6R – Putaki Rise).

Status of the fish stocks

A large portion of the southern blue whiting caught over the last decade has come from the Campbell Island stock. This has been the largest southern blue whiting stock, mainly because of very successful spawning in 1991 and above average success in 2001, 2002 and 2004. The size of the Campbell Island population is close to the target level and is expected to be maintained at this level over the next few years.

In 2008 an acoustic survey was conducted for the Bounty Islands stock. Echo sounders, used to determine how much southern blue whiting there is in the area, found that the population size had increased markedly from previous surveys. This is thanks to a very successful spawning in 2002.

Southern blue whiting around the Auckland Islands and on the Pukaki Rise fisheries are lightly fished and catch has not exceeded 20 percent of the total allowable catch of either of these fisheries in recent years.

Current management issues

The large increase in the amount of fish around the Bounty Islands has resulted in an increase in TAC. Further acoustic surveys will be undertaken to better determine the amount of southern blue whiting present in the stock.

The number of New Zealand sea lions captured in the southern blue whiting fisheries has increased in recent years with six recorded captures in the 2007/08 fishing year. Commercial fishers have adopted a voluntary code of practice to help avoid sea lion captures. Captures of marine mammals in general will also continue to be monitored.

A fishery plan for southern blue whiting is being developed and will help with future management decisions. The Bounty Islands acoustic survey was performed by a commercial fishing vessel rather than a dedicated research vessel. Using vessels that are involved directly in the southern blue whiting fisheries means significant savings in cost and resources.