Keeping tabs on giant tuna

During 2009 the Ministry of Fisheries will again be monitoring the Pacific bluefin tuna fishery off the West Coast.

The giants of the tuna world - which can grow to 350 kilograms or more - are the subject of a three-pronged research effort to help New Zealand to make the best possible management decisions.

• Since 2007, charter boat operators chasing Pacific bluefin off the West Coast over the winter have been voluntarily recording the number and weight of fish their anglers catch and land. The system complements the New Zealand Cooperative Tagging programme.
• The New Zealand Cooperative Tagging Programme is a cooperative project between the Ministry of Fisheries, the New Zealand Big Game Fishing Council and the most important constituent those anglers that tag and release gamefish. Recaptures provide information on movement, time at liberty, displacement rates, and growth rates. More importantly the programme encourages a conservation ethic that is particularly applicable to Pacific bluefin.
• Meanwhile scientists have been tracking the movements of some individual Pacific bluefin by satellite as they migrate vast distances around the Pacific. Researchers planted hi-tech tags on 23 fish over the winter of 2008. The devices can collect and store months of data on location, depth, water and body temperature before they pop off and rise to the surface to beam it to researchers. The Ministry of Fisheries is among the sponsors of this project.

Pacific bluefin tuna are managed under the Quota Management System—with one tonne of the Total Allowable Catch of 120 tonnes reserved for recreational fishers – a figure set before the rapid development of the West Coast recreational fishery. Given the size of the species, this means the allowance is currently only made for recreational catches of three to four fish in total.

Nevertheless the Ministry believes the total commercial and recreational catch in New Zealand is still within sustainable limits. This is because New Zealand landings are well below the Total Allowable Catch, catches are a small proportion of the international take, and the fish caught are large adults. Nevertheless it’s realistic to expect international moves to limit fishing, and the better New Zealand is able to document its interest, the better able it will be to offer constructive solutions to sustain the fishery.

For game fishers this is a large and powerful fish, and the chase and capture often a once in a lifetime achievement. But fish that are tagged and released confer the same bragging rights as landed fish and the fish may return and provide the same opportunity for other anglers.

Retaining fish can be wasteful and is often in quantities well in excess of the anglers needs or ability to consume. Because the flesh of fish caught during the season when the recreational fishery occurs is of poor quality, it’s really only good for smoking.

So tagging and releasing is something the Ministry wants to encourage with the added bonus that recaptures will add to our knowledge. This programme ultimately depends on anglers sending in Gamefish Tag Reports to record the fish they tag and release.

Recording catches on the voluntary reporting form reinforces the charter boat industry, and Government interest in making a long term management commitment to bluefin tuna. Game fish landings records are important for documenting New Zealand’s ability to monitor its bluefin fishery prior to more active international management controls. These assist in achieving an objective to develop a viable and sustainable world class game fishery for bluefin tuna in New Zealand waters.

Charter vessel operators are encouraged to download and fill out a voluntary reporting form.

 Download a copy of the Voluntary Reporting Form (PDF 97KB)

Please send completed forms to:
MFish, PO Box 19747, Auckland or email: graeme.mcgregor@fish.govt.nz, or phone 09 820 7689 or fax 09 820 1980.

Results to date

Background

Meetings held in Auckland and Westport during August 2008 have set the scene to improve the monitoring of bluefin catches

 Download report of meeting (PDF 83KB)

At West Port Charter boat operators agreed to furnish records of landed (retained fish) on forms to be circulated by the Ministry of Fisheries. The Ministry will estimate released fish from Gamefish Tag Reports.

 Download 2008 letter to monitor bluefin catches (PDF 56KB)

This letter was sent to those charter operators planning to fish the West Coast bluefin tuna season during the winter of 2007 (also published in the September/October 2007 edition of New Zealand Professional Skipper magazine - the official journal of the maritime transport industry).

 Download Pro-Skipper Letter 1 (PDF 38KB)

This article describes the differences between the bluefin species, how they breed and live and early results of the monitoring programme (also published in the November/December 2007 edition of New Zealand Professional Skipper magazine).

 Download Pro-Skipper Letter 2 (PDF 101KB)

This article describes tagging studies on Pacific bluefin tuna and the nature of the New Zealand ‘stock’.

 Download Pacific Bluefin Tuna Extract (PDF 59KB)

This article describes the management of Southern bluefin tuna in a New Zealand context.

 Download Southern Bluefin Tuna Extract (PDF 42KB)