We have all the heads and lengths we need for a solid analysis of yellowtail kingfish growth and mortality rates. Also enough to compare growth rates between east Northland/Hauraki Gulf and Bay of Plenty. Thanks for everyone who has contributed and to those who supported the project.
In all, recreational fishers have supplied measurements for 2072 kingfish and 476 heads for otolith extraction. If you have any tag cards or data sheets please post them in and we will add them to the database. Ageing work will get underway in the New Year and has to fit around existing NIWA commitments.
Congratulations John Baker
At the start of the year we said that a lucky draw would be made from participants - the prize being a Duel 20 Speedy reel. Congratulations to John Baker for winning the draw.
Long term recaptures will assist kingfish aging
We have the otoliths from a kingfish caught at the Volkner Rocks on Pursuit that was measured and tagged 10 years 11 months before recapture. The fish was 83 cm and about 7 kg on release and measured 129 cm and weighed 29 kg on recapture.
Another fish recaptured at White Island on Cascade was at liberty for 8 years 2 months and otoliths kept for aging. This fish was 125 cm and about 26 kg on release and measured 134.5 cm on recapture.
As fish get older their annual growth slows and the growth rings used for aging get jammed tightly together. We can’t be sure how old the fish was on release but long term recaptures help support the aging process.
If in the next couple of months you recapture a kingfish with a tag number less than G 100,000 Please measure accurately and keep the head then contact us and we will arrange pick up. It would make a nice addition to the project.
Catch by length and area
Below we compare the percentage of each 1 cm length class between the two main areas in Kingfish area 1. This area excludes the Three Kings and Ranfurly Banks. The proportion of catch is very similar for lengths between 86 cm and 107 cm. Larger fish tend to be a higher proportion of catch on the Bay of Plenty. Many of these fish were caught at White Island.
Thanks for everyones efforts
The project moves into the aging and analysis phase. We will keep you informed with further newsletters as the project progresses. Please send any existing data sheets and equipment by post to:
Blue Water Marine Research, PO Box 402081, Tutukaka, 0153