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Striped marlin fisheries in New Zealand

Striped marlin are one of a range of large oceanic pelagic species caught by recreational and commercial fishers in New Zealand waters. Generally, striped marlin are most abundant in summer and autumn, and northern New Zealand has a long established recreational target fishery for striped marlin. The largest striped marlin caught on rod and reel all come from New Zealand waters. The International Game Fish Association keeps records and 16 of the 22 striped marlin line class world records are held by anglers in New Zealand, including all the heaviest fish caught on line from 6 kg to 60 kg breaking strain.

Funded by the Ministry of Fisheries
Researchers Blue Water Marine Research
Richard Keller Kopf

Scope of Project

A sport fishery developed in New Zealand targeting marlin and sharks in the 1920s. International tourists brought heavy tackle and new fishing methods that proved highly successful. The quality of the fishery was praised by best selling author of the time Zane Gray in his book ‘Tales of the Angler’s Eldorado, New Zealand’ and others. Fishing clubs were established, and they weighed and recorded each fish landed. Charter boats were responsible for most of the catch as they had the specialist tackle and experience. Today, many private boats from 5 to 30 m in length participate in the fishery, and there are about 80 charter boats that target striped marlin seasonally.

Gamefish club records provide an almost complete record of striped marlin catch throughout the history of the fishery. Since 1990, 60% of the recreational catch has been tagged and released with only estimated weights available for these fish. The expansion of the areas fished and the number of private fishing vessels targeting marlin has increased along with the proportion of the catch not recorded in club records in recent years.

Striped marlin have been tagged by recreational fishers and a few commercial fishers in New Zealand since 1975. The number of fish tagged and released has increased dramatically since the N.Z. Big Game Fishing Council introduced a voluntary minimum weight of 90 kg for landed striped marlin in 1988. There are about 3 or 4 tagged striped marlin recaptured per year and these have been distributed widely throughout northern New Zealand and the sub-tropical southwest Pacific Ocean, but not beyond.

Results

Surface longlining is the main commercial method that catches striped marlin. The Japanese longline fleet moved into the South Pacific in the early 1950s and fishing effort expanded rapidly. Commercial reporting of surface longline landings on New Zealand forms became mandatory in 1980. Since October 1987, commercial fishers have been required to release all marlin (dead or alive), and since that time the number of marlin caught on commercial vessels has not been reliably captured on tuna longline catch and effort reports (TLCERs). Scientific observers record all fish caught and released, but historically observer coverage has been poor in the areas and season when striped marlin are caught. In the wider Pacific, striped marlin is mainly a bycatch, though occasionally a target species, for surface longline vessels and the annual catch is estimated at 15,000 t across the whole Pacific.

marlin-catch-rate

New Zealand commercial catches of striped marlin since 1980 peaked in the 1981–82 fishing year (October to September) with 2,843 fish, mainly taken by Japanese surface longline vessels. Catch declined with fishing effort and the moratorium on billfish during the late 1980s and early 1990s. The New Zealand domestic fleet developed in the mid to late 1990s and reported the highest striped marlin bycatch in 1998–99 with 1613 fish (Table 1).

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