| Hāpuku | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Perciformes |
| Family: | Polyprionidae |
| Genus: | Polyprion |
| Species: | P. oxygeneios |
| Binomial name | |
| Polyprion oxygeneios (Schneider & Forster, 1801) |
|
The hāpuku, hapuka or whapuku, Polyprion oxygeneios, is a wreckfish of the family Polyprionidae, found around southern Australia, Chile, Tristan da Cunha, and New Zealand at depths of between 30 and 800 m. Its length is between 60 and 180 cm, and it can weigh up to 100 kg.
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Hāpuku are grey in colour with a silvery white underbelly with juveniles generally being blue in colour. They have ten dorsal spines running along their back, rounded anal fin and pectoral fin, and have a large powerful square shaped tail. Its lower jaw protrudes from the top, and has very large eyes which are adapted for hunting and inhabiting low light conditions.[1][2]
Juveniles are thought to be pelagic, switching to demersal when they are approximately 50 cm in length. They inhabit temperate and subtropical waters of the southern Indian Ocean and Pacific Ocean, being found in Chile, south eastern Australia and New Zealand. They can be found in waters from anywhere between 10m – 800m, but generally prefer deeper waters greater than 50m. They are usually found living in cracks, caverns or caves when found in shallow waters. They are voracious predators feeding on a large range of other fish species, invertebrates and crustaceans, including red cod and blue cod, hoki, crabs and crayfish.[1][3][4][5]
Hāpuku are a large, slow growing, long-lived species. They reach sexual maturity between 10–13 years and have a life span of up to 60 years. They can grow as large as 100 kg, but are usually found around the 25 kg mark. They have an average size of 80–100 cm but can grow up to 180 cm in length.[3]
Hāpuku are a highly rated eating fish, reaching top dollar on both the local and international market. Chefs that have tasted farmed hāpuku have stated that it out performs wild-caught hāpuku.[1][6]
In New Zealand for the year of 2008, hāpuku had a commercial value of NZ$37m with an export value of NZ$4.29m at a price of NZ$10.29 per kg. Hāpuku is a species that is fished both commercially and recreationally in New Zealand. It is highly sought after but catches are relatively low, and is a species that is managed in the New Zealand Quota Management System (QMS). There is currently no size restriction in New Zealand but there is a bag limit of 5 individuals per day.[7]
There has been significant interest globally for development of this species for aquaculture. In Europe, a very similar species of wreckfish is highly prized and considered a local delicacy. Because of this, the Polyprion spp. have been overfished in most areas. Its premium market position, high value, and limited supply have created a lot of interest for this species in the aquaculture sector. In New Zealand, National Institute of Water and Atmospheric Research (NIWA) have embraced hāpuku as an opportunity for New Zealand to expand and have identified markets for this species locally in New Zealand and Australia and internationally in Europe and Asia.[8]
Since 2003, NIWA has accumulated the world’s largest broodstock resource for hāpuku and these broodstocks are held in large spawning tanks at Bream Bay Aquaculture Park. Each tank has its own controlled environment which is designed to maintain the optimum temperature and light for natural spawning. NIWA have now progressed through every aspect of hatchery technology development for hapuku. The complications that have been encountered in this process were similar to those of other commercialised finfish species such as halibut, turbot, sea bass, and sea bream. These complications were overcome with specific solutions developed for the early rearing of hapuku. The main technical complications that have been overcome are:
• The system design for the successful incubation of egg and yolk-sac larvae.
• Initiation of first feeding.
• The transition from live feed to formulated feeds to produce weaned juveniles ready for on-growing and transfer to sea cages.
Currently the sea cage trials and tank trials are base-lining the performance for hāpuku. These early on-growing trials and results are revealing that there is considerable growth potential in aquaculture for this species.
NIWA has been running a broodstock selection programme (which has been running since 2007), and the results are showing which broodstock are producing the surviving first generation. With this information, it will soon be possible to start selecting desirable performance traits for the breeding programme. NIWA’s aim is to maintain the competitive edge for hāpuku farming as it increases, and become an important species for New Zealand’s aquaculture sector.[8]