Bluenose

Antarctic butterfish, bluenose seabass, Antarctic cutlerfish, bluenose, stone eye, blue bream, blue-eye trevalla, bluenose warehou, trevalla, bonita, big-eye, blue eye cod, Griffins silverfish, deep-sea trevalla, deep sea trevally, sea trevally

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The Bluenose fishery is primarily fished in New Zealand and Australia within their respective Exclusive Economic Zones, and is considered a relatively new fishery. Bluenose is found throughout the southern Pacific and Indian Oceans, along continental slopes and on offshore seamounts. The Australian fishery ranges from central New South Wales to southern Western Australia. Life history parameters for bluenose have undergone major revisions within the last 5 years, and current estimates have nearly doubled the maximum age up to 50-60 years.

Recent recalculations of age based on bomb carbon have greatly increased the estimated maximum age of bluenose. The readjustment of the maximum age and recalculation of size at age have led to higher estimates of age at maturity. The new growth and aging parameters are of moderate to high conservation concern individually. Overall, based on a maximum age of more than 25 years, the overall inherent vulnerability is a moderate conservation concern, although it is just on the cusp of a high conservation concern. Finally the high levels of immature fish caught in the fishery as a result of migrations and schooling behaviors raises concern about the sustainability of the fishery. These areas of moderate concern combined with areas of low concern such as fecundity and range give bluenose a moderate inherent vulnerability ranking.

While fishery-dependent data on bluenose landings and CPUE show that the populations have remained relatively stable, there has not been a quantitative stock assessment for bluenose in New Zealand or Australia. Thus, population biomass is unknown, making accurate estimates of MSY impossible. However, the general thought is that the New Zealand stocks are healthy and above BMSY, while Australia’s stocks are fully fished. TACs/TACCs have worked well in ensuring a consistent catch and CPUE since the fishery expanded in 1989-1990, indicating that the stock is most likely above the target population size. However, due to the number of uncertainties and the lack of a quantitative stock assessment, the status of wild stocks ranks as a moderate conservation concern.

While incidental catch of finfish in the dropline fishery exceeds 100% of bluenose landed, the catch is counted against the allowable catch for the caught species and is not discarded. A predictable assemblage of finfish bycatch in the bluenose targeted fishery and in the fisheries where bluenose is bycatch has led to a rigorous management plan to ensure that bycatch is accounted for. There is concern about bycatch of benthic organisms in the bottom trawl fishery, but as this is a very small fraction of bluenose catch in a non-target fishery the threat is very low. Seabird bycatch is a concern in all bottom longline fisheries; however, both the Australian and New Zealand governments have taken an active role in reducing bycatch, and methods to reduce bycatch are incorporated in the fisheries’ management plans.

Habitat and ecosystem impacts are by far the greatest in the bottom trawl fishery, in which bluenose is taken as bycatch. The deepwater corals found on the deep sea fishing grounds where bluenose are caught are susceptible to damage by trawl gear and are slow to re-grow once damaged or removed. The effects of deepwater trawling are thus a high conservation concern.

The lack of a quantitative stock assessment in both New Zealand and Australia is a moderate concern with regard to the sustainable management of the bluenose stock. Both Australia and New Zealand admit that, while landings seem to be stable, catch limits may or may not be set at a sustainable level. The effectiveness of the management regime ranking of “moderate” is thus based primarily on the lack of a quantitative stock assessment. There are other management concerns as well. The high amount of bluenose bycatch in other fisheries has led to overcatch of the allowable catch. This has largely been controlled recently, but control measures have focused primarily on accommodating the catch limits, rather than reducing bycatch.

How was this Bluenose caught?

While all bluenose from Australia and New Zealand ranks as “some concerns” there is a lesser impact on the marine habitat with midwater trawls and setlines.

No health advisory at this time

No.