Enhancing reefs with juvenile lobsters
NIWA training for aquaculture
Tracking blue cod in Fiordland
What's best for mussels?
A helping hand from Australia
Hunting hoki in Cook Strait: the 2002 winter survey
Fishing stunted paua stocks
Enhancing paua fisheries
Foveaux Strait oyster update
Chasing southern blue whiting in the south
The aquaculture industry is growing faster in Australia than in most countries in the world. Andrew Jeffs went across to find out why.
Australia’s aquaculture industry produced over 30 000 t of seafood and products valued at over A$680 million in 2000. Over the last decade, the industry has grown in value by a compounding average of 16% a year, keeping well ahead of the global average. Forecasts for production are for continued growth, with a projected value of A$1.4 billion by 2005 and A$2.5 billion in annual sales by 2010.
Details of relative abundance and movement rates of blue cod in Fiordland are important to determine the best scale for management of this species. Blue cod are susceptible to localised depletion, and small-scale management may be needed in areas of high fishing pressure.
The Guardians of Fiordland’s Fisheries believe that Milford Sound, one of two access points for fishers visiting Fiordland, no longer supports a blue cod fishery of the quality formerly offered.
Paua stocks around Stewart Island have declined over the last 10 years, and this has led to reductions in the allowable commercial catch for the area. Innovative, industry-led initiatives are aiming to provide solutions to help rebuild these stocks.
The New Zealand Paua Management Company (NZPMC) and NIWA have recently implemented a programme aimed at increasing the productivity of the Stewart Island paua fishery. The work, jointly funded by the Foundation for Science, Research and Technology and the NZPMC, will evaluate three management strategies.
Voyage leader Richard O’Driscoll expressed considerable satisfaction with the cooperation of the weather and the acoustic survey equipment in reaching a successful conclusion to the 2002 winter survey of hoki in Cook Strait.
Echogram of hoki schools and spiny dogfish in Cook Strait Canyon, 16 August 2002.
A number of acoustic surveys of spawning hoki in Cook Strait have provided relative abundance indices for input to the stock assessment process.
Mussel growth and condition rely on the availability of naturally occurring food, mainly phytoplankton. In the Marlborough Sounds, the main mussel farming area, diatoms and flagellates are the most important food organisms for mussels, but the composition of the phytoplankton biomass is highly variable. There is, therefore, potential for great variability in growth and condition of mussels.
The Bonamia outbreak between 1986 and 1992 reduced the Foveaux Strait oyster population to about 9% of its earlier size. Subsequently, the oyster population in the Strait continued to build.
Oyster density in October 1999 (top), and regions where there was recent evidence of high oyster mortality (bottom).
The presence of Bonamia exitiosus in samples of oysters in early 2000 indicated the preliminary stages of another epizootic.
The Fisheries Research & Development Corporation of Australia is currently funding a joint NIWA and University of Tasmania project to explore the feasibility of reseeding juvenile lobsters in Tasmania and New Zealand.
A lobster re-seeding site at Scorching Bay, Wellington.
In Tasmania, aquaculturists have been granted permits to remove juvenile lobster (pueruli) for ongrowing to market size in captivity. To compensate for this removal from the fishery they are required to reseed 25% of their stock back into the wild after one year.
In many areas around New Zealand paua never reach the minimum legal size of 125 mm, and there is a perception by some that these stocks are under-exploited.
The reasons for so-called “stunting” in paua are complex, but on a large scale they appear to be related to water temperature. In the warmer waters of the northern North Island, paua generally don’t grow to a large size.
NIWA has been running paua courses for many years, and continued requests have urged us to look at further courses. This time, training will not only be for the paua industry, but will aim to be responsive to the training requirements of the wider aquaculture community.
Getting to know the pumps and tanks at Mahanga Bay.
The need to offer aquaculture training has long been recognised by NIWA. In the late 1980s, the staff at Mahanga Bay ran a series of paua farming courses that helped to support a fledgling industry.
The capabilities of NIWA’s deepwater research vessel Tangaroa were fully tested during the recently completed 28-day acoustic survey of pre-recruit and spawning biomass of southern blue whiting on the Campbell Island Rise in September. Winds were light for the first week and a half, but deteriorated during the next two weeks.
