The secrets of scampi stock assessment

18 July 2018
Dr Ian Tuck, Department of Statistics and NIWA (quantative marine students)
Dr Ian Tuck

Scampi are small and tasty members of the clawed lobster family, and we have plenty of them in New Zealand waters.

But you won’t see them on local plates very often; most of the 700-1000 tonnes of scampi caught here every year is frozen at sea and exported to North America and Asia. 

These are just two of the interesting facts you learn when talking with Dr Ian Tuck about his work, in which scampi has been a prime focus.

Ian is Principal Scientist, Fisheries, for the National Institute of Water and Atmospheric Research (NIWA), but spends a day a week in the Department of Statistics working on collaborative research projects.

His presence means opportunities for our quantitative marine science students: Ian has nine postgraduate students at present, with another 19 completing honours, masters and doctoral research with him since 2013.

“I enjoy my day on campus each week,” says Ian, originally from Norfolk in England. “I find everyone helpful and approachable.”

So of all the creatures in the sea, why is scampi so intriguing?

Ian came across scampi while doing his masters in marine and fisheries science in Aberdeen, Scotland; the Scottish scampi industry is highly lucrative.

“I really liked the fact that because scampi live in burrows, they are only available to the fishery when out of the burrow,” he explains. “So there were lots of biological and behavioural aspects that needed to be considered when working on the size and the health of the scampi fishery.”

Ian did his PhD on scampi fisheries ecology, and worked in Scotland before being lured to NIWA in 2006.

New Zealand scampi (Metanephrops challengeri) are slender and range in length from 13-18 cm. Unique to New Zealand, they burrow into muddy sea beds at 250-550m deep, and are seabed predators and scavengers that feed on seabed animals like worms and clams; they are prey for larger animals, particularly predatory fish like ling, sea perch, dog fish and rays.

Our main scampi fisheries are off the Bay of Plenty, Hawkes Bay and Wairarapa; in the Chatham Rise, which stretches some 1,000km out from the South Island; and near the subantarctic Auckland Islands.

Our scampi fisheries are in good health, says Ian, and catch rates are good. Ian is particularly interested in scampi stock assessment. However, he says, that presents some challenges: "You can catch scampi only when they emerge from their burrows, so on any given day it’s hard to know how what you’ve caught relates to the population.

"Research has established that scampi emergence varies through the day and the seasons – they tend to come out less at night – and patterns between the sexes differ."

Technology has played a pivotal role in better understanding scampi catchability and emergence. Ian and his colleagues have used cameras to count burrows, and have attached small acoustic tags to scampi that are detected only when the creatures exit their burrows.

There are a few things Ian hasn’t been able to do here because local scampi live in very deep water compared to their European shallow-water cousins Nephrops norvegicus.

In  Europe, to study burrow structure, Ian and colleagues poured polyester resin into burrows where they found juveniles living in small burrows off the sides of adult burrows, and up to four scampi living in a large burrow system more than 2m wide. It’s quite likely that local scampi also share burrow systems, says Ian, but it’s hard to check.

So, the question has to be asked: Does Ian eat scampi as well? “Oh yes!” he says – they’re best, he reckons, grilled on a barbecue.


Associated information         

 

 

 

Dr Ian Tuck sorts scampi from the catch while on a commercial fishing trawler in the Auckland Islands.
Dr Ian Tuck sorts scampi from the catch while on a commercial fishing trawler in the Auckland Islands.
Dr Ian Tuck examines scampi while on a commercial fishing trawler in the Auckland Islands.
Dr Ian Tuck examines scampi while on a commercial fishing trawler in the Auckland Islands.
Dr Ian Tuck collects and records data from scampi while on a commercial fishing trawler in the Auckland Islands.
Dr Ian Tuck collects and records data from scampi while on a commercial fishing trawler in the Auckland Islands.