Science Centres: Fisheries

Understanding pelagic fish behaviour is essential to accurately estimate their abundance using aerial sighting techniques. The development of relative abundance indices for pelagic species is a current objective of several Ministry of Fisheries projects.

We recently began surveys with sonar equipment to map schools of pelagic fish such as mackerels, kahawai, trevally, skipjack tuna, pilchards, and anchovies in the Bay of Plenty and Bream Bay. We are using multi-beam wide-angle sonar to estimate the relative sizes of fish schools and study school movements. Some of the work will incorporate a fish-spotter pilot to relate the view from the air to what’s happening below.

Pilchards and anchovies are an important link in the food chain, but are not yet fished commercially to any great degree in New Zealand, partly due to uncertainty about stock size. "One of the spin-offs of the surveys is to learn how their schooling behaviour might affect other species in the food chain," says NIWA fisheries biologist Paul Taylor.