Science Centres: Fisheries

NIWA fisheries scientist Darren Stevens measuring hoki in Tangaroa’s wet lab. (Photo: Neil Bagley, NIWA)

Hoki support New Zealand’s biggest fishery. NIWA works with the Ministry of Fisheries (MFish) and the fishing industry to develop a better understanding of hoki stocks in order to sustain them into the future.

This year, we completed the tenth and sixteenth summer surveys respectively of the western and eastern hoki stocks. NIWA carries out annual assessments of these stocks for MFish, based on data from research surveys and commercial fisheries. These show that the biomass of the western stock has been falling since the mid 1990s and now sits at between 15–24 % of its ‘unfished’ biomass.

Poor recruitment of young fish into the western hoki stock remains a key question for the fishery. One possibility is that many more young fish may die than we realise, by  getting damaged as they escape through trawl nets. We recently carried out a collaborative experiment with the Deepwater Group Ltd to find out how many fish of each length class escape during commercial fishing operations so that possible impacts can be modelled. We’re also investigating possible links between recruitment and changes in oceanic and climatic conditions within each spawning season.