Science Centres: Fisheries

Smart tags:
These 17 cm long tags can record temperature, depth, and light levels every 20 seconds for up to a year, then transmit a summary to overhead satellites to monitor the locations of the fish.

NIWA and Blue Water Marine Research (BWMR) are tracking swordfish in the southwest Pacific to improve knowledge of stock structure in this highly migratory species.

Broadbill swordfish are a valuable fish, targeted by tuna longliners in New Zealand waters.

Commercial swordfish catches in the southwest Pacific (about 20% of which is caught in the New Zealand EEZ) have declined in recent years. Knowledge of how different swordfish stocks relate to one another is needed to assess their status and manage the fishery accordingly.

Currently, little is known about the structure of swordfish stocks in the southwest Pacific. For instance, it’s not known whether swordfish caught in New Zealand and Australian waters are from separate populations.

To pin these highly migratory fish down, NIWA and BWMR are deploying 19 pop-up satellite archival tags (see photo) on swordfish caught on tuna longline vessels. The tags will record the swordfish’s movements between temperate New Zealand waters and their tropical spawning grounds. Of particular interest is whether these fish return to New Zealand waters or disperse across a wider area.

The Ministry of Fisheries, who are funding the study, will use the information in the stock assessment model being developed for the region.