Download FAR 2026/12 Intercalibration of research vessels, Kaharoa and Kaharoa II, for inshore bottom trawl surveys

The new Earth Sciences New Zealand research vessel Kaharoa II arrived in New Zealand in August 2024. Kaharoa II (36 m) is larger and more capable than the 28 m Kaharoa, which was launched in 1981 and was used for previous New Zealand inshore trawl surveys.

The change in research vessel from Kaharoa to Kaharoa II provided an opportunity to standardise survey gear and protocols across all inshore surveys. To allow continuation of existing inshore survey time-series for key fish species, an intercalibration experiment was carried out on the west coast South Island in March–April 2025.

The intercalibration was designed as a paired-tow comparison, where the two vessels towed on parallel tracks in the same direction, so that both vessels experienced the same tidal and wave conditions, with a minimum separation distance. Fifty-nine paired tows were conducted.

Biomass catchability ratios from the intercalibration were derived and these will be used to adjust future Kaharoa II survey catch results in the short term.