Download FAR 2024/78 Relative abundance, size and age structure, and stock status of blue cod off Kaikōura in 2023

Beentjes, M.P.; Page, M. (2024). Relative abundance, size and age structure, and stock status of blue cod off Kaikōura in 2023. New Zealand Fisheries Assessment Report 2024/78. 61 p.

South Island recreational blue cod fisheries are monitored by Fisheries New Zealand using potting surveys. The results of the Kaikōura surveys are important for assessing the status of the blue cod stock in this region.

This report describes the results of the random-site blue cod potting survey carried out in Kaikōura in December 2023 and compares these with the four previous surveys.

The length frequency distributions and mean length were generally similar among the five surveys. Survey mean catch rates show a progressive decline over time, dropping by 49% between 2011 and 2023. The sex ratio over the surveys was 47–60% male with indications that males are becoming more common in the population. The estimated fishing mortality (F) in 2023 was nearly double the target reference of F = 0.15 indicating that overfishing is occurring.

The catch rates of blue cod caught in the Hikurangi Marine Reserve over three surveys (2017, 2019 and 2023) indicate that abundance has not changed much over this period, and while greater than adjacent strata, abundance was only about one quarter of that in other parts of the survey area outside the reserve. Size of fish in the Marine Reserve was also not larger than in other parts of the survey area, but blue cod were of better condition.