Download FAR 2024/45 The 2023 stock assessment of gemfish (Rexea solandri) in SKI 1 and SKI 2

Langley, A.D.; Middleton, D.A.J. (2024). The 2023 stock assessment of gemfish (Rexea solandri) in SKI 1 and SKI 2. New Zealand Fisheries Assessment Report 2024/45. 116 p.

Gemfish (southern kingfish) are found throughout New Zealand waters and are generally caught by trawl fisheries in depths from 150 to 500 metres. There are two New Zealand stocks of gemfish, with the northern stock caught off both coasts of the North Island and a southern stock caught around the South Island.

A trawl fishery targeting the northern gemfish stock developed in the 1980s. Catches peaked in the early 1990s, but a decline in stock abundance led to a series of reductions in catch limits. Monitoring, using catch-per-unit-effort (CPUE), has demonstrated that abundance of the northern stock of gemfish increased substantially since the mid 2010s. New catch-at-age data from the target trawl fisheries were compiled for the 2012, 2014, and 2022 fishing years.

This report details a new, full quantitative stock assessment for the northern gemfish stock undertaken in 2023. The model estimated that northern genfish abundance increased throughout the mid-late 2000s, following higher recruitment in the late 1990s and early 2000s, then increased further during 2019–2023 following strong recruitments in 2013–2017. In 2023 abundance was estimated to be around the average level that would occur in the absence of fishing. This estimate is uncertain because the gaps in age sampling mean that the size of recent recruitments is uncertain, but it is likely that the stock can support higher catches, at least in the short term. It appears that gemfish stocks are sustained by intermittent periods of high recruitment.