FAR 2026/29 Recruitment of freshwater eels 1995–2025

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FAR-2026-29-Recruitment-of-freshwater-eels-1995-2025.pdf

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FAR-2026-29-Recruitment-of-freshwater-eels-1995-2025.pdf (3.6 MB)

Abstract
This study aimed to compile elver catch data for longfin and shortfin eels from hydroelectric dam sites during the 2022–23 to 2024–25 migration seasons. It continues a long-running monitoring programme designed to track juvenile abundance and support management of future adult eel stocks. Over the last three seasons, shortfin catches were generally low to moderate, while longfin catches were relatively high at the same sites. The average annual shortfin catch for the three fishing years was 2.6 million elvers, and was below the historical median, mainly because the Wairua Dam elver traps did not operate for two seasons and the Matahina Dam elver trap was being redesigned and did not capture elvers effectively for two seasons. If both sites had functioned normally, shortfin catch may have been closer to 6–7 million nationally. In contrast, the average annual longfin catch for the three fishing years was 721 061, which was above the historical median. Age structure differed markedly among sites and between seasons, showing that continued ageing work is needed to estimate recruitment strength accurately for individual years. Recruitment indices suggested that both shortfin and longfin recruitment have remained broadly stable over time, despite high year-to-year variability. Modelling results showed that water temperature was associated with daily longfin and shortfin catches at Karāpiro and Patea Dams. Other environmental variables such as moon phase, daylength, and seven-day mean river flow were also associated with daily elver catches, but their importance varied by species and site. Future work could expand modelling to more sites, account for age class specific patterns, and include broader climate indices to better understand the drivers of eel recruitment into New Zealand. 


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FAR-2026-29-Recruitment-of-freshwater-eels-1995-2025.pdf

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Wednesday, 26 August 2026

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