New Zealand commercial catches of jack mackerels have been recorded under the general code JMA. Therefore species-specific catch information is not available from the fishery data. Estimates of proportions of the three Trachurus species in the catch, based on observer data which includes separate codes for each species, are essential for assessment of the individual stocks.

 

This report updates the data collected by the New Zealand observer sampling programme from trawl landings of  jack mackerels in JMA 7 with the data collected during the 2021–22 fishing year, including estimates of species proportions and sex ratios in the landings, catch-at-length (fork length, cm), and catch-at-age for these species.

 

Estimated proportions of catch by species based on observer data have historically shown that T. declivis comprises 61–73% of the catch for all statistical areas, followed by T. novaezelandiae at 21–33%, and T. murphyi at 2–8%. In 2021–22, proportions of T. declivis, T. novaezelandiae, and T. murphyi were 77%, 23%, and less than 1%, respectively.

 

Sampled sex ratios of T. declivis and T. novaezelandiae were close to a sex ratio of 1:1 in the 2021–22 fishing year, and sex ratios for T. murphyi were biased towards females (56%) in 2021–22.

Trachurus declivis and T. novaezelandiae fish in the observer data indicated decreasing proportions of larger and older fish in the commercial catch in recent years, whereas the length and age data for T. murphyi indicated the catch mainly comprised large, older fish, with little evidence of younger fish coming through.

Document date
Thursday, 15 February 2024

Document type
V 1.3

File format
Adobe PDF

File size
4.0 MB

Reference number
2024/08

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FAR: 2024/08;
ISSN: 1179-5352;
ISBN: 978-1-991120-83-0;
AUTHOR: Moore, B.R; Ó Maolagáin, C.; Spong, K.; Barnes, T.;

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