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FAR-2024-80-Commercial-catch-sampling-of-jack-mackerel-JMA7-in-the-2022-23-fishing-year.pdf
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FAR-2024-80-Commercial-catch-sampling-of-jack-mackerel-JMA7-in-the-2022-23-fishing-year.pdf (4.0 MB)
Abstract
Jack mackerels support significant commercial fisheries in New Zealand, with over 75% of the total jack mackerel catch taken by trawl fisheries off the west coasts of the North Island and South Island, in the JMA 7 Quota Management Area. Three jack mackerel species are caught in New Zealand waters (Trachurus declivis, T. murphyi, and T. novaezelandiae) but commercial catches of jack mackerels are only recorded against the generic species 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 species code specific observer data are used to derive species-specific catch estimates from the JMA catch data.
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 2022–23 fishing year, including estimates of species proportions and the ratio of males and females in the landings, as well as the numbers caught by length and age.
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 2022–23, proportions of T. declivis, T. novaezelandiae, and T. murphyi were 64%, 36%, and less than 1%, respectively.
In 2022–23, sampled T. declivis and T. novaezelandiae were close to a sex ratio of 1:1 while sex ratios for T. murphyi were skewed towards females (54%).
For T. declivis and T. novaezelandiae, observer data indicate 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 very few observations of younger fish.
Document date
Friday, 15 November 2024
Document type
V 1.3
File format
Adobe PDF
File size
4.0 MB
Reference number
2024/80
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FAR-2024-80-Commercial-catch-sampling-of-jack-mackerel-JMA7-in-the-2022-23-fishing-year.pdf
Uploaded date
Friday, 15 November 2024
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AUTHOR:
Moore, B.R.;
Ó Maolagáin, C.;
Spong, K.;
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