Intra- and inter-annual variability in the fat content of Atlantic herring (Clupea harengus) as revealed by routine industry monitoring

Susan Elaine Kenyon*, Martin Pastoors, Steven Mackinson, Thomas Cornulier, C. Tara Marshall

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)
3 Downloads (Pure)


Fat content indicates individual condition and fuels annual reproductive cycles in many fish species. These cycles, coupled with ecosystem changes, can result in large intra- and inter-annual fluctuations in fat content. However, quantifying this variability is challenging when scientific sampling does not cover the full reproductive cycle. Scottish and Dutch fish processors routinely measure muscle fat content of North Sea autumn-spawning herring (Clupea harengus) throughout fishing seasons. We validated these high temporal resolution data by estimating a strong intra-annual signal in fat content, which matched herring reproductive status. Fat content increased from 4.5% 95% CI [0.03, 0.06] to 16.1% 95% CI [0.15, 0.17] during May and June before plateauing and decreasing to 9.1% 95% CI [0.08, 0.10] in September, which coincided with the onset of spawning. We also examined inter-annual variability in the seasonal pattern and the timing and magnitude of peak fat content from 2006 to 2020. Inter-annually, fat content differed from the mean pattern during the feeding or spawning periods in years 2013, 2015–2017, 2019, and 2020. There was no difference in the timing and magnitude of peak fat content between years. Our study validates the scientific use of routinely collected fat content data from pelagic fish processors.
Original languageEnglish
Pages (from-to)88-99
Number of pages12
JournalICES Journal of Marine Science
Issue number1
Early online date11 Dec 2021
Publication statusPublished - Jan 2022

Bibliographical note

This study was completed as part of a PhD studentship co-funded by the University of Aberdeen, the Pelagic Freezer-Trawler Association, and the Scottish Pelagic Fishermen’s Association. The authors would also like to thank Lunar Freezing and Cold Storage Ltd, Denholm Seafoods Ltd, Parlevliet and van der Plas BV, Cornelis Vrolijk BV, and WvanderZwan BV for collecting and providing data to use in this study. Additionally, we thank three anonymous reviewers for their constructive feedback on an earlier version of the manuscript.

Data Availability Statement

Anonymized data underlying this article will be shared upon reasonable request to MP or SM with permission from the data owners listed in the Acknowledgements.


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