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Research article - Peer-reviewed, 2019

Effects of freezing on length and mass measurements of Atlantic cod Gadus morhua in the Baltic Sea

McQueen, Kate; Mion, Monica; Hilvarsson, Annelie; Casini, Michele; Olesen, Hans J.; Hussy, Karin; Radtke, Krzysztof; Krumme, Uwe


An aggregated sample of 925 Atlantic cod Gadus morhua collected by four countries in different regions of the Baltic Sea during different seasons were measured (total length, L-T = 161-890mm and weighed (mass, M = 45-6900g) both before freezing and after defrosting. The cod were found to decrease significantly in both L-T and M following death and frozen storage. There was an average (+/- SD) change in L-T of -2.91% (+/- 0.05%) following freezing, independent of starting L-T. Total M changed by -2.65% (+/- 0.14%), independent of starting mass. Shrinkage of L-T and M did not differ significantly between 1 and 4 months frozen storage, though L-T shrinkage was significantly greater after 1 or 4 months in the freezer compared with after 5days. There was significant variation in L-T and M shrinkage between regions of capture. A significant negative relationship between condition of cod and L-T or M change was also observed. Equations to back-calculate fresh L-T and M from thawed L-T, M and standard length (L-S), gutted L-T, gutted L-S and gutted M are provided.


Baltic Sea; cod; freezing; Gadus morhua; measurement bias; shrinkage

Published in

Journal of Fish Biology
2019, Volume: 95, number: 6, pages: 1486-1495
Publisher: WILEY