Molt staging using pleopods in American lobster (Homarus americanus) : quantifying repeatability of assessments and impact of freezing.

Thumbnail Image



Journal Title

Journal ISSN

Volume Title


University of New Brunswick


Pleopod staging is a technique used in the American lobster fishery to assess lobster molt status, and hence “quality”, throughout the fishing season. The precision of this technique has not been evaluated, nor has the impact of pleopod freezing on molt stage assessment. In this study, 330 pleopods from 76 juvenile lobsters were sampled and staged twice prior to freezing in sea water, then twice after freezing. I found that (i) repeatability of molt stage assessments was moderately high (54-91%), (ii) there was no significant difference in the proportion of different molt stages identified before and after freezing, and (iii) paired assessments following freezing were moderately but significantly more consistent than those involving the same pleopods before freezing. This study suggests that repeatability of molt stage assessments made using pleopods may not be as high as researchers have assumed, but that freezing has minimal effect on these assessments.