Development of physical measurement strategies and methodologies for industrially harvested sea cucumber (Cucumaria frondosa)

The commercial fishery for Cucumaria frondosa, particularly in the North Atlantic, is expanding as its ecological and economic significance becomes more widely recognized. Accurate assessment of C. frondosa body size remains challenging due to the species’ morphological plasticity. Conventional linear measurements—commonly applied to finfish—fail to account for the fluid-dynamic morphology of sea cucumbers, where water retention can dramatically alter apparent size. These inaccuracies affect critical areas such as landed value determination, stock assessments, age estimation, and recruitment models, thus compromising the sustainability of harvest strategies. Recognizing this, the present thesis focused on developing robust, standardized strategies and methods for assessing C. frondosa size with minimal human-handling interference. This thesis shows that image processing is a promising tool for rapid, non-invasive size assessment, improving measurement consistency while minimizing handling-induced variability. Experimental simulations showed that sea cucumbers contract uniformly under drag-related stress, reinforcing the potential to standardize post-harvest measurements. While immersed weight initially appeared inconsistent, further analysis revealed its potential as a highly accurate metric, provided seawater density is correctly factored into the calculation. Together, the findings offer practical, scalable recommendations for improving both scientific data quality and industrial processing outcomes in C. frondosa fisheries.