Abstract

In this study, we designed, applied and evaluated a new methodology to estimate the direct fecundity of Lithodes santolla ovigerous females that can be applied during fishing expeditions or independent monitoring. Eighty-five ovigerous females were collected from the fishery and 24 high-resolution images of each egg mass were used to estimate the egg mass volume using three dimensional (3D) modeling in the laboratory. Second, the carapace length, clutch volume, number of eggs per clutch, and egg sizes were recorded for each ovigerous female. Third, the relationship between the observed clutch volume and the estimated volume from the 3D model was evaluated, in addition to the relationship between fecundity and clutch volume using linear models. Finally, two imaging surveys were carried out on fishing boats, resulting in 46 photogrammetric surveys (representing 46 ovigerous females). In the laboratory, the 3D modeling of clutch volume was successful in 66 ovigerous females (77 %), and explained 99 % of the variance when estimating the observed clutch volume. The most informative model for estimating fecundity was a linear model which explained 88 % of the variance and included carapace length as a covariable. This could be related to egg size, which should be studied in more detail. From the images obtained on fishing boats, the 3D modeling and fecundity estimates were successful for similar to 62 % of clutches. This non invasive method for estimating fecundity presents an opportunity to improve the estimation of per capita reproductive contribution in female Lithodidae crustaceans through monitoring, although the photogrammetric survey process on fishing boats needs improvement.