A novel morphometry-based method for assessing maturity in male Tanner crab
Accurate assessment of annual size-at-maturity in male crab is important to the management of commercial fisheries, and to understanding the ecology of the given crab species.
Current procedures can be difficult for investigators to apply, be inaccurate and lead to erroneous size-at-maturity estimates, or both.
To resolve these issues we developed a new procedure whereby a dataset comprising paired log-transformed chela height and untransformed carapace width measurements is subset at regular intervals.
Read this open access paper on the FACETS website.
We used kernel density estimation procedures to model the underlying bimodal data distribution for each subset, and identified the minima between the modes. A maturity classifier was created by fitting a linear model to these minima.
In comparisons to current methods our classification procedure provided improved performance, while also being easier to apply, and demonstrating robustness to procedural modifications.
In a test of our procedure, we also identified a multiyear decline in size-at-maturity in the western stock of Tanner crab in the eastern Bering Sea during the late 2010s, prior to a closure of the local fishery.
Read the paper — A novel morphometry-based method for assessing maturity in male Tanner crab, Chionoecetes bairdi by Jonathan I Richar and Robert J Foy.
