The National Parks and Wildlife Service (NPWS)  have recently released a new Irish Wildlife Manual that provides methods for repeat monitoring of numbers of adult freshwater pearl mussels at varying densities. It also describes the measurement of mussels used to produce demographic profiles that are essential to assessing the viability of a population. The manual also provides methods for monitoring the habitat suitability, quality and condition for the species.

Source: https://www.npws.ie/sites/default/files/publications/pdf/IWM122.pdf