Characterization of the reproductive cycle and physiological condition of Patella vulgata in the NW of the Iberian Peninsula: Relevant information for a sustainable exploitation

The reproductive cycle and physiological status of five populations of Patella vulgata have been studied along the Galician coast from July 2010 to June 2011. The use of generalized linear model has allowed to obtain parameters such as Day50 and Day95, which helped compare reproductive cycles among populations and allowed to determine the significance of the effect of size and degree of exposure on the start and duration of the cycle. On the other hand, a standardized condition index has been established, which enables the comparison of samples collected in different sites or seasons and composed by individuals of different size. Moreover, the use of a generalized nonlinear least squares model has allowed assessing the temporal variability of the physiological status of the populations and the effect of size and degree of exposure on its different components. This has contributed some useful information for planning a sustainable exploitation of this resource: sheltered areas turned out to be more productive, in terms of biomass. The reproductive cycle starts earlier and its duration is longer in sheltered areas. In addition, organisms showed minimum condition indexes during spawning periods, which makes these periods less suitable for the exploitation, both from a biological and from a commercial point of view. Larger organisms showed longer spawning periods. This highlights the importance of taking size composition into account, seeking to maintain a size structure which enables a reproductive period which is long enough to ensure future recruitment success.