Dynamics of the Shrimp Palaemon serratus Populations in Normandy, France: From the Knowledge of its Biology to its Sustainable Fishery
Résumé
The shrimp Palaemon serratus (Pennant, 1777) is a common species in Normandy rocky
shores. Professional and recreative fishermen have developed several techniques to harvest this
target species: landing net, trap and trawl. For two decades, the populations show high temporal
fluctuations and tend to decrease. During the GeDuBouq project (2020-2023), four sites has
been chosen to acquire data on the biology and dynamics of the species in Normandy. A twoyear
survey of the population at two sites (Grandcamp-Maisy and Blainville-sur-Mer) shows
that the species reproduces during winter and spring with the presence of larvae at the end of
spring; then the juveniles recruit in summer and rapidly grow to reach a total length of 5 cm
(the minimum size authorized to fish) at the beginning of the autumn. The longevity is estimated
to 2-5 years. At Blainville-sur-Mer, shrimps can be parasitised by bopyrid isopod, Bopyrus
squillarum with a mean prevalence of 6% throughout the survey. Using isotopes and stomach
contents at four sites (the two sites mentioned above plus Chausey and Antifer), an omnivorous
regime has been identified with prey differences at Grandcamp-Maisy under estuarine
conditions. Few professional vessels fish P. serratus in Normandy with a quantity of
disembarkation reaching ~ 22 tons in 2020. Conversely, the quantity of harvesting by recreative
fishermen remains unknowledge in spite of numerous fishermen in some Normandy spots. The
results obtain in this study can help the French maritime administration to adapt the season of
shrimp fish outside the period of ovigerous female presence.