Distribution and migrations of the prawn Palaemon longirostris in the Mira river estuary (southwest Portugal)

摘要: Palaemon longirostris was sampled monthly at 12 sites in the Mira River estuary (southwest Portugal) from October 1990 to September 1991. Animals were counted, measured, and sexed. The estuarine distribution of prawns appeared follow salinity displacement, animals being found river stations during summer autumn when saline encroachment up greater. During winter spring freshwater input greatest, thus moving gradient toward mouth, migrated downstream brackish areas. Ovigerous females collected only areas (January August), suggesting that reproduction does not take place habitats. Higher percentages than males generally observed. Females, particularly ovigerous ones, larger males.