Occurrence of vertebral deformities in Gobiidae (Pisces) from the Tagus estuary

In four species of gobiid fish caught in Tagus estuary during 1996, the incidence of skeletal deformities ranged from 2 to 5%. Differences between sampling stations or between the two most abundant species Pomatoschistus minutus and Gobius niger were statistically not significant (p > 0.05). The type of deformity depended upon species. P. minutus and P. microps showed bone nodules at the inferior side of the abdominal vertebrae, whilst G. niger and G. paganellus had shortened caudal vertebrae (achondroplasia) and deformed ural plates. The possible role of pollution or other conditions in the Tagus estuary is discussed.