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During 1989, light but persistent mortalities were detected in a turbot Scophthalnius maximus L. farm in Galicia (northwestern Spaln) and a virus with the characteristics of a blrnavirus was isolated. The purpose of this study was to characterize the viral agent and determine the susceptibility of turbot to this virus. Electron microscopic examination revealed that the particles were so metric, hexagonal and unenveloped with an average dlameter of 58 to 60 nm The molecular weights of the RNA segments were 1.9 and 2.0 X l o b daltons. The cells most susceptible to the turbot isolate were the CHSE-214, FHM and RTG-2 lines and the optimal temperature range for its replication was 15 to 2OoC. The RNA and polypeptide electropherotypes show that thls virus resembles the Ab serotype of infechous pancreahc necrosis vuus (IPNV); however, it dlffers in that it replicates in the FHM cell llne and is not neutralized by antisera to the classical serotypes of IPNV. lnfectiv~ty tnals conducted in turbot of different sizes indicated that the virus produced mortality only in small fish (2 g ) , although the larger fish (30 g ) harbored the virus for at least 35 d . Fish inoculated with this isolate showed no pancreatic necrosis although necrosis of the hematopoietic elements of the ludney and spleen was detected.

A comparative bacteriological and virological survey was conducted in two fish farms in the North of Portugal. The fish species examined included cultured rainbow trout, Oncorhynchus mykiss (Walbaum), and brown trout, Salmo trutta L., as well as wild fish captured near both facilities. The microbial load in Portuguese aquaculture. Qualitative and quantitative differences in microbial load were observed betweer cultured and wild fish. No notifiable bacterial or vira pathogens were detected in any of the feral specie! studied.