The bacteriology of Atlantic halibut: Hippoglossus hippoglossus (L.) larval rearing

A bacteriological survey of three different UK halibut hatcheries was undertaken. These were the Seafish Industry Authority (SFIA) Marine Farming Unit at Ardtoe in Argyllshire, Mannin Seafarms, Isle of Man and Otter Ferry Seafish. Otter Ferry operates different rearing practices to the other two hatcheries in that it uses marine copepods, as well as enriched Artemia, as a start feed for developing halibut larvae. SFIA Ardtoe and Mannin Seafarms rear their larvae intensively, only supplying first-feeding larvae with unenriched Artemia metanauplii and ongrown enriched Artemia. The bacterial flora of hatchery-reared Atlantic halibut eggs, larvae, juveniles and adults were monitored. The water in the halibut rearing tanks, and some of the possible sources of microbial inputs into the rearing system, were simultaneously sampled and analysed. Characterisation was done using a combination of traditional biochemical tests, the BIOLOGGN bacterial identification system, PCR-RFLP of 16S rRNA genes and partial 16S rDNA gene analysis. The gut microflora appeared to be seeded towards the beginning of the nonfeeding yolk-sac stage; by the onset of first-feeding this exceeded 10