Polypocephalus sp. (Cestoda : Lecanicephalidae) as a biological marker for banana prawns, Penaeus merguiensis de Man, in the Gulf of Carpentaria

Abstract

Parasites in banana prawns, P. merguiensis, from the Gulf of Carpentaria were surveyed. Only the lecanicephalid cestode Polypocephalus sp. seemed useful as a biological marker for banana prawns. Loads of Polypocephalus sp. were low and constant at salinities from 14 to 34. At higher salinities (38), both intensity and prevalence of infection rose markedly from 0.5 Polypocephalus sp. per prawn and 27% to 6.25 and 95%, respectively. The frequency distribution of Polypocephalus sp. was adequately described by a non-truncated form of the negative binomial distribution (n = 943, p = 35.4, k = 0.43) suggesting there were no parasite-induced mortalities. Loads of Polypocephalus sp. in prawns in the commercial catch from Albatross Bay were most similar to loads in prawns from the Mission River, which empties into Albatross Bay. Polypocephalus sp. loads in Penaeus merguiensis formed two other natural groupings, one in the south-east corner of the Gulf and one in the Cape Keerweer-Mitchell River area. There was no parasitological evidence for extensive migrations of adolescent P. merguiensis away from their nursery estuaries.