METAZOAN PARASITES OF THE SNAPPER, PAGRUS-AURATUS (BLOCH AND SCHNEIDER, 1801), IN NEW-ZEALAND .1. PREVALENCE AND ABUNDANCE

The prevalence and abundance of nine species of ectoparasites and seve n species of endoparasites found on the snapper, Pagrus auratus, colle cted from the Hauraki Gulf, New Zealand, is reported. The metazoan fau na of Pagrus auratus in this study was dominated by a single highly pr evalent and abundant species, Diphtherostomum sp., which accounted for 84% of all the parasites collected during this study and occurred in all snapper older than 2 years. Several other moderately abundant spec ies were highly prevalent, occurring in 50-60% of the snapper sampled. These included Lamellodiscus pagrosomi, Bivagina pagrosomi, Cucullanu s sp., and Unicolax chrysophryenus. The remainder of the parasite faun a comprised rare species of limited prevalence and low abundance, acco unting for 7.7% of the individuals collected. These included Choricoty le australiensis, phyllobothriid and dasyrhynchid plerocercoids, Proct oeces sp., Philometra lateolabracis, and Anisakis sp. Correspondence a nalysis indicated that different age classes of the host snapper had d istinctive parasitic faunas, with O+ snapper characterised by low abun dance and prevalence of all species except C. australiensis and the ph yllobothriid plerocercoid. A progressive increase in many of the speci es of parasites constituted the major faunistic differences between 1, 2+, and 3+ snapper. The implications for fisheries and aquaculture o f the composition of the metazoan parasitic fauna of P. auratus are di scussed.