Predictive Model for the Nematode (Hysterothylacium aduncum) in Horse Mackerel, Trachurus trachurus From the Black Sea

Abstract

Hysterothylacium aduncum is a parasitic nematode that infects mainly marine fish. The information on the heterogeneity in the aggregation of macroparasites in fish species is still limited, particularly for the Raphidascarid nematode H. aduncum that infects exploitable marine fish species including horse mackerel (Trachurus trachurus). This study aimed to investigate the heterogeneity of the distribution of H. aduncum to understand macroparasite aggregation better in marine fish. Weibull tests comprising Maximum likelihood were used to analyze the frequency distribution of parasites within a fish host population over the three years period. The parasite, H. aduncum (third larval stage) prevalence was found to be 88% and the condition factor was 1.30∓0.029 in un-infected fish and 1.12∓0.022 in infected fish. The clustered pattern was observed in H. aduncum in horse mackerel. The relation between parasite load and the fish condition factor was found to be significant and conformity of length and weight was affected by parasite load. It is the first time that aggregation has been observed in H. aduncum distribution and made forecasts of nematode intensity in horse mackerel. The findings related to the large individual variations suggest that this pattern is significant and should be considered for host-parasite dynamics.