A Temporal Analysis of Parasitic Infections in Indian Mackerel, Rastrelliger kanagurta (Cuvier, 1817) along the Western Coast of Karwar Bay, Karnataka: Employing a Monthly Assessment with histopathology

Abstract

The study showed the morphological identification, prevalence, and severity of the infestation of parasites in R. kanagurta from the Karwar coast, month-wise from January to December 2022. The current study investigated and found Norileca indica and Nerocila phaiopleura Trichodina spp., and developmental stages of helminths in R. kanagurta during this period. A total of 755 fish were examined, and the monthly prevalence was estimated. Statistical analysis revealed that the P value is lesser than the significant value (P<0.05, df=3), which indicates there are significant differences in PFI (% prevalence) values of each group/among the parasites (N. indica, N. phaiopleura, Helmenth, Trichodina spp.) and also there is a significant difference of prevalence in monthly (P<0.05,df=11). Weather changes like temperature, salinity, flood water, pollutants, ballast water, and sudden rainfall all play a key role in the infestation of parasites in the selected fish. Availability of the host (R. kanagurta), breeding season, and ban period (west coast) were also important factors causing the parasitic infestation.  In conclusion, Norileca indica and Nerocila phaiopleura, Trichodina spp., Isopods, and developmental stages of helminth parasites were causing histological alterations in the infected tissues.