Prevalence and abundance of larval Anisakis spp. in the argentine shortfin squid Illex argentinus: stock, age, size and cohort as surces of variability

IRIGOITIA, M.M.; BRAICOVICH, P.E.; LANFRANCHI, A.L.; GUTIÉRREZ, M. P.; IVANOVIC, M; PRANDONI, N. I.; ELENA, B.; MATTIUCCI, S.; TIMI, J.T.

Copenhague

Congreso; 15th International Congress of Parasitology; 2022

Word Federation of Parasitologists

Introduction: Illex argentinus is a semelparous squid, with a lifespan lasting about 1 year and non overlapping generations. Squids perform a latitudinal/bathymetric migratory cycle along which they grow, mature, visit different oceanographic regions and changes its diet. Its recruitment and population size are largely dependent on oceanographic conditions and, consequently, variable temporally. All such sources of variability are expected to have an effect on trophically transmitted parasites, especially for larval Anisakis that can persist for long periods and could be indicative of such changes. Aim: to evaluate the temporal variability of larval Anisakis spp. in relation to habitat,size and date of capture of I. argentinus.Methods: A total of 430 squids caught at different latitudes and dates in 2019-2021 were examinedfor Anisakis and their length and maturity index were determined. Samples were identified according to stock, geographical origin, date of capture and squid size. Parasites were counted and prevalence and mean abundance were calculated for each sample.Results: Larvae of Anisakis spp. (n= 270) were found encysted in viscera of 111 squids, mostly in the stomach. No larvae were found in the mantle. Both prevalence and mean abundance varied across stocks, increasing in southern ones, and cohorts. Burdens increased also with squid size and age. Cohorts of the same stock also differed in their loads between consecutive years.Conclusions: Despite some patterns were found, such as increasing loads southwards and in larger/older hosts, the nature of this parasitism seems as dynamic and unpredictable as that of populations of I. argentinus, being largely dependent on the feeding behavior of this host in each region it inhabits along its migratory cycle. PICT 2019-3376