Parasite risk of maricultured rainbow trout (Oncorhynchus mykiss Walbaum, 1792) in the Western Baltic Sea, Germany

Autor: Unger, P.; Palm, H.W. 2017
In:

Aquaculture International

ISBN: 1573143X, 09676120
DOI: DOI 10.1007/s10499-016-0096-8
Seite: 975 - 989
Jahr: 2017

Einordung:
Institut: Professur Aquakultur und Sea-Ranching

Abstract:
Harvest quality rainbow trout (Oncorhynchus mykiss Walbaum, 1792) raised in an
integrated multi-trophic aquaculture (IMTA) unit off the German coast in the Baltic Sea were
studied for ectoparasites and endoparasites. One hundred five specimens were sampled
between November 2013 and 2014. Four endoparasite taxa were found, while no zoonotic or fish pathogenic ectoparasites could be detected. Molecular identified metacercariae of
Diplostomum baeri were recorded at a non-critical level (18.1% prevalence, 1–4 intensity),
getting introduced into the Baltic Sea through the cultured rainbow trout from the freshwaterbased hatchery. The isolated acanthocephalan Echinorhynchus truttae was of freshwater origin, too. Pomphorhynchus laevis (Acanthocephala) and Brachyphallus crenatus
(Digenea) seem to be transmitted into the net cage from Baltic Sea intermediate hosts. The
parasite fauna was compared with those of wild living sea trout, Salmo trutta trutta studied at
the immediate area (Unger and Palm in Parasitol Res 115(1):165–174, 2016). Stomach content
analyses demonstrated that the farmed pellet-fed fish also utilized natural resources, especially
fouling organisms. A single escapee, caught from the wild in the vicinity of the cages, had a
massive intestinal infection with Baltic Sea parasites, the acanthocephalans Echinorhynchus
gadi, P. laevis and the nematode Hysterothylacium aduncum. The salinity (helminths) as well
as the culture conditions (trichodinids) at this pilot facility prevent significant transfer of fish pathogenic and zoonotic parasites as well as ectoparasite establishment and reduce the parasite
risk for maricultured rainbow trout. This sampled location is particularly suitable for healthy
and environmentally friendly aquaculture farming in the Baltic Sea.

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