Effects of the invasive swim bladder parasite Anguillicola crassus on health and condition indicators in the European eel

Abstract

Parasites negatively affect biological processes within their hosts, which may alter for example health, growth, and reproductive ability. Non-native invasive parasites, in particular, may have large effects on the endemic hosts, given that the hosts lack evolved specific defences against such parasites. The swim bladder nematode Anguillicola crassus, an invasive parasite originating from Asia, is found in the European eel (Anguilla anguilla, L. 1758), since the 1980s. We investigated whether A. crassus affected several indicators related to health of the European eel (spleen- and liver size, body fat content and relative condition). Our results indicate that during the continental residency of the eels, infection by A. crassus had no major negative impacts on the investigated health indicators at the generally low infection intensities present in this study (median 2-3 visible parasites). Given that many of the adult eels were found to have swim bladder damage, concerns about their spawning migration through deeper oceanic environments can still be raised. To allow further investigations, we suggest that quantification of swim bladder damage should be implemented in eel-monitoring programs. Compared to other parasite pressure parameters, swim bladder damage provides additional information about past infections and future problems.

Keywords

Anguilla anguilla; fat; nematode; relative condition; swim bladder damage

Published in

Journal of Fish Diseases
2023, volume: 46, number: 10, pages: 1029-1047
Publisher: WILEY

SLU Authors

• Myrenås, Elin

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

• Näslund, Joacim

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

• Persson, John

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

• Sundin, Josefin

  • Department of Aquatic Resources (SLU Aqua), Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Fish and Aquacultural Science
Medical Bioscience

Publication identifier

• DOI: https://doi.org/10.1111/jfd.13822

Permanent link to this page (URI)

https://res.slu.se/id/publ/122883