Parasite abundance in Atlantic cod (Gadus morhua) in shallow and deep waters around Iceland

Proper stock identification of atlantic cod (Gadus morhua) is necessary in modern Icelandic fisheries management to ensure that stocks of cod are not overfished. Today the cod fishery in Iceland is treated as a single stock but studies have shown that there might in fact be two. In addition to there being possibly two stocks there are also coastal and frontal ecotypes which inhabit different depths during the feeding season. Today these ecotypes are detected by molecular sequencing but here I show that parasites as biological tags might be a useful method in cod ecotype identification since results indicate that there is variation in parasite infection between the coastal and frontal types. I found that certain groups of parasites like copepods, nematodes and acanthocephalans appear to infect the ecotypes differently in terms of abundance and diversity of parasites. Deep-water cod had a mean abundance of 95.2 (SD = 68.4) nematodes, 2.2 (SD = 2.17) acanthocephalans and 3.8 (SD = 3.7) copepods. Shallow-water cod had a mean abundance of 72.1 (SD = 70.07) nematodes, 0.8 (SD = 1.08) acanthocephalans and 3.73 (SD = 3.67) copepods. Certain sites of infection showed interesting patterns of infection, but more research is needed before a parasite species can be chosen as a biological tag. These results support the use of parasites as biological tags for use of ecotype discrimination.

Author dc:creator

• Magnús Máni Dagsson 1997-

Contributors dc:contributor

• Háskóli Íslands

• Líffræði

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/1946/50304

OAI identifier oai:identifier

oai:skemman.is:1946/50304