Brown trout (Salmo trutta L. 1758) and Arctic charr [Salvelinus alpinus (L. 1758)] display different marine behaviour and feeding strategies in sympatry

• Published in: Journal of Fish Biology
• Main Authors: Davidsen, Jan Grimsrud, Halvorsen, Andrine Emilie, Eldøy, Sindre Håvarstein, Thorstad, Eva Bonsak, Vøllestad, Leif Asbjørn
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: VDP::Zoologiske og botaniske fag: 480; Arctic; Fors; Arctic charr; Salvelinus alpinus
• Online Access: http://hdl.handle.net/10852/106612; https://doi.org/10.1111/jfb.15354

Brown trout (Salmo truttaL. 1758) and Arctic charr [Salvelinus alpinus(L. 1758)] taggedwith acoustic transmitters migrated from fresh water to the sea mainly in May andJune, but with large individual variation in migration timing. ForS. trutta,largeindivid-uals (42–86 cm total length) migrated earlier in the season than small individuals (18–27 cm). ForS. alpinus, no such pattern was found, likely because of the small size rangeof tagged fish (28–41 cm).S. truttastayed longer at sea thanS. alpinus(average 2vs.1 month). Early migrants ofS. truttastayed for a shorter period at sea than latemigrants, whereas no such pattern was observed forS. alpinus.LargeS. truttamovedquickly away from the river and spent average 3 days to reach a receiver line 20 kmfrom the river mouth, whereas smallS. truttaandS. alpinusmigrating that far spent 2–3 weeks on the same distance.S. truttautilized the entire fjord system and had agreater proportion of long-distance migrants (>20 km, 78% and 59% of large and smallS. trutta, respectively) thanS. alpinus(29%).S. alpinusmostly stayed in the inner fjordareas, and none were recorded in the outermost part of the fjord. The difference in theuse of marine areas may be caused by variation in prey choice and spatial distributionof the preferred prey groups. Stable isotope analysis showed thatS. truttahad beenfeeding at a higher trophic level thanS. alpinus.S. truttahad mainly fed on marine fishand shrimps, whereasS. alpinushad large proportions of freshwater invertebrates inthe diet, suggesting that the estuary with benthos and amphipods drifting from theriver was an important feeding habitat forS. alpinus. In conclusion, major differences inhabitat use, migration patterns and feeding strategies were found between sympatricanadromousS. truttaandS. alpinuswhile at sea. acoustic telemetry, diet analyses, marine migrations, sea run Arctic charr, sea trout, stableisotopes Brown trout (Salmo trutta L. 1758) and Arctic charr [Salvelinus alpinus (L. 1758)] display different marine behaviour and ...