Diel and seasonal locomotor activity patterns in Arctic charr, Salvelinm alpinus (L.)

• Published in: Journal of Fish Biology
• Main Authors: Linnér, J., Brännäs, E., Wiklund, B.‐S., Lundqvist, H.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1990
• Subjects: Arctic; Hornavan; Arctic charr
• Online Access: http://dx.doi.org/10.1111/j.1095-8649.1990.tb02532.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1095-8649.1990.tb02532.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.1990.tb02532.x

One‐year‐old Arctic charr, Sulvelinus alpinus (L.), of the Hornavan strain were tested from February 1985 to January 1986 in an attempt to get an increased understanding of the annual rheotactic behaviour as well as the die1 and seasonal locomotor activity pattern. An annular stream tank equipped with photocells was used to measure the direction of swimming movements as well as the number of passings. From February to late May the locomotor activity was low but increased in July and peaked in September. After November the locomotor activity was again at low winter levels. During the activity peak from July to November the majority ofall movements was directed against the current while no preference for direction was noted during the rest of the year. The high level of swimming movements directed against the current in late summer and autumn may be related to an innate habitat change. From February until June, the charr exhibited a bimodal diurnal activity pattern. In July activity was evenly spread over the whole 24‐ hour period and in August and September activity was again mainly diurnal with a bimodal pattern. In October and November the activity was mainly nocturnal and in December and January activity was concentrated in the short light period. Both annual and die1 activity are discussed in relation to earlier findings in general locomotor activity in Arctic charr and other salmonids.