SPAWNING ACTIVITY OF MALE AND FEMALE PIKE, ESOX-LUCIUS L, DETERMINED BY ACOUSTIC TRACKING

Two male and three female pike, Esox lucius L., were tracked by means of intraperitoneally implanted acoustic transmitters prior to and thro ughout the 1988 spawning season in Loch Davan, Scotland. Highly signif icant variations in activity occurred on a diel and seasonal basis. Fi sh were relatively inactive at night for the whole of the tracking per iod. Mean daily distance moved ranged between 0.43 and 0.44 km . d-1 f or females and between 0.24 and 0.38 km . d-1 for males in the weeks p receding spawning (March 27 - April 16); increased to a peak of 1.13 k m . d-1 for females and 1. 72 km . d-1 for males in the week April 24- 30; and subsequently decreased to prespawning levels, 0.29 km . d-1 fo r females and 0.24 km . d-1 for males, by the week May 8-14. Levels of visually observed pike spawning activity followed a similar pattern. Males were more active than females for most of the spawning period; n o significant differences were found before and after spawning. Highes t levels of activity coincided with elevated water levels and water te mperatures of 8-1O-degrees-C.