Some observations on the population biology of capelin (Mallotus villosus) from Balsfjord, northern Norway

• Published in: ICES Journal of Marine Science
• Main Authors: Nyholmen, O., Hopkins, C. C. E.
• Format: Text
• Language: English
• Published: Oxford University Press 1988
• Subjects: Articles; Barents Sea; Norway; Balsfjord; Northern Norway
• Online Access: http://icesjms.oxfordjournals.org/cgi/content/short/44/3/264; https://doi.org/10.1093/icesjms/44.3.264

The population structure of capelin over a one-year period in Balsfjord (69°N 19°E), northern Norway, is described. At about one year old, young capelin changed over from a relatively pelagic orientation to one more closely associated with the bottom during the day. The semi-adult and adult part of the stock usually resided in the deep basin of the fjord during the autumn and winter (September to March) before migrating towards the head of the fjord (ca. 25 km away) in April. Beach spawning, at temperatures close to 0°C, occurred mainly in May. Although two-year-olds dominated (ca. 75%) the spawning stock in both sexes, there is a distinct likelihood of second-time spawning in females. The regression coefficient (β) for “wet” body weight on length varied greatly with season (min.–max.: males 1.980–3.867, females 2.667–3.136), significant differences were apparent between the sexes, and (β) deviated from 3 (isometric growth) in nearly all months. Possible reasons for changes in β-values are discussed. As the spawning migration is short the energetic costs of swimming cannot account for the pronounced catabolic changes noted at this time. Maturity and spawning parameters, as well as evidence from parasitological tags, indicate that Balsfjord capelin are an isolated fjordic population, segregated from the Barents Sea stock.