Survival of tagged Barents Sea capelin (Mallotus villosus Müller) and estimates of the 1973, 1974 and 1975 spawning stocks from tag returns

Abstract

Capelin tagged with internal stainless steel tags were kept in net enclosures for 8-9 days to obtain the survival factor. This was found to be 0.89 for males while additional information from routine tag recoveries indicated a survival factor of 0.51 for females. The 1973 spawning stock was calculated separately from two different groups of tagged fish released at different times during the fishery. The resulting estimates were 2.2 and 4.1 million metric tonnes. The 1974 spawning stock was calculated from three tagging experiments. The resulting estimates were 5.8, 1.1 and 1.9 million tonnes. The highest value is rejected as being obviously too high. The 1975 spawning stock was calculated from two tagging experiments. Both gave an estimate of 1.1 million tonnes. Some possible causes of error in the estimates are discussed.