Growth of Icelandic capelin (Mallotus villosus) larvae

Abstract

Predicting recruitment is a difficult task and requires solid biological information. Recruitment in capelin is important to the spawning stock biomass due to a short life span. Theory predicts that faster growing, larger individuals will have greater survival. Growth history of two year-classes of Icelandic capelin (Mallotus villosus) larvae was examined from hatching until end of summer in their first year of life. Precision of otolith analysis was independent of larval age and growth estimates were not statistically different between replicates. Estimated growth of 0.37 mm d⁻¹ for the 2001 year-class was in the upper end of growth rates while growth of the 2002 yearclass, 0.28 mm d⁻¹, was average for capelin larval growth reported in the literature. Increment width models demonstrated a common growth trajectory both within and among year-classes. Environmental conditions were better in 2001 as temperature was higher by roughly 0.7°C and zooplankton biomass was four times greater. This indicates that better environmental conditions facilitated growth of capelin larvae. The spawning stock biomass was similar between years but abundance of capelin larvae in August was three times higher in 2001 suggesting that survival rate of larvae was higher in 2001. The faster growth and greater abundance of the 2001 year-class suggests that growth of capelin larvae was density independent.