Growth and survival of Icelandic capelin Mallotus villosus larvae

Otolith increment analysis was used to reconstruct daily growth of 2 year-classes of capelin larvae, from hatch until 4 mo of age. Larvae were sampled on the continental shelf around Iceland during August 2001 and 2002. Mean hatch dates were not different between years, but hatching started earlier and lasted longer in 2002. Somatic growth was significantly faster in 2001 (0.4 mm d(-1)) than 2002 (0.3 mm d(-1)). Larvae shared a common otolith growth trajectory both within and between year-classes, described by 3 different growth phases: an initial latency period followed by a period of accelerating growth before reaching an asymptote. Daily otolith growth of the 2001 year-class was significantly faster in the age ranges 21 to 50 d and 61 to 100 d, with larvae having an average asymptotic growth of 2.1 mu m d(-1) in 2001 and 2.0 mu m d(-1) in 2002. Average daily otolith growth for calendar day increased from June to mid-July each year, decreased until early August, and then increased again. Average sea surface temperature on the capelin nursery ground increased from March to August, and was higher in 2001 than 2002. The decrease in growth during increasing ambient temperature indicates that other environmental factors have significant effects on seasonal growth. Survival rate of larvae from hatch until August was 3 times higher in 2001 when larvae grew faster. Faster growth and higher survival during the first 4 mo of the 2001 year-class did not carry over to higher absolute recruitment at maturity.