Interannual variability in the early growth rate and size of the Antarctic fish Gobionotothen gibberifrons (Lönnberg)

Abstract

Gobionotothen gibberifrons <1 year old, of the 1977, 1980, 1981, 1985, 1986, 1990 and 1995 cohorts, were sampled using nets, in various periods during summer (December to February) at South Georgia. Growth in standard length (L_s) was estimated using the exponential model. Among the seven cohorts, average growth rate varied between 0.33–2.1% L_sd⁻¹, and predicted L_s for mid-January varied between 21.6–29.1 mm. Average growth rate was inversely related to mean date of sampling but was not significantly related to mean L_s. Mean sea surface temperatures were available for the 1981–95 cohorts. Average growth rate and predicted L_s for mid-January were both negatively conelated with mean December–January sea temperature, but were not significantly related to mean weekly sea surface temperature during the sampling periods. Greater average growth rate and greater L_s in cooler summers may be partly due to a large-scale pattern of environmental variability, indicated by sea temperature, that governs the timing and magnitude of the production cycle and food availability.