Early life history traits and geographical distribution ofParachaenichthys charcoti

Abstract

AbstractThe geographical distribution of the two species of the genusParachaenichthysis allopatric and restricted to the inner shelves of South Georgia–South Sandwich Islands (P. georgianus) and South Orkney Islands–South Shetland Islands (P. charcoti). To evaluate the consistency between the geographical patterns of adult distribution and early life history traits ofP. charcoti, sagittal otoliths were used to estimate growth rate and pelagic duration in larvae and juveniles of this species collected in the Bransfield Strait in winter and summer, respectively. Individual age was determined through microincrement counts, assuming they were daily increments. The Gompertz model was fitted to age–length estimates, providing a mean growth rate of 0.22 mm day-1estimated for 28–204-day-old individuals. Larval hatching was spread over a relatively wide period, lasting from July throughout September. The pelagic larval duration ofP. charcotiwas about six months based on ageing data of larvae and juveniles, as reported forP. georgianusfrom South Georgia. The strong dependence of larvae on the inshore habitat may hamper their dispersal at large spatial scale limiting the connectivity among distant populations, providing clues to interpret the present geographical distribution of the two species.