Age, growth, distribution and ecological aspects of Conger conger leptocephali collected in the Azores, based on otolith analysis of premetamorphic specimens

A total of 29 specimens of the anguillid leptocephali Conger conger were collected by the R.V. "Arquipélago", Department of Fisheries and Oceanography, University of Azores, in the waters south of the central group of the Azores Islands in October 1999. The meristic counts, morphologic features and pigmentation patterns of the leptocephali agree with the descriptions by other authors of this species. Leptocephali were found to range from 51.5 to 126.5 mm length and show a positively skewed distribution. The somatic growth rate (0.31 mm day-1), estimated from the linear regression of length on age, falls within the ranges reported by several authors for other anguilliform species. Back-calculated hatching dates from the otolith microstructure suggests a long spawning season, from January to July, with one visible annual peak, occurring in summer. The analysis of our collection data in light of the current physical oceanographic knowledge of the NE Atlantic suggests that it is unlikely that the Azorean specimens came from the Mediterranean, unless the larvae were capable of very active and oriented swimming; thus the existence of another spawning place for this species somewhere near the Azores Archipelago is probable.