Preliminary estimates of the age and growth of immature smooth oreo Pseudocyttus maculatus Gilchrist 1906 (Oreosomatidae) in the Falkland Islands region of the South Atlantic

Abstract

Sectioned otoliths were used to estimate the age of 29 specimens of the smooth oreo (Pseudocyttus maculatus Gilchrist 1906) from the Falkland Islands region of the South Atlantic. This represents the first ageing study of this species in this region of the world. All specimens were immature (sub-adults), the largest having a maximum total length of 347 mm. Growth increments were observed in sectioned otoliths and assumed to be annual in periodicity. The maximum age estimate of individuals in this study was 20 years and the form of somatic growth was similar to previous research on this species from Australian waters. The otolith microstructure consisted of an inner, mostly opaque zone with wide increments followed by an outer, mostly translucent zone with narrower increments. It is suggested that these zones correspond to the two growth phases in the life history of this species, namely the pelagic juvenile phase (opaque zone) and the demersal sub-adult/adult phase (translucent zone).