Age determination and growth of orange roughy (Hoplostethus atlanticus): a comparison of annulus counts with radiometric ageing

Abstract

Ages of orange roughy (Hoplostethus atlanticus) determined by two methods (counting annuli on the surface of whole and in longitudinally sectioned otoliths) were similar up to maturity. Beyond maturity, age estimates from sectioned otoliths exceeded those from whole otoliths. Maximum recorded age was 125 years for an individual 41 cm standard length (SL), and age at maturity was estimated to be 25 years (30–32 cm SL). These are consistent with ages estimated previously by radiometric methods. Results demonstrated a two-stage linear relationship between otolith weight and age that confirmed the two-stage otolith mass growth model previously used in radiometric ageing. However, in the radiometric analyses the reduction in otolith growth was arbitrarily estimated at 45% of the immature rate whereas annuli data demonstrated a reduction after maturity to 62% of the immature rate. The new estimates of otolith mass growth rate were incorporated into the radiometric data and ages recalculated, which reduced age estimates for 38–40 cm SL fish from 77–149 to 59–101 years. The radiometric data were also recalculated using only the percentage reduction in otolith growth after maturity, giving the radiometric age of 125 ± 9 years for the oldest fish.

Biomass spectra in benthic fish assemblages in the Benguela System

“…Similarly, certain members of the most abundant species of teleost fishes on the lower slope have extremely slow growth rates (e.g. Smith et al 1995, Stewart et al 1995, unlike the predominant species on the shelf (Crawford et al 1987 and references therein).…”

Indicators of recovery for orange roughy (Hoplostethus atlanticus) in eastern Australian waters fished from 1987

“…Otoliths were longitudinally thin-sectioned to allow growth-zone counting. Preparation and ageing methods follow those developed by Smith et al (1995). Total orange roughy age is determined by the number of annuli counted from the primordia to the transition point (TZ) plus the number of zones counted from the TZ to the otolith edge.…”

Image-enhanced burnt otoliths, bomb radiocarbon and the growth dynamics of redfish (Sebastes mentella and S. fasciatus) off the eastern coast of Canada

“…For example, the orange roughy (Hoplostethus atlanticus) off New Zealand was fished intensively on the basis of a presumed longevity of 20-30 years (Tracey and Horn 1999). By the time it was realised that the species grew extremely slowly and could live to an age of more than 100 years (Smith et al 1995;Andrews et al 2009), the damage had been done and many populations had already been fished almost to the point of collapse. It is possible that roundnose grenadier (Coryphaenoides rupestris) in the north-west Atlantic will never recover from its fishery, in part because of slow growth rates and longevities of 60 years, which are much greater than previously suspected (Clarke et al 2003).…”