Radiometric age validation of golden redfish (Sebastes marinus) and deep-sea redfish (S. mentella) in the Northeast Atlantic

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

“…Bomb radiocarbon is well established as an effective method of age validation for long-lived species, often with a precision of as little as 1-2 years (Kalish 1993;Campana 2001). Given that two previous radiochemical studies have confirmed the overall accuracy of C&B preparations and sections for determining the age of S. mentella and S. marinus in the Atlantic (albeit with low precision; Campana et al 1990;Stransky et al 2005a), and in light of another two studies that have confirmed the accuracy of these methods for ageing S. mentella to an age of 10 years (Mayo et al 1981;Saborido-Rey et al 2004), the bomb radiocarbon results in the present study were initially puzzling. The consistent offset of 9 years between the NWA reference chronology and the redfish core chronology indicates that either our growth increment counts were underaged by 9 years in every fish that we aged or the NWA surface marine chronology was inappropriate for use on Sebastes spp.…”

“…Indeed, overexploitation leading to fisheries closures has already occurred in some areas (Department of SPECIAL ISSUE Fisheries and Oceans Canada, DFO 2012). The problem has been exacerbated by difficulties in age determination and controversy over the appropriate ageing method (Campana et al 1990;Nedreaas 1990;Stransky et al 2005a). Early attempts at redfish age determination using scales (Perlmutter and Clarke 1949) persisted until recently in some regions of the north-east Atlantic, but appear to grossly underestimate the ages of older fish (Nedreaas 1990).…”

“…Most redfish are now aged using either the 'crack and burn' (C&B) method or with otolith thin sections, two methods that appear to give roughly comparable results (Stransky et al 2005b). The accuracy of the C&B method has been validated in two independent radiometric studies (Campana et al 1990;Stransky et al 2005a). Nevertheless, growth parameters reported in different studies have varied widely, in part because of the difficulty of distinguishing among the three redfish species Sebastes marinus, S. mentella and S. fasciatus (Saborido-Rey et al 2004).…”

Radiometric age confirmation and growth of a deep-water marine fish species: The bank rockfish, Sebastes rufus

“…Kastelle et al (2000) detected possible increased 226 Ra activity with age for Pacific ocean perch, Sebastes alutus and rougheye rockfish, Sebastes aleutianus, but decreased 226 Ra activity with age for shortraker rockfish, Sebastes borealis. Stransky et al (2005) found no trends in 226 Ra activity with age for golden redfish, Sebastes marinus and deep-sea redfish, Sebastes mentella, but did note area-specific differences in 226 Ra activity for S. mentella.…”

Monitoring beaked redfish (Sebastes mentella) in the North Atlantic, current challenges and future prospects

“…For some stocks, indirect validation by following peaks in the length distributions has been attempted (e.g., Saborido-Rey et al 2004). Only few studies, however, have been conducted for direct validation (radiometric otolith analyses by Campana et al 1990;Stransky et al 2005), but these remain baseline studies due to their high methodological effort. For S. mentella in the Irminger Sea, longevity of at least 40 years has been confirmed (Fig.…”