Radiocarbon in otoliths of yelloweye rockfish (Sebastes ruberrimus): a reference time series for the coastal waters of southeast Alaska

Abstract

Atmospheric testing of thermonuclear devices during the 1950s and 1960s created a global radiocarbon (14C) signal that has provided a useful tracer and chronological marker in oceanic systems and organisms. The bomb-generated 14C signal retained in fish otoliths can be used as a time-specific recorder of the 14C present in ambient seawater, making it a useful tool in age validation of fishes. The goal of this study was to determine 14C in otoliths of the age-validated yelloweye rockfish (Sebastes ruberrimus) to establish a reference time series for the coastal waters of southeast Alaska. Radiocarbon values from the first year's growth of 43 yelloweye rockfish otoliths plotted against estimated birth year produced a 14C time series (1940–1990) for these waters. The initial rise of 14C occurred in 1958 and 14C levels rose to peak values (60–70‰) between 1966 and 1971, with a subsequent declining trend through the end of the record in 1990 (–3.2‰). In addition, the 14C data confirmed the longevity of the yelloweye rockfish to a minimum of 44 years and strongly support higher age estimates. This 14C time series will be useful for the interpretation of 14C accreted in biological samples from these waters.

Application of bomb radiocarbon chronologies to shortfin mako (Isurus oxyrinchus) age validation

“…Records from water samples (Nydal et al 1998) and corals (Druffel and Linick 1978;Druffel 1980Druffel , 1995Guilderson et al 1998) show a synchronous rise in radiocarbon levels in the late 1950s to the early 1960s, though the years of peak differ depending on the oceanography and depth of sampling. For fishes, most records have been from teleosts and followed the same trend (Kalish 1993;Campana 1997;Campana and Jones 1998;Kalish et al 2001;Kerr et al 2004). For elasmobranchs, one possible exception is with the school shark, Galeorhinus galeus, from the western South Pacific Ocean (Kalish and Johnston 2001); the first effects of the bomb radiocarbon signal may have appeared in 1979, more than 15 years after the onset recorded in otoliths from the same region (Kalish 1993).…”

Bomb dating and age validation using the spines of spiny dogfish (Squalus acanthias)

“…The D 14 C chronology of aragonitic fish otoliths in the NW Atlantic parallels that of North Atlantic corals and bivalves (Campana 1997), and thus is a good proxy for the D 14 C DIC history of the spiny dogfish environment. The reference chronologies for the northeast Pacific Ocean were drawn from known-age assays of Pacific halibut and rockfish otoliths (Kerr et al 2004;Piner and Wischniowski 2004).…”

Age validation of canary rockfish (Sebastes pinniger) using two independent otolith techniques: lead-radium and bomb radiocarbon dating

“…This uncertainty was assigned to the birth years as some indication of what might be the limit for the degree of precision in the age estimation criteria, and should not be confused with the degree of accuracy. Agreement of the estimated birth year range with the reference time-series, coupled with use of the exponential fit method, as suggested in Kerr et al (2004), was used as a basis for providing a minimum lifespan and age estimate accuracy.…”

“…ruberrimus; Kerr et al 2004) and Pacific halibut (Hippoglossus stenolepis; Piner and Wischniowshi 2004) because of the regional similarities to the canary rockfish collection locations and specifically yelloweye rockfish for the similarities in life history.…”

“…Because yelloweye rockfish were relatively easy to age from growth zone counts (CV = 4%) and lead-radium dating provided support for the age estimation procedures, a series of yelloweye rockfish otoliths were used to establish a bomb radiocarbon chronometer for the northeastern Pacific Ocean (Kerr et al 2004). The chronometer established by Kerr et al (2004) was further corroborated by an independent study of juvenile Pacific halibut (Hippoglossus stenolepis) from a similar region (Piner and Wischniowski 2004). These records subsequently provided an independent chronometer for age validation of the quillback (S. maliger; Kerr et al 2005) and bocaccio (S. paucispinis; Andrews et al 2005) rockfishes.…”