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Title: Radiometric validation of age, growth, and longevity for the blackgill rockfish (Sebastes melanostomus),
Description: As nearshore fish populations decline, many commercial fishermen have shifted fishing effort to deeper continental slope habitats to target fishes for which biological information is limited. One such fishery that developed in the northeastern Pacific Ocean in the early 1980s was for the blackgill rockfish (Sebastes melanostomus), a deep-dwelling (300-800 m) species that congregates over rocky pinnacles, mainly from southern California to southern Oregon. Growth zone-derived age estimates from otolith thin sections were compared to ages obtained from the radioactive disequilibria of 210Pb, in relation to its parent, 226Ra, in otolith cores of blackgill rockfish. Age estimates were validated up to 41 years, and a strong pattern of agreement supported a longevity exceeding 90 years. Age and length data fitted to the von Bertalanffy growth function indicated that blackgill rockfish are slow-growing (& = 0.040 females, 0.068 males) and that females grow slower than males, but reach a greater length. Age at 50% maturity, derived from previously published length-atmaturity estimates, was 17 years for males and 21 years for females. The results of this study agree with general life history traits already recognized for many Sebastes species, such as long life, slow growth, and late age at maturation. These traits may undermine the sustainability of blackgill rockfish populations when heavy fishing pressure, such as that which occurred in the 1980s, is applied., Cited By (since 1996):13, CODEN: FSYBA, ,
Author: Stevens, Andrews, Cailliet, Coale, Lundstrom
Date: 2004-01-01T00:00:00Z

Title: Application of an ion-exchange separation technique and thermal ionization mass spectrometry to 226Ra for radiometric age determination of long-lived fishes,
Description: Cited By (since 1996):31, , , ,
Author: Andrews, Coale, Nowicki, Lundstrom, Palacz, Burton, Cailliet
Date: 1999-01-01T00:00:00Z

Title: Radiometric validation of age, growth, and longevity for the blackgill rockfish (Sebastes melanostomus),
Description: Cited By (since 1996):13, , , ,
Author: Stevens, Andrews, Cailliet, Coale, Lundstrom
Date: 2004-01-01T00:00:00Z

Title: Bomb radiocarbon and lead-radium disequilibria in otoliths of bocaccio rockfish (Sebastes paucispinis),
Description: Longevity estimates for the bocaccio rockfish (Sebastes paucispinis) using traditional techniques range from less than 20 years to approximately 50 years. Otoliths of bocaccio are difficult to age, and previous attempts to validate ages have been unsuccessful. Because otolith age suggests the bocaccio are reasonably long-lived, lead-radium dating was used in an attempt to independently age bocaccio otoliths. The measured 210Pb and 226Ra activities were among the lowest reported and resulted in poor radiometric age resolution; however, the break-and-burn technique clearly underestimated age in some cases with the longevity of the bocaccio being at least 31 years. To provide better age resolution, the bomb radiocarbon approach was applied to individual otoliths. Based on measured radiocarbon levels relative to a reference time-series, several specimens were aged at approximately 30-40 years. To evaluate these determinations, the remaining otolith of the pair was sectioned and aged blind. The result was an excellent fit to the reference time-series and a validation of the age estimates. The maximum age from growth zone counts was 37 ± 2 years, which is consistent with a reported maximum age of approximately 50 years. © CSIRO 2005., Cited By (since 1996):18, Fish and Fisheries, CODEN: AJMFA, ,
Author: Andrews, Burton, Kerr, Cailliet, Coale, Lundstrom, Brown
Date: 2005-01-01T00:00:00Z

Title: Bomb radiocarbon and lead-radium disequilibria in otoliths of bocaccio rockfish (Sebastes paucispinis): A determination of age and longevity for a difficult-to-age fish,
Description: , , , ,
Author: Andrews, Burton, Kerr, Cailliet, Coale, Lundstrom, Brown

Title: Application of an ion-exchange separation technique and thermal ionization mass spectrometry to 226Ra for radiometric age determination of long-lived fishes,
Description: To improve the accuracy and precision of radiometric age determination using 210Pb: 226Ra disequilibria in otoliths of fishes, a technique was developed incorporating an ion-exchange procedure followed by isotope-dilution thermal ionization mass spectrometry (TIMS) to determine 226Ra. This technique counts ionized radium atoms directly; therefore, the uncertainty of the technique is superior to conventional radio-decay dependent techniques. Calcium and barium are major components of the otolith matrix that can interfere with TIMS analysis of radium. To remove these interferants, an ion-exchange separation procedure was developed. This procedure was tested by applying it to otolith samples from three fish species in three separate radiometric ageing studies. The resultant separations and TIMS determinations indicate that the procedure efficiently separates radium from calcium and barium. Measured 226Ra activities for each species were similar to previous radiometric ageing studies, with the exception of one sample. When results were compared with traditional 226Ra determination techniques, radon emanation and α-spectrometry, the separation procedure with isotope-dilution TIMS had significant advantages. Samples over three times smaller than attempted in other studies were processed with decreased uncertainty and processing time., Cited By (since 1996):30, Fish and Fisheries, CODEN: CJFSD, ,
Author: Andrews, Coale, Nowicki, Lundstrom, Palacz, Burton, Cailliet
Date: 1999-01-01T00:00:00Z