Download or read book Using Radioisotopes in the Age Determination of Shortraker Sebastes Borealis and Canary Sebastes Pinniger Rockfish written by Charles Edgar Hutchinson and published by . This book was released on 2004 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analysis of Age Determination Methods for Yellowtail Rockfish Canary Rockfish and Black Rockfish Off Oregon written by Lawrence D. Six and published by . This book was released on 1975 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Methods and utility of age determination of yellowtail rockfish (Sebastes flavidus), canary rockfish (Sebastes pinniger), and black rockfish (Sebastes melanops) collected off Oregon during 1972 to 1975 are discussed. Structures compared on the basis of the reproducibility of counts of annuli (consistency of readings) were the anal fin pterygiophore, opercle, otolith, scale, and vertebra. The effect of deviations between otolith readings on survival estimates and agelength relationships is presented. Consistency of otolith readings is generally superior to other structures for these three species. For yellowtail, canary, and black rockfish, respectively, 71, 76, and 77% of two independent otolith readings deviated by no more than ±1 assumed annulus. Consistency of otolith readings of all three species decreases with age. Chapman-Robson and catch curve estimates of survival and age-length relationships, derived from two readings of the same otolith, are not significantly different at the 95% level for any of the species.

Download or read book Age Validation of Canary Rockfish Sebastes Pinniger Using Two Independent Otolith Techniques written by and published by . This book was released on 2007 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: Canary rockfish (Sebastes pinniger) have long been an important part of recreational and commercial rockfish fishing from southeast Alaska to southern California, but localized stock abundances have declined considerably. Based on age estimates from otoliths and other structures, lifespan estimates vary from about 20 years to over 80 years. For the purpose of monitoring stocks, age composition is routinely estimated by counting growth zones in otoliths; however, age estimation procedures and lifespan estimates remain largely unvalidated. Typical age validation techniques have limited application for canary rockfish because they are deep dwelling and may be long lived. In this study, the unaged otolith of the pair from fish aged at the Department of Fisheries and Oceans Canada was used in one of two age validation techniques: (1) lead-radium dating and (2) bomb radiocarbon (14C) dating. Age estimate accuracy and the validity of age estimation procedures were validated based on the results from each technique. Lead-radium dating proved successful in determining a minimum estimate of lifespan was 53 years and provided support for age estimation procedures up to about 50-60 years. These findings were further supported by?14C data, which indicated a minimum estimate of lifespan was 44 ± 3 years. Both techniques validate, to differing degrees, age estimation procedures and provide support for inferring that canary rockfish can live more than 80 years.