Pacific halibut Hippoglossus stenolepis of known age were used to create a reference chronology of radiocarbon levels for the years 1944-1981. Levels of radiocarbon in Pacific halibut otoliths pre-1958 were among the lowest reported to date, but radiocarbon levels increased dramatically post-1960. Subsequently, this reference chronology was used to validate ages determined using the standard break and burn and surface ageing technique. These older fish were collected at a later date but were born during this period of rapidly increasing radiocarbon levels. Otolith cores were compared to the reference chronology based upon the presumed birth year determined from annulus counts and year of capture. The ages derived from both break and burn and surface ageing methods were determined to be accurate. # 2004 The Fisheries Society of the British Isles
The hypothesis was tested that the sagittae of age 2 year Pacific halibut Hippoglossus stenolepis are interchangeable, by analysing whole-otolith preparations for element-to-calcium ratios of 10 trace metals ( 7 Li, 25 Mg, 55 Mn, 56 Fe, 60 Ni, 63 Cu, 66 Zn, 88 Sr, 138 Ba and 208 Pb) and carbon and oxygen stable isotope ratios (d 13 C and d 18 O). After detrending for significant (a ¼ 0Á05) relationships between elemental concentration and otolith mass, significant (paired t-tests, P < 0Á01) asymmetry was detected in d 13 C and d 18 O, and 88 Sr: 48 Ca. Right (smaller) sagittae exhibited higher d 13 C and d 18 O, and lower 88 Sr: 48 Ca, than left sagittae. Significant (a ¼ 0Á05) left-right differences were not detected in the remained trace metals. Given that sagittae are the same size at hatch and diverge as H. stenolepis age, the larger otolith is presumably biased towards later-accreted carbonate. Estuarine-reared flatfish probably exhibit more pronounced dissimilarities than observed here, given greater environmental variability in such habitats relative to coastal halibut nurseries, and the importance of salinity and temperature in regulating elemental uptake.Journal compilation # 2008 The Fisheries Society of the British Isles No claim to original US government works
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