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Neah Bay, WA, United States

Gao Y.-W.,Makah Fisheries Management | Wang Q.-Y.,Chinese Academy of Fishery Sciences
Bulletin of Mineralogy Petrology and Geochemistry | Year: 2011

Identification of fish stocks is one of the most important tasks in fisheries science and management. In this paper,we illustrate the effect and application of stable oxygen and carbon isotopic composition of otoliths and the correlation of δ18O versus δ13C in identification of marine and anadromous fish stocks. Otoliths are aragonitic carbonate structures found in the inner ear of teleost fish and display rhythmic growth patterns. Compared with genetic methods in fish stock identification,stable oxygen and carbon isotope analyses have two distinct advantages in determining (1) a time series from the otolith microstructure to separation of the different life stages of marine and anadromous fish; and (2)the oceanographic and environmental conditions to which the fish were exposed. Thus,the isotopic signatures of otoliths and the correlation of δ18O versus δ13C play a new and important role in identification of fish stocks. Source


Gao Y.,Makah Fisheries Management | Gao Y.,Huazhong Agricultural University
Environmental Biology of Fishes | Year: 2012

Pacific halibut, Hippoglossus stenolepis, is one of the most important commercial groundfish and is managed as a single coast-wide population from Alaska to northern California. Nevertheless, genetic investigations did not show success in detecting the population structure of the species. Here I report stable oxygen and carbon isotope analyses (δ 18O and δ 13C) in otoliths to discriminate the stock differences from two sample locations between the Washington coast (WC) and the northern Puget Sound (PS), and two sample years in 2007 and 2008. In general the δ 18O values of halibut otoliths from WC ranged from -0. 2 to 1. 8‰, higher than the PS samples from -0. 5 to 1. 4‰. In contrast, the δ 13C values from WC ranged from -3. 6 to -1. 0‰, lower than the PS samples from -3. 2 to -1. 2‰. Results from the otolith nuclei (age-0 halibut) and the 8 th (the earliest maturity age for male halibut) and edge otolith rings (the latest location where the fish lived) showed significant differences between halibut samples from PS and WC. In particular, the sample location difference (between PS and WC) in both δ 13C and δ 18O data was significant and markedly larger than the sample year difference (between 2007 and 2008). These isotopic signatures provide evidence that the PS halibut may belong to a distinct stock that is significantly different from WC halibut. © 2012 Springer Science+Business Media B.V. Source


Gao Y.,Makah Fisheries Management | Gao Y.,Huazhong Agricultural University | Conrad R.,Northwest Indian Fisheries Commission | Bean D.,National Oceanic and Atmospheric Administration | Noakes D.L.G.,Oregon State University
Environmental Biology of Fishes | Year: 2013

Stable oxygen and carbon isotope (δ18O and δ13C) analyses of otoliths are becoming increasingly common in fisheries science and management. However, little is known about the statistical properties of isotopic data and few attempts have been made to explore appropriate statistical methods that could be used for otolith data analysis. In this paper, we present a pilot study on δ18O and δ13C data from otoliths of two anadromous fish species, Atlantic salmon (Salmo salar) and Pacific sockeye salmon (Oncorhynchus nerka). The results indicated that the salmon otolith data were not normally distributed, so that linear discriminant function analysis and commonly-used statistical tests such as ANOVA and the t-test may not be appropriate. Using non-parametric k-sample nearest neighbor discriminant analysis, we were able to discriminate with high accuracy among five hatcheries for Atlantic salmon and the origins of wild and hatchery sockeye salmon. Analyses also indicated that the sample sizes required to estimate δ18O and δ13C means based on the different sources of variability (between group or within group) and precision levels (≤ ±5.0 %) were not large. These results and conclusions not only address the statistical considerations of isotopic data from otoliths, but also have practical importance for fisheries management as well. © 2012 Springer Science+Business Media B.V. Source


Gao Y.,Makah Fisheries Management | Crowley S.,University of Liverpool | Conrad R.,Northwest Indian Fisheries Commission | Dettman D.L.,University of Arizona
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015

Otoliths are important proxies for climate change and ecological studies and are typically stored in glycerin or ethanol for preservation. This study is the first attempt to assess the isotopic effects of these preservatives on carbon and oxygen isotope ratios of otolith aragonite. Experimental tests from the 4th annulus of dried Pacific halibut otoliths were compared to samples from the same otoliths collected after 30day storage in either glycerin or ethanol. In addition, isotopic measurements of abiogenic pure aragonite samples soaked in glycerin, ethanol, acetone, dichlorom (DCM), and methanol were compared to the initial values following the same protocol. No δ18O effect was observed for otoliths stored in glycerin or ethanol; and no isotopic effects (both δ18O and δ13C) were observed for abiogenic pure aragonite stored in the five organic solvents commonly used in geochemical laboratories. Although there was a significant but very small difference in carbon isotope ratios of halibut otoliths, the shift was of a barely measureable magnitude and the statistically significant difference only in δ13C values may result from the inhomogeneous composition and structure of otoliths. Thus we concluded that there was no isotopic exchange during organic solvent storage or preservative interference in the isotope ratio measurements. © 2015 Elsevier B.V. Source


Gao Y.,Makah Fisheries Management | Dettman D.L.,University of Arizona | Piner K.R.,Southwest Fisheries Science Center
Transactions of the American Fisheries Society | Year: 2010

The management of many marine fish stocks suffers from a lack of genetic data or insignificant genetic differentiations, particularly for the commercially important groundfish along the U.S. Pacific coast. In this study, we investigated a large number of otoliths of various groundfish species from the coasts of Washington and Oregon and analyzed them for stable oxygen (18O/16O, or δ18O) and carbon isotope ratios (13C/12C, or δ13C). The isotopic results and correlation of δ18O versus d13C of Pacific hake Merluccius productus, sablefish Anoplopoma fimbria, Pacific halibut Hippoglossus stenolepis, and Pacific cod Gadus macrocephalus indicated that most of the groundfish we examined had two or more spawning stocks or subpopulations; the only tested species that might belong to a single coastwide stock was yelloweye rockfish Sebastes ruberrimus. Compared with genetic methods of stock identification, the isotopic signatures of otoliths have distinct advantages in determining (1) a time series to separate the different life stages of marine fish and (2) the oceanographic and environmental conditions to which fish are exposed. Thus, stable isotopic signatures in otoliths appear to be an alternative for marine fish stocks when there is little genetic differentiation between populations or no genetic data are available. © Copyright by the American Fisheries Society 2010. Source

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