Quantitative reconstruction of salinity history by otolith oxygen stable isotopes: An example of a euryhaline fish <scp><i>Lateolabrax japonicus</i></scp>

Chang

Rapid Comm Mass Spectrometry

et al. 2021

Self Cite

Rationale: For years, archaeologists, climatologists, and ecologists have used stable oxygen isotope values (δ 13 C, δ 18 O) in fish otoliths from archaeological sites to reconstruct the habitats, paleo-temperature, and seasonality of the fish captures.Otoliths from archaeological sites might have been heated when ancient people cooked the fish for food. Therefore, there are debates as to whether the cooking behaviors would cause further isotopic fractionations of the carbonate in the otoliths.Methods: In this study, we have evaluated the effects of the cooking methods on the otolith δ 13 C and δ 18 O values by comparing the otoliths of the javelin grunter (Pomadasys kaakan) from the same individuals, with the left otoliths taken out before the different cooking processes. Otolith sections of the fish were then made and several subsamples were milled along the microstructures visible in the otolith pairs, mostly annual check rings, followed by the stable isotope analyses.Results: There were no morphological changes between the cooked and uncooked otoliths. The δ 13 C and δ 18 O values were highly consistent for the otolith subsamples between the cooked and uncooked pairs, suggesting none or trivial effects of the cooking processes on the isotopic values of the otoliths. In addition, some javelin grunters showed lower δ 13 C (À5‰ to À6‰) and δ 18 O (À4‰ to À5‰) values deposited in the wide translucent zone of the otoliths, suggesting seasonal migration of the fish to estuaries during the summer.Conclusions: This study suggests that cooking processes do not change otolith stable isotopic compositions and will therefore allow for future research to use the otolith δ 13 C and δ 18 O values to better understand the life history and used habitats of the preserved fish remains in the middens. | INTRODUCTIONFish otoliths are biomineralized structures located in the inner ear of teleosts. Otoliths continuously grow by accreting CaCO 3 ($98%), organic matter ($2%), and a few other elements in a daily and seasonal period, 1 thus recording the age of the fish and environmental information. 2 Owing to the cranial protection, many otoliths were well preserved in the sediment and archaeological sites after the death of the fish. As a result, otoliths are often found in coastal archaeological sites around the world which have been used for the studies of anthropology, ecology, and climate changes. 3,4 For instance, site catchment, fish species and size historically utilized can be discovered from the morphology and the size of the otoliths. 5,6 Besides, biogeochemical analyses such as carbon (δ 13 C) and oxygen (δ 18 O)

Section: Discussionmentioning

confidence: 76%

Section: Discussionmentioning

confidence: 99%

Evaluation of cooking effects on otolith stable carbon and oxygen isotope values of teleostean fish Pomadasys kaakan (Cuvier, 1830)

Chang

Rapid Comm Mass Spectrometry

et al. 2021

Self Cite

“…Other than seawater temperature, seasonal fluctuations in primary productivity and food supply may also affect the deposition of translucent and opaque zones in the otoliths of S. commerson [24]. This phenomenon is observed in numerous subtropical and tropical species, in which opaque zones develop in otoliths during the cold season when fish metabolism is lower, and translucent zones develop during periods of accelerated growth (e.g., [39,40]).…”

Section: Age Validationmentioning

confidence: 99%

Demographics of Scomberomorus commerson in the Central Taiwan Strait

Weng

Cheng

et al. 2021

JMSE

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The narrow-barred Spanish mackerel Scomberomorus commerson is an economically essential species; however, few studies have investigated its demographic structure in the northwestern Pacific, which includes Taiwan’s waters. This study examined the growth parameters, age composition, mortality, and sex ratio of S. commerson catches by examining sagittal otoliths and other biological data collected in a 3-year project from June 2018 to June 2021. The transverse sections of sagittal otoliths exhibited alternating translucent and opaque zones, in annual cycles, and this observation was validated by otolith edge analysis. Opaque zones began to form in October; the growth peaked in December and lasted until March. Growth parameters were estimated for female (L∞ = 144.1 cm fork length [FL], k = 0.39 y−1, to = −0.85 y) and male (L∞ = 136.0 cm FL, k = 0.32 y−1, to = −1.49 y) specimens. The maximum recorded FL, body weight, and age were 159.0 cm, 27 kg, and 9.2 y for female and 135.0 cm, 17.8 kg, and 7.2 y for male specimens. Rapid growth was observed for both sexes, with FL reaching 66.8 ± 14.2 cm in female specimens and 70.1 ± 11.0 cm in male specimens during the first year of life. An age–length key based on the direct otolith aging and FL dataset (N = 646) was used to estimate the age composition of 3-year catches measured at landing (N = 16,133). The results verified that the S. commerson currently caught in the central Taiwan Strait are mainly young fish aged 1+ to 2+ y. The estimated fishing mortality (0.27 y−1) and exploitation rate (0.30) suggested that overfishing was not occurring in this stock. The findings of this study have helped clarify the population dynamics of the S. commerson in the Taiwan Strait, and the biological parameters reported herein can aid the management and conservation to ensure the sustainability of this species in this region.

“…In the case of marine fish, the 18 O: 16 O ratio (d 18 O) in otoliths is the most frequently used isotope ratio for iso-logging (e.g. Trueman et al, 2012;Hsieh et al, 2019;Sakamoto et al, 2019). d 18 O can be retrospectively measured from otoliths and reflects the ambient temperature experienced by the fish.…”

Section: Introductionmentioning

confidence: 99%

Using geostatistical analysis for simultaneous estimation of isoscapes and ontogenetic shifts in isotope ratios of highly migratory marine fish

et al. 2022

Tracking migration of highly migratory marine fish using isotope analysis (iso-logging) has become a promising tool in recent years. However, application of this method is often hampered by the lack of essential information such as spatial variations in isotope ratios across habitats (isoscapes) and ontogenetic shifts of isotope ratios of target animals. Here, we test the utility of geostatistical analysis to generate isoscapes of δ13C and δ15N in the western Pacific and estimate the ontogenetic shifts in δ13C and δ15N values of a target species. We first measured δ13C and δ15N in the white muscle of juvenile (n = 210) and adult (n = 884) skipjack tuna Katsuwonus pelamis sampled across the northwest Pacific. Next we fitted a geostatistical model to account for the observed spatial variations in δ13C and δ15N of skipjack by fork length and other environmental variables with spatial random effects. We then used the best-fit models to predict the isoscapes of δ13C and δ15N in 2021. Furthermore, we measured δ15N of amino acids (δ15NAAs) of skipjack (n = 5) to determine whether the observed spatial variation of isotope ratios resulted from baseline shifts or differences in trophic position. The geostatistical model reasonably estimated both isoscapes and ontogenetic shifts from isotope ratios of skipjack, and the isoscapes showed that δ13C and δ15N can clearly distinguish the latitudinal migration of skipjack in the western Pacific. The δ15NAAs supported the results of the geostatistical model, that is, observed variations in skipjack δ15N were largely derived from a baseline shift rather than regional differences in trophic position. Thus, we showed that geostatistical analysis can provide essential basic information required for iso-logging without compound-specific isotope analysis.