Experimental validation of otolith-based age and growth reconstructions across multiple life stages of a critically endangered estuarine fish
Background The application of otolith-based tools to inform the management and conservation of fishes first requires taxon- and stage-specific validation. The Delta Smelt (Hypomesus transpacificus), a critically endangered estuarine fish that is endemic to the upper San Francisco Estuary (SFE), Cali...
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| Format: | Article |
| Language: | English |
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PeerJ Inc.
2021-11-01
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| Series: | PeerJ |
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| Online Access: | https://peerj.com/articles/12280.pdf |
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| author | Wilson Xieu Levi S. Lewis Feng Zhao Rachel A. Fichman Malte Willmes Tien-Chieh Hung Luke Ellison Troy Stevenson Galen Tigan Andrew A. Schultz James A. Hobbs |
| author_facet | Wilson Xieu Levi S. Lewis Feng Zhao Rachel A. Fichman Malte Willmes Tien-Chieh Hung Luke Ellison Troy Stevenson Galen Tigan Andrew A. Schultz James A. Hobbs |
| author_sort | Wilson Xieu |
| collection | DOAJ |
| description | Background The application of otolith-based tools to inform the management and conservation of fishes first requires taxon- and stage-specific validation. The Delta Smelt (Hypomesus transpacificus), a critically endangered estuarine fish that is endemic to the upper San Francisco Estuary (SFE), California, United States, serves as a key indicator species in the SFE; thus, understanding this species’ vital rates and population dynamics is valuable for assessing the overall health of the estuary. Otolith-based tools have been developed and applied across multiple life stages of Delta Smelt to reconstruct age structure, growth, phenology, and migration. However, key methodological assumptions have yet to be validated, thus limiting confidence in otolith-derived metrics that are important for informing major water management decisions in the SFE. Methods Using known-age cultured Delta Smelt and multiple independent otolith analysts, we examined otolith formation, otolith-somatic proportionality, aging accuracy and precision, left-right symmetry, and the effects of image magnification for larval, juvenile, and adult Delta Smelt. Results Overall, otolith size varied linearly with fish size (from 10–60 mm), explaining 99% of the variation in fish length, despite a unique slope for larvae < 10 mm. Otolith-somatic proportionality was similar among wild and cultured specimens. Aging precision among independent analysts was 98% and aging accuracy relative to known ages was 96%, with age estimates exhibiting negligible differences among left and right otoliths. Though error generally increased with age, percent error decreased from 0–30 days-post-hatch, with precision remaining relatively high (≥ 95%) thereafter. Increased magnification (400×) further improved aging accuracy for the oldest, slowest-growing individuals. Together, these results indicate that otolith-based techniques provide reliable age and growth reconstructions for larval, juvenile, and adult Delta Smelt. Such experimental assessments across multiple developmental stages are key steps toward assessing confidence in otolith-derived metrics that are often used to assess the dynamics of wild fish populations. |
| first_indexed | 2024-03-09T07:27:21Z |
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| institution | Directory Open Access Journal |
| issn | 2167-8359 |
| language | English |
| last_indexed | 2024-03-09T07:27:21Z |
| publishDate | 2021-11-01 |
| publisher | PeerJ Inc. |
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| spelling | doaj.art-900dcf0f54c64784926a646ecf1900ff2023-12-03T06:52:06ZengPeerJ Inc.PeerJ2167-83592021-11-019e1228010.7717/peerj.12280Experimental validation of otolith-based age and growth reconstructions across multiple life stages of a critically endangered estuarine fishWilson Xieu0Levi S. Lewis1Feng Zhao2Rachel A. Fichman3Malte Willmes4Tien-Chieh Hung5Luke Ellison6Troy Stevenson7Galen Tigan8Andrew A. Schultz9James A. Hobbs10Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, CA, United States of AmericaDepartment of Wildlife, Fish, and Conservation Biology, University of California, Davis, CA, United States of AmericaDepartment of Wildlife, Fish, and Conservation Biology, University of California, Davis, CA, United States of AmericaDepartment of Wildlife, Fish, and Conservation Biology, University of California, Davis, CA, United States of AmericaInstitute of Marine Sciences, University of California, Santa Cruz, CA, United States of AmericaDepartment of Biological and Agricultural Engineering, University of California, Davis, CA, United States of AmericaDepartment of Biological and Agricultural Engineering, University of California, Davis, CA, United States of AmericaDepartment of Biological and Agricultural Engineering, University of California, Davis, CA, United States of AmericaDepartment of Biological and Agricultural Engineering, University of California, Davis, CA, United States of AmericaBay-Delta Office, United States Bureau of Reclamation, Sacramento, CA, United States of AmericaDepartment of Wildlife, Fish, and Conservation Biology, University of California, Davis, CA, United States of AmericaBackground The application of otolith-based tools to inform the management and conservation of fishes first requires taxon- and stage-specific validation. The Delta Smelt (Hypomesus transpacificus), a critically endangered estuarine fish that is endemic to the upper San Francisco Estuary (SFE), California, United States, serves as a key indicator species in the SFE; thus, understanding this species’ vital rates and population dynamics is valuable for assessing the overall health of the estuary. Otolith-based tools have been developed and applied across multiple life stages of Delta Smelt to reconstruct age structure, growth, phenology, and migration. However, key methodological assumptions have yet to be validated, thus limiting confidence in otolith-derived metrics that are important for informing major water management decisions in the SFE. Methods Using known-age cultured Delta Smelt and multiple independent otolith analysts, we examined otolith formation, otolith-somatic proportionality, aging accuracy and precision, left-right symmetry, and the effects of image magnification for larval, juvenile, and adult Delta Smelt. Results Overall, otolith size varied linearly with fish size (from 10–60 mm), explaining 99% of the variation in fish length, despite a unique slope for larvae < 10 mm. Otolith-somatic proportionality was similar among wild and cultured specimens. Aging precision among independent analysts was 98% and aging accuracy relative to known ages was 96%, with age estimates exhibiting negligible differences among left and right otoliths. Though error generally increased with age, percent error decreased from 0–30 days-post-hatch, with precision remaining relatively high (≥ 95%) thereafter. Increased magnification (400×) further improved aging accuracy for the oldest, slowest-growing individuals. Together, these results indicate that otolith-based techniques provide reliable age and growth reconstructions for larval, juvenile, and adult Delta Smelt. Such experimental assessments across multiple developmental stages are key steps toward assessing confidence in otolith-derived metrics that are often used to assess the dynamics of wild fish populations.https://peerj.com/articles/12280.pdfOtolithFishEstuarineFreshwaterGrowthValidation |
| spellingShingle | Wilson Xieu Levi S. Lewis Feng Zhao Rachel A. Fichman Malte Willmes Tien-Chieh Hung Luke Ellison Troy Stevenson Galen Tigan Andrew A. Schultz James A. Hobbs Experimental validation of otolith-based age and growth reconstructions across multiple life stages of a critically endangered estuarine fish PeerJ Otolith Fish Estuarine Freshwater Growth Validation |
| title | Experimental validation of otolith-based age and growth reconstructions across multiple life stages of a critically endangered estuarine fish |
| title_full | Experimental validation of otolith-based age and growth reconstructions across multiple life stages of a critically endangered estuarine fish |
| title_fullStr | Experimental validation of otolith-based age and growth reconstructions across multiple life stages of a critically endangered estuarine fish |
| title_full_unstemmed | Experimental validation of otolith-based age and growth reconstructions across multiple life stages of a critically endangered estuarine fish |
| title_short | Experimental validation of otolith-based age and growth reconstructions across multiple life stages of a critically endangered estuarine fish |
| title_sort | experimental validation of otolith based age and growth reconstructions across multiple life stages of a critically endangered estuarine fish |
| topic | Otolith Fish Estuarine Freshwater Growth Validation |
| url | https://peerj.com/articles/12280.pdf |
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