Insights from a year of field deployments inform the conservation of an endangered estuarine fish.

Autor:	Davis BE; California Department of Water Resources, 3500 Industrial Blvd., West Sacramento, CA 95691, USA., Hammock BG; Department of Anatomy, Physiology, and Cell Biology, University of California Davis, 1 Shields Ave., Davis, CA 95616, USA., Kwan N; California Department of Water Resources, 3500 Industrial Blvd., West Sacramento, CA 95691, USA., Pien C; California Department of Water Resources, 3500 Industrial Blvd., West Sacramento, CA 95691, USA.; U.S. Bureau of Reclamation Bay-Delta Office, 801 I St., Suite 140, Sacramento, CA 95814, USA., Bell H; Department of Wildlife, Fish, and Conservation Biology, University of California Davis, 1 Shields Ave., Davis, CA 95616, USA., Hartman R; California Department of Water Resources, 3500 Industrial Blvd., West Sacramento, CA 95691, USA., Baerwald MR; California Department of Water Resources, 3500 Industrial Blvd., West Sacramento, CA 95691, USA., Schreier B; California Department of Water Resources, 3500 Industrial Blvd., West Sacramento, CA 95691, USA., Gille D; California Department of Water Resources, 3500 Industrial Blvd., West Sacramento, CA 95691, USA., Acuña S; Metropolitan Water District of Southern California, 1121 L St., Suite 900, Sacramento, CA 95814, USA., Teh S; Department of Anatomy, Physiology, and Cell Biology, University of California Davis, 1 Shields Ave., Davis, CA 95616, USA., Hung TC; Fish Conservation and Culture Laboratory, Department of Biological and Agricultural Engineering, University of California Davis, 1 Shields Ave., Davis, CA 95616, USA., Ellison L; Fish Conservation and Culture Laboratory, Department of Biological and Agricultural Engineering, University of California Davis, 1 Shields Ave., Davis, CA 95616, USA., Cocherell DE; U.S. Bureau of Reclamation Bay-Delta Office, 801 I St., Suite 140, Sacramento, CA 95814, USA., Fangue NA; U.S. Bureau of Reclamation Bay-Delta Office, 801 I St., Suite 140, Sacramento, CA 95814, USA.
Jazyk:	angličtina
Zdroj:	Conservation physiology [Conserv Physiol] 2024 Dec 26; Vol. 12 (1), pp. coae088. Date of Electronic Publication: 2024 Dec 26 (Print Publication: 2024).
DOI:	10.1093/conphys/coae088
Abstrakt:	Freshwater fishes are increasingly facing extinction. Some species will require conservation intervention such as habitat restoration and/or population supplementation through mass-release of hatchery fish. In California, USA, a number of conservation strategies are underway to increase abundance of the endangered Delta Smelt ( Hypomesus transpacificus ); however, it is unclear how different estuarine conditions influence hatchery fish. The goal of this study was to evaluate a year of Delta Smelt field deployments to inform species conservation strategies of suitable conditions for smelt physiology. Hatchery-reared Delta Smelt was deployed in experimental cages (seven deployments) throughout the Estuary in the winter, summer and fall of 2019. Effects of season and location of cage deployments on fish health (condition factor and histological condition of liver and gill), growth, thermal tolerance and survival were evaluated. The results indicate both seasonal and location differences, with high survival in the winter (100%) and fall (88-92%) compared to lower survival in summer (67%). In the summer, one of the study sites had no surviving fish following high temperature exposure, which peaked ~26°C. After 29 days in the cages, surviving Delta Smelt in summer and fall showed signs of nutritional stress that may be related to biofouling of the cages limiting passive food inputs, restriction of natural foraging behaviour by containment in the cages, and water temperatures that were too high given the chronically low pelagic productivity in the Estuary overall. Field measurements of upper thermal tolerance (CTmax) following caging exposures suggest that laboratory measures of CTmax may overestimate the realized tolerance in a more stochastic field environment. This study demonstrates the utility of using cages as an experimental tool to better understand aspects of Delta Smelt physiological responses to environmental changes across estuarine habitats in a more natural-field setting, while also highlighting potential limitations of using cages. Competing Interests: There are no conflicts of interests. (© The Author(s) 2024. Published by Oxford University Press and the Society for Experimental Biology.)
Databáze:	MEDLINE
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