Growth and Survival of Apache Trout Under Static and Fluctuating Temperature Regimes. Issue 5 (30th August 2014)

• Record Type: Journal Article
• Authors: Recsetar, Matthew S.; Bonar, Scott A.; Feuerbacher, Olin G.
• Is Part Of: Transactions of the American Fisheries Society. Volume 143:Issue 5(2014)
• Page Start: 1247
• Page End: 1254
• Publication Date: 2014-08-30
• Subjects: Fish culture -- Periodicals; Fishery management -- Periodicals; Pisciculture -- Périodiques; 639.2
• DOI: 10.1080/00028487.2014.931298
• Languages: English
• ISSNs: 0002-8487

Abstract

Abstract: Increasing stream temperatures have important implications for arid‐region fishes. Little is known about effects of high water temperatures that fluctuate over extended periods on Apache Trout Oncorhynchus gilae apache, a federally threatened species of southwestern USA streams. We compared survival and growth of juvenile Apache Trout held for 30 d in static temperatures (16, 19, 22, 25, and 28°C) and fluctuating diel temperatures (±3°C from 16, 19, 22 and 25°C midpoints and ±6°C from 19°C and 22°C midpoints). Lethal temperature for 50% (LT50) of the Apache Trout under static temperatures (mean [SD] = 22.8 [0.6]°C) was similar to that of ±3°C diel temperature fluctuations (23.1 [0.1]°C). Mean LT50 for the midpoint of the ±6°C fluctuations could not be calculated because survival in the two treatments (19 ± 6°C and 22 ± 6°C) was not below 50%; however, it probably was also between 22°C and 25°C because the upper limb of a ±6°C fluctuation on a 25°C midpoint is above critical thermal maximum for Apache Trout (28.5–30.4°C). Growth decreased as temperatures approached the LT50. Apache Trout can survive short‐term exposure to water temperatures with daily maxima that remain below 25°C and midpoint diel temperatures below 22°C. However, median summer stream temperatures must remain below 19°C for best growth and even lower if daily fluctuations are high (≥12°C). Received June 26, 2013; accepted May 19, 2014