A pilot study of the performance of captive‐reared delta smelt <i>Hypomesus transpacificus</i> in a semi‐natural environment

Hung, Tien‐Chieh; Rosales, Marlin; Kurobe, Tomofumi; Stevenson, Troy; Ellison, Luke; Tigan, Galen; Sandford, Marade; Lam, Chelsea; Schultz, Andrew A.

doi:10.1111/jfb.14162

Cited by 9 publications

(8 citation statements)

References 52 publications

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“…However, in our study, and in Komoroske et al, the fish appeared calm at 25 °C, and only started to appear agitated when the temperature reached 27 °C 21 . Perhaps the most plausible explanation for the differences between Swanson et al 29 and more recent studies is that the Delta Smelt in our study and others 21 , 28 , 59 were obtained from the hatchery where Delta Smelt are cultured (FCCL), whereas Swanson et al used wild-caught Delta Smelt in their CTM experiments 29 . It is likely that the culture conditions at the FCCL are more optimal than those in the wild, which could account for the higher tolerance of the Delta Smelt we observed 60 .…”

Section: Discussioncontrasting

confidence: 63%

“…The wild-caught Delta Smelt underwent antibacterial and antifungal treatments during their acclimation period 29 , which also may have affected their temperature tolerance. In addition, cultured sub-adult Delta Smelt feeding on natural prey in unfiltered, untreated water pumped from the Delta also survived up to 27 °C 59 . Other explanations for the difference in CT max values include a slower temperature adjustment during the preference trial period in the present study (6 h), a potential social component (possibly better performance in the presence of companions), or genetic differences in the test populations 61 .…”

Section: Discussionmentioning

confidence: 99%

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Temperature and salinity preferences of endangered Delta Smelt (Hypomesus transpacificus, Actinopterygii, Osmeridae)

Hung

Hammock

Sandford

et al. 2022

Sci Rep

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Temperature and salinity often define the distributions of aquatic organisms. This is at least partially true for Delta Smelt, an imperiled species endemic to the upper San Francisco Estuary. While much is known about the tolerances and distribution of Delta Smelt in relation to these parameters, little is known regarding the temperature and salinity preferences of the species. Therefore, the temperature and salinity preferences of sub-adult Delta Smelt were investigated across a wide range of thermal (8–28 °C) and salinity (0–23 ppt) conditions. Replicates of ten fish were allowed to swim between two circular chambers with different temperature or salinity, and the distribution of fish between the chambers was recorded. We found that Delta Smelt showed no temperature preference below 15 °C, a modest aversion to the warmer tank from 15 to 28 °C, and a strong aversion to the warmer tank with elevated mortality at temperatures above 28 °C. Delta Smelt also preferred lower salinities, and this preference became more pronounced as salinity increased toward 23 ppt. These results indicate that Delta Smelt can tolerate high temperatures and salinities for a short time, and that their preferences for lower temperature and salinity strengthens as these variables increase.

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Section: Discussioncontrasting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Temperature and salinity preferences of endangered Delta Smelt (Hypomesus transpacificus, Actinopterygii, Osmeridae)

Hung

Hammock

Sandford

et al. 2022

Sci Rep

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“…During the spawning season from February through May, broodstock was sorted twice a week for ripe females. As delta smelt can spawn multiple times in a spawning season (refractory time between clutches is about 40–50 days; Hung et al., 2019), only the first‐time spawners were used in this study. The ripeness of fish was determined via the egg development by gently squeezing out a very small number of eggs (less than 20) during the sorting process.…”

Section: Methodsmentioning

confidence: 99%

Size, fecundity and condition factor changes in endangered delta smelt Hypomesus transpacificus over 10 generations in captivity

Ellison

Rahman

Finger

et al. 2023

Aquaculture Fish & Fisheries

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The once abundant delta smelt Hypomesus transpacificus is now on the verge of extinction. At the UC Davis Fish Conservation and Culture Laboratory, a refuge population has been maintained since 2008 as a safeguard against extinction and to breed and provide fish for research. Due to artificial aquaculture operations, it is assumed that the fish are impacted by life in captivity leading to questions about differences between cultured and captive wild fish. This study looked at the differences in fork length (FL), body weight (BW), fecundity (F) and condition factor (K) of cultured and wild (captive) delta smelt over the last 10 generations (2009–2018) to determine if there were any changes of life‐history traits between the two, which may indicate domestication. Results revealed that the cultured population had significantly higher FL, BW, F and K than the wild population. The correlation tests found significant positive relationships between all measured traits except FL and K of wild fish. Significant changes in the measured traits of the cultured population over time were found, whereas none was observed in most wild fish year‐classes. This study demonstrated changes of life‐history traits in a well‐managed fish population over 10 generations in captivity and provides critical information to the coming supplementation plan for the species.

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“…A key concern regarding supplementation of wild populations with cultured fish is whether domesticated populations will exhibit similar fitness and survival as wild populations 80 . The higher prevalence of vaterite observed in cultured delta smelt, for example, may correspond with reduced survival in situ, thus impacting the success of supplementation 28 .…”

Section: Consequences Of Otolith Abnormalitiesmentioning

confidence: 99%

Visual, spectral, and microchemical quantification of crystalline anomalies in otoliths of wild and cultured delta smelt

Lewis

Huang

Willmes

et al. 2022

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Developmental abnormalities in otoliths can impact growth and survival in teleost fishes. Here, we quantified the frequency and severity of developmental anomalies in otoliths of delta smelt (Hypomesus transpacificus), a critically endangered estuarine fish that is endemic to the San Francisco Estuary. Left–right asymmetry and anomalous crystalline polymorphs (i.e., vaterite) were quantified and compared between wild and cultured populations using digital image analysis. Visual estimates of vaterite were validated using X-ray diffraction, Raman spectroscopy, laser ablation ICPMS, and electron probe microanalysis. Results indicated that cultured delta smelt were 80 times more likely to contain a vateritic otolith and 18 times more likely to contain relatively large (≥ 15%) amounts of vaterite. Similarly, cultured fish exhibited 30% greater asymmetry than wild fish. These results indicate that cultured delta smelt exhibit a significantly higher frequency of vestibular abnormalities which are known to reduce fitness and survival. Such hatchery effects on otolith development could have important implications for captive culture practices and the supplementation of wild fish populations with cultured individuals.

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A pilot study of the performance of captive‐reared delta smelt Hypomesus transpacificus in a semi‐natural environment

Cited by 9 publications

References 52 publications

Temperature and salinity preferences of endangered Delta Smelt (Hypomesus transpacificus, Actinopterygii, Osmeridae)

Temperature and salinity preferences of endangered Delta Smelt (Hypomesus transpacificus, Actinopterygii, Osmeridae)

Size, fecundity and condition factor changes in endangered delta smelt Hypomesus transpacificus over 10 generations in captivity

Visual, spectral, and microchemical quantification of crystalline anomalies in otoliths of wild and cultured delta smelt

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