Fishes move to transient local refuges, not persistent landscape refuges during river drying experiment

Freshwater Biology, Journal Year: 2024, Volume and Issue: 69(6), P. 792 - 808

Published: April 1, 2024

Abstract Anthropogenically driven flow intermittency is increasing in freshwater streams, with important implications for the management and conservation of aquatic ecosystems. Because most fishes are mobile, they expected to emigrate from intermittent reaches, but this may not be true streams transitioning perennial intermittent. Here, we attempt determine if riverine vacate drying reaches before or remain local refuges. We implemented a controlled, situ experimental reduction resulting intermittency, reducing flows ~1.0 0 m 3 /s over 3‐week period. monitored fish fish‐habitat changes 5‐week period before, during after reductions. During reductions, total wetted habitat was ultimately reduced by 91%. Habitat loss time equal among types: pool increased slightly as run habit lost, backwater isolated habitats were strongly related discharge. Likewise, water depth decreased faster than other habitats. Only river carpsucker Carpiodes carpio appeared move upstream recession; seven species remained within sites. negatively affected populations, at lower rate that which until sites dried completely. Overall, two species, red shiner Cyprinella lutrensis western mosquitofish Gambusia affinis , had population growth study, whereas remaining declines. Fishes able find transient refuges reductions did conditions. Accounting lack emigration anthropogenic flow‐intermittent will designing actions threatened intermittency. Creation refuge effective widely dispersed do actively seek habitats, unless those support enough individuals maintain resilience following

Language: Английский

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Genetic erosion in an endangered desert fish during a megadrought despite long‐term supportive breeding

Conservation Biology, Journal Year: 2023, Volume and Issue: 38(1)

Published: July 25, 2023

Human water use combined with a recent megadrought have reduced river and stream flow through the southwest United States led to periodic drying of formerly perennial segments. Reductions in snowmelt runoff increased extent collectively threaten short-lived, obligate aquatic species, including endangered Rio Grande silvery minnow (Hybognathus amarus). This species is subject boom-and-bust population dynamics, under which large fluctuations abundance are expected lower estimates effective size erode genetic diversity over time. Rates loss also affected by additions hatchery-origin fish used supplement wild population. We demographic data from hatchery individuals examine relationship last two decades. Genetic was low during early 2000s, but metrics stabilized after program initiated environmental conditions improved. Yet, 2017 onward, allelic declined (Cohen's d = 1.34) remained despite stocking brief recovery. Across time series, single-sample based on linkage disequilibrium (LD N

Language: Английский

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Postrelease growth and maturity of hatchery-reared Rio Grande Silvery Minnow

North American Journal of Fisheries Management, Journal Year: 2025, Volume and Issue: unknown

Published: April 19, 2025

Abstract Objective Captive propagation and supplementation are used for conservation of endangered fishes. Breeding programs have been to prevent extinction the Rio Grande Silvery Minnow Hybognathus amarus. However, postrelease effectiveness is not often evaluated. Our objective was compare growth rate size at maturity between wild hatchery-reared individuals this short-lived species. Comparing patterns hatchery those will provide insight into optimization improve strategies. Methods We multiple long-term data sets length measurements estimate rates maturity. age obtained from otoliths compared them known-age released in middle Grande, New Mexico. First, we estimated von Bertalanffy parameters based on monthly intervals. Next, logistic regression collected 2018–2019 individuals. Results Hatchery-reared were smaller than their counterparts release remained so until an about 1.5 years. Hatchery fish grew slower (growth coefficient k = 0.08) (k 0.10) but had a larger average maximum (86.6 mm versus 78.6 standard length). that over 50% females sexually mature by April 14 during our study, 19 females. Conclusions Since upon length, they lower fecundity Fish culture methods raise may be more effective improving survival spawning increasing relative results guide design other small-bodied,

Language: Английский

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Movement patterns of a small-bodied minnow suggest nomadism in a fragmented, desert river

Movement Ecology, Journal Year: 2024, Volume and Issue: 12(1)

Published: July 31, 2024

Abstract Background Unfettered movement among habitats is crucial for fish to access patchily distributed resources and complete their life cycle, but many riverscapes in the American Southwest are fragmented by dams dewatering. The endangered Rio Grande silvery minnow ( Hybognathus amarus, RGSM) persists a remnant of its former range (ca. 5%), ecology understudied. Methods We tracked movements hatchery-reared RGSM, tagged with passive integrated transponder tags, using stationary mobile antennas from 2019 2022. quantified probability total distance moved RGSM released above below dam. then assessed how well two prevailing riverine theories (i.e., restricted paradigm [RMP] colonization cycle hypothesis [CCH]) explained patterns. Results detected 36.8% n = 37,215) making at least one movement. Movements were leptokurtic substantially greater than expected based on RMP both (1.7–5.9 m) (30.3–77.8 individuals. On average, large 75 days 12.2 rkm within year. maximum was 103 rkm. Similarly, we observed multimodal distribution sizes mean 2.4 78.2 found little support an upstream bias, as under CCH, most (74%) directed downstream. Conclusions Our data suggest highly mobile, ability make long-distance movements. Neither theory adequately described patterns RGSM; instead, our findings nomadic pattern apparent drift paradox matching recent studies other pelagic-broadcast spawning minnows where populations persist despite experiencing downstream larvae. Resolution may be achieved through further, targeted into different aspects species’ history. Quantification provides insights help define appropriate scale recovery efforts.

Language: Английский

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Embryology and Early Life History of Rio Grande Silvery Minnow Hybognathus amarus (Teleostei: Leuciscidae) with Detailed Morphological Description of Its Larva

Ichthyology & Herpetology, Journal Year: 2024, Volume and Issue: 112(3)

Published: Oct. 24, 2024

Understanding fundamental life history and ecological attributes of declining endemic fishes is essential for developing effective strategies their conservation recovery. In the Great Plains desert rivers North America, numerous imperiled leuciscids belong to a unique reproductive ecotype with drifting eggs larvae (pelagophils). Herein, we synthesize three decades research on embryology early Rio Grande Silvery Minnow Hybognathus amarus, federally endangered member this ecotype, explore how our findings can guide management these sensitive taxa. We investigated developmental aspects amarus through aquarium laboratory studies: 1) egg morphology, development, density, 2) larval growth, behavior, 3) morphologic meristic analysis juveniles. Eggs nearly doubled in size at 10 min post-fertilization, were nonadhesive neutrally buoyant (specific gravity: 1.0011–1.0024), hatched within 30 hrs water about 23°C. Recently emerged protolarvae first transformed mesolarvae after one week, metalarvae weeks, juveniles six weeks 20–24°C. Based candidate models, fish development (i.e., from juveniles) was best explained by cubic polynomial growth curve. While most developed gas bladder began feed complete complement fin rays required proficient swimming) had not fully formed until month post-hatching. Early characteristics (e.g., specific gravity ray formation), combined river fragmentation, flow regulation, habitat loss, profoundly affect upstream retention recruitment other native pelagophils. Long-term recovery highly species will depend restoring sufficient seasonal flows, floodplain connectivity, complexity promote successful spawning, survival.

Language: Английский

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Linking short-term movement rate of pelagic-broadcast spawning fishes to river fragment length and conservation status

Biological Conservation, Journal Year: 2024, Volume and Issue: 293, P. 110585 - 110585

Published: May 1, 2024

Fragmentation of rivers by dams affects riverine fish occurrence globally. In the Great Plains North America, reproductive guild fishes known as pelagic-broadcast spawning (PBS) minnows – characterized release non-adhesive, semi-buoyant ova that drift has declined substantially where are dammed. Two alternative management strategies proposed for improving conservation PBS fishes. Strategy One focuses on maintenance and restoration local channel heterogeneity floodplain connectivity, an effective strategy under condition do not engage in broad-scale movement. (103–105 m) longitudinal habitat movements. We used mark-recapture to measure movement distances rates seven across three southern rivers. found all species were 1–2 orders magnitude greater than expected Restricted Movement Paradigm, six included stationary mobile individuals. Across species, rate individuals was (1) positively correlated with previously published estimates minimum lengths connectivity required persistence (2) status such most imperiled moved most. Our findings suggest emphasis exclusion is likely insufficient outlook (i.e., both necessary). This work implications inhabiting fragmented around world.

Language: Английский

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Body condition in an endangered minnow is variable but not strongly related to environmental conditions

Marine and Freshwater Research, Journal Year: 2024, Volume and Issue: 75(9)

Published: June 6, 2024

Seasonal patterns in body condition may help identify sensitive time periods or environmental stressors fishes. Our objectives were to document spatiotemporal of wild and hatchery-released Rio Grande silvery minnows (Hybognathus amarus), an endangered species endemic the basin North America. We collected fish weekly bi-weekly from February September, 2017 through 2019, Grande, New Mexico, USA. time-series spanned extreme drought year 2018, allowing us observe changes relation markedly different flow conditions. measurements 2520 RGSM during 3 years our study. Spatiotemporal evident among within sampling reaches, but within-sample variation was high. Annual did not appear be related annual regime. Recaptured hatchery-reared slightly lower condition, followed same seasonal as fish. Contrary expectations, both females males higher 2018. Body useful for identifying small-bodied, short-lived fishes because individual variability is greater than spatial temporal variation.

Language: Английский

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Evaluation of visible implant elastomer (VIE) tags for use in supplementation of an endangered estuarine fish

North American Journal of Fisheries Management, Journal Year: 2024, Volume and Issue: 44(5), P. 962 - 972

Published: Aug. 23, 2024

Abstract Objective Delta Smelt Hypomesus transpacificus are thought to be close extinction in the wild, which has spurred multiagency conservation efforts supplement their population. In conjunction with these recent efforts, monitoring is needed assess effectiveness of supplementation. Such often uses large‐scale tagging released fish distinguish between hatchery‐origin and wild‐origin that captured during later surveys. Methods this study, we evaluated use visible implant elastomer tags determine whether survival, growth, or tag retention were dependent on (1) color (blue, green, orange, red, yellow, no‐tag control) (2) tagged body location (posterior‐dorsal, anterior‐dorsal, mid‐lateral line, control). Result Over 165 days first experiment, there was no difference growth rate (mean = 0.073 mm/d, range 0.072–0.075 mm/d) survival 68%, 63–77%) among colors. Across all groups, mean 96% (range 87–100%). 120 second had influence 0.064 0.062–0.067 50%, 43–58%). For surviving experiment 2, placed at line retained less (84% day 120) than those posterior‐dorsal anterior‐dorsal locations (99% 98%, respectively). Conclusion Our results suggest a suitable method for marking adult (>50 mm fork length) up can useful efforts.

Language: Английский

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Small Fish, Big Problems: Life History, Conservation, and the Future of the Rio Grande Silvery Minnow

Fisheries, Journal Year: 2024, Volume and Issue: 49(12), P. 577 - 587

Published: Sept. 19, 2024

Abstract The Rio Grande Silvery Minnow Hybognathus amarus is a small-bodied minnow emblematic of reproductive guild endemic to rivers the North American Great Plains. This species has been lost from over 90% its historical range. was federally listed as endangered in 1994 and intensive conservation efforts past three decades have averted extinction wild. article synthesizes life history species, causes decline existing threats, prospects for recovery considering ongoing efforts. Restoring multiple self-sustaining populations remains questionable given large-scale, irreversible changes basin, though resiliency established programs hold at least some potential advancing beyond simply preventing extinction.

Language: Английский

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