Decades of persistent natural and anthropogenic threats coupled with competing water needs have compromised numerous species of freshwater fishes, many of which are now artificially propagated in hatcheries. Low survival upon release is common, particularly in systems with substantial nonnative predator populations. Extensive sampling for Shortnose (Chasmistes brevirostris) and Lost River Suckers (Deltistes luxatus) in the Klamath River Basin on the California-Oregon border have failed to detect any new adult recruitment for at least two decades, prompting an investigation into artificial propagation as an extinction prevention measure. A comprehensive assessment of strategies and successes associated with propagation for conservation restocking has not been performed for any Catostomid. Here, we review available literature for all western lake sucker species to inform propagation and recovery efforts for Klamath suckers and summarize the relevance of these considerations to other endangered fishes.

Fish monitoring programs often rely on the collection, species identification, and counting of individual fish over time to inform natural resource management decisions. Thus, the utility of the data used to inform these decisions can be negatively affected by species misidentification. Fish species misidentification bias can be minimized by confirming identification using genetic techniques, training observers, or adjusting monitoring data using estimates of incomplete detection and false-positive misidentification. Despite the existence of well-established fish identification training and quality control programs, there is considerable uncertainty about fish species falsepositive misidentification rates and the effectiveness of fish identification training programs within the San Francisco Estuary. We evaluated the misidentification of fish species among Delta Juvenile Fish Monitoring Program observers by conducting five fish identification exams under controlled conditions at the Lodi Fish and Wildlife Office in Lodi, California, between 2012 and 2014. To assess the variability in false-positive misidentification, we fitted data to species and observer characteristics using hierarchical logistic regression. We found that fish species misidentification was fairly common, averaging 17% among 155 test specimens and 32 observers. False-positive misidentification varied considerably among species and was negatively related to fish size, the abundance of the species within monitoring samples, and observer experience. In addition, observers who were not formally trained or used as full-time observers were, on average, 6.0 times more likely to falsely identify a species. However, falsepositive misidentification rates among observers and specimens still varied considerably after controlling for observer experience and training, and species and size, respectively. Our results could be used to improve fish identification training and testing, increase the accuracy of fish occupancy or abundance estimation, and justify the allocation of resources to continually use and formally train full-time observers within long-term monitoring programs operating in the system.

Subterranean fishes are understudied worldwide and often at risk before their populations are discovered and described. The nature of karst systems limits the applicability of ecological paradigms and hinders our ability to identify and preserve endemic fauna. Aquatic karst taxa in particular are subject to environmental threats that increase in severity over time. Once a population or species is recognised as distinct, it is imperative we gain understanding of its biology to inform effective resource management and mitigate risk factors. The grotto sculpin (Cottus specus) is endemic to Perry County, Missouri, U.S. caves and was formally described and listed as endangered under the U.S. Endangered Species Act in 2013. We used mark–recapture methods to quantify population densities and estimate population sizes in two caves and two corresponding spring branches. Size structure varied among habitats and seasons. Spring branches were dominated by juveniles year‐round with peak young‐of‐year (YOY) densities in May. Adult densities in both macrohabitats decreased in winter, possibly due to recruitment or seasonal stress, and were lower at spring branches compared to caves and declined further during late winter which may be indicative of cave spawning. YOY were captured variably underground with peak densities in summer. The ecology of grotto sculpin appears to be more complex than has been reported previously for subterranean fishes. Variable patterns of demography requiring multiple contiguous habitats are unique for cave species and support the recently substantiated suggestion that subterranean systems are not as simple or disconnected as once thought.

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