Evaluating the Reintroduction Potential of Lahontan Cutthroat Trout in Fallen Leaf Lake, California

Translocations, defined herein as the human‐assisted movement of individuals from a source population to other waters within their historical range, are prevalent in recovery plans for endangered fishes. Many translocations fail to establish new populations, however, and outcomes are often poorly documented. Endangered Humpback Chub Gila cypha persist as a self‐sustaining population in Grand Canyon, Arizona, despite threats from introduced nonnative competitors and predators and modified flow, thermal, and sediment regimes due to river regulation. In the decades following the completion of Glen Canyon Dam, the Grand Canyon population has been primarily sustained through reproduction in a single Colorado River tributary, the Little Colorado River (LCR). To establish population redundancy and aid in recovery, we annually translocated between 243 and 509 juvenile Humpback Chub from the LCR to Havasu Creek, a smaller Colorado River tributary in Grand Canyon National Park. Juvenile Humpback Chub were collected from the wild and reared in a hatchery for 8–12 months prior to the translocations. Through biannual mark–recapture sampling in Havasu Creek, we estimated annual abundance for all of the translocated cohorts and found that apparent survival and growth rates met or exceeded the demographic rates that are published for the LCR. We observed reproductively mature adults each year in May, beginning in 2012, and untagged juvenile Humpback Chub beginning in the following year and every year thereafter, with results that indicated successful reproduction. Beginning in 2016, we noted recruitment to maturity of fish that were produced in situ and the population's abundance increased through 2018, indicating potential for the establishment of a self‐sustaining population. As an example of the successful translocation of an endangered species that demonstrates the potential importance of tributaries in the recovery of large‐river fishes, our study may help to inform future recovery planning.

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“…Indeed, the presence of nonnative fishes in translocation sites is a common cause of failure (Al‐Chokhachy et al. ; Cochran‐Biederman et al. ).…”

Section: Discussionmentioning

confidence: 99%

Establishment of a Reproducing Population of Endangered Humpback Chub through Translocations to a Colorado River Tributary in Grand Canyon, Arizona

Healy

Smith

Schelly

et al. 2020

N American J Fish Manag

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“…The RSIs are designed to consistently supply embryos with freshwater, while avoiding sedimentation problems associated with buried incubators, and have been used previously to successfully introduce other species of salmonid embryos (e.g., Donaghy and Verspoor 2000;Kaeding and Boltz 2004;Al-Chokhachy et al 2009). Hatched fry absorbed the yolk sac while in the RSI.…”

Section: Methodsmentioning

confidence: 99%

Juvenile Movement among Different Populations of Cutthroat Trout Introduced as Embryos to Vacant Habitat

Andrews

Shepard

Litt

et al. 2013

N American J Fish Manag

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Translocations are frequently used to increase the abundance and range of endangered fishes. One factor likely to affect the outcome of translocations is fish movement. We introduced embryos from five Westslope Cutthroat Trout Oncorhynchus clarkii lewisi populations (both hatchery and wild) at five different locations within a fishless watershed. We then examined the movement of age‐1 and age‐2 fish and looked for differences in movement distance among source populations and among introduction sites; we also examined the interactions among age, population, and introduction site. At age 1, most individuals (90.9%) remained within 1,000 m their introduction sites. By age 2, the majority of individuals (58.3%) still remained within 1,000 m of their introduction site, but considerably more individuals had moved downstream, some more than 6,000 m from their introduction site. We observed a significant interaction between age and source population (F 4, 1077 = 15.45, P < 0.0001) as well as between age and introduction site (F 41, 1077 = 11.39, P < 0.0008), so we presented results in the context of these interactions. Within age‐groups, we observed differences in movement behavior among source populations and among donor populations of Westslope Cutthroat Trout. We discuss these findings in light of previous research on juvenile salmonid movement.Received April 20, 2012; accepted June 3, 2013

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“…Over the past 50 years, incubators have become increasingly used in conservation programmes to improve salmonid ova survival and redistribute or re‐establish populations until solutions to population decline are identified and take effect (e.g. EA 2002; Kaeding & Boltz 2004; Al‐Chokhachy et al. 2009).…”

Section: Introductionmentioning

confidence: 99%

A review of factors influencing artificial salmonid incubation success and a spate river‐specific incubator design

Kirkland

2011

Fisheries Management Eco

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Salmonid incubators are a common means of introducing fish into rivers to re-establish or redistribute populations. Whilst survival rates of ova to emerging fry approaching 100% are reported, survival of <10% is not uncommon. Poor survival and compromised fitness in later life can result from many different environmental influences or aspects of incubator design and implementation. This paper reviews the effects of incubation conditions upon salmonid embryo mortality, development and fitness; in particular, the effects of factors influenced by, or a product of, artificial incubator design and operational protocol. This provides the basis to mitigate adverse effects through site-specific incubator design and operational protocols. In an example from a UK spate river, high sediment load effects were alleviated through the use of a novel incubation media, Enkamat, and a scouring capability to remove settled sediments from the incubator. In field trials, incubator siting and maintenance were also found to be essential to achieve high survival rates on a spate river. K E Y W O R D S : alevins, compensatory stocking, critical period, salmon, species conservation.

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Evaluating the Reintroduction Potential of Lahontan Cutthroat Trout in Fallen Leaf Lake, California

Cited by 25 publications

References 62 publications

Establishment of a Reproducing Population of Endangered Humpback Chub through Translocations to a Colorado River Tributary in Grand Canyon, Arizona

Establishment of a Reproducing Population of Endangered Humpback Chub through Translocations to a Colorado River Tributary in Grand Canyon, Arizona

Juvenile Movement among Different Populations of Cutthroat Trout Introduced as Embryos to Vacant Habitat

A review of factors influencing artificial salmonid incubation success and a spate river‐specific incubator design

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