Getting it Right: Contemporary Approaches to Captive Rearing and Release for Recreation, Restoration, and Recovery: Part II


8:20AM Development of a Growth Model for Lake Sturgeon
  Orey Eckes
This study evaluated the relationship between temperature and growth rate of juvenile Lake Sturgeon Acipenser fulvescens and determined optimal temperature for growth based on weight gain and length increase. Four temperature regimes (11.97 ± 0.46°C, 16.93 ± 0.26°C, 21.62 ± 0.38°C and 26.83 ± 0.56°C) were tested in triplicate to determine specific growth rates and daily length increases. In addition to growth rate, consumption rates were also assessed by recording the grams of feed offered to fish and the amount uneaten to ensure all fish were fed to satiation. Lake Sturgeon consumed 2.76, 9.63, 13.69 and 14.22 % body weight/day and grew at a specific growth rate of 0.50, 1.42, 2.01 and 1.75 mm/day, respectively. Fish consumed more food with increasing water temperature, however daily length increase declined at 26.83°C. This study may be used to construct growth models for production programs, project size at stocking and project feed rates based on water temperature.
8:40AM Innovative Approaches to Reduce Predation Risk on Hatchery-Reared Endangered Bonytail and Razorback Sucker
  Kristopher Stahr
Bonytail Gila elegans and Razorback sucker Xyrauchen texanus are two endangered fishes endemic to the Colorado River Basin. Population declines of both species are attributed to the introduction of non-native fishes and alteration to flow regimes. As part of the Lower Colorado Multi-Species Conservation Program, each year hatchery-reared Bonytail and Razorback Sucker are reintroduced back into the wild. Goals include stocking over 600,000 individuals of both species over the life of the program. However, post-stocking survival is often poor as offspring are naïve to predation. Therefore novel strategies are needed to increase the post-stocking survival of these critically imperiled fishes. This study evaluated two potential strategies to reduce predation on Razorback Sucker and Bonytail: the use of artificial structures and predator recognition conditioning. Using Largemouth Bass Micropterus salmoides as a model predator, subadult Razorback Sucker and Bonytail were used in three separate repeated-measures experiments to evaluate these strategies (each factor alone and the interaction between factors). Preliminary results indicate that artificial structure alone may effectively reduce the predation of naïve Bonytail, while a combination of both structure and predator recognition conditioning may be effective for Razorback Sucker.
9:00AM Lessons Learned from the Use of Pen-Reared Northern Bobwhite to Restore Wild Populations
  Robert Perez
The release of pen-reared bobwhites (Colinus virginianus) has been a controversial topic of quail management for over the past 60 years. Initially, debates focused on the effectiveness of the practice to increase or restore depleted populations of wild bobwhites. When research demonstrated that increasing wild populations with pen-reared birds was ineffective, the practice continued but for a different purpose (i.e., to supplement commercial hunting opportunities). Discussions now began to focus on the negative impacts that releasing of pen-raised bobwhites potentially could have on wild populations. Biologists expressed concerns regarding transmission of diseases and parasites, as well as possible changes in habitat use, social and genetic structure, and survival rates of wild bobwhites. Here we a summary of existing knowledge concerning use of pen-reared bobwhites to restore wild populations and discuss in particular population restoration of the endangered masked bobwhite (C. v. ridgwayi).
9:20AM Mccloud River Redband Trout (Oncorhynchus mykiss stonei): A Story of Drought-Driven Peril, Conservation through Modern Hatchery Methods, Heroic Reintroduction, and Lessons Learned.
  Farhat Bajjaliya
During the years 2011-2015 unprecedented drought and loss of stream habitat led to emergency rescues of McCloud River Redband Trout (Oncorhynchus mykiss stonei) from headwater streams in the upper McCloud River basin, California. With suitable stream habitat unavailable, it became necessary for the California Department of Fish and Wildlife (Department) to reassess and expand normal operations at Mt. Shasta Hatchery to establish a haven for these imperiled populations. Fish from three geographically and genetically isolated subpopulations of McCloud River Redband Trout were rescued and held in self-contained recirculating aquaculture systems. As drought conditions continued to persist and rescued fish became sexually mature, a genetically-based spawning-matrix was utilized to cross appropriate pairs. The winter of 2016-2017 brought above average precipitation and instream conditions began to improve. With improved conditions, McCloud River Redband Trout−both original rescue fish and their progeny−were reintroduced to their native habitat. McCloud River Redband Trout broodstock continue to be maintained at Mt. Shasta Hatchery to support both conservation efforts as well as recreational angling opportunity. The lessons learned through this process are applicable at other hatcheries. The Department intends to develop a similar program for Walker River Basin Lahontan Cutthroat Trout (Oncorhynchus clarkii henshawi) at Hot Creek Hatchery.
09:40AM Break
2:50PM Refreshment Break
3:20PM Spring-Run Chinook Salmon Captive Broodstock Program for the San Joaquin River Restoration Program; 2010-2019.
  Paul Adelizi
The San Joaquin River Restoration Program (SJRRP) has reared Chinook Salmon captive broodstock for the past 9 years to restore a self-sustaining population to the San Joaquin River. Because spring-run Chinook Salmon are locally threatened, a captive broodstock program was implemented to reduce impacts to native donor populations. While full-scale facilities were being designed, a pilot-scale rearing facility was constructed to refine fish culture techniques and conduct preliminary releases. Initial efforts resulted in high precocity levels, with up to 84% jack rates. This initiated several years of research which resulted in implementing a production strategy to manage precocity. All broodstock undergo genetic analysis to determine sex and relatedness. Males are segregated from females from age 11-18 months and the growth rates for males are significantly reduced. The strategy has resulted in jack rates as low as 7 percent. Additionally, stress is minimized by maintaining low densities (Density Index < 0.15) and oxygen levels above 80% of saturation. Quarantine and biosecurity protocols have resulted in few disease outbreaks. For the past four years, over 500 adult broodstock have been released to the wild and monitored for summer holding, redd construction and juvenile production. Additional details and updates will be provided.
3:40PM Ecosystem Simulation As an Intermediate Step to Establishing Devils Hole Pupfish in Captivity
  Olin Feuerbacher
The Devils Hole pupfish has twice in recent years teetered at the edge of extinction with fewer than 40 animals observed during annual surveys. Establishing a captive population of these fish has proved an elusive goal for decades. Laboratory propagation in aquaria and refuge attempts in large outdoor tanks showed promise, but ultimately failed. Endeavoring to establish a lifeboat population, the Ash Meadows Fish Conservation Facility built upon earlier efforts by utilizing a two-fold approach to population establishment: laboratory rearing of wild-collected eggs through hatch and grow-out until adults were released into a 100,000-gallon refuge tank designed to mimic the challenging habitat and ecosystem of Devils Hole. Adults reared from wild-collected eggs failed to produce viable offspring in aquaria. However, adults stocked into the refuge tank began reproducing, producing successive generations within the refuge tank. Unlike wild-collected eggs, captive-produced eggs subsequently collected from the refuge tank population produced fish which spawned in aquaria and have produced entirely laboratory-reared offspring. Though successful, this approach met significant challenges in the technology required to simulate Devils Hole and to monitor the progression of a complex quasi-ecosystem, and necessitated novel approaches to pathogen and predator control and monitoring of fish and ecosystem health.
4:00PM Captive Rearing of Endangered Klamath Suckers Using a Formal Adaptive Management Framework
  Evan Childress
Captive rearing involves numerous decisions surrounding how to obtain, raise, and release individuals. For many imperiled species, little information exists to guide these decisions, but recovery or extinction prevention may depend on making the best possible decisions. We use a formal adaptive management approach combining prior information with experimentation to provide rapid learning to optimize a captive rearing program for endangered Lost River and shortnose suckers. Wild individuals have not recruited to the adult spawning aggregations in over two decades. Thus, rapid progress toward the program goal of maximizing the number of individuals released into Upper Klamath Lake that recruit to the adult populations is critical to prevent extirpation. The adaptive framework includes 1) identifying the most critical uncertainties, 2) resolving the most important uncertainties through experimentation, and 3) updating operations based on observed outcomes. For example, results of a mark-recapture radio-tagging study are used to estimate post-release survival and provide feedback on the effects of release size and location. The degree of control offered by captive rearing and planned releases is rare in natural resource management and offers opportunities to learn and increase program success quickly.
4:20PM Bringing Back Gila Trout Using New Propagation Techniques
  Nathan Wiese
Mora National Fish Hatchery has been solely charged with Gila trout recovery since 2002. The Hatchery exclusively utilizes Recirculating Aquaculture Systems (RAS) for broodstock development, wild fish refugia, and rearing of Gila trout for recovery purposes. The Gila trout recovery program consists of 5 lineages of Gila trout and is guided by a genetic management plan to routinely infuse wild parents into broodstock lines along with genotyping to maximize diversity year classes. Recent infrastructure changes have improved Gila trout survival by 250% providing eggs and fish for additional recovery efforts. These improvements will ensure that Gila trout are available when habitat is secured and wildfire restoration is needed. The Hatchery has utilized naturalistic rearing components and recently retrofitted fiberglass circular tanks with 2-D naturalistic rearing substrate. These substrates along with increased swimming velocities to 2 body lengths/second have improved survival, coloration, and spawning success.
4:40PM Use of Environmental DNA to Test for the Presence of Non-Native Trout Prior to Reintroduction of Paiute Cutthroat Trout (Onchorynchus clarkii seleniris) to Its Native Range
  Kristen Ahrens
Environmental DNA (eDNA) methods have been effective in the detection of low abundance aquatic species, showing particularly high potential for target species identification in small, low order streams. Silver King Creek is a small, third order tributary to the East Fork Carson River, in Alpine County, California, which historically supported threatened Paiute Cutthroat Trout (Onchorynchus clarkii seleniris, PCT) populations in high abundance prior to introduction of non-native Brown Trout (Salmo trutta), hatchery Rainbow Trout strains (O. mykiss), and California Golden Trout (O. mykiss aguabonita). Non-native trout introductions led to the extirpation of PCT due to competition, predation on juvenile PCT, and in the case of Rainbow Trout species, hybridization with PCT. Chemical treatments (rotenone) for removal of non-natives throughout the Silver King Creek watershed have occurred over several decades. Utilizing quantitative PCR assays developed by the U.S. Forest Service, we tested eDNA samples (water samples filtered along stretches of Silver King Creek and its tributaries) for the presence of Rainbow and Brown Trout. We tested eDNA assay sensitivity, showing successful detection of very low quantity DNA. This method showed high efficacy for screening of non-native trout presence prior to reintroduction of PCT to its 11-mile, native range.

Organizers: Michelle L. “Mick” Walsh, Steve Lochmann, Valorie Titus
Supported by: AFS Fish Culture Section; TWS Hunting, Trapping, and Conservation Working Group

Location: Reno-Sparks CC Date: October 1, 2019 Time: 8:20 am - 5:00 pm