Propagated Fish in Resource Management

<em>Abstract.</em>—Floodplains are presumed to be important rearing habitat for the endangered razorback sucker <em>Xyrauchen texanus</em>. In an effort to recover this endemic Colorado River basin species, the Upper Colorado River Endangered Fish Recovery Program developed a floodplain acquisition and enhancement program. A levee removal study was initiated in 1996 as one component of this floodplain restoration program. The goal of the Levee Removal Study was to evaluate the system responses to levee removal and make specific recommendations concerning the value of floodplain reconnection for endangered species (specifically razorback sucker) recovery. However, because there were very few razorback suckers in the Green River, answers to several important questions pertaining to razorback sucker utilization of the floodplain were not answered during this initial study. In an effort to answer some of these questions, age-1 and larval razorback suckers were stocked into depression floodplain wetland habitats along the Middle Green River in northeastern Utah. Age-1 razorback suckers were stocked during the spring of 1999 and 2000 into The Stirrup (river kilometer [Rkm] 444.0), Baeser Bend (Rkm 439.3), and Brennan (Rkm 432.0) wetland sites. Larval razorback suckers were stocked during the spring of 1999 into The Strirrup and into Baeser Bend during 2001. At the time of stocking, each floodplain site was occupied by numerous nonnative fish, including black bullhead catfish <em>Ictalurus melas</em>, fathead minnow <em>Pimephales promelas</em>, green sunfish <em>Lepomis cyanellus</em>, and common carp <em>Cyprinus carpio</em>. The goal of this study was to test if floodplain depressions will aid in the recovery of razorback suckers.

Propagated Fish in Resource Management

<em>Abstract.</em>—Laboratory challenges of two rainbow trout <em>Oncorhynchus mykiss </em>strains with <em>Myxobolus cerebralis </em>triactinomyxons confirm the resistance to whirling disease of the Hofer trout strain. Although the number of fish that became infected and developed clinical disease was similar for the Hofer and the Trout Lodge strains at all challenge doses, the median spore numbers were lower at all challenge doses for the Hofer rainbow trout. Parasite challenge doses required to produce lesions of high severity were 10-fold lower for the Trout Lodge strain (100 triactinomyxons) than the Hofer strain (1,000 triactinomyxons). Challenges of the Hofer strain with other common salmonid pathogens; the myxozoans <em>Ceratomyxa shasta </em>and <em>Tetracapsuloides bryosalmonae</em>, the bacterium <em>Yersinia ruckeri</em>, and the viruses Salmonid herpes-like virus type 1 and infectious hematopoietic necrosis virus demonstrate that the susceptibility of the Hofer strain was similar to what would be expected for other strains of rainbow trout, either domestic or wild. These pathogen challenges provide evidence that the Hofer trout present a low risk for introducing any pathogen that might be detrimental to native or established fish populations or further amplifying those that are endemic.

Propagated Fish in Resource Management

<em>Abstract.</em>—Aquaculture development in the United States continues its expansion from freshwater into coastal and nearshore oceanic environments. As it does so, the selection of species to culture and the location of culture operations are generating much debate about the role of government entities, especially agriculture and conservation agencies, in the management of this development. Many in the industry argue that regulations are already too onerous, subsidies are too few, governmental encouragement is too little, and that the best way to correct these problems is to place all control over the development in governmental agriculture agencies. Others argue that the potential environmental impacts of aquaculture could be so adverse, or at least so uncertain that conservation agencies need to impose even more controls. This debate occurred in Texas in the 1980s as private aquaculture sought to increase the culture of nonindigenous species, in both private and public waters. The potential effects on native species in public waters led to legislation that attempted to balance economic development with environmental safeguards. However, only Texas was affected by the statute and subsequent regulations. Since the potential environmental affects of aquaculture development will undoubtedly cross local, state, and tribal boundaries, it is now felt by many that the regulation of the species cultured and sites selected should be a federal issue. The same questions about who within the federal government should have responsibility for managing aquaculture development require resolution. This paper will examine lessons learned from the Texas experience for possible application in the federal arena.

Propagated Fish in Resource Management

<em>Abstract.</em>—We evaluated the short-term survival of stocked walleye <em>Sander vitreus </em>fingerlings during 1997 through 2002 in lakes with no natural reproduction. Lake surface area ranged from 40 to 160 ha. The stocked fingerlings were reared in 0.2-ha, plastic-lined ponds at the Governor Tommy G. Thompson State Hatchery in Spooner, Wisconsin and stocked during early summer. Stocked fingerlings ranged from 30 to 45 mm in total length and were stocked at densities of 124/ ha (<em>N </em>= 18) or 248/ha (<em>N </em>= 8). Fall electrofishing surveys were conducted on all lakes after surface water temperatures were < 22°C. The Serns’ Index was used to predict fingerling abundance, which was then used to calculate percent survival for the 3-month period between stocking and fall sampling. Mean survival was 0.4% (SE = 0.1%; <em>N </em>= 26) and ranged from 0.0% to 2.9% for all lakes. Fall fingerlings were not detected for 15 of the 26 stocking events. Stocking density did not appear to be important in determining contribution to the fall fingerling population. The current stocking program for lakes lacking natural reproduction has the potential to establish low-density populations of adult walleye. Creel data showed stocked fisheries in the northern third of Wisconsin provided a mean harvest rate of 0.021 (SE = 0.0042; <em>N </em>= 18) walleye per hour of directed effort or one walleye harvested for every 48 h of directed fishing effort. In comparison, the harvest rate for lakes supported by natural reproduction was approximately four times higher (mean = 0.079; SE = 0.0056; <em>N </em>= 158).

Propagated Fish in Resource Management

<em>Abstract.</em>—This paper describes a database of fish stocking in Idaho dating from 1913. The database contains more than 75,000 complete records on stocking since 1967 and more than 50,000 partial records prior to that date. Information contained in the complete records includes watershed and water body, species and variety, size, stocking method, number per pound, pounds stocked, rearing hatchery, haul mortality, county, and management region. In order to compare numbers of salmonids stocked at differing life stages, we converted weight of stocked salmonids to a catch equivalent index (catch equivalent [CEQ] = weight of fish stocked/0.33). Our analysis of the data from the database indicated that since the 1960s, more than 2 million CEQ of rainbow trout <em>Oncorhynchus mykiss </em>have been stocked annually in Idaho. These comprise 23 different stocks, including Kamloops rainbow trout, redband trout, and 16 varieties of domestic rainbow trout. Since 1970, the number of rainbow trout stocked in Yellowstone cutthroat trout <em>O. clarkii </em>range has decreased by more than one-third. Triploid rainbow trout stocking commenced in 2000 and now exceeds 2 million CEQ annually. Largemouth bass <em>Micropterus salmoides </em>and smallmouth bass <em>M. dolomieu </em>stocking comprises nearly 1,814.4 kg per year. Crappie species are stocked at the rate of 590 kg annually. The rate of increase in stocking by the Idaho Department of Fish and Game has been about 300% in each of the last three decades, largely due to the construction of four large anadromous mitigation hatcheries. The human population in Idaho grew 22% per decade during that same time period, suggesting increasing reliance on stocked fish.

Propagated Fish in Resource Management

<em>Abstract.</em>—Fisheries managers have stewardship responsibility for aquatic resources. This means making decisions that are ecologically sound, economically sensible, and socially acceptable. The vexing problem lies in balancing ecological, economic, and sociologic ideals with ethical and moral (professional) stewardship responsibilities. Foresighted fisheries management has seven practical elements: (1) thoroughly inventory ecological and habitat characteristics of watersheds; (2) manage for native or wild fish wherever possible; (3) determine genetic strengths of broodstocks so their offspring are used where they are suited; (4) manage according to the fish production limits of waters; (5) stock only waters where trout reproduction is limited or absent; (6) develop fisheries management plans by drainage basin; (7) establish fisheries management programs based on recognition of all public desires, not just the utilitarian aspect. Once public, including angler, desires are understood, fisheries managers must work to instill in the public a sound resource philosophy and then integrate that public awareness with ecological technology to progress in fisheries management.

Propagated Fish in Resource Management

<em>Abstract.</em>—Westslope cutthroat trout <em>Oncorhynchus clarkii lewisi </em>are currently under a second review for listing as a threatened species under the Endangered Species Act. Both natural and anthropogenically induced hybridization has been previously documented between this subspecies and rainbow trout <em>O. mykiss </em>and between steelhead (anadromous rainbow trout) and coastal cutthroat trout <em>O. clarkii clarkii</em>. However, levels of reported introgression have varied greatly. To assess natural hybridization and the extent to which it may affect the frequency and persistence of <em>O. mykiss </em>alleles among sympatric populations of westslope trout, we used three nuclear loci to detect hybrids, and mitochondrial DNA to assess the direction of hybridization and introgression in Big Creek, Idaho and its tributaries. Natural hybridization between westslope cutthroat and sympatric rainbow trout/steelhead appears to occur at a relatively low frequency with numerous parental types still present in varying numbers within the drainage. Subsequent genetic analyses revealed no hybridization in samples from 2001 and percentages of hybrid genotypes within sample locations ranging from 1.6% to 13.3% in 2002. Differences between years may be attributable to sampling, time of year, and seasonal movements of westslope cutthroat trout and their hybrids. Furthermore, hybrids were more frequently observed (<em>p </em>< 0.01) with mitochondrial haplotypes of westslope cutthroat trout indicating a directional preference of westslope cutthroat females spawning with <em>O. mykiss </em>males.

Propagated Fish in Resource Management

<em>Abstract.</em>—Traditional hatchery salmonids lack many behavioral and morphological attributes needed to survive after release (Maynard et al. 1995). The Seminatural rearing concept hypothesizes that exposing hatchery salmonids to natural habitats, foods, predators, and currents will induce them to develop the wild behavior, physiology, and morphology needed for postrelease survival. The paper reviews recent studies investigating the efficacy of this concept. Rearing salmonids in seminatural rearing habitat, with natural fluvial substrates, structure, and overhead cover, usually improves survival. Supplementing hatchery fish diets with live foods often enhances their ability to hunt live prey. However, utilizing automated underwater feeders to feed Chinook salmon <em>Oncorhynchus tshawytscha </em>in a more natural manner did not alter their depth preference, response to novel visual stimuli at surface, or predator vulnerability as predicted. In most, but not all cases, conditioning salmonids to avoid predators improves their postrelease survival. Exercise usually improves growth and health, but does not always increase postrelease survival. Fisheries managers can use the increased survival successful seminatural rearing strategies offer to increase recruitment to the fishery and spawning population, reduce competitive impacts on listed stocks, or simply reduce operational costs.

Propagated Fish in Resource Management

<em>Abstract.</em>—Artificial propagation is a potential mechanism to aid recovery of U.S. Endangered Species Act (ESA)-listed stocks of Pacific salmon on the West Coast of the United States. Theoretically, one of the fastest ways to amplify population numbers for depleted stocks of Pacific salmon is through culture and release of hatchery-propagated fish. However, past attempts to use supplementation (i.e., the use of artificial propagation in an attempt to maintain or increase natural production) to rebuild naturally spawning populations of Pacific salmon have often yielded poor results. One solution is to develop protocols that increase fitness of hatchery-reared salmonids, thereby improving survival. A framework of conservation hatchery strategies to reduce potential impacts of artificial propagation on the biology and behavior of fish is presented. Operational guidelines for conservation hatcheries to help mitigate the unnatural conditioning provided by hatchery rearing are discussed and contrasted to those for production hatchery operation. These include (1) mating and rearing designs that reduce risk of domestication selection and produce minimal genetic divergence of hatchery fish from their wild counterparts to maintain long-term adaptive traits; (2) simulation of natural rearing conditions through incubation and rearing techniques that approximate natural profiles and through increasing habitat complexity (e.g., cover, structure, and substrate in rearing vessels) to produce fish more wildlike in appearance and with natural behaviors and higher survival; (3) conditioning techniques such as antipredator conditioning to increase postrelease behavioral fitness; (4) programming aspects of release size, stage, and condition to match the wild population in order to reduce potential for negative ecological interactions and to promote homing; and (5) aggressive monitoring and evaluation to determine success of conservation hatchery approaches. High priority must be given to basic scientific research to meet three principal goals: (1) maintain genetic integrity of the population, (2) increase juvenile quality and behavioral fitness, and (3) increase adult quality.

Propagated Fish in Resource Management

<em>Abstract.</em>—Progeny of wild, freshwater sequestered (resident) rainbow trout <em>Oncorhynchus mykiss</em>, descendants of a stocking of steelhead (anadromous rainbow trout) in 1926, and progeny of the wild, ancestral steelhead lineage and their reciprocal crosses were compared for two brood years in a hatchery environment to determine the effects of 70 years of freshwater residency on growth, survival, early maturity, and smolting proportion. Resulting smolts were tagged, released, and recovered as maturing adults to evaluate marine survival. For the 1996 brood, 75 families were maintained in separate freshwater raceways for 10 months. Approximately 100 fish from each family were tagged with passive integrated transponder tags, pooled by type, and cultured until age 2. An additional group was tagged with coded-wire tags and reared in the same manner. For the 1997 brood, 80 families were coded-wire-tagged, separated by breeding type, and cultured at different densities. Size-at-age and survival were reduced significantly in progeny of resident females when compared with progeny from anadromous females during the first 2 months after first feeding. No significant differences were observed in subsequent growth or survival through age 2. A higher proportion of smolting at age 2 and a lower proportion of early male maturity was observed in families from anadromous parents. Smolts produced by anadromous parents had four to five times higher marine survival than those from resident parents. While smolting proportions and smolt survival were lower for the progeny of freshwater resident fish, the results indicate that significant numbers of smolts and adults can still be produced by populations landlocked for up to 70 years and 20 generations. The results have substantial implications for the use of natural freshwater environments for the preservation of endangered anadromous stocks of rainbow trout, the rehabilitation of anadromous stocks, and the actual effective breeding size of anadromous rainbow trout populations.