Donald A. Larsen

Homing and Spawning Site Selection by Supplemented Hatchery- and Natural-Origin Yakima River Spring Chinook Salmon

Abstract It is well known that salmon home to their natal rivers for spawning, but the spatial scale of homing within a river basin is poorly understood and the interaction between natal site fidelity and habitat-based spawning site selection has not been elucidated. Understanding the complex trade-offs among homing to the natal site, spawning site selection, competition for sites, and mate choice is especially important in the context of hatchery supplementation efforts to reestablish self-sustaining natural spawning populations. To address these questions, we examined the homing patterns of supplemented Yakima River spring Chinook salmon Oncorhynchus tshawytscha released from satellite acclimation facilities after common initial rearing at a central facility. Final spawning location depended strongly on where fish were released as smolts within the upper Yakima River basin, but many fish also spawned in the vicinity of the central rearing hatchery, suggesting that some fish imprinted to this site. While...

Examining the Conflict between Smolting and Precocious Male Maturation in Spring (Stream-Type) Chinook Salmon

Abstract Precocious male maturation is a natural life history strategy for spring Chinook salmon Oncorhynchus tshawytscha. During spawning, precocious males employ a “sneaker” strategy to fertilize eggs in competition with full-size anadromous adults. Hatchery rearing practices may increase the incidence of this phenotype beyond its natural levels. Previous research reported high rates (>40%) of precocious male maturation at age 2 (minijacks) in the Yakima River spring Chinook salmon supplementation program in Washington State. Minijack rates in wild populations are believed to be less than 5%. We compiled seasonal profiles for size, condition factor (K), gill Na+,K+-ATPase activity, whole-body lipid levels, plasma 11-ketotestosterone (11-KT), insulin-like growth factor-I (IGF-I), and thyroxine (T4) in minijacks and immature smolts in the hatchery and during out-migration. In the hatchery, minijacks were larger and had higher K, whole-body lipid, plasma 11-KT, and IGF-I levels than smolts. Plasma T4 and g...

Early Life History Variation in Hatchery- and Natural-Origin Spring Chinook Salmon in the Yakima River, Washington

Abstract In male Chinook Salmon Oncorhynchus tshawytscha, age of maturation is phenotypically plastic, occurring at age 1 (referred to as precocious parr or microjack), age 2 (minijack), age 3 (jack), age 4, or age 5. Microjacks and minijacks are thought to forego migration to the ocean as smolts, instead remaining in headwaters and employing a “sneaking” strategy to fertilize eggs. We compared the prevalence of minijacks (minijack rate) among hatchery- and natural-origin spring Chinook Salmon from the Yakima River, Washington, over seven brood years (2001–2007). We quantified minijack rates and sex ratios in the hatchery population prior to release and during out-migration at a trap located 230xa0km downstream. Within this time period, we also monitored minijack rates in a 3-year (brood years 2002–2004) growth study designed to reduce minijack production at the hatchery. Minijacks made up an average of 41% of the male population in the hatchery, but annual minijack rates varied in response to the growth ra...

Upstream Migration of Minijack (Age-2) Chinook Salmon in the Columbia River: Behavior, Abundance, Distribution, and Origin

Abstract It has recently been demonstrated that a large percentage of yearling Chinook salmon Oncorhynchus tshawytscha smolts released from a production-scale hatchery on the Yakima River display an underappreciated life history strategy. Instead of migrating to the ocean for long-term rearing and growth, males may instead undertake a short-term migration downstream, turn around, and migrate back upstream where they reproductively mature at age 2. Following local hatchery traditions, these fish are referred to as “minijacks.” We used information produced from (1) large-scale passive integrated transponder (PIT)-tagging programs at hatcheries in the Columbia and Snake River basins and (2) the installation of PIT tag detectors in the fish passage ladders built into dams on these rivers to investigate the occurrence, behavior, distribution, and origin of minijacks. A minijack was operationally defined as a fish detected in a ladder after 1 June in the same year it was released. Minijacks were found in every ...

Variation in Minijack Rate among Hatchery Populations of Columbia River Basin Chinook Salmon

AbstractIn Columbia River spring and summer Chinook Salmon Oncorhynchus tshawytscha, age of male maturation ranges from age 1 (microjack), 2 (minijack), 3 (jack), to 4 or 5 (adult) years. The presence of minijacks has been noted in several experimental studies and documented for a few hatchery programs; but, a comprehensive survey of their occurrence in hatchery production programs has never been conducted. We measured the proportion of minijacks among males released from several spring- and summer-run Chinook Salmon hatchery programs throughout the Columbia River basin among brood years 1999–2010. The hatcheries surveyed included both segregated (uses only hatchery-origin spawners in broodstock) and integrated (includes some degree of natural-origin spawners in broodstock) programs. Minijacks were found in all programs monitored, and rates varied approximately 10-fold across release groups, ranging from 7.9% to 71.4% of males in spring Chinook Salmon programs and from 4.1% to 40.1% of males in summer Chi...

The Effect of Yakima River Spring Chinook Salmon Sire Life History Type on Emergence Timing and Size of Progeny

Abstract Two sets of half-sib families of Chinook salmon Oncorhynchus tshawytscha were generated by crossing four full-size anadromous males and four early-maturing males with each of two full-size anadromous females (eight males × two females) obtained from the Cle Elum Supplementation Research Facility on the Yakima River. Emergence timing differed by up to 5 weeks between families, with a highly significant difference between females. Within females there was no significant effect of male life history type on either median emergence timing or fry size; however, there was a suggestion of a relationship between individual sire and progeny emergence timing. There were significant differences in fry weight at emergence between the two females, but sire did not influence fry weight at emergence within females. This study demonstrates that ecologically significant differences in emergence timing may be generated solely through genetic and maternal affects, as all parents were spawned on the same day and all ...

Stock Differences in Growth, Smolting, and Early Male Maturation in Hatchery Spring Chinook Salmon: a Common-Garden Experiment

AbstractHatchery spring Chinook Salmon Oncorhynchus tshawytscha from Parkdale Hatchery on the Hood River, Oregon, and Carson National Fish Hatchery (CNFH) on the Wind River, Washington, were reared under a common-garden experimental regime at CNFH over three consecutive brood years (2008–2010) to assess the effects of stock on smoltification and early male maturation. Rearing groups were monitored for size, percent solid (a surrogate for whole-body lipid), gill Na+,K+-ATPase activity, and rate of precocious maturation in males (i.e., age-2 minijack rate). Despite rearing of the stocks under identical conditions, the out-of-basin Hood River stock was significantly smaller throughout the study and at release as smolts, had lower whole-body lipid at release, and had lower gill Na+,K+-ATPase activity at release than the Carson stock; furthermore, the Hood River stock exhibited much higher mean minijack rates than the Carson stock (45% versus 23% of males). Using logistic regression, we demonstrated that the t...

Suitability of Insulin-Like Growth Factor 1 (IGF1) as a Measure of Relative Growth Rates in Lingcod

Abstract The effectiveness of spatial management strategies is typically evaluated through traditional biological measurements of size, density, biomass, and the diversity of species inside and outside management boundaries. However, there have been relatively few attempts to evaluate the processes underlying these biological patterns. In this study, we take the first step toward developing a relative index of body growth for lingcod Ophiodon elongatus using plasma insulin-like growth factor 1 (IGF1) with the ultimate goal of measuring spatial differences in relative growth rates. Insulin-like growth factor 1 is one of the principal hormones that stimulates growth at the cellular level in all vertebrates and shows significant relationships with body growth in many fishes. In the laboratory, we found that the level of IGF1 was related to the instantaneous growth of juvenile lingcod. In the field, we measured size, condition, and plasma IGF1 level in 149 lingcod from eight locations inside and outside marine protected areas in the San Juan Islands, Washington. The IGF1 levels in wild lingcod were highly variable from site to site for both genders, and we were able to detect differences in IGF1 across space in males. Multivariate analyses showed that the spatial patterns of IGF1 differed from those of traditional biological measurements. More work is needed to validate the relationship between IGF1 and growth in larger individuals, but our research shows the potential for IGF1 to be used as an ecological indicator.

The Impact of Different Hatchery Rearing Environments on Smolt-to-Adult Survival of Spring Chinook Salmon

AbstractThe aim of this study was to assess the effect of differing hatchery rearing environments on smolting, early male maturation, and smolt-to-adult return rates (SARs) in Chinook Salmon Oncorhynchus tshawytscha. In this investigation, SARs were compared for spring Chinook Salmon from Hood River stock reared at three different hatcheries and then released into the Hood River, replicated over three separate years (2010–2012). Differences in SARs were found both between rearing groups and release years. Smolts reared at Pelton Ladder had consistently higher SARs than those reared at either Parkdale or Carson hatcheries. Smolt length at release was positively correlated to SARs across years and rearing groups. In addition, multiple regression models suggested that attributes related to smolt quality were positively related to SARs while the minijack rate was negatively related to SAR. Migration of smolts downstream after release was also assessed. Larger smolts were faster downstream migrants and migrati...

Use of Morphological and Physiological Indices to Characterize Life History Diversity in Juvenile Hatchery Winter-Run Steelhead

AbstractSteelhead Oncorhynchus mykiss exhibit significant life history plasticity, including variation in freshwater residence time, age of smoltification, and maturation that are influenced by exceeding specific thresholds in size or body energy stores. Fish that do not reach minimum thresholds for smoltification or exceed thresholds for maturation may “residualize” in freshwater. Understanding life history diversity is important in steelhead hatchery programs. The objective of this investigation was to characterize life history diversity in Hood River, Oregon, hatchery winter-run steelhead prior to release. We used both morphological and physiological indices to assess degree of smoltification in both sexes and maturation in males. Smoltification was categorized by measuring size, visual smolt index, and gill Na+/K+-ATPase activity. All females were determined to be immature. Male reproductive development required histological staging of testes. Other indices of maturation—including gonadosomatic index,...