Migratory Patterns of Wild Chinook Salmon Oncorhynchus tshawytscha Returning to a Large,Free-Flowing River Basin

Upriver movements were determined for Chinook salmon Oncorhynchus tshawytscha returning to the Yukon River, a large, virtually pristine river basin. These returns have declined dramatically since the late 1990s, and information is needed to better manage the run and facilitate conservation efforts. A total of 2,860 fish were radio tagged during 2002–2004. Most (97.5%) of the fish tracked upriver to spawning areas displayed continual upriver movements and strong fidelity to the terminal tributaries entered. Movement rates were substantially slower for fish spawning in lower river tributaries (28–40 km d^-1) compared to upper basin stocks (52–62 km d^-1). Three distinct migratory patterns were observed, including a gradual decline, pronounced decline, and substantial increase in movement rate as the fish moved upriver. Stocks destined for the same region exhibited similar migratory patterns. Individual fish within a stock showed substantial variation, but tended to reflect the regional pattern. Differences between consistently faster and slower fish explained 74% of the within-stock variation, whereas relative shifts in sequential movement rates between “hares” (faster fish becoming slower) and “tortoises” (slow but steady fish) explained 22% of the variation. Pulses of fish moving upriver were not cohesive. Fish tagged over a 4-day period took 16 days to pass a site 872 km upriver. Movement rates were substantially faster and the percentage of atypical movements considerably less than reported in more southerly drainages, but may reflect the pristine conditions within the Yukon River, wild origins of the fish, and discrete run timing of the returns. Movement data can provide numerous insights into the status and management of salmon returns, particularly in large river drainages with widely scattered fisheries where management actions in the lower river potentially impact harvests and escapement farther upstream. However, the substantial variation exhibited among individual fish within a stock can complicate these efforts.     

Behavioral Thermoregulation by Juvenile Spring and Fall Chinook Salmon, Oncorhynchus Tshawytscha, during Smoltification

Fall chinook salmon evolved to emigrate during the summer months. The shift in the temperature preference we observed in smolting fall chinook but not spring chinook salmon may reflect a phylogenetic adaptation to summer emigration by (1) providing directional orientation as fall chinook salmon move into the marine environment, (2) maintaining optimal gill function during emigration and seawater entry, and/or (3) resetting thermoregulatory set-points to support physiological homeostasis once smolted fish enter the marine environment. Phylogenetically determined temperature adaptations and responses to thermal stress may not protect fall chinook salmon from the recent higher summer water temperatures, altered annual thermal regimes, and degraded cold water refugia that result from hydropower regulation of the Columbia and Snake rivers. The long-term survival of fall chinook salmon will likely require restoration of normal annual thermographs and rigorous changes in land use practices to protect critical thermal refugia and control maximum summer water temperatures in reservoirs.     

Paternal Genetic Effects on Offspring Swimming Performance Vary with Age of Juvenile Chinook Salmon, Oncorhynchus tshawytscha

While fish swimming behaviour has been extensively studied, the parental genetic basis of this critical behaviour has been rarely examined, especially past the earliest stages of development. We used a quantitative genetic breeding design to measure the critical swimming speed (U-crit) of offspring (15 and 18 weeks post-hatch) from 36 families of Chinook salmon (Oncorhynchus tshawytscha), a species with a nonresource-based mating system. We investigated the roles of dam, sire, and dam × sire on offspring U-crit, and estimated contributions of additive and nonadditive genetic effects and maternal effects to phenotypic variation in U-crit at both ages. We also used existing ‘high-survival’ and ‘low-survival’ lines of Chinook to determine if these two lines show differences in U-crit. At 15 weeks, there were no significant genetic effects, but at 18 weeks there were significant sire effects. Furthermore, additive genetic effects increased from 26 to 100 % from 15 to 18 weeks post-hatch. The two survival lines also showed differences in U-crit at 18 weeks post-hatch, with higher U-crit associated with “high-survival” sires. Collectively, the present study provides evidence for increasing importance of paternal identity (additive genetic variation) on swimming as juvenile offspring age. Given that mortality is high in young Pacific salmon and swimming ability is crucial, the sire effects could potentially shape survival though subsequent developmental stages. The change in the magnitude of effects in the present study indicates that future research should investigate genetic effects across multiple stages for better understanding of how phenotypic traits could respond to selection.     

Effects of Paternal Reproductive Tactic on Juvenile Behaviour and Kin Recognition in Chinook Salmon (Oncorhynchus tshawytscha)

Salmonids are characterized by alternative reproductive tactics, which can lead to an asymmetry in relatedness among offspring within nests and consequently the benefit of discriminating among nestmates. In this study, we examined the effect of paternal reproductive tactic on juvenile behaviour and kin discrimination in Chinook salmon. We created maternal half‐sibling families by collecting eggs from mature females and fertilizing one‐half with the milt of a precocious 2‐yr‐old male and the other half with the milt of a non‐precocious 4‐yr‐old male. These families were reared in full‐sibling groups for approximately 9 mo, and social interactions were then observed in groups of six fish of mixed relatedness. We found evidence for kin discrimination, as significantly less aggression was directed towards related fish than unrelated fish, and the same trends were observed regardless of whether social interactions included full‐siblings or half‐siblings. These results show that familiarity is not required to recognize kin and thereby implicate phenotype matching as the mechanism of kin recognition. We also found that the offspring of 2‐yr‐old males were larger and more aggressive than the offspring of 4‐yr‐old males, which is consistent with other studies showing that precocious males are the fastest‐growing members of their cohort. However, kin‐directed behaviours did not differ between the offspring of 2‐ and 4‐yr‐old males.     

The Effects of Disease-Induced Juvenile Mortality on the Transient and Asymptotic Population Dynamics of Chinook Salmon (Oncorhynchus tshawytscha)

The effects of an increased disease mortality rate on the transient and asymptotic dynamics of Chinook salmon (Oncorhynchus tshawytscha) were investigated. Disease-induced mortality of juvenile salmon has become a serious concern in recent years. However, the overall effects of disease mortality on the asymptotic and transient dynamics of adult spawning abundance are still largely unknown. We explored various scenarios with regard to the density-dependent process, the distribution of survivorship over the juvenile phase, the disease mortality rate, and the infusion of stray hatchery fish. Our results suggest that the sensitivity to the disease mortality rate of the equilibrium adult spawning abundance and resilience (asymptotic return rate toward this equilibrium following a small perturbation) varied widely and differently depending on the scenario. The resilience and coefficient of variation of adult spawning abundance following a large perturbation were consistent with each other under the scenarios investigated. We conclude that the increase in disease mortality likely has an effect on fishery yield under a fluctuating environment, not only because the mean equilibrium adult spawning abundance has likely been reduced, but also because the resilience has likely decreased and the variance in adult spawning abundance has likely increased. We also infer the importance of incorporating finer-scale spatiotemporal information into population models and demonstrate a means for doing so within a matrix population modeling framework.     

Controls on the Entrainment of Juvenile Chinook Salmon (Oncorhynchus tshawytscha) into Large Water Diversions and Estimates of Population-Level Loss

Diversion of freshwater can cause significant changes in hydrologic dynamics and this can have negative consequences for fish populations. Additionally, fishes can be directly entrained into diversion infrastructure (e.g. canals, reservoirs, pumps) where they may become lost to the population. However, the effect of diversion losses on fish population dynamics remains unclear. We used 15 years of release and recovery data from coded-wire-tagged juvenile Chinook Salmon (Oncorhynchus tshawytscha) to model the physical, hydrological and biological predictors of salvage at two large water diversions in the San Francisco Estuary. Additionally, entrainment rates were combined with estimates of mortality during migration to quantify the proportion of total mortality that could be attributed to diversions. Statistical modeling revealed a strong positive relationship between diversion rate and fish entrainment at both diversions and all release locations. Other significant relationships were specific to the rivers where the fish were released, and the specific diversion facility. Although significant relationships were identified in statistical models, entrainment loss and the mean contribution of entrainment to total migration mortality were low. The greatest entrainment mortality occurred for fish released along routes that passed closest to the diversions and certain runs of Chinook Salmon released in the Sacramento River suffered greater mortality but only at the highest diversion rates observed during the study. These results suggest losses at diversions should be put into a population context in order to best inform effective management of Chinook Salmon populations.     

Juvenile Salmon Usage of the Skeena River Estuary

Migratory salmon transit estuary habitats on their way out to the ocean but this phase of their life cycle is more poorly understood than other phases. The estuaries of large river systems in particular may support many populations and several species of salmon that originate from throughout the upstream river. The Skeena River of British Columbia, Canada, is a large river system with high salmon population- and species-level diversity. The estuary of the Skeena River is under pressure from industrial development, with two gas liquefaction terminals and a potash loading facility in various stages of environmental review processes, providing motivation for understanding the usage of the estuary by juvenile salmon. We conducted a juvenile salmonid sampling program throughout the Skeena River estuary in 2007 and 2013 to investigate the spatial and temporal distribution of different species and populations of salmon. We captured six species of juvenile anadromous salmonids throughout the estuary in both years, and found that areas proposed for development support some of the highest abundances of some species of salmon. Specifically, the highest abundances of sockeye (both years), Chinook in 2007, and coho salmon in 2013 were captured in areas proposed for development. For example, juvenile sockeye salmon were 2–8 times more abundant in the proposed development areas. Genetic stock assignment demonstrated that the Chinook salmon and most of the sockeye salmon that were captured originated from throughout the Skeena watershed, while some sockeye salmon came from the Nass, Stikine, Southeast Alaska, and coastal systems on the northern and central coasts of British Columbia. These fish support extensive commercial, recreational, and First Nations fisheries throughout the Skeena River and beyond. Our results demonstrate that estuary habitats integrate species and population diversity of salmon, and that if proposed development negatively affects the salmon populations that use the estuary, then numerous fisheries would also be negatively affected.     

Changes in Size and Age of Chinook Salmon Oncorhynchus tshawytscha Returning to Alaska

The average sizes of Pacific salmon have declined in some areas in the Northeast Pacific over the past few decades, but the extent and geographic distribution of these declines in Alaska is uncertain. Here, we used regression analyses to quantify decadal trends in length and age at maturity in ten datasets from commercial harvests, weirs, and spawner abundance surveys of Chinook salmon Oncorhynchus tshawytscha throughout Alaska. We found that on average these fish have become smaller over the past 30 years (~6 generations), because of a decline in the predominant age at maturity and because of a decrease in age-specific length. The proportion of older and larger 4-ocean age fish in the population declined significantly (P < 0.05) in all stocks examined by return year or brood year. Our analyses also indicated that the age-specific lengths of 4-ocean fish (9 of 10 stocks) and of 3-ocean fish (5 of 10 stocks) have declined significantly (P < 0.05). Size-selective harvest may be driving earlier maturation and declines in size, but the evidence is not conclusive, and additional factors, such as ocean conditions or competitive interactions with other species of salmon, may also be responsible. Regardless of the cause, these wide-spread phenotypic shifts influence fecundity and population abundance, and ultimately may put populations and associated fisheries at risk of decline.     

Genetic Structure of Wild Chinook Salmon Populations of Southeast Alaska and Northern British Columbia

Allozyme variation was used to examine population genetic structure of adult chinook salmon, Oncorhynchus tshawytscha, collected between 1988 and 1993 from 22 spawning locations in Southeast Alaska and northern British Columbia. Thirty-five loci and two pairs of isoloci were variable, and of these, 25 loci and one pair of isoloci expressed the most abundant allele with a frequency of less than or equal to 0.95 in at least one collection. A neighbor-joining (NJ) tree of genetic distances defined five regional groups: (1) King Salmon River (the only island collection), which has large allelic frequency differences from other populations in this study; (2) heterogeneous coastal populations from southern southeast Alaska; (3) transmountain collections from the Taku and Stikine Rivers on the eastern side of the coastal mountain range; (4) Chilkat River in northern Southeast Alaska; and (5) northern coastal Southeast Alaska, which consists of the Situk River and the Klukshu River, a tributary of the Alsek River. A second NJ tree that included collections from the Yukon River and British Columbia did not reveal any strong genetic similarity between Southeast Alaska and the Yukon River. The data suggest that Southeast Alaska may have been colonized from both northern and southern refugia following the last glaciation — a period of sufficient time to allow for isolation by distance to occur.     

Ouabain Suppresses the Migratory Behavior of Lung Cancer Cells

The migratory capability of cancer cells is one of the most important hallmarks reflecting metastatic potential. Ouabain, an endogenous cardiac glycoside produced by the adrenal gland, has been previously reported to have anti-tumor activities; however, its role in the regulation of cancer cell migration remains unknown. The present study has revealed that treatment with ouabain at physiological concentrations is able to inhibit the migratory activities of human lung cancer H292 cells. The negative effects of ouabain were found to be mediated through the suppression of migration regulatory proteins, such as focal adhesion kinase (FAK), ATP-dependent tyrosine kinase (Akt), and cell division cycle 42 (Cdc42). We found that the observed actions of ouabain were mediated via a reactive oxygen species (ROS)-dependent mechanism because the addition of ROS scavengers (N-acetylcysteine and glutathione) could reverse the effect of ouabain on cell migration. Furthermore, ouabain was shown to inhibit the spheroidal tumor growth and decrease the cancer cell adhesion to endothelial cells. However, the compound had no significant effect on anoikis of the cells. Together, these findings shed light on the understanding of cancer cell biology by exploring the novel function of this endogenous human substance.     

Temporal and Spatial Occurrence of Female Chinook Salmon Carrying a Male-Specific Genetic Marker in the Columbia River Watershed

Recent declines in many chinook salmon, Oncorhynchus tshawytscha, populations within the Columbia River watershed have prompted an examination of their reproductive biology. In a previous study many female fall chinook salmon collected in 1999 from the Hanford Reach of the Columbia River tested positive for a male-specific DNA marker (OtY1) found on the Y chromosome. The purpose of this study was to determine if females testing positive for the OtY1 marker could be found in other populations of fall chinook salmon from the Columbia River, and to assess the prevalence of OtY1 incidence in different female cohorts. Post-spawned male and female fall chinook salmon from three different naturally spawning populations (Hanford Reach, Yakima River and Ives Island) and one hatchery population (Priest Rapids Hatchery) on the Columbia River were tested in 2000 and 2001 for the OtY1 marker. Among naturally spawning populations, 57.4% of the females tested positive from the Hanford Reach, 33.3% tested positive from the Yakima River, and 32.5% tested positive from Ives Island. Of the Priest Rapids Hatchery fish, 62.5% of the females tested positive, and significant differences were detected between the 1995–1996 and 1997–1998 female cohorts from this population. No significant differences were detected between any of the female cohorts from the naturally spawning populations. All male chinook salmon samples, tested positive for OtY1.     

Ontogenetic shifts in the diets of juvenile Chinook Salmon: new insight from stable isotopes and fatty acids

Variations in marine prey availability and nutritional quality can affect juvenile salmon growth and survival during early ocean residence. Salmon growth, and hence survival, may be related to the onset of piscivory, but there is limited knowledge on the interplay between the prey field, environment, and salmon ontogeny. Subyearling Chinook Salmon (Oncorhynchus tshawytscha) and their potential prey were sampled in coastal waters off Willapa Bay, USA to explore this issue. Three seasonal prey assemblages were identified, occurring in spring (May), early summer (June – July), and late summer (August – September). The onset of piscivory, based on salmon stomach contents, fatty acids, and stable isotopes occurred later in 2011 compared to 2012, and coincided with the appearance of Northern Anchovy (Engraulis mordax). Salmon fork length (FL) and carbon isotope values (δ¹³C) increased with a fatty acid biomarker for marine phytoplankton and decreased with a freshwater marker, indicating dietary carbon sources changed as salmon emigrated from the Columbia River. Salmon FL also increased with nitrogen isotope ratios (δ¹⁵N), trophic position, and a fatty acid marker for piscivory – a consequence of the ontogenetic shift in diet to fish. Salmon grew faster and obtained larger size and condition by September 2011 compared to 2012, which was related to inter-annual differences in ocean conditions and the duration over which Northern Anchovy were available. Our results support the idea that juvenile salmon growth depends on the onset and duration of piscivory, suggesting both of these factors may be important components of lifetime growth and fitness.     

Development,Growth and Survivorship of Juvenile Calanoid Copepods on Diets of Cyanobacteria and Algae

Nauplii and immature copepodites of Boeckella triarticulata, B. hamata and B. dilatata were tested for their ability to survive and grow on monospecific diets of four species of filamentous cyanobacteria, Cyclotella (Cy) and Cryptomonas (Cr) at 2 mg dry weight 1⁻¹. Cr supported the development from nauplius to adult of all three calanoid species; complete development on other diets occurred only in B. dilatata on Cy and Anabaena oscillarioides (Ao). Differences between nauplii and copepodites of B. dilatata and B. hamata in survivorship and development on diets of Cy, Anabaena flos-aquae (Af), Ao and Nostoc sp. 2 (N2) imply ontogenetic shifts in resource utilization with developmental phase. Ranked in order of their ability to support the development of juvenile boeckellids the foods were Cr > Cy > Ao > N2 > Af > Nostoc calcicola = no food.     

The Development of Fast-Start Performance in Fishes: Escape Kinematics of the Chinook Salmon (Oncorhynchus tshawytscha)

C-starts are high acceleration swimming movements critical forpredator avoidance by fishes. Since larval fishes are particularlyvulnerable to predation, C-start behavior is likely to be especiallyimportant during early life history stages. This paper examinesthe developmental changes in C-start performance with kinematicdata on immature chinook salmon (Oncorhynchus tshawytscha) (eleuthroembryostage, sensu Balon, 1975). The scaling of C-start kinematicsof immature fishes differs from that of adults. Adult C-startdurations increase with increasing body length while C-startdurations of immature fishes decrease (e.g., adult stage 1 duration[sec] = 0.0019.length [L] [cm] $ 0.026 [R² = 0.77] [Webb, 1978];eleuthroembryos stage 1 duration [sec] = –0.026L [cm]$ 0.100 [R² = 0.81]). Distance traveled during stage 2 alsodiffers between adult and immature fishes. Adult distance traveledscales directly with length (distance [cm] = 0.38L^1.01 [cm],R² = 0.96 [Webb, 1978]) while chinook eleuthroembryo distancetraveled is positively allometric with length (distance [cm]=0.37L¹³¹ [cm], R² = 0.83). There are similarities in the developmentof C-starts and burst swimming. For example, mean velocity scalessimilarly between the two locomotor modes (For burst swimming:U_mean [cm/sec] = 8.1 ± 1.1L [cm] $ 4.89 [R² = 0.86] [Webband Corolla, 1981]. For C-start stage 2: U_mean [cm/sec] = 10.96L[cm] - 14.09 [R² = 0.70]). This study demonstrates that C-startescape performance improves during early post-hatching development.Comparisons of immature chinook salmon fast-starts with dataon larval burst swimming and on adult C-starts suggest thatchanges specific to developing fish affect the scaling of kinematicparameters.     

Bridging the Gap Between Salmon Spawner Abundance and Marine Nutrient Assimilation by Juvenile Salmon: Seasonal Cycles and Landscape Effects at the Watershed Scale

Ecosystems - Anadromous Pacific salmon are semelparous, and resource subsidies from spawning adults (marine-derived nutrients, or MDN) benefit juvenile salmonids rearing in freshwater. However, it...     

Extensive Direct-Tandem Organization of a Long Repeat DNA Sequence on the Y Chromosome of Chinook Salmon (Oncorhynchus tshawytscha)

A long repetitive DNA sequence (OtY8) has been cloned from male chinook salmon and its genomic organization has been characterized. The repeat has a unit length of 8 kb and is present approximately 300 times per diploid male nucleus. All internal fragments within the 8-kb repeat segregate from father to son, suggesting that the entire repeat unit is located on the Y chromosome. The organization of this sequence into an 8-kb repeat unit is restricted to the Y chromosome, as are several male-specific repeat subtypes identified on the basis of restriction-site variation. The repeat possesses only weak internal sequence similarities, suggesting that OtY8 has not arisen by duplication of a smaller repeat unit, as is the case for other long tandem arrays found in eukaryotes. Based on a laddered pattern arising from partial digestion of genomic DNA with a restriction enzyme which cuts only once per repeat unit, this sequence is not dispersed on the Y chromosome but is organized as a head-to-tail tandem array. Pulse-gel electrophoresis reveals that the direct-tandem repeats are organized into at least six separate clusters containing approximately 12 to 250 copies, comprising some 2.4 Mb of Y-chromosomal DNA in total. Related sequences with nucleotide substitutions and DNA insertions relative to the Y-chromosomal fragment are found elsewhere in the genome but at much lower copy number and, although similar sequences are also found in other salmonid species, the amplification of the repeat into a Y-chromosome-linked tandem array is only observed in chinook salmon. The OtY8 repetitive sequence is genetically tightly associated with the sex-determination locus and provides an opportunity to examine the evolution of the Y chromosome and sex determination process in a lower vertebrate. Received: 4 April 1997 / Accepted: 22 July 1997     

Juvenile Chinook salmon,Oncorhynchus tshawytscha,use of the Elwha river estuary prior to dam removal

The estuary of the Elwha River, on Washington’s Olympic Peninsula, has been degraded and simplified over the past century from sediment retention behind two large dams, levee construction, and channelization. With the removal of Elwha Dam and initiation of Glines Canyon Dam’s removal in fall 2011, sediment deposits will change the estuary and affect anadromous and nearshore marine fishes. Juvenile Chinook salmon commonly use estuaries and the river’s population is part of an Evolutionarily Significant Unit listed as Threatened under the U.S. Endangered Species Act. This study reports on monthly sampling in part of the river’s estuary from March 2007 through September 2011 to characterize the seasonal changes in relative abundance of yearlings and sub-yearlings, and size distributions prior to dam removal. Most (69 %) of the yearlings were caught in April, when this life history type was released from the hatchery, and to a lesser extent in May (28 %) and June (3 %). Yearlings caught in the estuary were smaller than those released from the hatchery (means: 153 mm?±?28 SD vs. 175 mm?±?5 SD), suggesting more rapid departure by larger fish. Sub-yearlings were much more abundant in the estuary, and were caught from March through November, increasing in mean fork length by 8.7 mm month^-1. The hatchery-origin sub-yearlings were not marked externally and so were not distinguishable from natural origin fish. However, 39 % of the sub-yearlings were caught prior to June, when sub-yearlings were released from the hatchery, indicating substantial use of the estuary by natural-origin fish. Thus, even in a reduced state after a century of dam operation, the highly modified estuary was used over many months by juvenile Chinook salmon. The information on juvenile Chinook salmon prior to dam removal provides a basis for comparison to patterns in the future, when the anticipated increase in estuarine complexity may further enhance habitat use by juvenile Chinook salmon.