Steelhead Kelts Research Articles

Reproductive development in captive reconditioned female steelhead kelts: evidence for consecutive and skip spawning life histories

Reconditioning of post-spawned anadromous rainbow trout (steelhead kelts, Oncorhynchus mykiss) is being implemented as a recovery tool on the Yakima River in the mid-Columbia River Basin. We assessed reproductive development in female Yakima River kelts by measuring plasma estradiol-17β (E2) and vitellogenin (VG) levels during reconditioning in 2009–2011. Plasma E2 and VG levels showed that fish separated into rematuring (consecutive spawning) and nonrematuring (presumed skip spawning) cohorts by October. Rematuration rates varied from 25% to 65%. Rematuring fish were consistently detected migrating toward spawning areas after release, whereas nonrematuring fish were occasionally detected on spawning migrations the following year. Rematuring fish grew more rapidly than nonrematuring fish over the reconditioning period and had higher muscle lipid levels and condition factor in October. Plasma E2 was elevated in rematuring fish by June–July, whereas plasma VG was elevated by June–August, suggesting that maturation decisions occur early in reconditioning. Rematuring and nonrematuring females could be separated by plasma E2 and VG levels by August–September, enabling separate management of consecutive and presumed skip spawners.

Physiological comparisons of steelhead kelts emigrating from the Situk River, AK and Clearwater River, ID

The physiological status of migrating steelhead kelts (Oncorhynchus mykiss) from the Situk River, Alaska, and two tributaries of the Clearwater River, Idaho, was evaluated to explore potential differences in post-spawning survival related to energy reserves. Blood plasma samples were analyzed for metrics related to nutritional and osmotic status, and samples of white muscle tissue collected from recent mortalities at weirs were analyzed for proximate constituents. Female kelts from the Situk River had significantly higher plasma cholesterol, triglycerides, glucose and calcium concentrations, all of which suggested higher lipid and energy stores. Additional support for energy limitation in kelts was provided by evaluating the presence of detectable proteins in the plasma. Most all kelts sampled from the Situk River populations had detectable plasma proteins, in contrast to kelts sampled from the Clearwater River tributary populations where 27 % of kelts from one tributary, and 68 % of the second tributary were below the limits of detection. We found proximate constituents of kelt mortalities were similar between the Situk and Clearwater River populations, and the lipid fraction of white muscle averaged 0.1 and 0.2 %. Our findings lend support to the hypothesis that energetic limitations likely affect post-spawn survival in the Clearwater River kelts.

Proximate Composition and Energy Density of Stream‐Maturing Adult Steelhead during Upstream Migration, Sexual Maturity, and Kelt Emigration

AbstractIn anadromous salmonids, muscle tissue provides the primary source of energy to support spawning migrations and spawning. We examined changes in the lipid content, protein content, and energy density of white muscle collected from stream‐maturing Snake River–Columbia River steelhead Oncorhynchus mykiss during several phases of reproduction. At a basinwide scale, we estimated that between early freshwater entry and postspawning (kelt) emigration, the lipid content of white muscle was reduced by 94% to levels less than 1% of wet tissue weight. Lipid was depleted more rapidly than protein during the reproductive cycle and afterward provided the only remaining somatic energy source for the postspawning migration. We found that protein content was consistently higher in sexually mature male steelhead than in females, suggesting that energy allocation prior to reproduction varies between the sexes. In kelts, the lipid content, protein content, and energy density of white muscle were significantly higher in good‐condition individuals than in poor‐condition fish. Fork length was positively correlated with both protein content and energy density in kelts, suggesting that larger kelts have higher somatic energy than smaller kelts. We found no evidence of significant interannual variation in lipid, protein, and energy density of sexually mature steelhead and steelhead kelts. Postspawning survival of steelhead is likely limited by the low energy density of kelts, and our data lend support to observations of low iteroparity rates in this and other populations of inland stream‐maturing steelhead.

Physiological indices of seawater readiness in postspawning steelhead kelts

AbstractManagement goals to improve the recovery of steelhead (Oncorhynchus mykiss) stocks at risk of extinction include increasing the proportion of postspawning fish that survive and spawn again. To be successful, postspawning steelhead (kelts) migrating downstream to the ocean must prepare physiologically and physically for a seawater transition. We sampled blood, gill filaments, and evaluated the external condition of migrating kelts from an ESA‐listed population in the Snake/Columbia River system over two consecutive years to evaluate their physiological readiness for transition to seawater. We chose attributes often considered as measures of preparation for seawater in juveniles, including gill Na+,K+ ATPase activity, plasma electrolytes and hormones to consider factors related to external condition, size and sex. We found kelts in good external condition had plasma profiles similar to downstream‐migrating smolts. In addition, we found more than 80% of kelts ranked in good external condition had smolt‐like body silvering. We compared measures from migrating kelts with samples obtained from hatchery fish at the time of spawning to confirm that Na+, K+ ATPase activity in kelts was significantly elevated over spawning fish. We found significant differences in gill Na+, K+ ATPase activity in migrating kelts between the years of sampling, but little indication of influence of fish condition. We conclude that the postspawning steelhead sampled exhibited a suite of behaviours, condition and physiology characteristic of fish prepared for successful transition to a seawater environment.

Survival and Traits of Reconditioned Kelt Steelhead Oncorhynchus mykiss in the Yakima River, Washington

AbstractWe evaluated the traits and survival to release of reconditioned kelt steelhead Oncorhynchus mykiss in the Yakima River (Washington State, USA). From 2001 to 2011, we captured a total of 9,738 downstream‐migrating kelts at an irrigation diversion facility, an average about 27% of each annual wild steelhead return. Captured kelts were reared for 4.5–10 months in an artificial environment, treated for diseases and parasites, and fed both krill and pellets. Surviving reconditioned fish were released into the Yakima River during the peak of the upstream migration of prespawn steelhead. Reconditioned steelhead kelts were predominantly (>92%) female. Annual survival to release ranged from 20% to 62% and averaged 38% over the course of the study, the surviving reconditioned kelts showing increases in FL, weight, and Fulton's K condition factor compared with their preconditioning status. Kelts in good condition and those with bright coloration at the time of collection were more likely to survive than those of poorer status at collection. Postrelease timing of upstream migration by reconditioned kelts was spread over several months and correlated well with the run timing of prespawn migrants upstream. The empirical results we observed demonstrate the potential for kelt reconditioning to provide recovery benefits for repeat spawning imperiled wild populations in highly developed river systems.Received July 17, 2012; accepted March 15, 2013

Resident rainbow trout produce anadromous offspring in a large interior watershed

Rainbow trout (Oncorhynchus mykiss) have diverse life histories, including both freshwater-resident and anadromous “steelhead” life-history forms. Here, we demonstrate that female resident rainbow trout produce anadromous offspring that survive and return to spawn as adult steelhead. This study represents the first successful attempt to quantify steelhead production rates from female resident rainbow trout across a large watershed. Otolith microchemistry (87Sr/86Sr) techniques were used to determine the maternal life history (resident or anadromous) of 498 emigrating steelhead kelts in the Yakima Basin, Washington. Five geochemically distinct freshwater rearing regions were identified within the basin. All five regions were predicted to produce steelhead with resident maternal life histories. Basin-wide, 20% and 7% of steelhead collected in 2010 and 2011, respectively, had resident maternal life histories. Cross-life-history form production may be critical to persistence of anadromous life histories within partially anadromous salmonid populations, particularly in areas where anadromous fish abundance is low due to natural or anthropogenic influences.

Archival and acoustic tags reveal the post-spawning migrations, diving behavior, and thermal habitat of hatchery-origin Sacramento River steelhead kelts (Oncorhynchus mykiss)

Acoustic and geolocating archival tags were deployed on steelhead kelts to study their post-spawning migrations, diving behavior and thermal habitat. Fourteen reconditioned steelhead kelts were surgically implanted with LAT2510 archival and V7-2 L acoustic tags, and released from Coleman National Fish Hatchery. An array of acoustic receivers in the Sacramento River and Delta, and the San Francisco Bay estuary detected the downstream movement of the steelhead. Two steelhead kelts (J and M) with archival tags were recovered at the hatchery after 219 and 285 days at liberty respectively. Based on changes in geolocations, vertical movements, and water temperatures, the migrations of steelhead J and M were divided into five and six phases respectively. Steelhead J moved into coastal California waters while steelhead M remained in freshwater for the majority of its time at liberty. Large increases in temperature and opacity were recorded before and after the ocean phases, likely as the steelhead moved through the Sacramento Delta. Both steelhead kelts remained relatively close to the surface throughout their migration but there were diurnal differences in the vertical movements. In freshwater, the steelhead tended to be deeper during the day (e.g., steelhead J: 3.08 ± 1.50 vs 1.65 ± 1.15 m, day vs night) but in the ocean, the steelhead were typically deeper during the night (1.32 ± 1.61 vs 5.63 ± 6.11 m). Both steelhead kelts appeared to be less oceanic than a previous study in Scott Creek, a small coastal stream approximately 100 km south of the mouth of San Francisco Bay. Although this study has a small sample size, the results suggest that steelhead kelts from a large river and estuary system, like the Sacramento River, may be relatively less oceanic than steelhead kelts from small coastal streams.

Freshwater Survival of Stranded Steelhead Kelts in Coastal Central California Streams

AbstractDuring 2008, spring drought conditions in the Santa Cruz Mountains of California resulted in hundreds of postspawn adult steelhead Oncorhynchus mykiss becoming stranded in streams and unable to return to sea. These individuals had no other option than to spend the entire summer and fall in freshwater habitats. As the fate of stranded kelts is poorly documented, we attempted to estimate the oversummer survival of steelhead kelts and to assess whether local habitat characteristics influenced survival rates. We found that nearly 40% of kelts observed during summer surveys were still alive in late October, just before the first significant rains of the season, and most individuals were observed to be in fair condition. Survival was higher for fish that resided in pools with substantial cover than for fish that occupied pools with only partial or no concealment. Overall, the unexpectedly high survival rates of stranded kelts suggest that the rescue and relocation of stranded steelhead to other habitats or to hatcheries may only be warranted when there are clear imminent threats to survival. Managers should consider the effects of strandings on population viability given that climate change may increase the frequency of strandings and decrease the survival of stranded individuals.Received September 28, 2010; accepted April 28, 2011

Electronic tags and genetics explore variation in migrating steelhead kelts (Oncorhynchus mykiss), Ninilchik River, Alaska

Acoustic and archival tags examined freshwater and marine migrations of postspawn steelhead kelts ( Oncorhynchus mykiss ) in the Ninilchik River, Alaska, USA. Postspawn steelhead were captured at a weir in 2002–2005. Scale analysis indicated multiple migratory life histories and spawning behaviors. Acoustic tags were implanted in 99 kelts (2002–2003), and an array of acoustic receivers calculated the average speed of outmigration, timing of saltwater entry, and duration of residency in the vicinity of the river mouth. Ocean migration data were recovered from two archival tags implanted in kelts in 2004 (one male and one female). Archival tags documented seasonal differences in maximum depth and behavior with both fish spending 97% of time at sea <6 m depth (day and night). All study fish were double tagged with passive integrated transponder (PIT) tags implanted in the body cavity. Less than 4% of PIT tags were retained in postspawn steelhead. Molecular genetics demonstrated no significant differences in genetic population structure across years or among spawning life history types, suggesting a genetically panmictic population with highly diverse life history characteristics in the Ninilchik River.

Transportation of Steelhead Kelts to Increase Iteroparity in the Columbia and Snake Rivers

AbstractWe tested the feasibility of transporting steelhead Oncorhynchus mykiss kelts (postspawned adults) around hydroelectric dams on the Snake and Columbia rivers to increase the returns of repeat spawners. Altogether, 5,878 kelts were collected, tagged with passive integrated transponder tags, and assigned to transported or in‐river treatment groups at Lower Granite Dam (n = 5,320 [2002–2004]) on the Snake River and John Day Dam (n = 558 [2002]) on the Columbia River. Returns of repeat spawners differed by site and year: 11.1% (62/558) for the John Day Dam sample and 1.4% (27/1,959), 0.5% (6/1,241), and 0.8% (17/2,120) for the Lower Granite Dam samples in 2002, 2003, and 2004, respectively. Transportation tests indicated that kelts transported from the Snake River were approximately 2.3 times more likely to return than fish allowed to migrate in‐river. Transport benefits were greatest for wild‐origin female kelts, a demographic with high conservation value. There was no significant benefit for kelts transported from John Day Dam, although transported fish returned at a slighter higher rate (1.1 times). Comparisons between treatment groups (in‐river versus transport) and locations (Snake River versus Columbia River) indicated that the greatest potential transport benefit may be for Snake River kelts owing to the population's low overall iteroparity rate and numerous potential kelt collection sites. The small sample sizes of returning fish limited our ability to examine more complex trends and environmental effects on return rates. Additional research is needed to fully evaluate the efficacy of kelt transportation in the context of regional steelhead recovery efforts.

Evaluation of a Surface Flow Bypass System for Steelhead Kelt Passage at Bonneville Dam, Washington

AbstractA surface flow bypass system for juvenile Pacific salmon Oncorhynchus spp. began operation at the second powerhouse (B2) of Bonneville Dam on the lower Columbia River in spring 2004. This surface bypass, called the “B2 corner collector,” is the result of extensive modification of the original B2 sluice chute. Because steelhead O. mykiss are iteroparous, the effect of this bypass and the unmodified sluiceway at the older first powerhouse (B1) on downstream migration of postspawn steelhead (i.e., kelts) may be an important factor in the rate of iteroparity. As such, passage at Bonneville Dam (river kilometer (rkm) 234, measured from the mouth of the Columbia River) was examined to understand the efficiency of surface bypass in passing kelts. Steelhead kelts were collected, radio‐tagged, and volitionally released from the juvenile bypass facilities at McNary Dam (rkm 465) and John Day Dam (rkm 345) on the Columbia River during spring 2004. Forebay residence times for kelts passing via B2 (with the corner collector operating) were significantly reduced relative to residence times published from a prior period with similar water flows at B2 (2002). Passage efficiency (nonturbine passage) at B2 significantly increased in relation to this same period. Over 80% of kelts at B2 and nearly the same percentage at B1 were routed away from turbines via surface flow routes passing up to 5% of total discharge at each powerhouse, indicating that relatively small amounts of surface flow are needed to pass kelts via nonturbine routes. Providing surface flow passage routes may provide an efficient means of bolstering iteroparity rates by increasing the number of kelts that successfully navigate Bonneville Dam during the spring.

Erratum: Downstream Passage of Steelhead Kelts through Hydroelectric Dams on the Lower Snake and Columbia Rivers

Erratum: Downstream Passage of Steelhead Kelts through Hydroelectric Dams on the Lower Snake and Columbia Rivers

Downstream Passage of Steelhead Kelts through Hydroelectric Dams on the Lower Snake and Columbia Rivers

AbstractAfter spawning, iteroparous steelhead Oncorhynchus mykiss from the Columbia River basin must navigate several hydroelectric dams on their way to the Pacific Ocean. We used radiotelemetry to investigate migration rates, downstream passage routes, and success of adult steelhead kelts migrating past lower Snake River and Columbia River dams during the springs of 2001 and 2002. Seaward‐migrating kelts were collected, radio‐tagged, and volitionally released from the juvenile bypass facilities at Lower Granite Dam (LGR) on the Snake River and at McNary Dam (McN) and John Day Dam (JDD) on the Columbia River. Migration success rates from LGR to the study area exit (8 km east of Portland, Oregon) were poorer during the low‐flow nonspill conditions of 2001 (4.1%) than in the more typical flow year of 2002 (15.6%). Kelts tagged and released at Columbia River dams had substantially higher migration success than those released on the Snake River; 59.6% and 62.3% of the kelts released at McN and 63.6% and 80.0% of those released at JDD were contacted at the study area exit during 2001 and 2002, respectively. Kelt dam passage was predominately via spillways and surface flow routes, and during periods of spill 90.0% or more kelts typically passed via nonturbine routes. Only 47.2% of kelts were guided out of turbine intakes by screen systems during nonspill periods. Turbine passage, the primary alternative route during nonspill periods, may be a substantial source of kelt mortality. The poor migration success rate of Snake River kelts in both 2001 and 2002 suggests that additional management (i.e., kelt reconditioning, transportation, or both) may be warranted to boost iteroparity rates in this population.

Identification and Enumeration of Steelhead Kelts at a Snake River Hydroelectric Dam

Improvement of iteroparity rates in U.S. Endangered Species Act (ESA)-listed Snake River populations of steelhead Oncorhynchus mykiss requires a means of distinguishing prespawn (mature) steelhead from postspawners (kelts) and sufficient kelt abundance to aid recovery efforts. We used ultrasound imaging of gonads to identify and enumerate prespawn steelhead and kelts incidentally collected in the juvenile bypass facility at Lower Granite Dam (LGR) on the Snake River, Washington. We also evaluated the accuracy of visual identifications based on external coloration and condition in relation to the known maturational status determined by ultrasound examinations. Steelhead (n = 1,353) were sampled during 10 weeks between April and June 2000, a period that spanned the peak of adult steelhead occurrence in the juvenile bypass system. Based on ultrasound appraisals, we estimated that kelts composed 94.6% of the 3,968 adult steelhead encountered in the LGR juvenile bypass system during the study period. Of these kelts, 2,050 were wild or naturally produced ESA-listed steelhead. This number represents 17% of the entire protected Snake River population that passed the LGR fishladder as prespawners during 1999. Visual methods grossly underestimated the number of kelts; only 18% of the ultrasound-sampled adults were classified as kelts by visual identification. Most kelts were in good external morphological condition (69.5%) and were either bright or intermediate in coloration (84.7%). Most kelts also were female (77.0%). Clearly, the potential for iteroparity persists in Snake River steelhead, but we do not yet know what proportion of these kelts survive to spawn again.