Search

Elucidation of genetic mechanisms underpinning migratory behavior could help predict how changes in genetic diversity may affect future spatiotemporal distribution of a migratory species. This ability would benefit conservation of one such declining species, anadromous Pacific lamprey ( Entosphenus tridentatus). Nonphilopatric migration of adult Pacific lamprey has homogenized population-level neutral variation but has maintained adaptive variation that differentiates groups based on geography, run-timing and adult body form. To investigate causes for this adaptive divergence, we examined 647 adult lamprey sampled at a fixed location on the Columbia River and radiotracked during their subsequent upstream migration. We tested whether genetic variation [94 neutral and adaptive single nucleotide polymorphisms ( SNPs) previously identified from a genomewide association study] was associated with phenotypes of migration distance, migration timing, or morphology. Three adaptive markers were strongly associated with morphology, and one marker also correlated with upstream migration distance and timing. Genes physically linked with these markers plausibly influence differences in body size, which is also consistently associated with migration distance in Pacific lamprey. Pacific lamprey conservation implications include the potential to predict an individual's upstream destination based on its genotype. More broadly, the results suggest a genetic basis for intrapopulation variation in migration distance in migratory species. [ABSTRACT FROM AUTHOR]

Variability is a hallmark of animal behavior and the degree of variability may fluctuate in response to environmental or biological gradients. For example, diel activity patterns during reproductive migrations often differ from those in non-breeding habitats, reflecting trade-offs among efficient route selection, reproductive phenology, and risk avoidance. In this study, we tested the hypothesis that diel movements of anadromous fishes differ among freshwater migration habitats. We analyzed diel movement data from ~13 000 radio-, PIT-, and acoustic-tagged adult fishes from five Columbia River species: Chinook salmon, Oncorhynchus tshawytscha; sockeye salmon, O. nerka; steelhead, O. mykiss; Pacific lamprey, Entosphenus tridentatus; and American shad, Alosa sapidissima. All five species were active during most of the diel cycle in low-gradient, less hydraulically complex reservoir and riverine habitats. Movement shifted to predominantly diurnal (salmonids and American shad) or nocturnal (Pacific lamprey) at hydroelectric dam fishways where hydraulic complexity and predator density were high. Results suggest that context-dependent behaviors are common during fish migrations, and that diel activity patterns vary with the degree of effort or predation risk required for movement. [ABSTRACT FROM AUTHOR]

We conducted an experiment to assess the effects of radio- tagging on adult spring Chinook salmonOncorhynchus tshawytschaduring the late stages of their spawning migration. Fish were captured at Roza Dam, Yakima River, Washington (river kilometer 208). Each fish had a radio tag inserted into the stomach via the esophagus and was then transported to a raceway and held for 50 d to assess survival. In the same raceway we also held a control group that was handled but not tagged and a group with externally attached transmitters. Survival of fish with gastrically implanted radio tags was low (10%), while 70% of controls and 90% of fish with externally mounted tags survived to the end of the experiment. Postmortem dissections revealed that after implantation, some radio tags had migrated from the stomach position to the posterior digestive tract and peritoneum. Fish from all treatments exhibited some level of tissue degeneration of the gastrointestinal tract. Gastric implantation should be used with caution, particularly for fish at vulnerable life stages. For spring Chinook salmon in the Columbia River basin, tagging with gastric implants should be conducted early in the freshwater migration to improve survival and reduce tag effects. Received September 30, 2011; accepted June 4, 2012 [ABSTRACT FROM PUBLISHER]

Due to tribal concerns over the recent decline of Pacific lamprey Lampetra tridentata, a restoration program was initiated to establish a self-sustaining, harvestable lamprey population within the ceded lands of the Confederated Tribes of the Umatilla Indian Reservation in Oregon. We hypothesized that low returns of adult lampreys to spawning areas in the Umatilla River were caused by loss of habitat connectivity in this watershed. We conducted a study to determine whether the ubiquitous, low-elevation irrigation diversion dams in the main-stem Umatilla River were obstacles to adult lamprey spawning migration. Radiotelemetry was used to assess lamprey passage efficiency at seven dams located within the lowest 55-km reach of the Umatilla River. During this 4-year study, we tracked 217 adult Pacific lampreys that were implanted with radio transmitters and released downstream from the dams. Logistic regression analysis indicated that dam design, fish size, and temperature had the greatest effects on passage efficiency. Poor performance (<30% fitted passage probability) was recorded at the two lowest dams in the system and resulted in limited escapement to upper sites. During the study, one dam was breached, after which passage efficiency there immediately improved from 32% to 81%. In addition, water augmentation actions at Three Mile Falls Dam apparently contributed to improved mean passage efficiency of migratory-phase fish (from 17% to 50%). Thus, actions to improve adult lamprey access to historical spawning areas are feasible and are key to successful restoration of this species. Received June 29, 2011; accepted February 13, 2012 [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Fisheries & Aquatic Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Adult Pacific lampreys Lampetra tridentata migrate through areas of difficult passage and high water velocity by attaching their oral discs to substrate and then releasing and bursting upstream. In fishways at dams, this burst-and attach behavior can be ineffective, particularly where suitable attachment surfaces are unavailable. We used an experimental fishway to test performance of adult Pacific lampreys when confronted with a series of structural challenges. These included vertical steps near fishway weir orifices, squatted versus rounded orifice entrances, and floor-mounted metal grates. All experimental challenges simulated common existing structures in weir-and-orifice fishways at Columbia and Snake River dams. Most experiments were paired with field evaluations of radio-tagged Pacific lampreys or video observations of untagged individuals in situ. Field and experimental results consistently indicated that the structural challenges reduced passage efficiency and lengthened passage times. Improving Pacific lamprey passage may be facilitated by removing or modifying vertical steps and other sharp-edged corners and by providing adequate attachment surfaces. Such accommodations should be especially beneficial in areas with high water velocity. The findings demonstrate how fish morphology and behavior should be explicitly considered in the design or retrofitting of fish passage structures. [ABSTRACT FROM AUTHOR]

Dams in the Columbia River basin present significant obstacles to declining populations of anadromous Pacific lampreys Lampetra tridentata. Mitigation efforts have focused on fine-scale improvements in passage at individual dams, but there is an increasing need for basinwide estimates of survival and escapement. We developed a half-duplex passive integrated transponder (PIT) tag monitoring array at five Columbia and Snake River dams to evaluate adult lamprey migrations. We tagged 3,598 lampreys over 3 years and calculated the rates of main-stem escapement through 15 river reaches. From these data, we assessed the relative effects of lamprey size, river discharge, water temperature, and migration timing on upstream passage. The results indicated high attrition as lampreys progressed upstream. In each year, about one-half of the fish passed one dam, 28-33% passed two dams. 17-19% passed three dams, 4-5% passed four dams, and about 1% passed Ihe first dam on the Snake River (five dams and >300 km upstream from their release sites). In most reaches, upstream passage was strongly size dependent, the largest lampreys being two to four times more likely to pass than the smallest fish. Lamprey size was more predictive of passage than were the river discharge, temperature, or migration timing variables. These findings suggest that adult Pacific lamprey migration is affected by physiological constraints and that effective mitigation for the difficult passage conditions at dams should include size-related considerations. [ABSTRACT FROM AUTHOR]

Highlights: [•] Timing data are difficult to analyze because conditions vary during the observation period. [•] We demonstrated methods to analyze “time-to-event” data under time-varying conditions. [•] We applied parametric models to the time for migrating salmonids to successfully pass a barrier. [•] The model captured pronounced diel behavior and the effects of time-varying covariates. [Copyright &y& Elsevier]