No abstract

Dams have contributed to the decline of migratory fishes by blocking access to historical habitat. The active transport (trap and haul) of migratory fish species above existing dams can sometimes support population recovery when the use of fish ladders or dam removal is infeasible. However, little is known about the efficacy of trap and haul conservation strategies. Here we used genetic parentage assignments to evaluate the efficacy of reintroducing adult Chinook salmon (Oncorhynchus tshawytscha) above Cougar Dam on the South Fork McKenzie River, Oregon, USA, from 2008 to 2011. We found that mean reproductive success (RS) declined as adults were released later in the spawning season in 2009 and 2010; however, release location did not affect RS. In 2010 and 2011, we tested for RS differences between hatchery and natural origin (HOR and NOR, respectively) adults. HOR males were consistently less fit than NOR males, but little evidence for fitness differences was apparent between HOR and NOR females. Interestingly, the effect of origin on RS was not significant after accounting for variation explained by body length. Our results indicate that release date and location have inconsistent or no effect on the reproductive success of reintroduced adults when active transport strategies are employed for migratory fishes.

Human polymorphonuclear neutrophils rapidly incorporated radiolabeled platelet-activating factor, 1-O-Ihexadecyl-9, 10-3H21-2-acetyl-sn-glycero-3-phosphocholine (I3HIPAF), and then metabolized it into its sn-2-fatty acyl derivative.

Neutral genetic markers are routinely used to define distinct units within species that warrant discrete management. Human-induced changes to gene flow however may reduce the power of such an approach. We tested the efficiency of adaptive versus neutral genetic markers in differentiating temporally divergent migratory runs of Chinook salmon (Oncorhynchus tshawytscha) amid high gene flow owing to artificial propagation and habitat alteration. We compared seven putative migration timing genes to ten microsatellite loci in delineating three migratory groups of Chinook in the Feather River, CA: offspring of fall-run hatchery broodstock that returned as adults to freshwater in fall (fall run), spring-run offspring that returned in spring (spring run), and fall-run offspring that returned in spring (FRS). We found evidence for significant differentiation between the fall and federally listed threatened spring groups based on divergence at three circadian clock genes (OtsClock1b, OmyFbxw11, and Omy1009UW), but not neutral markers. We thus demonstrate the importance of genetic marker choice in resolving complex life history types. These findings directly impact conservation management strategies and add to previous evidence from Pacific and Atlantic salmon indicating that circadian clock genes influence migration timing.

The unambiguous identification of Central Valley spring‐run chinook salmon has become imperative since their proposed listing in 1998. The accuracy of methods used to assign individuals to their stock of origin is critical for understanding juvenile migration patterns and determining the success of protection measures. Existing microsatellites discriminate between the endangered winter‐run and other chinook but are insufficient to characterize phylogenetically less distinct runs. Here, we isolated and developed highly variable tetranucleotide microsatellites for the specific goal of increasing discriminatory power among closely related populations, providing a new power towards the reliable differentiation of nonwinter runs

Previous studies have concluded that cytosolic Ca2+ [( Ca2+]i) transients are essential for neutrophils (PMN) to degranulate and make superoxide anion when challenged with the receptor agonists N-formyl-methionyl-leucyl-phenylalanine, platelet-activating factor and leukotriene B4. This view is based on the profound unresponsiveness of PMN that have their [Ca2+]i fixed at resting levels by removing storage Ca2+ and loading the cells with greater than or equal to 20 microM of a Ca2+ chelator, quin2 AM. We too observed this unresponsive state in PMN loaded with 10-32 microM-quin2 AM, fura-2 AM or 1,2-bis-(2-aminophenoxy) ethane-NNN'N'-tetra-acetic acid (BAPTA). When loaded with less than or equal to 1 microM fura-2 AM, however, Ca(2+)-depleted PMN failed to alter [Ca2+]i appreciably, yet still had substantial degranulation and superoxide-anion-generating responses to the receptor agonists. Function thus did not require [Ca2+]i transients. Moreover, Ca(2+)-depleted PMN had 20-35% decreases in receptor numbers for each of the three agonists, and chelator loading of these cells decreased receptor availability by 30-50%. All receptor losses were reversed by incubating PMN with Ca2+ at 37 degrees C, but not at 4 degrees C, and agonist binding at 4 degrees C was not influenced by the presence or absence of extracellular Ca2+. Ca2+ thus caused PMN to up-regulate their agonist receptors at 37 degrees C, and the effect persisted at 4 degrees C regardless of ambient Ca2+. We conclude that Ca2+ acts in at least three ways to regulate responses to receptor agonists. First, some pool of (probably cellular) Ca2+ maintains receptor expression. Second, [Ca2+]i transients potentiate, but are not required for, function. The [Ca2+]i pool may or may not be the same as that influencing receptors. Finally, another pool(s) of Ca2+ signals or permits responses. This last pool, rather than [Ca2+]i transients, appears essential for the bioactions of standard Ca(2+)-mobilizing stimuli.

Expected daily FL ranges (length at date) of juvenile Chinook Salmon Oncorhynchus tshawytscha have been used throughout California's Central Valley to identify federally listed winter‐run and spring‐run juveniles in a mixed four‐race stock. Accurate race identification is critical both to species recovery and to management of the water supply for 25 million people and a multibillion‐dollar agricultural industry. We used genetic race assignment of 11,609 juveniles sampled over 6 years to characterize the accuracy of the length‐at‐date approach, specifically by testing two of its central assumptions: (1) juvenile FL distributions do not overlap between races on a daily basis; and (2) the growth rates that are used to project FL at date are accurate. We found that 49% of FLs for genetically identified juveniles occurred outside the expected length‐at‐date ranges for their respective races, and we observed a high degree of overlap in FL ranges among the four races. In addition, empirical growth rates were well below those from which length‐at‐date criteria were derived. Given the high degree of FL overlap between races, we conclude that modification of the length‐at‐date method will not substantially reduce identification error. Thus, we recommend that genetic assignment be used at least as a supplemental approach to improve Central Valley Chinook Salmon race identification, research, and management.Received January 7, 2014; accepted July 22, 2014

Dams, utilized for hydroelectric or flood control purposes, obstruct organism dispersal and have contributed to the decline of many migratory fish populations. For threatened Chinook salmon (Oncorhynchus tshawytscha) from the Willamette River Basin in Oregon, human-assisted reintroductions are being used to facilitate dispersal to historical habitats located above dams. However, little is known about the reproductive outcomes of reintroduced individuals or the efficacy of reintroductions towards the goal of population demographic viability. Using genetic parentage assignments to 3-, 4-, and 5-year-old adult recruits, we estimated the fitness of hatchery and wild Chinook salmon reintroduced above Foster Dam on the South Santiam River, a tributary of the Willamette River. Our parentage assignments indicated that the fitness of reintroduced salmon was highly variable, with individuals producing a range of 0–40 adult progeny. We also detected a possible trend towards reduced fitness in mate pairs composed of hatchery versus wild salmon. For each of three brood years (2007, 2008, 2009), adult offspring recruitment achieved or exceeded population replacement. We observed the highest cohort replacement rate in 2009, the first year that managers aimed to release wild salmon solely above the dam. Taken together, our results suggest that human-assisted reintroductions of mature adult salmon to historical spawning habitats are a promising method of restoring natural production in populations affected by dams. Moreover, the continued used of wild fish in reintroduction operations may improve population productivity and the prospect of recovery within the South Santiam River.