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Population introductions and reintroductions have become a common tool for conserving threatened species, but oftentimes introduced populations have reduced the genetic diversity compared with the source population they were founded from. Population introductions played an important role in the recovery of the Oregon Chub Oregonichthys crameri, a small floodplain minnow found in western Oregon. Unlike many introduction efforts, introduced populations of Oregon Chub were founded using large numbers of individuals (hundreds in many cases) and each population had a unique introduction history (e.g., number of founders, source populations selected, duration of the introduction effort). We used microsatellite loci to examine 13 introduced populations and their respective sources to evaluate how well the introduction program captured genetic diversity present in the wild populations. Genetic variation was reduced by roughly 25% in one introduced population, and three introduced populations showed eviden...

We examined the distribution of Umpqua Chub Oregonichthys kalawatseti, an endemic, vulnerable minnow in western Oregon, and whether six ecological populations (based on distribution patterns) had sufficient genetic cohesion to be considered evolutionary populations. We also evaluated the influence of Holocene geological events and recent nonnative predator introductions on the timing of population formation or fragmentation. Based on data from 10 microsatellite loci, we found evidence for four evolutionary populations of Umpqua Chub. One population, in the Smith River, is isolated by the Umpqua estuary and is more than 100 river kilometers from the other three populations: Elk Creek, Calapooya Creek–Olalla Creek, and Cow Creek–South Umpqua River. Quantile regression was used to examine the timing of genetic divergence among evolutionary populations assuming a genetic isolation-by-distance model. The quantile regression suggested that the genetic differentiation index (F ST) should change by at le...

The Oregon chub Oregonichthys crameri is a small floodplain minnow endemic to the Willamette River basin of western Oregon. Historically the species was widely abundant and probably relied on periodic floods for dispersal and genetic exchange among populations. The species has declined substantially in the past 100 years due to habitat alterations and the introduction of nonnative species and is currently listed as threatened under the U.S. Endangered Species Act. Information on the level of genetic variation within and among populations did not exist when the species was listed or when a recovery plan was being developed. In this study, we used a suite of nine microsatellite loci to characterize genetic variation within and among 16 sampling locations and provide information to help guide future recovery efforts. Even though many locations are presently isolated from one another, we observed relatively high levels of genetic variation within collections. Temporal samples revealed that the levels...

Conservation banks are permanently protected lands that contain habitat elements which may be critical to the protection and recovery of federally-listed species under the Endangered Species Act. These banks are managed in perpetuity and used to mitigate impacts occurring elsewhere to the species' habitat. We developed a species crediting methodology to assess conservation credits and debits for the endangered Oregon chub (Oregonichthys crameri) to support conservation banking. Our methodology is based on prior studies assessing relationships between population abundance and habitat parameters for the species. The methodology also incorporates ratings for piscivory risk, site location, and the abundance and status of existing and proximal populations. Our approach assigns more credits to functioning bank sites that support abundant, stable populations and requires more credits when impacted sites negatively affect these populations. Examples show the credit value calculations for determining baseline cond...

The objectives of this study were to determine the distribution and abundance of endangered Oregon chub Oregonichthys crameri, a small floodplain minnow endemic to the Willamette Valley of western Oregon; to describe the fish communities in current and historic chub habitats; and to establish new populations through introductions. Various sampling gears were used, including seines, minnow traps, dip nets, and a gill net. Oregon chub distribution was found to be restricted in comparison with their historical range, whereas nonnative fishes were widespread in the off-channel habitats preferred by Oregon chub. Oregon chub were absent, or low in abundance, when nonnative fishes were present, and several populations declined or were extirpated when their habitats were invaded by nonnative fishes. Isolated habitats with low connectivity supported larger populations of Oregon chub and were less likely to contain nonnative fish species than were habitats with high connectivity. In habitats that supported...

We describe the isolation and development of 16 polymorphic tetranucleotide microsatellite loci for the endangered Oregon chub (Oregonichthys crameri). Two loci appear to be duplicated. For the remaining 14 loci, we observed between three and 19 alleles per locus in a sample of 42 fish. Thirteen of these loci were also polymorphic in the closely related Umpqua chub (O. kalawatseti). These loci will aid in our understanding of the molecular ecology and conservation of these two species.

Why is it worth so much money and time to recover the little Oregon Chub – a fish most people do not even know exists?The Oregon Chub Oregonichthys crameri has been described as an indicator specie...

Thomas E. Bigford tbigford@fisheries.orgThe Obama administration announced on September 22, 2015, that it would not list the greater sage grouse under the federal Endangered Species Act (ESA). That...

Available information on aquatic biota of the Willamette Basin was reviewed and summarized to describe current and historical conditions as part of the U.S. Geological Survey's National WaterQuality Assessment Program. Biological parameters emphasized include the status, distribution, and trends of aquatic biota, particularly algae, macroinvertebrates, and fish; the condition of aquatic and riparian habitat in which these biota reside; and the response of these biota to natural and human-associated impacts, including the level, type, and effect of contaminants. Considerable data are available on aquatic biota in the Willamette Basin, although the information is highly uneven relative to taxa and spatial scope. Extensive information exists for highprofile taxa, such as salmonid fishes, but less information is available for macroinvertebrates, and relatively little data exist for algae. Additionally, some areas such as the H.J. Andrews Experimental Forest and the main stem Willamette River have been extensively studied, whereas data are limited for many other areas. The basin supports a diverse aquatic macroinvertebrate fauna. Available data indicate a relatively high diversity of taxa and a high richness of Ephemeroptera, Plecoptera, Trichoptera (EPT) taxa in the upper reaches of the basin. In the lower main stem reaches, macroinvertebrate assemblages are dominated by pollution tolerant organisms and those adapted to low dissolved oxygen levels. Most of the limited data on algae are from sampling in the main stem Willamette River. Diatoms and blue-green algae are the dominant algal forms. Approximately 61 fish species occur in the basin, although nearly half are introduced. Species richness and distribution are highly correlated with elevation, stream gradient, and water temperature. High elevation, cold water, mountain streams are characterized by a few species of salmonids, sculpins, suckers, and whitefish. Low elevation, main stem reaches of major rivers and streams are dominated by warm water species, such as bass, catfish, and several species in the panfish group. The only species of fish listed as threatened or endangered is the Oregon chub (Oregonichthys crameri). The effect of an expanding human presence in the Willamette Basin has substantially altered aquatic and riparian habitats, and the biota that use or reside in these habitats. Construction of dams, channelization and bank stabilization of rivers, species introductions, supplementations of fisheries through aquaculture, timber harvesting, agricultural activities, and urbanization have contributed to changes in aquatic habitats and biota from historical conditions. Aquatic toxicological investigations in the basin have focused primarily on fish. These studies have addressed chlorinated pesticides, polychlorinated biphenyls (PCBs), dioxins and furans, polycyclic aromatic hydrocarbons (PAHs), and trace elements in aquatic tissue, as well as fish health assessments, skeletal abnormalities, and aquatic toxicological responses. Several pesticides exceeded U.S. Environmental Protection Agency and State water-quality criteria for the protection

Evaluation of the movement patterns of small-bodied fish is often hindered by the lack of a suitable long-term mark. We evaluated several techniques for long-term group and individual identification of adult (40–70 mm total length [TL]) Oregon chub (Oregonichthys crameri). We marked Oregon chub with one of two different sized passive integrated transponder (PIT) tags (a 9 × 2.12 mm, 0.067 g PIT tag [PIT-tag] or a 8.4 × 1.4 mm, 0.033 g PIT tag [PICO-tag]), a red visible implant elastomer (VIE) tag, or a freeze brand. We monitored survival, tag retention, and mark quality over 150 days. In addition, we assessed the minimum length and weight thresholds to achieve 80% and 90% survival of PIT-tagged fish. Marking with a freeze brand, PICO-tag, or VIE tag had no effect on survival (P >0.05). In contrast, marking with a PIT-tag was associated with significantly lower (P

The Oregon chub Oregonichthys crameri is an endangered floodplain minnow en- demic to the Willamette River drainage in western Oregon. We determined age and growth of Oregon chub at 3 locations and the timing of spawning at 2 locations. We found that Oregon chub live much longer than previously thought (up to 9 y) and that most of the fish older than 5 y were females. We found strong relationships between somatic growth and otolith (lapillus) growth within populations and considerable variation among populations. Mature fish were primarily-2 y old, and all fish >40 mm long had gonads that were developing or mature. Oregon chub spawned from mid-May through early August with peak activity in July. Juveniles that hatched prior to mid-June were not found in October, suggesting reduced survival of early hatched fish.

The Umpqua chub, a new species of Oregonichthys, is described from the Umpqua River of southern Oregon. The two species of Oregonichthys are allopatric sibling species that differ in spawning substrates but are generally similar in appearance: the Umpqua chub spawns on rocks, lives in a variety of streamside habitats with moderate to no water flow, has a naked breast and a slightly subterminal mouth; the Oregon chub of the Willamette River, 0. crameri, spawns in plants, lives in pond or slough habitats with little or no water flow, has a scaled breast and a terminal mouth. A Late Cenozoic stream capture is postulated as the vicariant event responsible for allopatry. Recent surveys indicate that the Oregon chub is restricted to about 30 km of the Middle Fork of the Willamette River and that its continued existence is endangered.