Douglas F. Markle

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We examined near-shore habitat use by larval shortnose and Lost River suckers in the lower Williamson River and Upper Klamath Lake of south-central Oregon. Emergent macrophytes Scirpus, Sparganium and Polygonum supported significantly more, larger, and better-fed larvae than submergent macrophytes, woody vegetation, or open water. Abundance, size, and gut(More)
Parasites may be an important component of early life mortality in fishes, but assigning part of total mortality to parasites is difficult. The Chapman-Robson mortality estimator is a robust and potentially valuable way to quantify the added mortality of parasites when age data are available. We used daily age data and the Chapman-Robson catch-curve(More)
The Willamette River, one of 14 American Heritage Rivers, flows through the most densely populated and agriculturally productive region of Oregon. Previous biological monitoring of the Willamette River detected elevated frequencies of skeletal deformities in fish from certain areas of the lower (Newberg pool [NP], rivermile [RM] 26 - 55) and middle(More)
We described skeletal deformities in Willamette River fishes from larval and juvenile specimens collected in 2002 and 2003. Deformities were found in most taxa examined but were more frequent in native broadcast spawners, especially minnows and suckers, than in native or exotic nest builders. Caudal deformities were uniformly distributed throughout the(More)
Seventy-four lapilli from Lost River suckers captured in Upper Klamath Lake in 1970 during a snag fishery on spawning adults and 192 lapilli from adults sacrificed from 2001–2006 were examined to determine age and growth parameters; lapilli from 165 shortnose suckers sacrificed from Upper Klamath Lake from 2001–2006 were also examined. Relative marginal(More)
We examined 120 vexillifer larvae of Echiodon dawsoni and 40 of Carapus bermudensis collected from the continental shelf and slope of the Gulf of Mexico and the western North Atlantic to Nova Scotia. Age was estimated for a subset of vexillifers, from which otoliths (sagittae) were excised and growth increments were recognizable, and a linear, estimated age(More)
Stomach content analysis of a neustonic marine juvenile white hake (Urophycis tenuis (Mitchill)), revealed the presence of a unusual 0.70 mm bolus, consisting of a freshwater rotifer, Keratella cochlearis, and several species of freshwater phytoplankton: Asterionella formosa, Melosira granulata, Dinobryon bavaricum and Dinobryon cylindricum. Other gut items(More)
Over 100 years ago, a work with a similar title, “The fishes of North and Middle America”, was a “descriptive catalogue” with keys and a focus on identifying fishes (Jordan and Evermann 1896). Identification and alpha taxonomy are still important as witnessed by the value of guides such as Page and Burr (2011). Although identification of freshwater fishes(More)
Hybridization has been identified as a significant factor in the evolution of plants as groups of interbreeding species retain their phenotypic integrity despite gene exchange among forms. Recent studies have identified similar interactions in animals; however, the role of hybridization in the evolution of animals has been contested. Here we examine(More)
Common name: Lost River sucker, mullet, c’waam. Conservation status: Endangered: (USFWS 1988; Gimenez Dixon 1996). Identification: D 10–12, LL 82–113, gill rakers 23–37 in adults >200 mm, 44–48 post-Weberian vertebrae. Elongate body with long, narrow head, long snout, small eyes. Upper lip thin (two to five rows of large papillae). Lower lip (one to three(More)
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