Food of the Rocky Mountain Whitefish <i>Prosopium williamsoni</i> (Girard)

McHugh, James L.

doi:10.1139/f40-013

Cited by 14 publications

(8 citation statements)

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“…An important aspect of our study was that species (taxa) diversity was determined only for fish and for invertebrate taxa in orders and families that were important prey for fish in our study area (McHugh 1940, Rawson and Elsey 1948, Donald and Anderson 1982, Donald and Alger 1993, Campbell et al 2000. Perhaps not coincidently, some such as the Cladocera, Trichoptera, and Chironomidae are also the most diverse macroinvertebrate groups in lakes.…”

Section: Methodsmentioning

confidence: 99%

Resistance of the Prey-to-Predator Ratio to Environmental Gradients and to Biomanipulations

Donald

Anderson²

2003

Ecology

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Species and their abundances change along environmental gradients, and populations of some species are decimated by introductions of foreign species. We show that the prey‐to‐predator species ratio is resistant to change. We determined that ratios were about 3:1 for 50 lakes with diversity ranging from 5 to 58 taxa, and with a total combined fauna of 140 insects, crustaceans, and fish. The prey‐to‐predator ratio range (1.25:1 to 5.20:1) was only 9% of the potential range. Ratios were not related to chemical, thermal, or physical characteristics of lakes. Ratios were generally the same for fishless lakes, for lakes with one or two introduced predators (salmonids), and for lakes with more complex communities with up to 14 predators including five fish species. For the simplest model, this suggests that when a fish species is introduced and becomes established in a lake there is a fundamental ecological compensatory adjustment with either a three species increase in the diversity of prey or the loss of a predator (but no change in diversity). However, we show more complex prey–predator ratio changes occur because certain keystone species regulated community structure and prey diversity. When the keystone fish (a predatory salmonid) was removed from five lakes, the penultimate littoral predator (lake chub) occupied both the pelagic and littoral zones. Consequently, amphipod density decreased, chironomid density increased, and total zooplankton and benthic diversity increased by 31% or 7.8 taxa per lake on average. The mean prey–predator ratio for these five lakes increased significantly from 2.32:1 to 4.16:1. These community based prey–predator ratios were established by single keystone species from their influence on prey, other predators, and community structure.

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Section: Methodsmentioning

confidence: 99%

Resistance of the Prey-to-Predator Ratio to Environmental Gradients and to Biomanipulations

Donald

Anderson²

2003

Ecology

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“…Mountain whitefish fry, adult Ephemeroptera, and Plecoptera found in lake trout stomachs were included in stable isotope analyses. Additional data for Bow Lake fish dietary habits were obtained from an Environment Canada database for the years of 1984, 1991, and 1993 and from published mountain whitefish studies from the 1930s (Rawson 1939;McHugh 1940). The presence of plerocercoid larval cysts of Diphyllobothrium ditremum on the surface of fish stomachs was noted, as it provides an indirect measure of zooplanktivory.…”

Section: Field Methods and Analyses Of Fish Stomach Contentsmentioning

confidence: 99%

“…In 1994, Trichoptera were the dominant prey item (50% of mountain whitefish stomachs), along with Lymnaeidae (33%). No chironomids were found in 1994 mountain whitefish stomachs, but McHugh (1940) and Rawson (1939) found mostly chironomids (³20%) in mountain whitefish collected from Bow Lake earlier this century (Table 2). Ephemeroptera nymphs were found in a significant number of mountain whitefish from the 1930s, although not in the mountain whitefish from 1994.…”

Section: Fish and Copepod Gut Contents And Dietary Habitsmentioning

confidence: 99%

Organochlorine transfer in the food web of subalpine Bow Lake, Banff National Park

Campbell¹,

Schindler²,

Muir³

et al. 2000

Journal canadien des sciences halieutiques et aquatiques

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Lake trout (Salvelinus namaycush) from subalpine Bow Lake, near the Continental Divide in Banff National Park, have been reported to have higher concentrations of toxaphene than other lake trout populations of the Rocky Mountains. Our original hypothesis was that unusually high biomagnification via a long food chain was responsible for elevated levels of toxaphene and other persistent organochlorines in the lake trout. This hypothesis was refuted by the analyses of stable carbon (d 13 C) and nitrogen (d 15 N) isotope ratios in lake biota. Stable nitrogen isotope analyses demonstrated that the food chain length in Bow Lake was short. The sources of carbon (pelagic or benthic), as indicated by stable carbon isotope values, were highly correlated with organochlorine concentrations in the food web. Lake trout with more pelagic carbon signatures had higher organochlorine concentrations than littoral-feeding mountain whitefish (Prosopium williamsoni) and lake trout. The pelagic copepod Hesperodiaptomus arcticus had higher organochlorine concentrations (wet weight basis) than any other organism, including the fish. This was attributed to the high lipid content of copepods and possibly their ingestion of suspended solids, including glacial silt or direct absorption from solution in glacial inflows. Résumé : Les touladis du lac Bow, lac subalpin du parc national Banff situé près de la ligne de partage des eaux, semblent présenter des concentrations de toxaphène plus élevées que d'autres populations de touladis des montagnes Rocheuses. Nous sommes partis de l'hypothèse qu'une bioamplification anormalement forte le long d'une chaîne trophique très longue était responsable des teneurs élevées en toxaphène et en d'autres organochlorés persistants chez les touladis. Cette hypothèse a été réfutée après l'analyse des rapports des isotopes stables du carbone (d 13 C) et de l'azote (d 15 N) dans le biote du lac. D'après les analyses des isotopes stables de l'azote, nous avons établi que le réseau trophique du lac Bow est raccourci. Les sources de carbone (pélagiques ou benthiques), d'après les valeurs des isotopes stables du carbone, étaient fortement corrélées aux concentrations d'organochlorés dans le réseau trophique. Les touladis présentant de plus fortes signatures de carbone pélagique avaient des concentrations plus élevées d'organochlorés que les ménominis de montagnes et les touladis qui se nourrissaient sur le littoral. Le copépode pélagique Hesperodiaptomus arcticus présentait des concentrations d'organochlorés plus élevées (poids humide) que tout autre organisme, poissons y compris. Ce phénomène est attribuable à la forte teneur en lipides des copépodes, et peut-être au fait qu'ils ingèrent des solides en suspension, notamment du silt glaciaire, ou qu'ils absorbent directement des composés en solution dans l'eau d'origine glaciaire. [Traduit par la Rédaction] Campbell et al. 1269

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“…Mountain whitefish are often perceived by anglers and fisheries managers as competitors with resident trout (McHugh 1940. However, there is little evidence to support these perceptions.…”

Section: Introductionmentioning

confidence: 99%

Polymorphic mountain whitefish (Prosopium williamsoni) in a coastal riverscape: size class assemblages, distribution, and habitat associations

Starr

Torgersen

2014

Ecology of Freshwater Fish

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Polymorphic mountain whitefish (Prosopium williamsoni) in a coastal riverscape:Size class assemblages, distribution, and habitat associations James Chamberlain StarrChair of Supervisory Committee: Affiliate Assistant Professor Christian E. Torgersen School of Environmental and Forest SciencesFluvial mountain whitefish (Prosopium williamsoni) offer a rare example of trophic polymorphism among stream dwelling salmonids in temperate North American river systems.Trophic polymorphism is a form of resource-based phenotypic diversification that occurs when exploitation of under-utilized resources necessitates specific morphological characteristics.Studies of trophic polymorphism in the species are few, focusing on diet, foraging behavior, genetic variation, and snout morphology. Pinocchio whitefish develop an elongated snout used to overturn substrate while foraging for benthic invertebrates, whereas normal whitefish have an even sloping head shape and feed primarily on drifting prey. I hypothesized that (1) morphotypes would be associated with distinctly different habitat features based on known feeding behavior and diet, and (2) these differences in habitat association would segregate morphotypes at channel unit and reach scales. In this study, I first compared the spatial distributions of morphotypes and size classes. I then assessed the assemblage structure of morphotypes and size classes and their relationships with aquatic habitat. Finally, I quantified the associations between specific morphotypes and longitudinal variation in aquatic habitat. Spatially continuous sampling was conducted over a broad extent (29 km) in the Calawah River, WA (USA). Whitefish were enumerated via snorkeling in three size classes: small (10-29 cm), medium (30-49 cm), and large (≥ 50 cm). Spatial distributions were compared among size classes of morphotypes by relating cumulative abundance to distance upstream. Assemblage structure and relationships with aquatic habitat were assessed with non-metric multidimensional scaling (NMS). Unit-scale differences between morphotypes in pool and non-pool habitats were quantified with Wilcoxon rank sum tests. Associations between specific morphotypes and habitat were quantified at the 1-km reach scale with generalized additive models (GAMs) using thin-plate regression splines. Large size classes of both morphotypes were distributed downstream of small and medium size classes, and normal whitefish were distributed downstream of pinocchio whitefish. Normal whitefish size classes were associated with higher gradient and depth, whereas pinocchio whitefish size classes were positively associated with pool area, distance upstream, and depth. Normal whitefish relative density did not differ between habitat types at the unit scale (p = 0.34, W = 3085), but pinocchio whitefish were more dense in pool habitat than in non-pool habitat (p < 0.0001, W = 1084). Reach-scale GAMs indicated that normal whitefish were associated with larger substrate size in downstream reaches (R 2 = 0.64), and pinocchio wh...

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Food of the Rocky Mountain Whitefish Prosopium williamsoni (Girard)

Cited by 14 publications

References 0 publications

Resistance of the Prey-to-Predator Ratio to Environmental Gradients and to Biomanipulations

Resistance of the Prey-to-Predator Ratio to Environmental Gradients and to Biomanipulations

Organochlorine transfer in the food web of subalpine Bow Lake, Banff National Park

Polymorphic mountain whitefish (Prosopium williamsoni) in a coastal riverscape: size class assemblages, distribution, and habitat associations

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