–  The consequences of individual behaviour to dynamics of populations has been a critical question in fish ecology, but linking the two has proven difficult. A modification of Sale's habitat selection model provides a conceptual linkage for relating resource availability and individual habitat selection to exploratory behaviour, emigration and population‐level responses. Whole‐population experiments with pupfish Cyprinodon macularius that linked all factors along this resource to population continuum lend support to this conceptual model, and illustrate that emigration may be much more common in fish populations than considered in most individual‐ or population‐based models. Accommodating emigration can enhance the ecological appropriateness of behavioural experiments and increase confidence in extrapolation of experimental observations to population‐level effects. New experimental designs and advancing technologies offer avenues for assessing population consequences of habitat selection and emigration by individual fish. Emigration often is the key linkage between individual behaviour and population responses, and greater understanding of the underlying factors affecting this often‐overlooked demographic parameter could offer new approaches for management and conservation of fishes.

Like all grasslands across North America, the distribution of desert grasslands has been reduced markedly, and remnants have been altered extensively by humans. In Arizona, New Mexico, Texas, USA, and in Mexico, desert grasslands have been invaded by dozens of non‐native plants, especially perennial grasses that evolved in arid systems with similar climate and disturbance regimes. In desert grasslands invaded by non‐native plants, biomass, richness, and diversity of native plants typically decrease, whereas plant density, biomass, and litter typically increase. These changes in composition and structure of the plant community affect animals that inhabit grassland ecosystems, with the direction and magnitude of effects reflecting the resource needs of each species, the degree of plant invasion, and the contrast in structure between invading and native plants. When non‐native plants present similar structural cues but provide different levels of resources than native plants, cues that trigger habitat selection by animals may be decoupled from the resources linked evolutionarily to that cue, creating the potential for an ecological trap. Plant invasions also influence the ecological drivers that maintain grasslands in an open condition, which will alter the long‐term dynamics of plant and animal populations. Specifically, by increasing fuel load and continuity, fires in invaded grasslands increase in frequency and intensity relative to those in native grasslands. Although eradication is unlikely once a non‐native plant has naturalized, retaining patches of native vegetation within a matrix of non‐native plants may provide a strategy to reduce effects of plant invasions on wildlife in grasslands. © 2013 The Wildlife Society.

Standard weight (Ws) equations have been used extensively to examine body condition in sport fishes. However, development of these equations for nongame fishes has only recently been emphasized. We used the regression‐line‐percentile technique to develop standard weight equations for four rare desert fishes: flannelmouth sucker Catostomus latipinnis, razorback sucker Xyrauchen texanus, roundtail chub Gila robusta, and humpback chub G. cypha. The Ws equation for flannelmouth suckers of 100–690 mm total length (TL) was developed from 17 populations: log10 Ws = −5.180 + 3.068 log10TL. The Ws equation for razorback suckers of 110–885 mm TL was developed from 12 populations: log10 Ws = −4.886 + 2.985 log10TL. The Ws equation for roundtail chub of 100–525 mm TL was developed from 20 populations: log10 Ws = −5.065 + 3.015 log10TL. The Ws equation for humpback chub of 120– 495 mm TL was developed from 9 populations: log10 Ws = −5.278 + 3.096 log10TL. These equations meet criteria for acceptable standard weight indexes and can be used to calculate relative weight, an index of body condition.

Invertebrate drift in large rivers has often been sampled at only one depth, under the assumption that drift density is equal throughout the water column. A new sampling apparatus showed that the vertical distribution of drift density for the baetid mayflies Pseudocloeon and Baetis and for the caddisflies Hydropsyche and Cheumatopsyche was not uniform.

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The flannelmouth sucker Catostomus latipinnis is one of the few native fish that persists in the lower Colorado River basin. Little is known about the effects of hypolimnetic releases of cold, swift water from Colorado River dams on flannelmouth sucker populations. We conducted fatigue velocity tests on age‐0 flannelmouth suckers in the laboratory to evaluate the effects of water temperature and fish size on swimming ability. Fish of 25‐114 mm total length (TL) were subjected to incremental increases in water velocity until the upper limit of their swimming ability was reached. Swimming tests were conducted at 10, 14, and 20°C. Swimming ability increased with fish length and was directly related to water temperature at all fish sizes. A decrease in water temperature from 20°C to 10°C resulted in an average decrease in swimming ability of 40%. Mean swimming ability of wild‐caught flannelmouth suckers was 7 cm/s higher than that of captive‐reared flannelmouth suckers of similar size at 20°C and 14°C. Flannelmouth suckers subjected to an abrupt 10°C temperature drop did not have significantly different swimming ability than flannelmouth suckers acclimated to 10°C over 4 d.