Digestive tract evacuation in northern squawfish (Ptychocheilus oregonensis) (170–1900 g) was studied in fish allowed to feed voluntarily on salmon (4–70 g) at three water temperatures (10, 15, and 20 °C). Squawfish were sacrificed at 1- or 2-h intervals until evacuation approximated 90%. Amount of food evacuated for a given time interval increased approximately three times as the temperature was increased and as the prey weight was increased and two times as the predator weight was increased. The 90% emptying time (ET90) decreased by about two thirds as the temperature doubled and by about one half as the predator weight increased 10 times, but approximately doubled when the prey weight increased 4 times. Two-fish meals (17–20 g each, 35–39 g total) were evacuated more slowly than meals of one fish weighing 17–20 g, but at the same rate as meals of one fish weighing 35–40 g. Equations derived are easily applied to a wide range of water temperatures, prey weights, and predator weights.

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Sockeye salmon (Oncorhynchus nerka) fry from the Weaver Creek – Harrison Lake population were tested to determine whether they exhibited directional orientation in the absence of water flow. The fry oriented in a generally north-northeast direction. The presence of the moon greatly enhanced the strength of the northward orientation response, and the moon may have provided the fry with guidance information. Tests with newly emerged fry indicated little or no response to a directionally altered magnetic field. Both the passage of time and exposure to Harrison River – Harrison Lake water enhanced the compass orientation response, implying that an inherited response is triggered by environmental and temporal cues.

A spatially explicit linear, additive model was developed for quantifying site characteristics of riparian areas of the lower Cedar River, Washington, USA. The spatial complexity and distribution of combined habitat and anthropogenic landscape features were used to define habitat "indices" that indicate the relative quality of riparian habitats. Patches of contiguous grid cells were measured in terms of their locations, sizes, and relative degree of fragmentation. Additionally, intrapatch heterogeneity was measured to identify unique combinations of habitat and anthropogenic factors for individual grid cells within patches. Model verification indicated that existing floodplain riparian habitats received positive indices more than 90% of the time. Mean patch sizes and fragmentation indices were similar for all positive indices throughout the reaches in the valley floor. Among all reaches, reach 7 had the highest number of positive patches due to a higher degree of meandering in this reach. This procedure and model outputs provide unique screening opportunities for prioritizing management of riparian areas (e.g., conservation, restoration and enhancement).

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