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We examined the contribution and distribution of wild-origin chinook salmon (Oncorhynchus tshawytcha) in the Salmon River, New York, during the 2005 spawning run. To determine the origin of each fish, we used scale metrics and a recently developed discriminant function model. We estimated that approximately 32% (∼20,000 individuals) of chinook salmon were of wild-origin and that there was a greater proportion of wild fish in younger age groups than in older groups (age-1 = 48.6%, age-2 = 47.2%, and age-3 = 21.1%). We also observed spatial differences in the distribution of wild- and hatchery-derived fish, with a higher proportion of wild-origin chinook salmon in the lower section of the river (47.5%) than in the upper sections (28.2%). The lowest proportion of wild fish was found in the Salmon River hatchery (12.4%), located in the upper section of the river. These findings suggest that wild-origin fish were more evenly distributed along the river, whereas hatchery fish were more likely to reach the upper parts of the river or enter the hatchery. [ABSTRACT FROM AUTHOR]

We examined feeding periodicity of three size groups of the rusty crayfish (Orconectes rusticus) at four-hour intervals over a 28-hour period during July in a headwater stream of the Susquehanna River drainage in central New York. Feeding activity was expressed as the ratio of stomach weight divided by the crayfish wet weight. The did food consumption patterns of all three size groups of rusty crayfish (i.e., ≤ 10 mm, 11-20 mm, and >20mm carapace length) were significantly different. Peak feeding of the smallest crayfish occurred during crepuscular periods. Food consumption of the intermediate size crayfish was highest at 2000 h, and feeding of large crayfish was consistently high from 1200 h to 0400 h. Feeding intensity of both small and intermediate size crayfish was highest when feeding intensity of large crayfsh was lowest. Ontogenetic differences in feeding periodicity may be associated with predation pressure from large rusty crayfish on smaller individuals. [ABSTRACT FROM AUTHOR]