Experiments were conducted to determine survival, growth, and accumulation of HEOD (major component of dieldrin) in the tissues of steelhead trout (Salmo gairdneri) embryos, alevins, and fry exposed to dieldrin concentrations ranging from 0.012 to 52 ppb. The fish were held in specially designed exposure chambers provided with continuously renewed...
This report summarizes a study which sought to provide toxicity data for pulp mills near Coos Bay through a series of toxicity bioassays. The study also surveyed benthic and beach fauna to identify macro-organisms so individual assessments of water quality requirements could be made.
Patterns of seasonal abundance of harbor seals at Netarts and Tillamook Bays, Oregon, were documented by recording numbers of seals hauling out on tidally exposed sand flats in both bays. Harbor seal abundance at Tillamook Bay peaked during pupping (May-June) and molting (August) periods, while peak abundance at Netarts Bay...
Rockfishes, Sebastes spp.. were the most numerous and speciose fishes seen during 16 submersible dives from 64 to 305 m depth in the vicinity of Heceta Bank off the coast of Oregon. Dense schools of juvenile rockfishes and large yellowtail rockfish, S. flavidus, were observed only over rocky, high relief...
We conducted a 3-year study of helminth parasites to assess their effect on the lesser prairie-chicken Tympanuchus pallidicinctus. Helminth parasites were found in most of the examined wild prairie chicken carcasses: 95% had eye worm Oxyspirura petrowi, 92% had stomach worm Tetrameres sp., and 59% had caecal worm Subulura sp....
We used mark-recapture methods to estimate age-specific apparent survival rates for male Lesser Prairie-Chickens (Tympanuchus pallidicinctus), a gamebird of conservation concern. A total of 311 male prairie-chickens (135 yearlings, 176 adults) were captured and banded during a 5-year study in southwest Kansas. Time-since-marking models were used to estimate apparent survival...
The ability to ascertain gender and age of juvenile grouse is essential for determining gender-specific population age structure and studying timing of reproductive events, respectively. We examined outer rectrix feathers from juvenile Lesser Prairie-Chickens (Tympanuchus pallidicinctus) captured at 30–40 and 50–60 days post-hatching. Blood samples were collected from most chicks...
Recent comparative studies across sex-changing animals have found that the relative size and age at sex change are strikingly invariant. In particular, 91%–97% of the variation in size at sex change across species can be explained by the simple rule that individuals change sex when they reach 72% of their...
Invertebrates are an important food source for grouse chicks, especially within the first 2 weeks of life. Invertebrate abundance is highly patchy and dependent upon herbaceous cover and vegetation structure. We examined the relationship between invertebrate biomass (from sweepnet samples) and habitat structure at lesser prairie-chicken (Tympanuchus pallidicinctus) brood-use and...
The goal of this study was to describe the duration and magnitude of the physiological stress response in lingcod Ophiodon elongatus after exposure to brief handling and sublethal air stressors. The response to these stressors was determined during a 24‐h recovery period by measuring concentrations of plasma cortisol, lactate, glucose,...