Between 1968 and 1971, upriver movement of bass from Lake Simcoe was highly correlated with water temperature and discharge (r = 0.704, P <.001). Vital statistics and growth were similar to lacustrine and riverine stocks at similar latitude. Total annual mortality averaged 0.56 with 65% attributable to angler exploitation, principally in the river. Some 34% (after mortality) river spawners returned upriver in subsequent years. Repeat spawners (65% female) comprised an average 19% of the spawning runs. Most adults moved downriver in late June and July when water temperatures approached 25 °C. Adults remaining in the spawning area experienced water temperatures to 29 °C before emigrating during freshets in July and August. Lake migrants intermingled on shoal areas with lacustrine and possibly other potamodromous stocks each summer.

Nuclear rocket research and development was initiated in the United States in 1955 and is still being pursued to a limited extent. The major technology emphasis occurred in the decade of the 1960's and was primarily associated with the Rover/NERVA Program where the technology for a nuclear rocket engine system for space application was developed and demonstrated. The NERVA (Nuclear Engine for Rocket Vehicle Application) technology developed twenty years ago provides a comprehensive and viable propulsion technology base that can be applied and will prove to be valuable for application to NASA's Space Exploration Initiative. Also the unique organization that evolved to successfully manage this effort requiring major contributions and involvement of two government agencies in partnership with industry is a useful model when a similar development is initiated for SEI. This paper, which is historical in scope, provides an overview of the conduct of the NERVA Engine Program, its organization and management, development philosophy, the engine configuration and significant accomplishments.

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Behaviour of wild juvenile smallmouth bass, Micropterus dolomieui, in the laboratory was significantly influenced by water temperature, current, and illumination. Activity increased with increasing water temperature and (or) water current. When exposed to black and white substrate, selection of black was inversely dependent on temperature and current, and highly correlated with fish activity (r = 0.995, P < 0.001, inverse cubic relation). Substrate pattern influenced fish activity, aggregation, and social interaction. Activity levels increased with increasing incident illumination whereas selection of black substrate declined, particularly at higher water temperatures. Older juveniles became less active with age and preferred black substrate when available, thereby indicating a developing behavioural pattern which favours survival and energy conservation under natural nursery conditions by the discrete use of available cover.

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