Dynamics of fisheries that affect the population growth rate coefficient

Conventional surplus production models indicate that destruction of fish populations by overfishing is difficult, if not impossible, but catastrophic declines in abundance of exploited populations are common. Surplus production models also do not predict large continuing fluctuations in yield, but large fluctuations in yield are common. Conventional surplus production models assume that fisheries do not impact the population's capacity to increase, but changes in age structure or a decrease in age-specific fecundity resulting from fishing can decrease the coefficient of increase. A surplus production model is developed in which fishing reduces the capacity of a population to increase; the model is applied to describe the fluctuations observed in yield of lake herring (Coregonus artedii) from the upper Great Lakes. The fisheries of the Great Lakes were decimated by the combined effects of heavy fishing and a changing environment. For some species, yield increased to high levels and then the fisheries collapsed; for other species, yield and effort fluctuated greatly.     

Sweet for the sour: Incentives in environmental mediation

The siting of facilities with undesirable environmental characteristics often leads to public conflict. Efforts to resolve the conflict and make siting decisions frequently exacerbate the problem. Environmental mediation, the process of negotiating an agreeable settlement, is an accepted approach to resolving conflict. This paper explores the use of incentive systems as a means of achieving equity in environmental mediation. Obnoxious and noxious characteristics of facilities are discussed as the basis of conflicts. Four types of incentives—mitigation, compensation, reward, and participation—are discussed. The paper concludes with a discussion of the utility and application of incentives for solving environmental conflicts.     

Soybean row-spacing: Effects on arthropod population patterns and sampling considerations

Two soybean field experiments were conducted during 1979 to investigate the effects of different row-spacing patterns (1.0 m vs 0.5 m, and 1.0 m vs broadcast) on population levels of selected herbivorous and beneficial arthropods. Sweepnet sampling was used in both experiments, and the ground-cloth shake method was also used in the 1.0-m vs 0.5-m study. Sweepnet results suggested that both herbivorous and beneficial arthropods tended to be more abundant in narrow row-spacings. However, there were exceptions among both groups, with some species (for example, bean leaf beetle) being more abundant in the conventional row-spacing in one experiment, and with several other species (for example, bigeyed bugs) showing no significant differences. Also, ground-cloth data for lepidopteran larvae showed trends opposite to those from sweepnet data in the 1,0-m vs 0.5-m experiment. Results clearly illustrate the importance of sampling methodology in the interpretation of soybean row-spacing research.     

The effects of pathway configuration, landmarks and stress on environmental cognition

The results of this study indicate that manipulations of the pathway grid configuration and landmark placement in a setting cause changes in environmental knowledge. These experimental manipulations were accomplished using a realistic, dynamic simulation technique at the Berkeley Environmental Simulation Laboratory. Measures of environmental knowledge include: memory for incidental information along the simulated urban route, accuracy of route maps, relocation memory for scenes along the route, and questionnaire measures. Data are also presented showing both positive and negative effects of stress from noise on the processes of environmental cognition.     

Community opinion concerning airport noise-abatement alternatives

In the present study we examined (1) community opinion of airport noise-abating alternatives and (2) the influence of perceived control on attitudes concerning noise-abatement policies and annoyance toward aircraft noise. We proposed that residents who perceive themselves as having little control over aircraft noise exposure would express higher levels of annoyance than residents who believe they have some degree of control. Furthermore, residents with low levels of perceived control would be less favorable toward proposed noise-abatement alternatives. Survey results collected from 239 households within the 65 CNEL contour of a community airport in Southern California support these hypotheses. Findings indicate strong public support for noise abatement and strong opposition to land-use alternatives. In addition, residents' perceptions of control in the airport planning and management process are significantly related to their annoyance with noise and their opinions about noise management policies.     

Household size and composition and implications for housing need in Kumasi,Ghana: a research note

A simple method of calculating the scale of housing need for Kumasi, Ghana, uses two likely variations in household size distribution and an overcrowding threshold of 3 p.p.r., and a measure of preference. The two household size distributions take account both of trends and of changes which may occur if and when new housing is provided. At that time, released from the current constraints, household formation along traditional lines may again be possible. The preferred supply equates households’ perceived need to their ability to pay at current rents. The resulting range of rooms required is wide but even the lowest need is so far in excess of supply that conventional approaches are self‐evidently inadequate and greater client involvement must be encouraged.     

DEVELOPMENT OF EARTH SATELLITE TECHNOLOGY FOR THE TELEMETRY OF HYDROLOGIC DATA1

ABSTRACT The use of satellite telemetry is playing a major role in the collection of hydrologic data. Advancing technology and availability of government satellites have permitted many agencies to take advantage of new procedures for acquiring data from automated remote data collection stations. Experiments with Earth satellite technology started in the 1960's and 1970's, with the polar-orbiting National Aeronautics and Space Administration Nimbus and Landsat satellites. Subsequent advancements took place through the development phase to operational systems using the Geostationary Operational Environmental Satellite (GOES) of the National Oceanic and Atmospheric Administration. This satellite system supports more than 2,500 active telemetry sites, of which approximately 1,200 are Geological Survey stream-gaging stations for the collection of hydrologic data. A satellite data collection system is made up of three primary components; a small battery-operated radio, and Earth-orbiting satellite, and an Earth receive and data processing station. The data relay satellites' vast aerial view of the Earth's surface gives satellite telemetry a large advantage over ground-based systems for the collection of real-time hydrologic data for flood warning, reservoir management, irrigation water control, hydropower generation, and the operation of hydrologic stations.     

AN INEXPENSIVE WEIR AND PROPORTIONAL SAMPLER FOR MINIATURE WATERSHED ECOSYSTEMS1

ABSTRACT A weir system with a proportional sampler for use on miniature watershed ecosystems is described. Eight weir collection systems were evaluated for their ability to measure and sample inputs and outputs of soil-island ecosystems which occur on granite outcrops. The proportion of water actually collected by the weir systems was generally less than the proportion the systems were designed to sample, but adequate for supplying data needed for estimating elemental budgets. The weir systems were not able to account for 25 to 50 percent of the variation in total water passing over the cutoff wall. Several ways of improving overall performance of the weir systems are discussed.