Papers by David C Schneider
Ecology and evolution, Mar 1, 2018
Statistical analyses are an integral component of scientific research, and for decades, biologist... more Statistical analyses are an integral component of scientific research, and for decades, biologists have applied transformations to data to meet the normal error assumptions for and tests. Over the years, there has been a movement from data transformation toward model reformation-the use of non-normal error structures within the framework of the generalized linear model (GLM). The principal advantage of model reformation is that parameters are estimated on the original, rather than the transformed scale. However, data transformation has been shown to give better control over type I error, for simulated data with known error structures. We conducted a literature review of statistical textbooks directed toward biologists and of journal articles published in the primary literature to determine temporal trends in both the text recommendations and the practice in the refereed literature over the past 35Ā years. In this review, a trend of increasing use of reformation in the primary literat...
Ecology and Society, 2014
Aggressive behavior in migratory shorebirds occurs primarily between foraging individuals and pro... more Aggressive behavior in migratory shorebirds occurs primarily between foraging individuals and probably depends on such factors as density of foraging shorebirds, foraging methods, and density and patchiness of prey items (Recher and Recher 1969, Goss-Custard 1970). Frequency and intensity of aggression varies widely between and within shorebird species (Recher and Recher 1969). In this p p a er we present
Marine bird populations interact with fisheries in a variety of ways, with diverse outcomes. Eval... more Marine bird populations interact with fisheries in a variety of ways, with diverse outcomes. Evaluation of these outcomes requires a means of comparison across cases, and a means of identifying the relative importance of concomitant processes at relevant space and time scales. We describe a general quantitative framework that permits comparison of quantitative findings among studies of seabird-fisheries interactions. We then review the results of seabird-fsheries studies within this framework. We discuss the use of ad hoc ratios and dimensional analysis to make decisions about competing processes at relevant space and time scales.
Human Ecology, 2008
Some recent scholarship has focused on integrating local and/or traditional knowledge with conven... more Some recent scholarship has focused on integrating local and/or traditional knowledge with conventional scientific information in fisheries management to improve the factual foundation of and strengthen support for management decisions. This article compares a sequence of historical and contemporary scientific texts and maps about the migrations and stock structure of cod in the Northern Gulf of St. Lawrence with texts and maps generated by the authors through the collection, aggregation and interpretation of commercial fish harvesters' ecological knowledge. We find that the relationship between fisheries science and harvesters' ecological knowledge is dynamic and has changed over time, and that both are 'situated' socially and ecologically. Overall, each paints an incomplete picture of cod movements and stock structure but the knowledge of harvesters provides a valuable complement to scientific information, particularly at the local scale, and has the potential to contribute to the identification of local cod stocks that are new to science and management. We end by considering how this case study informs the larger discussion about the challenges and potential benefits of the so-called integration project to bring together science and the ecological knowledge of fish harvesters.
Journal of Marine Research, 1988
The response of schooling fish (Capelin Mal/otus vii/os us Milller) to coastal upwelling events i... more The response of schooling fish (Capelin Mal/otus vii/os us Milller) to coastal upwelling events in the southern Labrador Current was investigated during the summer of 1984 and 1987. Theoretical calculations showed that summer wind events, which prevail from the southwest, were capable of inducing upwelling along the western boundary of the Avalon Channel. Significant drops in the temperature of subsurface water near the coast occurred in response to longshore wind stress. Coherence of longshore winds arid thermal fluctuations was significantly greater than zero at periods between 3.8 to 6.1 days at two exposed locations along the coast. Regression of temperature on longshore winds was significant when effects of cross-shore winds were removed by regression. Regression of temperature on cross-shore winds was not significant when effects of longshore winds were removed by regression. During 1984 the relative catch rate of male capelin at a trap increased when water temperature rose rapidly after upwelling events. During 1987 increases in the catch rate of males at the trap were correctly predicted from cessation of upwelling favorable winds (i.e., from the south). Shoreward movement of capelin after wind driven upwelling may synchronize spawning with periods of light wave action on beaches in eastern Newfoundland.
Continental Shelf Research, 1986
lt has been hypothesized that differentiation in food web structure occurs across the Bering Sea ... more lt has been hypothesized that differentiation in food web structure occurs across the Bering Sea continental shelf as a result of seasonal differentiation of water masses. We tested this idea using an apex predator, pelagic birds. Seasonal abundance of birds in central Bristol Bay was estimated from counts made while underway between hydrographic stations. Prey and body mass were determined from birds collected at sea. Daily intake was estimated as an allometric function of body mass. Annual occupancy was estimated as the integral of a normal curve fit to seasonal data. Estimated carbon flux to seabirds in the middle domain was 0.12 gC m -2 y-i in 1980, 0.18 gC m -2 y-~ in 1981. Carbon flux to seabirds in the adjacent waters of the outer shelf domain was 1.8 times higher than in the middle domain in 1980, 1.6 times higher in 1981. Carbon flux to seabirds in the inner domain was 1.2 times higher than in the middle domain in 1980, and 3.3 times higher in 1981. Carbon flux to seabirds in the outer domain was due primarily to non-diving species, principally northern fulmars (Fulmarus glacialis) during the summer and autumn, and Larus gulls in the autumn and winter. Flux to seabirds in the inner domain was due to diving birds, principally murres (Uria sp.) in the spring and shearwaters (Puffinus sp.) during the summer. The euphausiid Thysanoessa raschii was the primary food source of shearwaters in shallow waters of the inner shelf domain. A more diverse set of prey, including squid, jellyfish, hyperiids, and fish, was taken by shearwaters and fulmars in the deeper waters of the outer and middle shelf domains. This result suggests that prey diversity is higher in seasonally stratified waters of outer Bristol Bay than in mixed waters of inner Bristol Bay. Greater energy flux to diving species in shallow water, and greater energy flux to non-divers in deep water may be a function of topographic control of prey patchiness.
Canadian Journal of Fisheries and Aquatic Sciences, 2004
When modeling the stock-recruitment (S-R) relationship, the Cushing, Ricker, and other S-R models... more When modeling the stock-recruitment (S-R) relationship, the Cushing, Ricker, and other S-R models are fitted to the observed S-R data by estimating parameters with assumptions made concerning the model error structure. Using a generalized linear model approach, we explored and identified the appropriate model error structure in modeling S-R data for gadoid stocks. The S-R parameter estimation was found to be influenced by the choice of error distributions assumed in the analysis. In modeling S-R data for gadoid stocks, the Beverton-Holt model was found to be more sensitive to the assumption of model error distribution than the Cushing and Ricker models. The lognormal and gamma distributions had higher probability of being acceptable model error distributions. Cluster analyses and summary statistics of error distributions in S-R modeling did not show consistent patterns in the identification of an acceptable model error structure among species, geographic distributions, and sample sizes. A better understanding of the factors and mechanisms resulting in differences in the choice of appropriate model error distributions for different populations is needed in future research. We recommend that the generalized linear model be used to identify acceptable model error structures in quantifying S-R relationships.
Canadian Journal of Fisheries and Aquatic Sciences, 1999
Fishers have detailed knowledge of their resources, their environment, and their fishing practice... more Fishers have detailed knowledge of their resources, their environment, and their fishing practices that is rarely systematically collected. We conducted three types of interviews with coastal Newfoundland fishers to identify the range of information available, to see if it could be quantified, and to explore its potential for reconstructing trends within fisheries. These fishers have many terms for Atlantic cod (Gadus morhua), each associated with characteristic patterns of seasonal movement and availability to gear and indicating the location of several coastal spawning areas. They described a variety of changes in fishing practice. Of the four changes that could be quantified, all contributed to decadal-scale increases in catch efficiency prior to 1992, while change in catch per unit of effort for cod was consistently negative at decadal scales. For these fishers' lumpfish (Cyclopterus lumpus) roe fishery, catch per unit of effort was consistently negative in the 1990s. We describe ways to access the large reservoir of information held by fishers, the use of several cross-checks to identify consistent patterns, and the use of trends and patterns to broaden the basis for interpreting quantitative surveys used in fisheries assessment. Local information from resource users can be assembled in forms usable in quantitative stock assessments.
Environmental and socioeconomic restructuring has had profound consequences for coastal communiti... more Environmental and socioeconomic restructuring has had profound consequences for coastal communities in Canada. The decline of traditional resource-based industries-fisheries, forestry, and mining-and the emergence of new economic activities, such as tourism and aquaculture, compounded by concurrent shifts in social programs, have affected the health of environments, communities, and people. Drawing on research conducted as part of the interdisciplinary major collaborative research initiative Coasts Under Stress, we examined the implications of interactive restructuring for the health of people and communities on Canada's east and west coasts. The research is guided by a socioecological framework that identifies the pathways from interactive restructuring through health determinants to health risks and health outcomes. The utility of the proposed framework is exemplified by a specific place-based example in Prince Rupert, British Columbia, and a case-based example from coastal communities in Newfoundland and Labrador. A focus on interactive restructuring draws our attention to the many challenges associated with promoting health in a context of rapid and often accelerating environmental and institutional change that is relevant to other areas and contexts.
Coastal Management, 2007
In this article we use a multi-scale, multi-method historical reconstruction of post-World War II... more In this article we use a multi-scale, multi-method historical reconstruction of post-World War II social-ecological interactions within fisheries in Newfoundland and Labrador to explore the dynamics of intensification, expansion, and resource degradation in managed fisheries. Our case study draws on landings statistics, other archival information, and the Local Ecological Knowledge (LEK) of fish harvesters to explore these linked dynamics at the macro, meso, and micro levels. By some measures we found large scale trends toward intensification of effort leading to over-harvesting at macro (province wide) levels. At the same time, at the local level (micro-scale) and across sectors and regions (the meso-scale), we found highly fluid fishing practices and a complex suite of stated motivations for change. As a basis for effective governance, an understanding of the dynamics of interactive restructuring in social ecological systems will require multiscale analyses that are sensitive to this complexity.
Canadian Journal of Fisheries and Aquatic Sciences, 1999
Fishers have detailed knowledge of their resources, their environment, and their fishing practice... more Fishers have detailed knowledge of their resources, their environment, and their fishing practices that is rarely systematically collected. We conducted three types of interviews with coastal Newfoundland fishers to identify the range of information available, to see if it could be quantified, and to explore its potential for reconstructing trends within fisheries. These fishers have many terms for Atlantic cod
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Papers by David C Schneider