摘要:

This supplement is the product of a special symposium organized on "Space, time, and scale: new perspectives in fish ecology and management" held during the 127th annual meeting of the American Fisheries Society in Monterey, California, August 1997. The purpose of this supplement is to illustrate the breadth and diversity of ideas and applications being explored for integrating space, time, and scaling issues and to highlight future directions. Topics cover a variety of studies, techniques, and applications from salt water to freshwater, from lotic to lentic habitats, and across various scales that can be used as background for integrating space, time, and scale in ongoing and future fish research and management.

ISSN:0706-652X    

DOI:10.1139/f99-223

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

We developed a generalized spatial dynamic age-structured multistock production model by linking bioenergetic principles of physiology, population ecology, and community trophodynamics to a two-dimensional finite-element hydrodynamic circulation model. Animal movement is based on a search of an environmental-habitat feature vector that maximizes cohort production dynamics. We implemented a numerical version of the model and used scientific data visualization to display real-time results. As a proxy for larger regional-scale dynamics, we applied the model to study the space-time behavior of recruitment and predator-prey production dynamics for cohorts of spotted seatrout (Cynoscion nebulosus) and pink shrimp (Penaeus duorarum) in the tropical waters of Biscayne Bay, Florida.

ISSN:0706-652X    

DOI:10.1139/f99-216

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

We evaluated the costs and benefits of long-distance horizontal migration by pelagic planktivores, Atlantic herring (Clupea harengus), blue whiting (Micromesistius poutassou), mackerel (Scomber scombrus), and capelin (Mallotus villosus) in the Norwegian and Barents seas using a numerical model and tested model predictions against field observations. Specifically, we considered (i) energetic costs as a function of body size, water currents, swimming speed, and distance, (ii) time costs as a function of speed and distance, and (iii) energetic gain in terms of differences in food intake between areas. The model demonstrates how body size restricts large-scale horizontal migration patterns. Model and field results suggest that the extent of migration will increase with increasing body length. The model predicts that long-distance migration costs may exceed energy intake for fish <20 cm, due to increased hydrodynamical drag with decreasing fish size. Field results suggest that migration distance is a function of length, weight, and age. Food abundance and distribution, current speed and direction, and differences in day length at boreal latitudes are believed to be the major driving forces influencing large-scale migration distance, direction, and timing in pelagic planktivores. Northwards latitudinal rather than longitudinal feeding migrations are explained by the improved feeding opportunities with increased day lengths.

ISSN:0706-652X    

DOI:10.1139/f99-222

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

We simulated geographic dispersal of exotic rainbow smelt (Osmerus mordax) as a function of present introduction rates, the probability of invasion through stream connections among lakes and watersheds, and survival based on physical and chemical factors of lakes within a northern Wisconsin watershed. One fourth of the habitable lakes contained rainbow smelt after 1000 years if dispersal was restricted to stream corridors. In contrast, with present rates of human transport, half contained rainbow smelt after 200 years, three quarters after 300 years, and all after 1000 years. Simulated human introductions increased the number of epicenters for spread and were the most influential parameter in the model. Stream connections between lakes increased the number of lakes colonized; decreases in migration ability led to fewer invaded lakes. Although extinction was operating, human introductions outweighed extinction and led to a saturation of rainbow smelt across all habitable lakes within the watershed within 1000 years. Our results highlight the importance of human vectors in driving exotic fish dispersal, suggest that isolated lakes are important refuges for species negatively affected by rainbow smelt, and show that agencies interested in controlling the spread of exotic fishes need to strongly consider the human vector of transport.

ISSN:0706-652X    

DOI:10.1139/f99-220

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Stream size interacted with mean July air temperature to influence the distribution of brown trout (Salmo trutta) in southeastern Wyoming streams. The geographic range of brown trout was positively associated with mean July air temperatures of 19-22°C. Within this thermal zone, brown trout were more likely to occur in large streams (>4 m wetted width) than in small streams. We used a geographic information system to examine spatial patterns in the distribution of anomalous sites (i.e., sites predicted to have brown trout but which lacked this species). Sites that lacked brown trout but contained brook trout (Salvelinus fontinalis) tended to be on small streams at the cold margin of the 19-22°C thermal window. Sites lacking both brown trout and brook trout tended to be on small streams clustered in three of the six study drainages. The spatial aggregation of these sites suggests that additional regional factors influence the occurrence of brown trout in southeastern Wyoming. It is hypothesized that these factors could involve land-use practices interacting with basin geology and geomorphology. Classification models that incorporate a few general habitat factors are useful for identifying stream reaches with the potential to support brown trout and for directing management efforts to sites where this potential is not realize

ISSN:0706-652X    

DOI:10.1139/f99-210

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Analyses of fish distributions rarely account for spatial arrangement of habitat types, are typically conducted at a single scale, and use a null model of random distributions without considering other null models. This study demonstrates a procedure to circumvent these difficulties by analyzing telemetry data collected on largemouth bass (Micropterus salmoides) in Long Lake, Michigan. Bass were highly aggregated within the littoral region, showing peaks of aggregation at small (<60 m) and large (>160 m) spatial scales. A neutral movement model (no taxis or kinesis within habitat types) could explain some of the observed aggregation, yet substantial aggregation remains unexplained. Much of the large-scale aggregation could be generated by including a taxis towards the eastern half of the basin, but taxes towards shallower cells or cells containing woody emergent macrophytes were unable to generate the observed degree of small-scale aggregation. Our results highlight the utility of analyzing spatial distributions at multiple scales and the importance of the spatial arrangements of habitat types and suggest that nonrandom distributions at one scale may be due to processes occurring at different scales.

ISSN:0706-652X    

DOI:10.1139/f99-213

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Habitat selection by fishes involves balancing the benefits of foraging opportunities and the risk of predation. Size-dependent overwinter mortality imposes a time constraint on behavioral programs of juvenile fishes: individuals must achieve a sufficient size by the end of the growing season to survive. I developed a dynamic optimization model to evaluate how severity of size-dependent overwinter mortality alters habitat use by minnows. The littoral zone was the safest habitat with respect to predation. In lakes where zooplankton exhibit diel vertical migration, fish migrate to the pelagic at night and return to the littoral during the day to maximize foraging rates. Model results demonstrated that size-dependent overwinter mortality should lead to development of more pronounced predation risk-taking by fishes in lakes with severe winters. Individuals are predicted to initiate diel littoral-pelagic migrations at smaller sizes as winter severity increases or as hatch date within a season increases. This analysis suggests that the time constraint imposed by size-selective overwinter mortality has important consequences for life history strategies of juvenile fishes. The effects of time constraints on behavior are expected to be especially important near the high latitudinal limits of a species' geographic distribution.

ISSN:0706-652X    

DOI:10.1139/f99-219

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Variability in Lake Michigan salmonid microcontaminant data may arise from differences in contaminant concentrations in the water column, fat content, diet, age, location, and species-specific factors. Polychlorinated biphenyl (PCB) concentrations for salmonids in Lake Michigan have been determined for fish collected from a wide variety of locations and sizes for each of five species. Lake managers and policy makers wishing to evaluate trends in these concentration data must either remove this variability before trend assessment or leave it and settle for less statistical power for identifying the underlying time trend. Classification and regression trees (CART) have proven to be a useful tool for identifying nonlinear patterns of variability in these data and portraying them graphically. We used CART to study patterns of variability in PCB concentrations in five species of Lake Michigan salmonids, using data collected from 1972 to 1994 by both the Michigan and Wisconsin Departments of Natural Resources. For most of the species studied here, length was the major source of variability, followed by location.

ISSN:0706-652X    

DOI:10.1139/f99-211

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

The Hudson River commercial striped bass (Morone saxatilis) fishery has been closed since 1976 due to high polychlorinated biphenyl (PCB) contamination. Accurate forecasting of PCB levels in striped bass has been confounded by high variance in contamination among individuals. We investigated the relationship between habitat use and PCB contamination in Hudson River and Long Island Sound striped bass using electron microanalysis of otolith strontium to generate time series of individual salinity habitation. Males with highly contaminated levels (mean PCB = 8.3 ppm) showed freshwater resident behavior, rarely experiencing salinities >5 ppt. Several individuals showed large habitat shifts. Shifts from brackish or marine habitats to freshwater habitats were often associated with high PCB levels. A third pattern was apparent in large females, where polyhaline/euhaline salinity habitation was associated with lower PCB levels. Total PCB body burden was inversely correlated with mean salinity encountered during the most recent growth season prior to capture. Fish with recent exposure to polyhaline salinities showed high variability in PCB body burdens (0.4-9.0 ppm), suggesting a local source of PCB contamination in the New York Harbor region.

ISSN:0706-652X    

DOI:10.1139/f99-209

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Stable isotope ratios of carbon and nitrogen were used to identify seasonal and spatial patterns in carbon and nitrogen and to determine source of energy (Prince William Sound (PWS) versus the Gulf of Alaska (GOA)) for juvenile fishes in PWS. PWS-wide samples of bulk net zooplankton (all noncalcareous zooplankton collected in 335-µm-mesh nets), individual late copepodid stage of the large herbivoreNeocalanus cristatus, juvenile Pacific herring (Clupea pallasi), and juvenile walleye pollock (Theragra chalcogramma) were collected in spring, summer, and fall in 1994 and 1995. For bulk zooplankton andN. cristatus, there was a strong13C/12C gradient but weak15N/14N gradient within PWS and GOA. Zooplankton15N/14N was positively correlated with13C/12C during the phytoplankton bloom but was not correlated during the zooplankton bloom, suggesting a decoupling of nitrogen and carbon cycles. Plankton isotopic signatures suggested a diagnostic13C/12C for GOA carbon. For juvenile fishes and diapausing copepods in PWS,13C/12C varied between years, suggesting that the origin of carbon differed between years (GOA more so in 1995 than in 1994). Use of a natural stable isotope tracer provided evidence for biophysical coupling via inferred fluctuations in oceanographic processes.

ISSN:0706-652X    

DOI:10.1139/f99-212

出版商:NRC Research Press    

年代:1999

数据来源: NRC