Unit Leader - Research Fish Biologist
Cooperative Research Units
Email:
bjirwin@usgs.gov
Office Phone:
706-542-0790
Fax:
706-542-8356
ORCID:
0000-0002-0666-2641
Location
PTX - U of GA-School of For Res-2524
School of Forest Resources
University of Georgia
Athens
, GA
30602-0001
US
Supervisor:
Elisabeth B Webb
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We present a case-study evaluation of gillnet catches of Walleye Sander vitreus to assess potential effects of large-scale changes in Oneida Lake, New York, including disruption of trophic interactions by double-crested cormorants Phalacrocorax auritus and invasive dreissenid mussels. We used the empirical long-term gillnet time series and a negative binomial linear mixed model to partition variability into spatial and coherent temporal variance components, and we propose that variance partitioning can help quantify spatiotemporal variability and examine if variance structure differs before and after large-scale perturbation. Here, we found that average catch and total variability of catches decreased following...
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The number of fish collected in routine monitoring surveys often varies from year to year, from lake to lake, and from location to location within a lake. Although some variability in fish catches is expected across factors such as location and season, we know less about how large-scale disturbances like climate change will influence population variability. The Laurentian Great Lakes in North America are the largest group of freshwater lakes in the world, and they have experienced major changes due to fluctuations in pollution and nutrient loadings, exploitation of natural resources, introductions of non-native species, and shifting climatic patterns. In this project, we analyzed established long-term data about...
Categories: Project;
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: 2012,
CASC,
Climate change,
Completed,
FY 2012, All tags...
Fish,
Fish,
Northeast,
Northeast CASC,
Northeast Climate Science Center,
Projects by Region,
Wildlife and Plants,
Wildlife and Plants,
ecosystem variability,
population variability, Fewer tags
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The number of fish collected in routine monitoring surveys often varies from year to year, from lake to lake, and from location to location within a lake. Although some variability in fish catches is expected across factors such as location and season, we know less about how large‐scale disturbances like climate change will influence population variability. The Laurentian Great Lakes in North America are the largest group of freshwater lakes in the world, and they have experienced major changes due to fluctuations in pollution and nutrient loadings, exploitation of natural resources, introductions of non‐native species, and shifting climatic patterns. In this project, we analyzed established long‐term data about...
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The success of natural resource management depends on monitoring, assessment and enforcement. In support of these efforts, reference points (RPs) are often viewed as critical values of management-relevant indicators. This paper considers RPs from the standpoint of objective-driven decision making in dynamic resource systems, guided by principles of structured decision making (SDM) and adaptive resource management (AM). During the development of natural resource policy, RPs have been variously treated as either ‘targets’ or ‘triggers’. Under a SDM/AM paradigm, target RPs correspond approximately to value-based objectives, which may in turn be either of fundamental interest to stakeholders or intermediaries to other...
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Abstract: (from ScienceDirect): Empirical evidence has shown increased variability in harvest and recruitment of exploited fish populations, which can result directly from exploitation or indirectly from interactions between external drivers and the internal dynamics of age-structured populations. We investigated whether predation in a freshwater system could affect a prey fish population, in the same way fishing affects targeted populations. Using fishery-independent trawl survey data and a suite of quantitative indicators, we evaluated changes in the alewife population in Lake Michigan. Our results provide evidence for a reduction in the mean spawner age, a reduction in the diversity of age classes and the distribution...
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