Temporal variability in the distribution and abundance of a desert trout: implications for monitoring design and population persistence in dynamic stream environments. Meeuwig, M., H. and Clements, S., P. Technical Report Oregon Department of Fish and Wildlife, 2015.
Temporal variability in the distribution and abundance of a desert trout: implications for monitoring design and population persistence in dynamic stream environments [pdf]Paper  Temporal variability in the distribution and abundance of a desert trout: implications for monitoring design and population persistence in dynamic stream environments [link]Website  abstract   bibtex   
Fisheries management and conservation strategies often rely on an understanding of the abundance of target species. However, providing precise estimates of abundance for species or populations can require a considerable amount of effort in terms of time, or personnel, or both. During protracted sampling events, fish may be moving throughout the target study system, and if these movements are non-random they may bias abundance estimates when not accounted for by sample design. The objective of this study was to evaluate whether spatio-temporal variability in fish distribution and density of redband trout in Rock Creek, Oregon, may bias population-level abundance estimates. Specific emphasis was placed on spatio-temporal variability in distribution and density associated with stream drying. We estimated that the wetted habitat available to redband trout in Rock Creek decreased substantially from 3 June to 2 September 2015. During this time period, we sampled a total of 620 redband trout and uniquely tagged 481 redband trout. We observed movement of six tagged redband trout among samples sites (i.e., 100-m stream reaches) during the study; four fish were recaptured about 0.1 km from their original capture location, one fish was recaptured about 0.2 km from its original capture location, and one fish was recaptured about 1.8 km from its original capture location. Additionally, we did not observe any redband trout among 22 sample sites in the lower 13.1 km of Rock Creek that were sampled prior to desiccation in 2015; despite the fact that redband trout have been observed in this area during previous surveys conducted from 2007 – 2012. Over the sample period we estimated that redband trout abundance decreased from a high of 1,487 individuals to a low of 665 individual. These estimates represent about a 90% decrease in population abundance compared to previous surveys (i.e., surveys conducted from 2007 – 2012); although there were some differences in sampling methodology. Combined, these data suggest that redband trout in Rock Creek are generally not redistributing in response to stream drying, but are likely becoming stranded and die as stream habitats fragment and dry. Additionally, the number of successive years of drought or near-drought conditions, and not just the magnitude of drought in any one year, may contribute the ability to redband trout to recolonize previously dry habitats and may greatly influence the abundance of redband trout. Finally, understanding patterns of stream drying may aid in identifying drought-resistant refuge habitats that warrant special protection.
@techreport{
 title = {Temporal variability in the distribution and abundance of a desert trout: implications for monitoring design and population persistence in dynamic stream environments},
 type = {techreport},
 year = {2015},
 websites = {https://drive.google.com/open?id=0ByK3XP5e4RdCUExNMEZmc01nV3M},
 institution = {Oregon Department of Fish and Wildlife},
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 created = {2016-02-22T18:08:53.000Z},
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 last_modified = {2017-03-17T15:13:39.047Z},
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 abstract = {Fisheries management and conservation strategies often rely on an understanding of the abundance of target species. However, providing precise estimates of abundance for species or populations can require a considerable amount of effort in terms of time, or personnel, or both. During protracted sampling events, fish may be moving throughout the target study system, and if these movements are non-random they may bias abundance estimates when not accounted for by sample design. The objective of this study was to evaluate whether spatio-temporal variability in fish distribution and density of redband trout in Rock Creek, Oregon, may bias population-level abundance estimates. Specific emphasis was placed on spatio-temporal variability in distribution and density associated with stream drying. We estimated that the wetted habitat available to redband trout in Rock Creek decreased substantially from 3 June to 2 September 2015. During this time period, we sampled a total of 620 redband trout and uniquely tagged 481 redband trout. We observed movement of six tagged redband trout among samples sites (i.e., 100-m stream reaches) during the study; four fish were recaptured about 0.1 km from their original capture location, one fish was recaptured about 0.2 km from its original capture location, and one fish was recaptured about 1.8 km from its original capture location. Additionally, we did not observe any redband trout among 22 sample sites in the lower 13.1 km of Rock Creek that were sampled prior to desiccation in 2015; despite the fact that redband trout have been observed in this area during previous surveys conducted from 2007 – 2012. Over the sample period we estimated that redband trout abundance decreased from a high of 1,487 individuals to a low of 665 individual. These estimates represent about a 90% decrease in population abundance compared to previous surveys (i.e., surveys conducted from 2007 – 2012); although there were some differences in sampling methodology. Combined, these data suggest that redband trout in Rock Creek are generally not redistributing in response to stream drying, but are likely becoming stranded and die as stream habitats fragment and dry. Additionally, the number of successive years of drought or near-drought conditions, and not just the magnitude of drought in any one year, may contribute the ability to redband trout to recolonize previously dry habitats and may greatly influence the abundance of redband trout. Finally, understanding patterns of stream drying may aid in identifying drought-resistant refuge habitats that warrant special protection.},
 bibtype = {techreport},
 author = {Meeuwig, Michael H and Clements, Shaun P}
}
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