Evaluating techniques for sampling stream crayfish (Paranephrops planifrons)
TL;DR: Electrofishing was effective in collecting koura from different habitats and resulted in the highest abundance estimates, and mark-recapture estimates appeared to be more precise than depletion estimates, especially if multiple recaptures were made.
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Abstract: We evaluated several capture and analysis techniques for estimating abundance and size structure of freshwater crayfish (Paranephrops planifrons) (koura) from a forested North Island, New Zealand stream to provide a methodological basis for future population studies. Direct observation at night and collecting with baited traps were not considered useful. A quadrat sampler was highly biased toward collecting small individuals. Handnetting at night and estimating abundances using the depletion method were not as efficient as handnetting on different dates and analysing by a mark-recapture technique. Electrofishing was effective in collecting koura from different habitats and resulted in the highest abundance estimates, and mark-recapture estimates appeared to be more precise than depletion estimates, especially if multiple recaptures were made. Handnetting captured more large crayfish relative electrofishing or the quadrat sampler. to
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CHAPTER 29 – Secondary Production of Macroinvertebrates
Arthur C. Benke,Alexander D. Huryn +1 more
- 01 Jan 2007
161
Food Web Structure and Basal Resource Utilization along a Tropical Island Stream Continuum, Puerto Rico
TL;DR: Stable isotope analysis demonstrates that algal-based resources are very important to stream consumers, even in small forested headwater streams, and also demonstrates the importance of doing assimilation-based analysis when studying food webs.
149
Effects of crayfish (Paranephrops planifrons: Parastacidae) on in-stream processes and benthic faunas: a density manipulation experiment
TL;DR: Densities of invertebrates other than crayfish were not significantly different among treatments; however, taxa richness and invertebrate biomass were significantly lower in high koura channels than in controls.
134
Evaluating active and passive sampling methods to quantify crayfish density in a freshwater wetland
TL;DR: 1-m2 throw traps provide better estimates than baited minnow traps of crayfish densities in shallow vegetated habitats and the form of the relationships between CPUE and density did not improve when large-male CPUE was used in the regressions.
Sampling stream invertebrates using electroshocking techniques: implications for basic and applied research
TL;DR: Electroshocking techniques can provide accurate estimates of population size and diversity, minimize disturbance to benthic habitats, and reduce processing time.
77
References
The Removal Method of Population Estimation
TL;DR: A biweekly posttreatment fish census was taken along a 5,600-foot ditch traversing the marsh; enumerations and estimates of the numbers of each species encountered were supplemented by sampling collections as mentioned in this paper.
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Redefining the role of crayfish in aquatic ecosystems
TL;DR: To completely understand their role, crayfish should be viewed from two perspectives: that of an individual attempting to complete its life cycle, and the collective functioning of a population in the ecosystem, which can produce a serious ecological impact.
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Sample Size in Petersen Mark–Recapture Experiments
TL;DR: In this article, a method of choosing sample sizes such that experimental costs are minimized is described, and graph and formulas are given defining sample size to attain preassigned levels of accuracy and precision of population estimation.
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