# Abundance from Depletion Data

Lake Guntersville Largemouth Bass

Estimate abundance of Largemouth Bass in Lake Guntersville (AL) using electrofishing depletion data.
Exercise
Depletion/Removal
Abundance
Bass
Author

Derek H. Ogle

Published

Mar 8, 2019

Modified

Feb 13, 2023

Maceina et al. (1995) examined the population of harvestable Largemouth Bass (Micropterus salmoides) in Conner Cove of Lake Guntersville, Alabama (a 28,000 ha impoundment of the Tennessee River) in March, 1992. Their objective was to estimate the abundance of harvestable bass through the depletion of catches due to electrofishing. In their study, they electrofished for 15 minutes at each of four depth strata in Conner Cove. The total number of bass captured and removed from the population in the full hour of electrofishing at the four depths was recorded. Thus, a total of one hour of electrofishing constituted one unit of effort. Six one-hour periods were used to deplete the population of bass in one Conner Cove. The number of bass caught in each successive sampling period was 23, 12, 13, 14, 9, and 7. Enter these data into vectors in R and use them to answer the following questions.

1. What is the best estimate and 95% confidence interval for the catchability coefficient? Very carefully interpret what this estimate means relative to Conner Cove Largemouth Bass.
2. How does your catchability estimate compare to that published in Maceina et al. (1995)? Explain discrepancies (if any).
3. What is the best estimate and 95% confidence interval for the population size?
4. How does your populations size estimate compare to that published in Maceina et al. (1995)? Explain discrepancies (if any).
5. Estimate the expected number of bass that would be caught in the first sampling period given your best estimates of $$q$$ and $$N_{0}$$, and the amount of effort used in each sample period.1
6. Estimate the expected number of bass that would be caught in the second sampling period, again given your best estimates of $$q$$ and $$N_{0}$$, and the amount of effort used in each sample period.
• 1 Symbols are as used in Ogle (2016).

• Solution Code:

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## References

Maceina, M., W. Wrenn, and D. Lowery. 1995. Estimating harvestable Largemouth Bass abundance in a reservoir with an electrofishing catch depletion technique. North American Journal of Fisheries Management 15:103–109.
Ogle, D. H. 2016. Introductory Fisheries Analyses with R. CRC Press, Boca Raton, FL.