Complete and Sampled Counts
- Summary of Random Sampling types:
Sample
Use
Advantages
Disadvantages
SRS
small geographic area w/ not much variation, not many sample units
simple formulas
long travel time
Stratified RS
distribution depends clearly on well defined attributes
more efficient estimates
its okay
systematic sampling
anywhere, as long as first unit is randomly placed
best type, most efficient
problems with small samples
- Mark-recapture
- mark resight: used for large animals or other animals that are not good to recapture
- Distance Sampling: plot and line samples; incomplete counts are corrected by visibility bias. Stand and look. Doesn't sound legit.
- Indicies: instead of counting the number of animals, count their "effects" (footprints, etc).
- Field methods for fish:
- Pilot studies should be done first
- Sampling should extensive, not intensively based
- Fish distribution is different than for other animals--they are clumped tightly (they Hilborne and Walters, 1992)