Field Survey & Data Collection Flashcards
7 cards from real CFP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Field Survey & Data Collection flashcards as text
A biologist uses a stratified random sampling design for a lake survey. The primary advantage over simple random sampling is:
Answer: It reduces variance within strata and improves precision for subgroups
Stratified sampling reduces overall variance by grouping similar units together, improving estimates for each stratum.
When sampling benthic macroinvertebrates in a riffle habitat, the Surber sampler is preferred because it:
Answer: Samples a defined area while a net captures dislodged organisms downstream
The Surber sampler frames a fixed area and catches organisms dislodged from that substrate with a downstream net.
Catch-per-unit-effort (CPUE) data are most useful when:
Answer: Gear efficiency remains constant across surveys
CPUE is a valid index of abundance only when catchability (gear efficiency) is consistent across time and space.
A trawl survey is being conducted in a large reservoir. At minimum, how should tow locations be selected to ensure representative sampling?
Answer: Randomly or systematically across available habitat types
Random or systematic placement across habitats ensures unbiased coverage and representative CPUE estimates.
Which of the following is a major limitation of using scales for aging fish compared to otoliths?
Answer: Scale annuli may be reabsorbed or false rings may form, reducing accuracy
Scale resorption during periods of stress and false check formation can cause underestimation of age.
During electrofishing, a biologist notices reduced catch rates despite no change in effort. Which factor is most likely responsible if water temperature has increased significantly?
Answer: Increased fish swimming speed allowing escape from the anode
Warmer water increases fish metabolism and swim speed, allowing fish to escape the electrical field more easily.
A biologist records substrate composition in a stream using the Wentworth scale. A particle measuring 32 mm would be classified as:
Answer: Cobble
The Wentworth scale classifies particles 16–256 mm as cobble, so a 32 mm particle falls in the cobble category.