Aquatic Species Monitoring 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 Aquatic Species Monitoring flashcards as text
In radio telemetry studies of fish movement, which factor most reduces detection efficiency of a stationary receiver array?
Answer: High background electrical conductivity attenuating signal range
Elevated specific conductance increases signal attenuation in water, reducing the effective detection range of fixed hydrophone or radio receiver arrays.
When designing a long-term population monitoring program for a stream fish species, which sampling approach best controls for temporal variation in gear efficiency?
Answer: Standardized sampling protocols applied at fixed sites during the same season annually
Standardizing protocols, sites, gear, and seasonal timing removes many confounding sources of variation and makes year-to-year comparisons valid.
A fisheries manager finds elevated mercury concentrations in piscivorous fish at a reservoir. Which monitoring approach would best identify the trophic pathway of mercury bioaccumulation?
Answer: Stable nitrogen isotope (δ15N) analysis of fish and prey across trophic levels
Stable nitrogen isotopes enrich predictably with each trophic step, allowing researchers to link mercury concentrations to trophic position across the food web.
Which stream fish sampling method is best suited for estimating the total biomass of a cryptic benthic species such as sculpin?
Answer: Three-pass depletion electrofishing with removal
Depletion electrofishing removes fish across successive passes, allowing capture probability and total population size (and thus biomass) to be estimated for species difficult to detect otherwise.
A biologist calculates weight-at-length residuals for a sample of bluegill to generate a relative weight (Wr) index. What does a Wr value of 85 indicate?
Answer: Fish are below average condition relative to the standard weight equation
A Wr below 100 means the observed weight is less than the standard weight for fish of that length, indicating below-average condition.
Which regulatory trigger would most appropriately prompt an emergency stock assessment for a commercially harvested marine species managed under a federal fishery management plan?
Answer: Stock biomass index falling below the minimum stock size threshold (MSST)
Under U.S. federal fisheries law, a stock falling below the MSST triggers mandatory status determination and rebuilding analysis.
When monitoring fish passage efficiency at a dam, which metric directly measures the proportion of fish successfully navigating the upstream passage facility?
Answer: Passage efficiency = fish counted upstream / fish counted at the base of the dam
Passage efficiency is calculated as the ratio of fish counted at or above the passage exit to those counted approaching the dam, providing a direct measure of facility performance.