CFP Conservation & Sustainability 3 — Questions and Answers
Question 1: Maximum Sustainable Yield (MSY) is best defined as:
- The harvest level that eliminates all natural mortality
- The largest catch that can be taken from a stock indefinitely without causing population decline (Correct answer)
- The total biomass of a fish population at any given time
- The minimum population size needed to avoid extinction
Correct answer: The largest catch that can be taken from a stock indefinitely without causing population decline
MSY represents the theoretical maximum harvest that can be sustained over time without depleting the population's long-term reproductive capacity.
Question 2: Spawner-recruit models are used in fisheries management primarily to:
- Estimate the minimum mesh size for selective gear
- Describe the relationship between parent stock size and subsequent recruitment (Correct answer)
- Calculate the weight-at-age of harvested fish
- Determine seasonal migration timing
Correct answer: Describe the relationship between parent stock size and subsequent recruitment
Spawner-recruit models such as Beverton-Holt and Ricker quantify how many juveniles are produced per unit of spawning stock biomass, informing safe harvest levels.
Question 3: A stock is considered 'overfished' under US federal fisheries law when:
- Any bycatch of the species occurs
- Biomass falls below the minimum stock size threshold (MSST) (Correct answer)
- Recreational harvest exceeds commercial harvest
- The species is listed under the Endangered Species Act
Correct answer: Biomass falls below the minimum stock size threshold (MSST)
Under the Magnuson-Stevens Act, a stock is overfished when its biomass falls below the MSST, typically set at one-half of the biomass at MSY (B_MSY).
Question 4: Slot limits in recreational fisheries management are primarily designed to:
- Maximize total harvest weight
- Protect both juvenile fish and large, highly fecund adult spawners (Correct answer)
- Eliminate catch-and-release mortality
- Ensure equal access among anglers
Correct answer: Protect both juvenile fish and large, highly fecund adult spawners
Slot limits prohibit retention of fish below and above a specified size range, protecting small fish from overharvest and large fish that produce disproportionately more eggs.
Question 5: Which stock assessment method estimates fish abundance by marking a sample, releasing them, and later recapturing a second sample?
- Hydroacoustic surveying
- Mark-recapture (Petersen method) (Correct answer)
- Length-frequency analysis
- Depletion electrofishing
Correct answer: Mark-recapture (Petersen method)
The Petersen mark-recapture method uses the ratio of marked to unmarked fish in a recapture sample to estimate population size.
Question 6: Ecosystem-based fisheries management (EBFM) differs from single-species management primarily in that it:
- Ignores predator-prey relationships
- Considers the broader ecological interactions and cumulative impacts across multiple species and habitats (Correct answer)
- Sets harvest quotas only for commercially valuable species
- Relies exclusively on recreational angler survey data
Correct answer: Considers the broader ecological interactions and cumulative impacts across multiple species and habitats
EBFM explicitly accounts for trophic linkages, habitat dependencies, and multi-species dynamics rather than optimizing each species' harvest in isolation.
Question 7: Genetic diversity within a fish population is important for long-term conservation because it:
- Eliminates the need for catch limits
- Increases the population's adaptive capacity to environmental change and disease (Correct answer)
- Guarantees trophy-sized individuals
- Reduces competition between year classes
Correct answer: Increases the population's adaptive capacity to environmental change and disease
Populations with high genetic diversity have more allelic variation that can be selected for when conditions change, improving resilience to stressors like climate change or novel pathogens.
CFP Conservation & Sustainability 3
Maximum Sustainable Yield (MSY) is best defined as: