Frequently Asked Questions (FAQs)
What is the maximum sustainable yield or MSY?
- It is the largest long-term average catch that can be taken from a fish population under prevailing environmental and fishery conditions.
What is the optimum yield or OY?
- It is the amount of fish that will provide the greatest overall benefit to the Nation, particularly with respect to food production and recreational opportunities, and taking into account protection of marine ecosystems.
- It is reduced from MSY as qualified by any relevant economic, social, or ecological factors.
- In the case of an overfished population, it allows for population rebuilding to a level that produces the MSY for the population.
What is the maximum fishing mortality rate or MFMT?
- A population is considered undergoing overfishing (too many fish are being removed from the population) if the fishing mortality rate (F) is above MFMT.
- MFMT may not exceed FMSY or FMSY Proxy.
- FMSY or FMSY Proxy is the rate of fishing mortality that, if applied over the long term, would result in catching the MSY or MSY proxy.
What is the minimum stock size threshold or MSST?
- A fish species is considered overfished if the population size falls below the minimum stock size.
- MSST cannot be less than 50% of the population size.
What are MSY proxies?
- In stock assessments, sometimes MSY cannot be calculated and so a proxy is used instead.
- The most common proxy used is some percent of the spawning potential ratio (SPR).
- SPR assumes that a certain amount of fish must survive and spawn in order to replenish the stock.
- It is calculated as the average number of eggs per fish over its lifetime when the stock is fished compared to the average number of eggs per fish over its lifetime when the stock is not fished.
- For most reef fish species, 30% SPR is used for the MSY proxy.
- For goliath grouper, a more conservative SPR of 50% is used since this species is vulnerable to overfishing because of its long life-span and slow growth rate.
|
