Question related to biology about survivorship curves and harvesting?
1. explain your view of the survivorship curves of automobiles, redwood trees, salmon, and a set of dishes. how would you draw this?
2. if you were in the business of growing, harvesting, and selling freshwater fish, to insure a maximum long term yield from your "farm," at what point in the population growth would you harvest? at what point would you take no more fish? what other factors would affect yields and how would you adjust your operation?
any help is appreciated. thank you.
2 Responses
Rugar
06 Feb 2011
Justin D
06 Feb 2011
1. I know that inanimate objects have a type 2 survivorship curve (equal mortality or breakage over entire lifespan) salmon and redwoods I am not sure about. Salmon reproduce once late in life I know.
2. The best time to harvest for maximum yield is when the population equals one half of the carrying capacity, according to the logistic growth equation. You harvest the new growth (dN/dT).
As to that first one, no idea. That’s an extremely odd question.
The answer to the second one is complex and will require a bit of explanation on your part. In short, the concept of maximum sustainable yield means that you need to harvest an amount of fish equal to the growth rate. Simplistically, if you have 1000 female fish and they each produce 1000 surviving offspring each year then you can theoretically harvest 1,000,000 fish (1000 females x 1000 offspring) – 1000 females (as broodstock for the next season) / year or 999,000 fish/year. Clearly, the largest factors influencing your production would be % survival of the offspring and growth rate.
I’d suggest that you look over the concept of Maximum Sustainable Yield for a more detailed explanation.