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Hello, I would like to know if anyone can help me solve this exercise.
Consider a sturgeon fish farm, which has the following process: There are a certain number of females (300), of which 2% reach the age of caviar harvest per month, of which 95% are available for Harvest, while the other is left for breeding (we will assume that an average of 20 offspring are obtained).
The offspring are fed until they are mature (we will assume 2 years), 98% of those born to males are sold (about 40% of offspring), while females are evaluated to determine a third Will be converted into crop females. We will assume that the females have a life expectancy of 7 years and the age distribution of the females is uniform.
Develop the causal diagram and flow chart and levels of the previous system:
Consider the following proposal: A zootechnical company offers you a new breed of sturgeon, with a capacity to procreate 27 offspring a month and an average life expectancy of 4 weeks.
Under the initial system model: Do you recommend the implementation of this new breed? To answer, state the flow chart and levels under the conditions of the new breed of sturgeons and justify their response

We can help. What is the problem with your model?

You might take a look at this model for inspiration:
http://metasd.com/2010/06/bifurcating-salmon/

Also, there should be quite a few fisheries models in the SD Conference proceedings. Erling Moxnes has done several papers on this, for example.
http://citeseerx.ist.psu.edu/viewdoc/do ... 1&type=pdf

The problem seems ill-posed. If it takes two years to reach maturity, and the new sturgeon have a life expectancy of 4 weeks, they'll all be dead before they mature.

What happens is that another situation arises with a new race

Administrator wrote:We can help. What is the problem with your model?

In the first two years I think that there can be no reproduction of pups, I do not know how to introduce that in equation

The two year delay implies that there's an additional state. So, you need two stocks - one for juvenile fish, and one for reproducing adults.

... or maybe more than 2, if you want to keep track of males and females separately. I don't think that' necessary for a first cut though.