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Suppose this fish is divided into four age groups: 1 year-old fish … and 4-year-old fish. The average weight of each fish in each age group is 5.07, 1 1.55, 17.86 and 22.99 (g) respectively. The natural mortality rate of fish in all age groups is 0.8( 1/ year): this fish lays eggs in a seasonal concentration, with an average of 1. 109x 105 (one fish); The number of eggs laid by the 3rd instar fish accounts for half, while the 2nd instar fish and 1 instar fish do not lay eggs, and the spawning incubation period is the last 4 months of each year. The hatching survival rate of eggs is 1 fish, and the survival rate (ratio1.22x111.22x165433)

According to the regulations of the fishery management department, fishing is allowed within 8 months before spawning and oozing every year. Such as the annual fishing capacity (such as the number of fishing boats and the number of nets, etc.). ) is fixed, and the fishing amount per unit time will be directly proportional to the number of fish of all ages. The proportional coefficient can be called the fishing intensity coefficient. Trawls with a mesh of 1.3mm are usually used, and only 3-year-old fish and 4-year-old fish can be caught, and the ratio of fishing intensity coefficient between them is 0.42: 1. The fishing industry calls this method fixed effort fishing.

1) to establish a mathematical model and analyze how to carry out sustainable fishing (that is, when fishing starts every year, the fish resources of all age groups in the fishing ground remain unchanged), and on this premise, the highest harvest (total fishing weight) in the whole year can be obtained.

2) A fishing company has contracted the fishing business of this kind of fish for five years, and the contract requires that the productivity of fish schools should not be greatly damaged. It is known that the number of fish in each age group is 122, 29.7, 10. 1 3.29(x 109) respectively. What strategy can the company take to maximize the total harvest if the fixed-concentration fishing method is still adopted? . ：