(6.7.1 & 6.7.2)
The following table presents the annual total catches and the corresponding total fishing efforts of a shrimp stock in the Arabian Sea during the period 1969 to 1978 (Sparre and Venema, 1992).
|
Year |
Catch, Y |
Total effort |
|
1969 |
546.7 |
1.224 |
|
1970 |
812.4 |
2.202 |
|
1971 |
2493.3 |
6.684 |
|
1972 |
4358.6 |
12.418 |
|
1973 |
6891.5 |
16.019 |
|
1974 |
6532.0 |
21.552 |
|
1975 |
4737.1 |
24.570 |
|
1976 |
5567.4 |
29.441 |
|
1977 |
5687.7 |
28.575 |
|
1978 |
5984.0 |
30.172 |
GROUP I
1. Draw a graph of the annual abundance index against the corresponding fishing mortality index.
2. The Fox model was adjusted to the data. The following parameters were obtained:
|
|
a = 6.150 |
b = - 0.028 with a determination coefficient, r2 = 0.78. |
a) Calculate and draw the curves of the equilibrium conditions of the abundance index and of the total catch against fishing effort.
b) Determine the target-points MSY and 0.1.
c) Determine the parameters (kq), (r/q) and (kr).
GROUP II
Knowing that the adjustment of the Schaefer model to the same set of data, resulted in the following values of the parameters:
a = 444.454
b = - 8.055
(r2 = 0.77)
1. Repeat the calculations of the previous Group.
