Fish Population Dynamic and Stock Assessment (2+1)

Problem

Mean length and growth rate estimation is essential for calculation of growth equation in Gulland and Holt method.

Problem:

Using the following data, calculate the growth rate and mean length.

Age in years (t)	Length (Lt) in cm
1	30.1
2	36.3
3	40.9
4	44.5
5	53.2
6	54.8
7	60.1

Mean length (t) =$$\overline{L}(t) = {L(t) + \Delta t + L(t) \over 2}$$

Growth rate =$${\Delta L \over \Delta t} = {L(t) + \Delta t - L(t) \over \Delta t}$$

t is expressed in years.

Draw a graph by taking $$\overline {L}$$ as x

$${\Delta L \over \Delta t}$$ as y, to estimate $$L_{\infty}$$