You are a fisheries manager and one of your responsibilities

You are a fisheries manager and one of your responsibilities is to estimate the effect of pressure from sport fishing on the viability of a population of kokanee. First you obtain the following data from sampling the spawning bed, and from conducting sein samples of the lake

Assume that there is a 50:50 sex ratio, females will reproduce first at age 3 and lay on average 300 eggs each, and females will reproduce again at age 4, lay 600 eggs and then die.

i. Construct a life table for the population.

ii. Calculate lx, Qx, mx and ex values for all age classes.

iii. Is this population increasing or decreasing at current mortaliy levels? Do the appropriate calculations to determine this.

iv. Imagine that fishing increases natural mortality rate of all fish 2 years of age and older by a factor of 20% (e.g., if it is presently 50%, it will become 70%). How would this affect the cohort replacement rate and the ex values for the fish?

v. Plot two survivorship curves for this population on the same graph; one for the population in the presence of fishing pressure and one for the population in its absence. How will fishing affect survivorship pattern? Explain what is going on.

I am wanting to take a population biology class next semester and this is a question from the text. I have no idea where to start for this, and would like to gain the fundamentals before taking the class. Thank you so much for your help!

Age 0 (eggs) 2 Number 150,000 6,000 2,000 750 250

Solution