5. Fisheries Science

Stock Assessment — Quiz

Test your understanding of stock assessment with 5 practice questions.

Practice Questions

Question 1

Using the Ricker stock–recruitment model $R=\alpha S e^{-\beta S}$, derive the spawning biomass $S_{\mathrm{MSY}}$ that maximizes recruitment. If $\beta=0.002\,\text{unit}^{-1}$, what is $S_{\mathrm{MSY}}$?

Question 2

During a catch-curve analysis, the slope of the descending limb of a plot of $\ln(N_a)$ versus age $a$ is -0.3 per year. What are the instantaneous total mortality rate $Z$ and the annual survival fraction $S$?

Question 3

In the Schaefer surplus-production model $Y=rB\left(1-\frac{B}{K}\right)$, what is the maximum sustainable yield (MSY) when $r=0.4\,\mathrm{yr}^{-1}$ and $K=1000\,\mathrm{t}$?

Question 4

If total mortality is $Z=0.8\,\mathrm{yr}^{-1}$ and natural mortality is $M=0.3\,\mathrm{yr}^{-1}$, what is the exploitation rate $E$?

Question 5

Which characteristic distinguishes the Beverton–Holt stock–recruitment model from the Ricker model?