Describe a named method for determining the size of fish populations and the challenges in conserving world fish stocks.

challenges:
d. maintain fish as an important food source for humans/other animals;
e. a sustainable yield means not overfishing an area/not causing a decline in the population/ not catching faster than the fish can replace themselves / OWTTE;
f. pollution threatens world fish stocks/habitat;
g. disagreements as to what is a sustainable population;
h. disagreements in the collection of data of population sizes;
i. requires international cooperation to define conservation measures/regulations/quotas;
j. difficult to reinforce/control regulations / monitor practices / OWTTE;
Award [4 max] if only challenges addressed.

Named method could be any of the three examples given above but the description and limitation must be based on one named method only.

This question caused some difficulty as, although many candidates correctly named a method and described it, most could not mention limitations of the named method or even had difficulty describing it properly. The described challenges were often too vague and not focusing on conserving world fish stocks; many simply listed problems without going any further (e.g. net mesh size, fishing in breeding seasons, fish migration, etc.).