New tags were used for the second population estimate. Assuming the blue tags st
ID: 174158 • Letter: N
Question
New tags were used for the second population estimate. Assuming the blue tags stay on well during the year, what changes the proportion of the blue tags in the population and makes the use of red tags more accurate? Hint: Consider the assumptions made by the Petersen method. [2 pt; L2; I.A.5]
the fish might eat the tags
random loss of the tags might be sufficiently large to change the proportion of tagged fish
we cannot assume the tags would stay on longer than six months, so we need new tags for the fish
as tagged fish die and larvae that were not tagged reach maturity the proportion of tagged fish changes
Explanation / Answer
Answer) In this case, red tags were used as new tags for the second population estimate and we are assuming that the blue tags stay on well during the year. considering the assumptions made by the Peterson method makes us conclude that any loss of old tag may be very random such that it does not affect the total proportion of tagged fish. neither the fish can eat the tag or it will be lost randomly in large proportion.
hence, the only possibility to change the proportion of fish tagged with blue is that either the tagged fish die or the immature (say larvae) untagged fish become mature enough to be counted as a fish.
therefore "option D) as tagged fish die and larvae that were not tagged reach maturity, the proportion of tagged fish changes" allows the most accurate use of red tags to the newly matured untagged fishes only.