Question

declining fishing technology costs and overexploitation of near - shore fishing grounds have made isolated oceanic reefs, which often lack regulatory protections, increasingly attractive to commercial and sport fishers. a team led by octavio aburto - oropeza surveyed the biomass density and species composition of two isolated reefs: alacranes, a protected (fishing prohibited) reef 133 kilometers from the yucatán peninsula, and bajos del norte, an unprotected reef 25 kilometers further out to sea. species at the highest level of the trophic pyramid constituted 34% of the biomass at alacranes and 10% of the biomass at bajos del norte. aburto - oropeza and colleagues attribute this difference to the two reefs difference in regulatory status. which finding, if true, would most directly support aburto - oropeza and colleagues explanation? a) total biomass at alacranes is much greater than total biomass at bajos del norte, though the reefs biomass densities are similar. b) it is somewhat more expensive for commercial and sport fishers to reach bajos del norte than it is to reach alacranes. c) some of the species that compose the highest trophic level at bajos del norte are not found at alacranes. d) commercial and sport fishers tend to disproportionately remove species at the highest trophic level.

Explanation:

The researchers attribute the biomass difference between the two reefs to regulatory status (protected vs. un - protected). Option D supports this by showing that commercial and sport fishers (where fishing is allowed at un - protected Bajos del Norte) tend to disproportionately remove species at the highest trophic level, which can explain the lower biomass there compared to the protected Alacranes. Option A just compares total biomass and biomass density without relating to fishing impact. Option B mentions cost of reaching the reefs, not related to regulatory impact on biomass. Option C shows species differences, not how fishing regulations affect biomass.

Answer:

D. Commercial and sport fishers tend to disproportionately remove species at the highest trophic level.