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Question

Difficulty: MediumMain Point

Ecologist: Marine resource managers often establish artificial reefs constructed from decommissioned steel vessels under the premise that these structures expand regional fish populations by providing new breeding habitats. However, underwater acoustic tracking reveals that the vast majority of fish colonizing these reefs are mature adults that migrated from nearby natural rocky reefs rather than newly bred individuals. Moreover, by concentrating fish in isolated, predictable coordinates, artificial reefs dramatically elevate the catch efficiency of commercial trawlers. Thus, the deployment of such artificial reefs primarily facilitates the exploitation of existing fish stocks rather than augmenting total marine biomass.

Which of the following most accurately expresses the main conclusion of the ecologist's argument?

  1. A
    Artificial reefs constructed from decommissioned vessels inevitably cause a total collapse in the biodiversity of adjacent natural reef habitats.
  2. B
    Constructing artificial reefs from steel vessels creates critical new spawning grounds that increase overall regional fish populations.
  3. Deploying decommissioned steel vessels as artificial reefs serves more to ease the capture of current fish populations than to increase overall marine abundance.Answer
  4. D
    The primary mechanism by which artificial reefs operate is by significantly increasing the catch efficiency of commercial fishing vessels.
  5. E
    Adult fish that migrate from natural rocky reefs to artificial structures suffer higher natural mortality rates than those that remain in their original habitats.

Answer

Deploying decommissioned steel vessels as artificial reefs serves more to ease the capture of current fish populations than to increase overall marine abundance.
The author's ultimate claim is stated in the final sentence: the deployment of artificial reefs primarily facilitates the exploitation of existing fish stocks rather than augmenting total biomass. The preceding sentences supply evidence regarding adult migration and trawler efficiency to establish this point. The correct answer is an accurate paraphrase of this ultimate claim.

Step-by-Step Solution

1
Analyze the structure of the argument and identify the author's primary stance.
The argument opens with a common belief held by resource managers, presents contradictory empirical evidence (mature adult migration and increased fishing efficiency), and concludes with a definitive judgment signaled by 'Thus'.
Dissecting argument components separates background claims and supporting premises from the author's ultimate thesis.
2
Differentiate between intermediate premises and the main point.
The observation that trawlers experience elevated catch efficiency serves to support the final assertion that these reefs facilitate exploitation rather than biomass growth.
LSAT Main Point questions regularly present supporting evidence as distractor choices to test whether the reader can identify the ultimate deduction.
3
Match the identified main conclusion to the paraphrased option.
The statement expressing that artificial reefs facilitate fish harvesting rather than augmenting overall abundance precisely captures the author's conclusion.
The correct answer to a main conclusion question must accurately reflect the overarching claim without exceeding its scope or stopping at supporting premises.

Key Concept

Distinguishing the main conclusion from background context, opposing views, and supporting premises in an argument.
Estimated Time:1m 20s
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