Question:
Compared with bony fish, many shark species show steeper population declines in response to heavy fishing pressure. Which one of the following options explains this?
Compared with bony fish, many shark species show steeper population declines in response to heavy fishing pressure. Which one of the following options explains this?
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For fisheries vulnerability, look for \textbf{late maturity}, \textbf{low fecundity}, and \textbf{long lifespan}. These traits signal slow population growth and high collapse risk under heavy harvest.
Updated On: Aug 26, 2025
- Sharks are dangerous to humans.
- Sharks evolved over 400 million years ago
- Sharks are long lived and late maturing.
- Sharks are only found in open oceans.
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The Correct Option is C
Solution and Explanation
Step 1: Recall life-history differences.
Many sharks are K-selected: slow growth, late age at maturity, low fecundity (few pups), and long lifespans. Bony fishes targeted by fisheries often have faster life histories (earlier maturity, many eggs), allowing quicker rebound.
Step 2: Link life history to decline under fishing.
High fishing mortality removes breeding adults. If a species matures late and produces few offspring, the replacement rate is low \(\Rightarrow\) populations decline faster and recover slowly under sustained harvest.
Step 3: Evaluate options.
(A) Human danger is irrelevant to demographic decline.
(B) Ancient origin does not determine present recovery rates.
(C) Correct: late maturity + longevity + low fecundity \(\Rightarrow\) steep declines.
(D) False: many sharks use coastal/nursery habitats; distribution alone doesn’t explain steep declines. Final Answer:
\[ \boxed{\text{(C) Long-lived and late-maturing life history leads to steep declines}} \]
Many sharks are K-selected: slow growth, late age at maturity, low fecundity (few pups), and long lifespans. Bony fishes targeted by fisheries often have faster life histories (earlier maturity, many eggs), allowing quicker rebound.
Step 2: Link life history to decline under fishing.
High fishing mortality removes breeding adults. If a species matures late and produces few offspring, the replacement rate is low \(\Rightarrow\) populations decline faster and recover slowly under sustained harvest.
Step 3: Evaluate options.
(A) Human danger is irrelevant to demographic decline.
(B) Ancient origin does not determine present recovery rates.
(C) Correct: late maturity + longevity + low fecundity \(\Rightarrow\) steep declines.
(D) False: many sharks use coastal/nursery habitats; distribution alone doesn’t explain steep declines. Final Answer:
\[ \boxed{\text{(C) Long-lived and late-maturing life history leads to steep declines}} \]
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