Around 1900, fishermen in the Chesapeake Bay area landed more than seventeen million pounds of shad in a single year, but by 1920, overfishing and the proliferation of milldams and culverts that have blocked shad migrations up their spawning streams had reduced landings to less than four million pounds.
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Athat have blocked shad migrations up their spawning streams had reduced landings to less
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Bthat blocked shad from migrating up their spawning streams had reduced landings to less
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Cthat blocked shad from migrating up their spawning streams reduced landings to a lower amount
分析该选项
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Dhaving blocked shad from migrating up their spawning streams reduced landings to less
分析该选项
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Ehaving blocked shad migrations up their spawning streams had reduced landings to an amount lower
分析该选项