Humans have a history of overfishing many commercially-important ocean fisheries, depleting populations to levels where they are no longer economical to harvest.
(Humans; have; a history of overfishing many commercially-important ocean fisheries, depleting populations to levels) (they; are; T:no longer; economical; L:levels) (they; to harvest; )
Humans they they
have are to harvest
a history of overfishing many commercially-important ocean fisheries, depleting populations to levels
T:no longer economical L:levels