( ( Some species ) ( ( have ( been overharvested ) ) ; ) )
(ROOT (S (NP (DT Some) (NNS species)) (VP (VBP have) (VP (VBN been) (VP (VBN overharvested)))) (: ;)))
Some species have been overharvested;
(ROOT (S (NP (NNP Overharvesting)) (VP (VBZ is) (NP (DT a) (JJ serious) (NN threat)) (ADVP (RB particularly)) (PP (TO to) (NP (JJ aquatic) (NNS species)))) (. .)))