Final answer:
Commercial fishing can have detrimental effects on marine ecosystems, leading to loss of biodiversity, economic hardship for fishing communities, and the collapse of certain fish populations.
Step-by-step explanation:
A negative consequence of commercial fishing is the radical restructuring of the marine ecosystem, where dominant species are over-harvested to become ecologically minor, leading to unpredictable effects on the entire ecosystem. This not only causes a loss of biodiversity but also long-lasting economic impacts on local human populations dependent on fisheries for their livelihood and nutrition. Other consequences include the loss of certain large-bodied marine species like sharks, tunas, and sea turtles, the by-catch of non-target species, and habitat destruction.