The marine environment, and hence the food chain on the continental shelf is negatively impacted by multiple stressors.
Round up the usual suspects; habitat loss from bottom trawl fishing, chemicals, including the reproductive hormone disruptor BPA from plastics as they degrade concentrating in fish tissue up the food chain, mercury from dirty coal burned in foreign countries concentrating in apex predators, introduced exotics like Lionfish, new species moving north like mangroves trees and mangrove snapper as waters warm, over fishing, occasionally poor fisheries management by State and Federal fisheries management, and intense overfishing of the highly migratory species particularly the tunas, inside and outside US waters.
We see this in greatly reduced fish numbers. Ask any Old Salt or fisheries biologist; fish populations are small fractions seen in earlier days.