The Impact of Overfishing

Many of the fish that we so enjoy consuming are also the most sought after. Often times, such fish are caught before they are capable of reproduction. In conjunction with rapid, modern-day fishing practices,  their numbers have been greatly depleted. Rebuilding fish populations becomes hard when it is nearly impossible for significant reproduction to occur. These fish exist as top predators in their ecosystems. When these species begin to disappear from their respective food webs, ecosystems begin to change. Food webs experience great shifts. Lower trophic level, smaller fish begin to replace the predators at the top. Due to their lower trophic level status, more of these fish are needed to provide the same amount of energy to a consumer that fewer top predator species could produce. As a result, larger numbers of these smaller fish are needed, and even more overfishing begins to occur. 
A large part of the impact of overfishing comes from the actual methods of fishing. In most methods of commercial fishing, bycatch, any marine organism that is caught along incidentally with commercial species, is the main problem. Bycatch is estimated to account for over a fourth of the world's total marine catch, yet the majority of these organisms either die or are dying before being thrown back into the ocean. This has lead to the endangering of a significant number of the species that end up as bycatch. Perhaps one of the most destructive forms of fishing is shrimp trawling, which is not only responsible for a large portion of the world's total bycatch but also for the destruction of numerous seabed communities as nets with weighted trawl doors are dragged across them. This method is so damaging that is has been likened to the clearing of forests.