The environmental effects of fishing can be divided into:

• issues that involve the availability of fish to be caught, such as overfishing, sustainable fisheries, and fisheries management; and
• issues that involve the impact of fishing on the environment, such as by-catch.

Marine conservation issues are addressed in fishery science programs.  According to a study published by the Journal  of Science in November 2006, the world would run out of wild-caught seafood in 2048.  The decline is a result of overfishing, pollution and other environmental factors.

Some fishing techniques such as dynamite fishing and cyanide fishing harm surrounding habitat.  Bottom trawling removes around 5 to 25% of an area’s seabed life on a single run.  Overfishing has led to the breakdown of some sea ecosystems and several fishing industries.  The extinction of many species has also been reported.  By targeting specific species, fishing may disrupt food webs.  Too much fishing of prey species such as sardines and anchovies reduces the food supply for the predators.  Likewise, when the target fishes are predator species such as salmon and tuna, it may cause the increase of prey species.  By-catch is the portion of the catch that is not the target species which are either kept to be sold or discarded.

Governments and intergovernmental bodies have implemented fishery management policies to curb the environmental impact of fishing.  Fishing conservation controls the human activities that may decrease a fish stock or washout an entire aquatic environment.  The fisherylaws include quotas on the total catch of particular species in a fishery, the limits on the number of vessels allowed in specific areas, and the imposition of seasonal restrictions on fishing.  Even though there are negative impacts on nearby wild fish, fish farming is proposed as a more sustainable alternative to traditional capture of wild fish.