How does sustainable fishing stop overfishing?
Some methods of fishing are less harmful to the environment compared to others.Axel Hein
The gear used when fishing can cause unintentional or incidental damage to the seafloor or to marine wildlife. Some fishing practices can even cause irreversible harm to the environment and destroy important marine habitats. Others might have bycatch of marine wildlife and can bring species at the brink of extinction, as it´s the case for the vaquita. The vaquita is now the world’s rarest marine mammal. 
Innovative solutions and marine protected areas
New innovative and affordable solutions for fishing gear that reduce the impact on marine biodiversity and ecosystems are therefore important to support healthy oceans. Marine protected areas that are well planned and fully implemented are important to provide refuge for marine species and support healthy fish stocks.
Including small scale fishermen and women in developing countries in planning for and implementation of sustainable fisheries management and co-management is a promising way forward, too.
3 facts on seafood and… sustainable fishing & farming
E.g. in Brazil 46% of marine litter is fishery related debris. 
Ok, but what can I do?
Watch out for recommendations in the local WWF Seafood Guide!Axel Hein
 Jaramillo-Legoreta et al (2016) Passive acoustic monitoring of the decline of Mexico’s critically endangered vaquita. Conservation Biology https://doi.org/10.1111/cobi.12789
 Cashion et al 2018 Reconstructing global marine fishing gear use: Catches and landed values by gear type and sector. Fisheries research 206:57-64
 Reference Macfadyen et al 2009. Abandoned, lost or otherwise discarded fishing gear. UNEP Regional Seas Reports and Studies, No. 185; FAO Fisheries and Aquaculture Technical Paper, No. 523. Rome, UNEP/FAO. 2009. 115p http://www.fao.org/tempref/docrep/fao/011/i0620e/i0620e.pdf