Possible ecosystem impacts of applying maximum sustainable yield policy in food chain models

• MSTY policy in traditional prey–predator system may be a sustainable policy.
• In case of generalist prey–predator system, MSY is a sustainable policy.
• MSTY policy may cause the extinction of prey species if the predator is generalist.
• We investigate the MSY policy in a food chain model with n (>2) trophic levels.
• MSY of (n−1)th trophic level causes the extinction of the top predator.

This paper describes the possible impacts of maximum sustainable yield (MSY) and maximum sustainable total yield (MSTY) policy in ecosystems. In general it is observed that exploitation at MSY (of single species) or MSTY (of multispecies) level may cause the extinction of several species. In particular, for traditional prey–predator system, fishing under combined harvesting effort at MSTY (if it exists) level may be a sustainable policy, but if MSTY does not exist then it is due to the extinction of the predator species only. In generalist prey–predator system, harvesting of any one of the species at MSY level is always a sustainable policy, but harvesting of both the species at MSTY level may or may not be a sustainable policy. In addition, we have also investigated the MSY and MSTY policy in a traditional tri-trophic and four trophic food chain models.