Branch TA, Hively DJ, Hilborn R (2013) Is the ocean food provision index biased? Nature 495:E5-E6
How close to maximum sustainable food provision is current seafood harvest from the world’s oceans? Halpern et al.  suggest that the answer is 25% from a global index of food provision, part of their multifaceted index of ocean health. Rigorous methods used for management, however, demonstrate that their food provision index is uncorrelated with actual food provision, and that global ocean food provision is in the range of 71–95%. Their results stem from an uncertain method of estimating maximum sustainable yield (MSY), and we believe that this approach should be avoided as a measure of food provision.
 Halpern BS et al. (2012) An index to assess the health and benefits of the global ocean. Nature 488:615-620