This piece, authored by IFFO's Dr Brett Glencross, was published in the November 2023 edition of International Aquafeed magazine.

We’ve all heard of “peak oil”, where our capacity extract mineral oil reserves reach their maximum capacity, and after that they become increasingly scarce. Some may have even heard about “peak phosphate”, where inorganic phosphate reserves, which are so critical for agricultural productivity, also reach their peak extraction. But what about “peak fish”, the maximum volume of fish we can sustainably extract from the oceans? Well apart from the difference between finite non-regenerative resources as the case with oil and phosphates, the finite regenerative resource of fisheries offers several contrasts. Based on fishery yields and catch per unit effort data, recent scientific reviews suggest that this was probably about twenty years ago. So, aside from potentially increasing that volume by further fishing down trophic levels into planktonic species or finding ways to exploit those difficult to access mesopelagic fish species, the reality is that we are unlikely to find more fish to use for any purpose, food or feed. So, if we are looking at a “fixed” volume of fish, then the recourse has to be how do we better use what we have? How do we move towards 100% utilisation of what we already catch.

Seafood contrasts much of other food production by having a very short shelf life. Fish can spoil within days or even hours unless treated right. We can extend this shelf life with refrigeration and ice, and push that even further with freezing, and even further still with canning. But these all come at a cost. Sometimes the cost of which is greater than the value of the fish themselves. An often-overlooked means of preservation of seafood is dehydration. Means for dehydrating fish products to stabilise them can push the shelf life of fish products out to 12-months or more. As a stabilising strategy this also works well at VERY large scales. Think of millions of tonnes of fish being harvested in small geographic areas over a few months of the year, and still be able to stabilise that product for use in food production, either directly or indirectly for the following 12-months, then that gives you some idea of the scale at which this operates every year in many places around the world. This fish provides for much needed nutrients and transfer of those nutrients across global food production systems, where such resources can significantly amplify their impacts around four- to five-fold, based on estimates by Kok et al. (2020).

However, the dehydration of whole-fish strategy is one that is not only applied to those large-scale fisheries of forage species like anchoveta, blue whiting, and menhaden. Many of the other fisheries what we catch directly for human consumption also provide raw materials that can be used. For example capture of species like tuna, herring and mackerel for canning, smoking, and even fresh products often produces up to 60% of the volume of fish caught as by-product that is not eaten. The value of this biomass can still be captured as valuable nutrients for future use in our food-chain by applying stabilisation and in doing so it contributes as arguably one of the largest scale circular protein resources available in doing so. At most recent estimates by-product fishmeals and oils were around 2.5 million tonnes of production annually. So, by applying 100% utilisation thinking, we ensure that we keep moving towards making to most of what fish we have and continue to amplify their effects on our food chain.