Earlier this year, a research team from Spain released a surprising new estimate of mesopelagic fish biomass that is 10 times greater than previous estimates. This new study raises the total estimated biomass of mesopelagic fish from 1 billion tons to 10 billion tons, accounting for 95% of all fish biomass. The news media ran with dozens of variations on the “plenty of fish in the sea” trope, suggesting that the global fisheries may be more abundant and reversing the doom-and-gloom message of fisheries decline.
This is not correct.
The fish in question are small, mid-water species like myctophids and cyclothones, fish that are incredibly important for ocean ecosystems, but commercially non-viable. The reason they were missed in previous studies is that these small, agile fish avoid nets; This new study uses SONAR and other acoustic tools to measure biomass. So while there is a huge, untapped fish stock in the mid-water world, it is not a commercial fishery.
Let’s put things in perspective.