Widely Accepted Indicator of Fisheries Health Questioned; “Humans Don’t Appear To Be Fishing Down the Food Web”

Spanish Fishing boat

The most widely accepted method of being able to determine the health of the world’s oceans and fisheries led to inaccurate conclusions in almost fifty percent of the ecosystems where it was utlilized.

This new analysis was done by an international group of fisheries researchers, and has been published in this week’s issue of the journal Nature.

“Applied to individual ecosystems it’s like flipping a coin; half the time you get the right answer and half the time you get the wrong answer,” explained a University of Washington aquatic and fisheries researcher, Trevor Branch.

“Monitoring all the fish in the sea would be an enormous, and impossible, task,” explains a program director in the National Science Foundation’s Division of Environmental Biology, Henry Gholz, whose department helped to fund the research with NSF’s Division of Ocean Sciences.

“This study makes clear that the most common indicator, average catch trophic level, is a woefully inadequate measure of the status of marine fisheries.”

Back in 1998, the journal Science released a groundbreaking report that was the first to utilize trends in the trophic levels of fish which were reeled in to help figure out the health of world fisheries.

The trophic level of an organism indicates where it falls in the different food chains, with microscopic algae at a trophic level of one and large predatory creatures – such as sharks, halibut and tuna – at a trophic level of about four.

This 1998 report relied on forty years of catch data, and took the average of the trophic levels of those specimens which were caught.