A recent study by Trevor Branch and colleagues asserted that the decline in the mean trophic index is no longer present in the global catch data. But does it really cast doubt on the depletion of big ocean species?
In an article published today at Scientific American, journalist Mike Orcutt explores how best to measure commercial fishing’s impact on ocean biodiversity. He discusses the findings of Brach et al. in light of the new study quantifying fisheries expansion. Orcutt reports:
Pauly says the new PLoS One paper “completely invalidates” Branch’s Nature paper because the authors failed to account for the spatial expansion described in the former. As fisheries move offshore, he says, they first target large fish high on the food web—just as they did closer to shore. “Hence, moving offshore will mask inshore declines in mean trophic levels.”
Read the full article here.
Photo: Tiny fish caught by a trawler off of Hong Kong by Stanley Shea/BLOOM.