A new study found that the potential harvest of a certain fish stock has very little to do with the abundance of that fish.
According to researcher Ray Hilborn of the University of Washington (UW), out of 230 fish stocks assessed in the study, abundance was closely linked to harvest in only 18 percent. Harvest of the remaining 82 percent of stocks was either controlled by environmental shifts or was completely random.
These are important findings, as most fishery management plans are based on abundance. The study suggests that increased abundance won’t always provide the promised increase in harvest.
“There have been competing ideas about productivity,” Hilborn said. “One is that it depends primarily on abundance. The other is that productivity of a stock mostly depends on whether there’s a period of good conditions or a period of bad conditions.”
“What we’ve done in this study is take 230 fish stocks and ask which of these explanations explains the data for each fish stock better,” he explained.
Although the researchers found that abundance isn’t often linked with harvest, Hilborn notes that we should still try to manage fisheries at high abundance because it is beneficial to the marine ecosystem. Overall, these findings need to be taken into account when formulating new management plans.
“If fish populations experience substantial shifts in productivity unrelated to stock size, then management based on a single set of management targets (for example maximum sustainable yield) will be either inefficient or risky,” the paper explains.
To learn more:
- Read the full story from UW: Potential harvest of most fish stocks largely unrelated to abundance
- Find the study, published in the journal PNAS, here: Frequency and intensity of productivity regime shifts in marine fish stocks
Copyright © 2013 by Marine Science Today, a publication of Marine Science Today LLC.