During August 2019, more than 40,000 tourists visited Hawaii’s Molokini island to snorkel or dive. In March 2020, the worldwide COVID lockdown dropped that number to zero providing scientists with a unique opportunity to study how underwater tourism impacts marine fishes.
Published in the journal PLOS One, the results of this natural experiment were clear. “When tourism shut down due to COVID,” said Alan Friedlander of the National Geographic Society, “species that had been displaced from shallow habitats by high human presence moved back in on a timescale of months, increasing fish biomass as well as the proportion of larger predators.”
The study also concluded that human-induced displacement of predatory fishes from Molokini’s crater likely sends ripples throughout the entire local food web. Previous studies have shown that a drop in the abundance of predatory fishes affects not only the herbivorous fishes they count as prey, but the algae and other primary producers eaten by the herbivores.
“As Hawaii formulates marine management plans and undertakes the Sustainable Hawaii Initiative,” said Laura Gajdzik of the Hawaii Department of Land and Natural Resources, “lessons from Molokini can help inform managers and help facilitate an effective response. As part of this process, we need to think strategically about the scale and configuration of tourism in Hawaii to optimize earnings and employment without damaging the environment.”
“Our study indicates that the intensity of non-consumptive uses, especially in heavily visited MPAs, should be considered for the long-term health and resilience of these ecosystems,” said lead author Kevin Weng of William & Mary’s Virginia Institute of Marine Science. “Management of tourism should be guided by biological research, and include clear and well-enforced rules, adaptive management and broad stakeholder involvement.”
More information: Kevin C. Weng et al, Decreased tourism during the COVID-19 pandemic positively affects reef fish in a high use marine protected area, PLOS ONE (2023). DOI: 10.1371/journal.pone.0283683
Journal information: PLoS ONE
