Island surveys show effects of human populations on reef fish

By Lori Balster on April 8, 2015

Even low human populations can cause large declines in fish biomass near reefs. (Credit: Ben Ruttenburg / NMFS SEFSC)

Logging in over 2,000 hours of diver observations and other types of data, University of Hawaii at Manoa researchers and other scientists were able to show enormous effects from human activity on the coral reef fish populations of almost 40 Pacific islands and atolls studied, according to a recent press release from the university.

The study was part of the National Oceanic and Atmospheric Administration’s Pacific Reef Assessment and Monitoring Program, one of the biggest coral reef monitoring programs in the world. The survey included some of the larger Hawaiian islands, American Samoa and the Mariana Archipelago.

Surveys showed that even relatively low human populations could cause large declines in fish biomass near reefs. Reefs around populated islands showed declines from 20 to 78 percent. Sharp decreases in fish biomass were observed with even relatively low human populations, and fish declines became gradually worse with further increases in human population.

In addition to diver observation data, satellite data was also used. Data included sea surface temperature, wave energy and ocean productivity. Computer models were used to determine which factors affecting each reef population were natural and which were specifically from human influence.

Top image: Even low human populations can cause large declines in fish biomass near reefs. (Credit: Ben Ruttenburg / NMFS SEFSC)