Pacific Reef Shark Populations in Steep Decline

According to scientists pacific reef sharks have dropped sharply near populated islands in the Pacific Ocean.

The survey by the University of Hawaii showed that the numbers were drastically lower near populated islands in Hawaii, the Mariana Archipelago and American Samoa, compared to more pristine, remote areas in the ocean. As said lead author Marc Nadon from the Joint Institute for Marine and Atmospheric Research at the University of Hawaii they estimate that pacific reef shark numbers have dropped substantially around populated islands, generally by more than 90 percent compared to those at the most untouched reefs. The latest research was based on a method called “towed-diver surveys,” in which paired scuba divers record shark sightings while being towed behind a small boat. It’s a method which provides a more accurate census of mobile reef fish like sharks over large areas. Researchers analyzed data from over 1,600 towed-diver surveys taken from 2004-2010, in combination with information on human population growth and reef area, as well as satellite-data on sea surface temperature and ocean traits. As said Nadon around each of the heavily populated areas they surveyed, in the main Hawaiian Islands, the Mariana Archipelago and American Samoa, reef shark numbers were greatly depressed compared to reefs in the same regions that were simply further away from humans. They estimate that less than 10 percent of the baseline numbers remain in these areas. Researchers counted five types of pacific reef sharks for the study, including the most common types, gray and whitetip pacific reef sharks, as well as blacktip reef sharks, Galapagos sharks and nurse sharks.