Hawaiian petrels which are one of the native birds of Pacific usually feeds on fish and squid for thousands of years. During the past 100 years, the species has become endangered due to the shift in food resources. In a recent study, scientists found industrial fishing is one of the main cause for their current condition.
A team of paleontologists from Smithsonian's National Museum of Natural History and Michigan State University analyzed bone and fossil samples of Hawaiian petrels and found that their food web has been damaging since industrial fishing and other human activities taking place. In the journal of Proceedings of the Royal Society B, researchers wrote that it's really difficult to take a survey from the vast ocean so taking a survey from the museum is easier to monitor.
curator-in-charge of the museum's bird collection department Helen James said,“In order to understand the rapid change that's going on globally now, we really need historical records to reconstruct how things have changed over time”.Hawaiian petrels fly thousand of miles from the equator to the Aleutian Islands in search of food. After that, they start their breeding session at the Hawaiian Islands.
James collected the bone samples from the breeding site of Hawaiian Islands and compared it with the thousands of old samples to recover the data. According to Phys, they looked into the Nitrogen structures of the bones. Generally, there are two types of Nitrogen isotopes available in every organism. When a predator eats another organism then those isotopes travel to the predator’s body. So, by analyzing isotopes in Hawaiian petrel's bones, scientists can determine the steps of the food web.
In 2013 Anne Wiley analyzed Nitrogen isotopes in hundreds of Hawaiian petrels and found a recent change in food resources had shortened the petrel's food chain, which is known as trophic decline. However, Japan Agency for Marine-Earth Science & Technology(JAMSTEC) started re-examining James’s and Ostrom’s findings for more precise analysis.
JAMSTEC professor Yoshito Chikaraishi found no evidence of a change in nitrogen processing at the base of the food web. So it is clear that the food-web on North Pacific has been changed. United Nations' Food and Agriculture Organization has announced that in 2014 more than 1.9 million metric tons of food were removed from the Eastern Central Pacific including Hawaii. Scientists said that depletion of limited resources could be responsible for Hawaiian petrel's food web shift.
