Stellar insights

Abstract

Astronomy researchers have developed a novel tool to help them analyse patterns in the night sky but Michael Gross reports on a novel use of this astronomical software to help track individual whale sharks, a spectacular, spotted marine species under increasing disturbance from human activity. Astronomy researchers have developed a novel tool to help them analyse patterns in the night sky but Michael Gross reports on a novel use of this astronomical software to help track individual whale sharks, a spectacular, spotted marine species under increasing disturbance from human activity. Interdisciplinary research may be all the rage, but it is still rare to find astronomical methods being used in conservation research. And yet, NASA researcher Zaven Arzoumanian and marine biologist Brad Norman from Murdoch University in Australia have teamed up to do just that. They have modified the so-called Groth algorithm, which astronomers use to compare triangular patterns in photos of the night sky, to adapt it to the task of identifying spotted animals such as whale sharks (Rhincodon typus), the largest living fish species. Like the night sky, the whale shark sports a conspicuous spatter of bright spots on a dark background. Identifying individual animals is an important, yet difficult, task in conservation research. When researchers are able to identify the sharks by their spot patterns, this removes the need for more time-consuming and invasive procedures, such as capturing and tagging individual animals. The researchers have shown that the ‘astronomical’ method allows for the identification of animals with equally high precision (J. Appl. Ecol. (2005), 42, 999–1011). With the help of software expert Jason Holmberg, they have already incorporated the new method into an online photoidentification library (http://photoid.whaleshark.org), which archives digital images of whalesharks. Brad Norman is enthusiastic about the performance of his new research tool. “The program even made matches that I had initially missed and it has since made more than 100 new matches that were later verified manually. We've now eliminated the need to scatter all the images on the floor.” With the help of the environmental research charity Earthwatch, Norman is now able to apply the technique on a large scale, and literally anybody can join in. Earthwatch has pioneered new ways of involving fee-paying volunteers in research projects that would otherwise be unfeasible due to the lack of manpower. Founded in 1971 in Boston, Massachusetts, Earthwatch now employs 3,500 volunteers per year who work on 140 different projects around the globe (www.earthwatch.org). Brad Norman's Earthwatch-sponsored project, ‘Whale Sharks of Ningaloo Reef’, is aimed at identifying how tourism and environmental conditions are affecting the survival and migration behaviour of whale sharks, which feed by filtering sea water and are entirely harmless. Between April and June 2006, eight teams of six to eight volunteers will work one week each to observe and photograph the animals in Ningaloo Marine Park, off the coast of Western Australia, where these and other ocean dwellers have become a focus of a flourishing ecotourism. Specifically, the research is designed to establish the rate of return of the animals to the region and to specific parts of the reef, any site preferences of individuals, their growth rates, and their behaviour under the pressure of the growing tourism industry (although this is widely applauded as an example of ‘best-practice’ ecotourism). So far, conservation efforts have been hampered by the lack of the most essential information, including global population size and typical life history of individuals. By manning the observation project with volunteers throughout the shark season over several years, Norman and his team hope to substantially expand the knowledge base for this species. “The project aims to gather new information on the threatened whale shark — to ultimately assist with their worldwide conservation. Any policy decisions will carry greater weight and encourage broad support among the many stakeholders if based on strong data… We look forward to the support of community volunteers in this important conservation project”, says Norman. While the methodology was developed for the whale shark project, the researchers emphasise that it is widely applicable to other species as well, as long as they have spots. Roger Mitchell, chief scientist at Earthwatch Institute (Europe) points out that “lions, for example, have small dark spots where their whiskers attach to their noses, and this differentiating feature might help to track them in the near future.”