Miami , Florida ( CNN ) -- They 're at the top of the ocean 's food chain -- but it is still a mystery how the oil disaster is affecting the shark population in the Gulf of Mexico . Even if sharks never touch the oil slick , their sources of oxygen and food are at risk . And a reduced shark population could impact the entire Gulf ecosystem , according to Neil Hammerschlag , a researcher at the University of Miami , who has been studying sharks for a decade -- tagging them to determine their migratory patterns and other behaviors . Today , his research focus has changed . `` The oil spill opens up a whole new avenue for critical research , '' says Hammerschlag . As with most weekends , Hammerschlag leads a university research team packed into a boat with interns and high school students , to fish for sharks . They research the impact of the oil on sharks and other species of fish in the Gulf of Mexico . Because sharks eat nearly everything beneath them on the food chain , they provide a lot of information about the ecosystem . `` If you see high levels of oil in a shark , you better believe it 's in the whole food chain , '' says Hammerschlag 's assistant , Austin Gallagher . In order to take biological samples from the sharks , first they must be caught . Ten lines are baited in areas believed to be attractive to sharks . `` Sharks do n't chew their food they swallow it , '' Hammerschlag says . The lines are equipped with special circle-shaped hooks to prevent the sharks from harming themselves when they swallow the bait . Swallowing a circle hook , with an inward point does not hurt the shark , Hammerschlag says . The shark swallows the bait and , as it starts to swim away , the hook turns and catches the animal 's jaw . He compares it to a lip piercing . `` It heals very , very quickly , '' he says . Once a shark is on the line , it is pulled up to the side of the boat . Larger sharks are kept in the water . The researchers lean over the side of the boat and gather tissue and blood samples , before attaching a tag to the fin . The process usually takes just a few minutes from the time it is reeled in until the shark 's release . The information has been used for creating protected marine areas , as well as medical research . Large sharks that migrate long distances -- bull , hammerhead , and tiger sharks -- are outfitted with satellite tracking devices with sensors . When the shark breaks the water 's surface , its location is sent to a satellite . Hammerschlag then receives an e-mail containing the coordinates . The data on the sharks ' movement -- published on the University of Miami 's website -- will tell researchers whether the sharks encounter the oil in the Gulf of Mexico . Hammerschlag thinks the odds are high that sharks will swim through water filled with oil , but he ca n't be certain because there 's no precedent . He 's hopeful the sharks can outsmart the environmental disaster . `` There is a possibility that these animals might be able to anticipate the oil and sense the oil and actually move away from it , '' he said . Swimming through the oil could be deadly for sharks . `` Sharks breathe through the water , '' says Hammerschlag . `` They take in the water , the water goes over their gills and they extract oxygen out of the water . '' If the water is mixed with oil , it would hinder their normal breathing pattern , he says . It 's still too early in Hammerschlag 's research to determine whether sharks are swimming through the oil . `` Hurley '' the hammerhead shark had transmitted a signal nearly every day for three months , until just a couple of days after the rig explosion that caused the oil spill . `` The tag could have failed or it could have headed off somewhere else into deep water and just not come up in the last few months , '' Hammerschlag says . `` But that 's very unlike the shark 's characteristics . '' Either way , as long as there are fish in the oiled area , Hammerschlag and his team will be looking at the effects on sharks . `` You know , there 's fishing areas closed in the Gulf of Mexico because they do n't want people catching and eating that fish , '' he said . `` But I do n't know if the sharks got the memo . ''
Researcher Neil Hammerschlag has been tracking sharks for 10 years . Now , his research is focusing on the impact of the oil spill . Hammerschlag and his team catch sharks , then tag them with transmitters . It 's still unclear if the sharks are avoiding the oil spill .