When an oil spill cannot be kept away from areas where animals are, it is sometimes possible to keep the animals away from the oil. Techniques have been developed to scare animals away from areas that are most likely become affected or where oil already has arrived. A wide variety of techniques can be used, but the effectiveness of any of them often depends on the species concerned or the environmental conditions at the time. Methods also need to be changed regularly as animals become accustomed to one method, resulting in reduced effectiveness over time.
Deterrence methods can be auditory, visual or both. They are used to scare animals away from a certain area by creating disturbances. In the best case, animals will react to the disturbance by moving away from the area and relocating to an alternative area where the threat of pollution is less or non existent. Continuous disturbance over time is needed to ensure that the animals do not come back.
Hazing methods are considered more aggressive techniques in the range of possible disturbances. Helicopters may be used to fly low over the animals, effigies can be placed in the area (similar to the use of scare crows in fields) or amplified distress calls or the voices of predator species may be played to move the animals away from oiled areas.
Deterrence and hazing methods must ensure that animals being harassed do not move toward the oil spill rather than away.
Pre-emptive capture is the capture of healthy, unoiled animals from an area that is likely to become affected by the oil. By its very nature, this is an aggressive disturbance of individuals which only can be justified if the net benefit is clearly in the interest of the animal’s welfare in the longer term.
An important consideration before beginning pre-emptive capture is where the captured animals will be held, and for how long, before they can be released in an alternative, safe habitat within their natural and seasonal range. The capture and subsequent stay in captivity will be a stressful experience for the individual animal and a potential threat to that animal's welfare and survival. Pre-emptive capture has been successfully used to prevent oiling of penguins (e.g. Treasure 2000, South Africa when ca. 20,000 animals were captured and relocated), but is less likely to be effective in the case of birds that are not flightless. Having personnel experienced in mist netting as part of the capture team increases the effectiveness of pre-emptive capture in these cases.
The relocation of sea turtle nests from beaches that are threatened by oil is also considered a form of pre-emptive capture. In such cases the eggs are dug out and hatched in special facilities. Hatchlings are subsequently released from beaches that are not threatened by oil. This method was used to some extent during the Deepwater Horizon Spill (Gulf of Mexico, USA 2010) where 700-800 egg clutches were relocated to clean beaches.