The assignment of animals to one of the five triage categories will change with the phase and type of spill. In a catastrophic spill, oil is released in a single event and degrades relatively uniformly with time. As a result, the degree of contamination and the associated medical problems of wildlife decline with time and subsequent weathering of the oil. This was observed for sea otters following the EVOS (Table 11.1). The highest percentage of urgent care animals arrived during the first three weeks of the spill. Later in the spill, a greater proportion of animals required only minimal care.
Chronic spills, such as oil platform blowouts and incidents like the Persian Gulf spill, involve the long-term release of fresh oil into the environment. A consequence of chronic spills is prolonged contamination of wildlife by oil containing the highest concentrations of aromatic compounds. Because these compounds are considered the most toxic components of oil, a chronic spill may lead to a prolonged, high incidence of medical problems. Triage will be more difficult during a chronic spill because most animals will require urgent or immediate care until the release of oil is stopped.