Our knowledge about the health of living dolphin populations is sadly incomplete. The grave danger is that some unique and fascinated dolphin species will 【S1】______ be gone. Urgent action is needed to avoid the deaths of hundreds of thousands of dolphins that accidentally 【S2】______ killed every year. Some years, the figure has surpassed half a million worldwide—all because of human activities. This is more than 10 time the number of large 【S3】______ whales that were slaughtered in the early 1930s, the worst years of whaling. Dolphins may be dying because of pollution from dumping at sea, oil spills and farm pesticides and other chemical runoff that enters the rivers, particularly 【S4】______ in the Mediterranean and off the east coast of the United States. For some cases, food poisoning from red-tide 【S5】______ organisms may have been the cause. It is not enough for humans to stop killing dolphins and some other sea animals for food or other sources. 【S6】______ We must reserve a place for it in the sea. They 【S7】______ need habitat, as did all animals—places free from 【S8】______ fishing nets, oil spills, pollution and too many ship 【S9】______ traffic. We must also consider all the species in the dolphins' food chain. Which fish are the dolphins eating? Which fish and other organisms are the fish eating? To protest habitats, all these things must 【S10】______ be taken into account. 【S1】