Toothed whale swallow fishing hooks. Gillnetting and Seine netting are significant causes of mortality in cetaceans and other marine mammals. Porpoises are commonly entangled in fishing nets. Whales are also affected by marine pollution. High levels of organic chemicals accumulate in these animals since they are high in the food chain. They have large reserves of blubber, more so for toothed whales, as they are higher up the food chain than baleen whales. Lactating mothers can pass the toxins on to their young. These pollutants can cause gastrointestinal cancers and greater vulnerability to infectious diseases. They can also be poisoned by swallowing
Captive killer whales twice that length or and a minimum depth of , giving a minimum volume of for two killer whales. Each additional killer whale requires a pool with an additional of volume. 9 CFR 3.104 also requires a minimum of surface area per killer whale in Table IV (the example with a cylindrical tank in diameter for two whales provides of surface area per killer whale). Swiss regulations require a larger minimum volume: × deep for two killer whales, or . The Alliance of Marine Mammal Parks and Aquariums (AMMPA) goes further, and recommends for two killer whales. The US exhibitors