South Asian river dolphin The sphincter-like structure is capable of sensing light, and may be able to sense the direction from where the light was emitted. However, the muddy waters, or low light conditions, that the "Platanista gangetica" inhabit negate the use of the little vision that remains. The Ganges subspecies shows object-avoidance behavior in both the consistently heavily murky waters of its habitat and in clear water in captivity, suggesting that it is capable of using echolocation effectively to navigate and forage for prey. However, there is limited information on how extensively vocalization is utilized between individuals. This subspecies of river dolphin is
Endangered Species Act of 1973 required, likely costs, and estimated timeline to recover endangered species (i.e., increase their numbers and improve their management to the point where they can be removed from the endangered list). The ESA does not specify when a recovery plan must be completed. The FWS has a policy specifying completion within three years of the species being listed, but the average time to completion is approximately six years. The annual rate of recovery plan completion increased steadily from the Ford administration (4) through Carter (9), Reagan (30), Bush I (44), and Clinton (72), but declined under Bush II (16 per year