Beaked Whale - Conservation

Conservation

For many years, most beaked whale species were insulated from anthropogenic impacts because of their remote habitat. However, there are now several issues of concern:

• Studies of stranded beaked whales show rising levels of toxic chemicals in their blubber.
• As a top predator, beaked whales, like raptors, are particularly vulnerable to build-up of biocontaminants. They frequently ingest plastic bags (which do not break down and can be lethal).
• They more frequently become trapped in trawl nets, due to the expansion of deepwater fisheries.
• Decompression sickness

A major conservation concern for beaked whales (family Ziphiidae) is they appear to be vulnerable to modern sonar operations, which arises from recent strandings that temporally and physically coincide with naval sonar exercises. Postmortem examinations of the stranded whales in concurrence with naval exercises have reported the presence of hemorrhaging near the ears or gas and fat emboli, which could have a deleterious impact on beaked whales that is analogous to decompression sickness in humans. Gas and fat emboli have been shown cause nervous and cardiovascular system dysfunction, respiratory distress, pain, and disorientation in both humans and animals. In the inner ear, gas embolism can cause hemorrhages, leading to disorientation or vestibular dysfunction.

Breath-holding divers, like beaked whales, can develop decompression-related problems (the “bends”) when they return to the surface after deep dives. This is a possible hypothesis for the mass strandings of pelagic beaked whales associated with sonar-related activities. To illustrate, a diving beaked whale may be surfacing from a deep dive and must pass vertically through varying received sound levels. Since the whale has limited remaining oxygen supplies at the end of a long dive, it probably has limited abilities to display any normal sound avoidance behavior. Instead, the whale must continue to swim towards the surface to replenish its oxygen stores. Avoiding sonar inevitably requires a change in behavior or surfacing pattern. Therefore, sonar in close proximity to groups of beaked whales has the potential to cause hemorrhaging or to disorient the animal, eventually leading to a stranding.

Current research reveals two species of beaked whales are most affected by sonar: Cuvier’s beaked whales (Z. cavirostris) and Blainville’s (M. densirostris) beaked whales. These animals have been reported as stranding in correlation with military exercises in Greece, the Bahamas, Madeira, and the Canary Islands. The livers of these animals had the most damage.

Though some evidence indicates sonar-related activities can actually lead to a form of decompression sickness in beaked whales, the topic is still up for debate. A significant limiting factor in determining the likelihood of bubble formation in whale tissues and the risk of decompression sickness is the lack of information on their normal diving and surfacing patterns. More research is necessary to determine the extent of whale tissue damage caused by sonar exercises.

Four species are classified by the IUCN as "lower risk, conservation dependent": Arnoux's and Baird's beaked whales, and the northern and southern bottlenose whales. The status of the remaining species is unknown, preventing classification.