Vulnerability

Cetaceans rely on sound as a means of social communication and hunting (Hoelzel 2002). Although they are adapted to change in noise levels (Richardson et al. 1995), growth and advancement of commercial shipping has caused the background noise in the ocean has, in some areas, increased tenfold (McDonald et al. 2006).

It has been well documented that naval sonar events have coincided with mass strandings of beaked whale (Figure 10)(Zimmer & Tyack 2007, Tyack et al. 2011, DeRuiter et al. 2013). Postmortem analysis of these animals revealed hemorrhaging (blood clotting) in the ear canal, most likely the result of intense sound (Evans & England 2001), as well as the gas-bubble lesions in the tissue indicative of decompression sickness (DCS)(Jepson et al. 2003). How exactly the noise is causing these injuries is largely unknown.

Fig 10. Strandings of beaked whales could become a regular sighting as the number of shipping vessels in the ocean increases.
Fig 10. Strandings of beaked whales could become a regular sighting as the number of shipping vessels in the ocean increases. Image copyright of Avenue.

Cuvier’s beaked whale (Ziphius Cavirostris) has been observed reacting to shipping noise by changing its diving and foraging behaviour (Aguilar Soto et al. 2006). The frequencies produced by faster boating vessels mask echolocation noises, ships reduce the time beaked whales can stay vocal, and therefore the time they have to forage for food. Given the trend in the increase of faster vessels, it is evident that further research must be done to protect the beaked whale.

 

So what does the future look like for beaked whales?

We still know very little about beaked whales. Research on them remains difficult for these elusive animals, sparse visual accounts mean we have little idea how the vulnerable these animals are, the IUCN lists most Ziphiidae as ‘data deficient’. Consequently, the extreme adaptations that allow them to live such a dangerous lifestyle are still far from understood.

How exactly to help to conserve these animals, should they need conserving, has proven difficult, as we have base knowledge of how they are, or will, be affected by a rise in ocean pollution, global warming or fisheries by-catch (Madsen et al. 2014). We are aware how vulnerable they are to anthropogenic noise and so conservation of these animals thus far has been to protect the beaked whales from the high intensity noises that can ultimately prove fatal. Bubble curtains and sound barriers have already been set in place and have shown to reduce the changes in behaviour of harbour porpoise, Phocoena phocoena, as a result of anthropogenic noise (windfarms)(Camphuysen 2011). Whether such technology could help beaked whales remains to be seen.

The future of the beaked whales, much like most of their existence, remains unknown.

 

 

 

Leave a Reply

A look at extreme mammal divers