Friday, 18 November 2011

A Summary : Tasmania Whale Strandings

As many reading this will already know, major marine news as of late has included the mass stranding of sperm whales along Tasmania's west coast.
In brief...
A large pod of whales washed ashore, many still alive, in various remote places along the Tasmania west coast (Australia). Work started almost immediately to free beached whales and return them to deeper waters and two individuals trapped inside Hells Gates were freed, but 22 at Ocean Beach died. Whilst escorting the two survivors through Macquarie Harbour to the open sea, two dead minke whales were also found. The total death toll from the stranding was 26. 65 pilot whales also died in New Zealand due to strandings in a remote location, the tip of Farewell Spit.

But the question I am particularly interested in is why?
Whale beachings are 'relatively common' in Australia, especially in summer months, but scientists are not completely sure why they occur.
In recent years, studies have linked strandings to high intensity sonar which occurs underwater. However, findings are not conclusive. Certain beaches also have more occurances of strandings than others. This is due to the shape and make-up of the beach. Sand banks can cause marine animals to be caught in too shallow water, with receding tides ensuring the animal cannot return to deeper waters.
Naturally, we also turn to climate change to explain these events. Southerly and westerly winds cause colder (and more nutritious) waters going from the Antarctic to southern Australia. The attractiveness of these waters attracts whales closer to the shore than in previous years, increasing the chance of stranding.
It is vital that more information is gained about these events, as strandings become more frequent. Is there any way we can assist in reducing the likelihood of these events? Future studies need to focus on the variables (climate, location, species, season) surrounding the strandings, to find common links. We also need to focus on the individuals that are returned to the water, and their chances of survival after being seperated from their pod (with in many cases, most individuals in the social group being killed due to strandings) and possibly suffering from stress or injuries due to being beached.

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