Why Biopsy Whales ?10th Feb 2009 The IWDG successfully obtained tissue samples from fin and humpback whales this year. This work is part of the ongoing Large Whale Survey, which started in 1999 and since 2001 has been collecting images suitable for photo-identification.
These tissue samples were obtained using biopsy sampling. This involves firing a dart with a sampling tip into the whale with a standard crossbow from a distance of around 50m. The tip measures 7mm in diameter and ranges from 10-30mm in length depending on the aims of the study and the tip used. A sample of skin and underlying blubber is removed and the dart bounces off the whale and then floats on the waters surface, enabling researchers to recover the dart. Biopsy sampling is used throughout the world in cetacean research and in Ireland has been used successfully on bottlenose dolphins as well as large baleen whales.
These tissue samples can be used for to explore a number of issues, including genetics, pollution and isotope studies. Samples can and are taken from stranded individuals but these species rarely strand and the providence of these stranded animals is not known. It is essential to know whether these stranded individuals represent animals that occur in Irish waters ?
Genetic studies enable us to determine what breeding stock/population fin whales in Ireland belong too ? indeed how many stocks are there in the North Atlantic ? how many and where are the breeding grounds in the North Atlantic ?
Where are the breeding grounds of humpbacks in Irish waters ? do they belong to the healthy and expanding Caribbean population or the still severely depleted and endangered west African population ? are there breeding grounds elsewhere, off the south coast of Ireland as has been speculated ?
Determining the gender of whales in Ireland, especially when combined with photo-id studies are very useful. It has been speculated that humpbacks in Ireland could be young, immature males prospecting new feeding areas. If this is the case the conservation measures would be different to say adults with calves or a more local population.
Biopsy samples can be used in pollution studies as many persistent pollutants, especially organochlorines (PCBs, DDT, etc) have a high affinity for lipids which the blubber of course stores. These studies can help managers determine the potential threat pollutants offer to a population and also enables pollutant levels to be monitored. Ideally you need to obtain a sample of the entire blubber profile as organochlorines are stratified in the blubber.
Pollutants can also be used as markers to explore migration routes and site fidelity. Exposure to specific chemicals, known to occur in specific sites, will/may accumulate in the lipid profile. E.g. Radiocaseum 37 in the Irish Sea.
Stable isotope analysis of blubber samples can help explore feeding behaviour. What is the importance of herring/sprat in the diet of large baleen whales off the south coast. What do they fed on when not in coastal waters. What trophic level are they feeding in,. The implications of this are in fisheries management. If you want to protect the food resource you need to know what is the food and for how long/where is it important. Do we need to consider timed-area closures ? If you are presenting this to the fishing community and impacting on livelihoods you need to be able support your proposals.
History of biopsy sampling in Ireland
Biopsy sampling started in the Shannon estuary on bottlenose dolphins by the Shannon Dolphin and Wildlife Foundation (see www.shannondolphins.ie) a