Biology Biotech
Instruments attached to marine mammals in the Arctic provide important information about the animals’ eating habits to fisheries that need to work at sustainable levels. An international team of researchers led by Akvaplan-niva in Tromsø has been harnessing the power of improved sensors to create devices that can provide valuable data on the energy expenditure and body condition of wild animals.
Estimating body condition and energy expenditure of wild marine mammals
Devices used to track marine mammals such as seals and whales have existed for around 25 years, but the information they provide has been mainly limited to migration pathways and diving behaviour. Recent improvements in sensors such as accelerometers — the microchips found in smartphones that
measure three
dimensional movement — means that it is now within the realms of possibility to collect information on energy expenditure and body condition. “High accuracy swim speed sensors and
accelerometers allow us to accurately measure the body movement of seals as they move through the water,” explains Dr
Martin Biuw of Akvaplan-niva. “We are now collecting data on energy expenditure of captive seals which, combined with accurate data on their 3D movements, will allow us to estimate the amount of energy that is expended by an individual seal based on its movement. Once we can do this successfully for captive seals, we will apply this to studies of seals in the wild.” Captive seals fitted with accelerometers
are placed in specially designed sea-pens in which they can dive freely, but can only come up for breath at the surface in one particular place, in which a respirometry system that measures oxygen consumption is located. Energy expenditure is directly proportional to oxygen consumption, so the data on oxygen consumption can be used in conjunction with the movement data to construct an algorithm that can estimate
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the energy expenditure of a given animal based on its movements. Biuw and his colleagues are also working
on a method for estimating body condition — essentially the proportion of body fat in an individual — using data from the accelerometer. An animal with a higher proportion of body fat will be less dense than an animal with low body fat. This means that when diving, it will have to kick harder to counter its relatively high buoyancy, but will expend less effort when surfacing. Conversely, individuals with low body fat will find it easier to dive but harder to surface. By measuring the actual body fat of captive seals and then comparing it with the differences in the way that they dive and surface in the water, another algorithm can be created to estimate the body fat of wild individuals based on acceleration data.
Insight Publishers | Projects
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