Question: how do you catch sea-lions and when you have them what information do you gather from them and how do you get it?

Paddy Brock answered on 14 Jun 2011:

How we catch the sea lions depends on how old they are. If they are young (i.e. less than 3 months), we catch them gently by hand. This means picking them up by their back flippers and putting them under your arm (and so pinning the fore flippers down) while gently holding the head. To catch juveniles and adults we have to use nets. They are about a metre in diameter, cone shaped and about a meter and half deep, with a little breathing hole at the end and a long handle. The idea is to get the hoop over the animal’s head and then it will move further into the cone. Some animals are much more wary than others and sometimes we have to spend a couple of hours slowly creeping up on particular individuals to have a chance of catching them.

Once in the cone we hold the flippers and the head through the net (and try not to get thrown off!). We then collect the data. We start with body length, measured with a measuring pole from the tip of the nose to the tip of the tail. Then we measure fore flipper length and width using a ruler. We then weigh the sea lions using a balance. We have to weigh them in the nets (otherwise they’d escape) so after they’ve been released we have to the weigh the empty net to calculate the animal’s weight. We measure the girth (i.e. circumference) along a line just behind the fore flippers. This is quite tricky as it’s difficult to pass a tape measure underneath a 100kg sea lion lying on rock! We also take hair, skin and blood samples. After realeasing each animal we monitor their behaviour to make sure they’re OK.