How many pups?

Scientists want to know how big the seal population is and whether it is increasing, stable or decreasing. But, it is impossible to count all the seals as:

• there are so many colonies and haul-out sites;

• at each one, seals are always coming and going;

• seals can switch between places;

• they mostly look the same.

Scientists calculate the size of the seal population by recording the number of pups. Pups are the only age class that does not go to sea. They have black coats so you can easily tell them from older seals. Scientists have worked out that by multiplying the number of pups by about four or five, they can get a rough estimate of total colony population.

Even if the population is stable, though, pup numbers will go up and down between years. This is because through the years there are changes in the amount of prey for the cows. Also, differences in weather between years can influence survival of the pups. Because of the variation, scientists get counts of pups over several years and look at the long-term trends.

Please click on the tabs to learn more about seal pup numbers.