History Lessons: How Important It Is to Estimate Populations Correctly
05 Mar — 2018
History Lessons: How Important It Is to Estimate Populations Correctly

Ob March 3 we celebrated 147 years after the signing of a document, which played an important role in formation of modern northern fur seal population on the Commander Islands. On February 18, 1871 O.S. Russian Ministry of Internal Affairs and Hutchinson, Kool and Co. trading company signed an agreement, under which seal hunting grounds on the Commander Islands and Tuneliy Island were rented out for 20 years. 

 A part of Renting Contract for Seal Rookeries on the Commander Islands


According to the contract, the trading company acquired the exclusive right to hunt the northern fur seal on the Commander Islands. It changed a lot on the islands. The company built houses for the employees, organized regular food supply and the state took part in the protection of seal rookeries. 

Before the contract was signed, Russian-American Company had acted here before 1867. About 3 000 seals were killed annually and the number could be as high as 5 000 depending on the year. The hunters also killed this year’s brood – the so-called “grey” – without any differentiation of sex. Some specialists say that it had a negative impact on the population on the islands, but it is hardly true, if we pay attention to the numbers. During the years of lack of authority (1868 to 1870) the people on the islands were left to their own devises and “beat the seals no matter their sex or age”, which made about 21 000 individuals on average. When Hutchinson, Kool and Co. trading company came on the islands, they decided to hunt mainly young male seals 2-3 years old. By the way, it became a tradition and n the XX century this group remained the main hunted one. It is thought to be the less radical strategy, which allows saving the population and using it for as long as possible. 

 The number of northern fur seals killed on the rookeries of the Commander Islands (1847-1911)


In the first year of their work on the islands, Hutchinson, Kool and Co. trading company killed 12.5 thousand seals. Throughout all the period of their work, the mean hunting rate was 37 thousand per year with maximum at 55 thousand. Some authors say that the reason of such growth is explained by rational hunting organization and that it was seamless for the whole population. Unfortunately, there are a number of facts, which force us to doubt this point of view. 

According to the 5th point of the contract the company “was obliged to kill” only the number of seals directed by “Russian Authority”. Therefore, the company killed only young males and no other groups of seals and local authorities stated the number of animals to be killed. When the islands were rented out to Hutchinson, Kool and Co. trading company in 1877-1907 the governor of the islands was N.A. Grebnitsky and he was responsible for the amount of animals to hunt. To understand how many animals can be killed, he needed to know the total number of animals, so the first population counts took place. 

 Northern fur seal rookery


In the second half of the XIX century, there were no counts in their modern form and population was estimated by eye. The first seals population estimations on the islands were made by N.A.Grebnitsky. He thought that the total population on all the rookeries of the islands was about 2 million seals so killing 40-45 thousand (about 2.2-2.5%) is acceptable. However, a research conducted by A.E. Kuzin – a famous Soviet northern fur seal specialist - in 1980s showed that in that period there were only 500-700 thousand individuals on the Commander Islands. 4 times less, then Grebnitsky thought. 

 Northern fur seal population dynamics on the Commander Islands rookeries in 1880-2017 


The mistake in estimation of the original population level and top-heavy hunting rates given by the local authority led to the total demolition of northern fur seal rookeries on the Commander Islands. 

 Korabelnoye rookery on Medny Island has been empty for more than 100 years. 


As a result in 1911, when the North Pacific Fur Seal Convention was signed, the coasts of the islands harbored only 9 000 seals. The merciless exploitation of the coastal population combined with illegal hunting off the coast, killing of females and a number of other factors. That is why several rookeries ceased their existence, such as Poludennoye rookery on Bering Island and Korabelnoye rookery on Medny Island, and some of them shrank, such as Glinkovskye rookeries on Medny Island. 

 Modern Urilye rookery on Medny Island is just a small part of giant complex of Glinkovskye rookeries in the area


By the way, Glinkovskye rookeries were home for more seals, than we see today on all the rookeries of the Commander Islands combined! 

History taught us to appreciate accurate data in total population estimation and in choosing the right method to count the animals. 

Заповедная Россия English

Заповедная Россия English