Nearly a decade ago, only 115 western gray whales were seen swimming, feeding and fleeing from Sakhalin Island, a Russian territory north of Japan, where oil was being drilled. However, a new IUCN report says the species is expereincing a rebound.

Latest report released from IUCN (International Union for Conservation for Nature) website on Saturday says the western gray whale population has grown 3 to 4 percent annually, from an estimated 115 animals in 2004 to 174 in 2015, thanks to the efforts made by the Sakhalin drillers.

The western gray whale population is currently listed as Critically Endangered on the IUCN Red list of Threatened Species since 2003. A deal agreement 12 years ago made the two opposing parties to work together for whales' sake.

The massive gray whales, Esrichtiius robustus, were facing deadly threats like underwater noise, ship collisions and entanglements in fishing gears. Through the deal, loans to Russia's Sakhalin Energy were restricted unless the oil company paid for a panel of marine scientists to advise its offshore operations.

In 2004, in response to the growing concern over Sakhalin Energy's plans for expansion around the Sea of Okhotsk with the possible impact on the critically endangered whales, IUCN established WGWAP (Western Gray Whale Advisory Panel), easily known as the Sakhalin drillers.

"The process began as a 'David versus Goliath' and wound up as a 'David and Goliath story," said Azzedine Downes, president and CEO of the International Fund for Animal Welfare (IFAW), from News.

Sakhalin Energy, an oil and gas company with Gazprom, Shell, Mitsui and Mitsubishi as shareholders, is the only current company involved in the agreement.

Western grey whales are the longest migrating mammal known today. Each whale travels 6,760 miles (10,880 kilometers) from Sakhalin to to Mexico's Baja California peninsula, SBS notes.

Female grey whales are fighting for their life. Fourty-three female whales are breeding in the group in 2015, a big increase from the 27 female whales in 2004.

Furthermore, the panel's work also led to the development of one of the most comprehensive Monitoring and Mitigation Plans for seismic surveys, which now serves as the industry's global guide. A new guide developed to help industry design and carry out effective and responsible geophysical surveys was released by IUCN. The current deal between IUCN and Sakhalin drillers is extended another five years, until 2021.