Complex sentence: Not much is known about the endangered Sea of Okhotsk population, however, nowadays whales are regularly observed at Shantar Islands, very close to shores such as at Ongachan Bay.
Split into simpler sentences: Not much is known about the endangered Sea of Okhotsk population. However, since recent times whales have been regularly observed at Shantar Islands, very close to shores such as at Ongachan Bay.