As a part of ‘theme 6’ ecosystem and biodiversity research program, ArCS researchers studied seabirds breeding on St Lawrence Island, Northern Bering Sea. This season is the fourth year of our fieldwork, which started in 2016. Researchers from NIPR and University of Alaska Fairbanks worked together with native guides from St. Lawrence Island, from mid-June to mid-August. I traveled to join the fieldwork during 19 June – 6 July 2019.
Last year, the Bering Sea experienced a record-low sea ice extent. On St. Lawrence Island, we observed many washed carcasses of seabirds (mainly thick-billed murres) and breeding failure of murres and auklets. This year, the sea ice extent remained low throughout winter. We wondered how breeding seabirds on the island would be affected this year.
When we arrived at Savoonga in June, it was still in the time of snow-melting. After pulling out our ATVs from winter storage, we headed to seabird cliffs along the coast. It was sometimes challenging to cross over flooded rivers with meltwaters, or over snowfields that can trap our ATVs. After finally reaching the cliff, we were relieved to see many seabirds nesting there, unlike last year. We were able to recover several geolocators that we attached on birds in 2016 and 2017. We left the island in early July with a hope that seabirds continue to breed successfully until the end of the season.
When our team went back to Savoonga in late July, the seabird breeding situation had already changed. Drs. Alexis Will and Jean-Baptiste Thiebot of NIPR reported that the number of murre chicks was low in the monitoring plots, about one-third of 2017. Crested and least auklets failed to fledge chicks, similarly to the situation in 2018. The team did not observe the mass-mortality of murres but found many carcasses of crested auklets washed ashore. Also, the team found many giant jellyfish washed ashore on the beaches, which also surprised local people there.
Massive breeding failure of seabirds on St Lawrence Island occurred two years in a row, which appears to coincide with low sea ice extent in the Northern Bering Sea. Such breeding failures may indicate a system change of the whole marine ecosystem in the Northern Bering Sea, which requires wider investigations from various data sources.
Akinori Takahashi (NIPR / a member of Theme 6)