Story | 11 Jul, 2019

IUCN scientific panel calls for investigation of decline in prey of western gray whales

IUCN’s Western Gray Whale Advisory Panel is concerned that waters immediately outside the mouth of Piltun Lagoon in the Russian Far East may be losing their ability to support the recovery of Endangered western gray whales.

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Photo: Dave Weller

In an Open Statement of Concern issued today, the Panel noted that a steep decline in the biomass of benthic amphipods (small shrimp-like animals that form the main prey of gray whales) was underway when, in 2016, oil and gas companies operating off northeastern Sakhalin Island decided to terminate their long-term research program to monitor the benthos. Although there has been no benthic sampling for the last few years, an ongoing shift in the whales’ distribution away from this formerly rich feeding spot suggests that the biomass decline is continuing.

The whale population as a whole appears to be making much greater use of an offshore feeding area that remains highly productive. Unfortunately, however, the mother-calf pairs that are so vital to population recovery are only able to forage in the much shallower nearshore Piltun feeding area.

Because of the implications for the overall health and productivity of the Sakhalin gray whale population, the Panel implores the oil and gas companies (or other interested and capable parties) to explore the nature and causes of the decline in amphipod biomass in much greater depth and detail than has been done to date. Studies should consider multiple explanatory hypotheses, some of which may relate to changes in the demography or behaviour of the whales and others to biophysical events or processes in the regional marine ecosystem, which may or may not be driven, or at least influenced, by human activities. Also, the Panel feels it is crucially important that benthic sampling is reinitiated and carried out on a regular basis to determine whether the observed decline in nearshore amphipod biomass has continued since 2016, when the industry-sponsored studies were discontinued.

Click here to read the full Panel’s Open Statement of Concern.