Environmental News Network - Northern and Southern Resident Orcas Hunt Differently, Which May Help Explain the Decline of Southern Orcas

Details: By University of Washington; 10.Mar

In the Pacific Northwest and British Columbia, scientists have been sounding the alarm about the plight of southern resident orcas.

Cheryl Porter

In the Pacific Northwest and British Columbia, scientists have been sounding the alarm about the plight of southern resident orcas. Annual counts show that population numbers, already precarious, have fallen back to mid-1970s levels. Most pregnancies end in miscarriage or death of the newborn. They may not be catching enough food. And many elderly orcas — particularly post-reproductive matriarchs, who are a source of knowledge and help younger generations — have died.

With just 73 individuals left, conservationists and members of the public alike are concerned that southern resident orcas may not survive.

Yet over the same period, the region’s northern resident orcas, who have a similar diet and an overlapping territory, grew steadily in population. Today, there are more than 300 northern resident orcas, leaving scientists wondering why these two similar but distinct populations have had such dissimilar fates over the past half century.

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Northern and Southern Resident Orcas Hunt Differently, Which May Help Explain the Decline of Southern Orcas