Researcher Matthew Germishuizen warns that southern right whale mothers visiting South Africa are producing calves less frequently, with intervals rising from about three years historically to four or five years since 2009. Long-term surveys and satellite tracking link the trend to Southern Ocean warming, which has reduced sea ice by an estimated 15–30% and diminished krill stocks. With less prey, mothers travel farther and often arrive at breeding grounds in poorer condition, threatening population recovery and regional eco-tourism. Scientists call for stronger marine protections and reductions in greenhouse gas emissions to address the root cause.
Southern right whales birthing fewer calves as Antarctic warming shrinks krill habitat
Researcher Matthew Germishuizen warns that southern right whale mothers visiting South Africa are producing calves less frequently, with intervals rising from about three years historically to four or five years since 2009. Long-term surveys and satellite tracking link the trend to Southern Ocean warming, which has reduced sea ice by an estimated 15–30% and diminished krill stocks. With less prey, mothers travel farther and often arrive at breeding grounds in poorer condition, threatening population recovery and regional eco-tourism. Scientists call for stronger marine protections and reductions in greenhouse gas emissions to address the root cause.
11:03, 08.11.2025Environment
Declining births among southern right whales linked to warming Antarctic waters
Marine researcher Matthew Germishuizen, writing in The Conversation, has identified a worrying decline in the birth rate of southern right whales that visit South African breeding grounds. Although overall numbers have been recovering since the end of intensive commercial whaling, females are now producing calves less frequently — historically about one calf every three years, but since roughly 2009 the interval has increased to four or five years.
Decades of survey data and satellite tracking point to a major driver: warming in the Southern Ocean. Rising temperatures have reduced sea ice in key Antarctic feeding regions (estimated declines of about 15–30%), which undermines krill reproduction and abundance — krill being the tiny crustaceans that form the primary food source for these whales.
With less prey available near traditional feeding grounds, mother whales must travel farther and expend more energy to forage, often arriving at South African breeding areas in poorer condition. That reduced body condition delays reproduction and risks reversing population gains made after the end of large-scale whaling.
Southern right whales act as a sentinel for ocean health; their struggles point to broader ecological shifts. The Southern Ocean plays a critical role in absorbing heat and carbon dioxide, so changes there can cascade into altered fisheries, weather patterns and threats to food security.
Researchers are using satellite tags, genetic analyses and long-term monitoring to track how whales are responding and to identify important feeding habitats. Conservation organizations such as the Dyer Island Conservation Trust and Whale Coast Conservation are raising public awareness and pressing for stronger protections of marine habitats.
Experts stress that reducing greenhouse gas emissions is essential to address the root cause of these ecosystem changes. Individuals can help by choosing sustainable seafood, supporting clean-energy transitions and advocating for policies that protect marine biodiversity.
Protecting whales and the oceans they depend on is inseparable from protecting our own future. — Matthew Germishuizen