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Shrinking North Atlantic right whales have fewer offspring

A new study by oceanologists from the U.S. and Scotland throws a curveball in our understanding of North Atlantic right whales.

The research reveals a surprising connection between the size of these giants and their ability to reproduce. The findings raise concerns about the future of this critically endangered species.

Relentless hunting of North Atlantic right whales

The name of the species reflects a grim history. These gentle giants were once deemed the “right” whales to hunt due to their slow pace, unfortunate tendency to float when killed, and plentiful blubber. 

Relentless hunting pushed North Atlantic right whale populations to the very edge of disappearing by the 1900s.

Despite international protection since the 1930s, their population struggles to recover, with only a few hundred individuals clinging to survival. The future of the species remains precarious.

The experts discovered that smaller female North Atlantic right whales have fewer babies. This is concerning because this species is already in danger of disappearing. 

“The effects of decreasing mean body size on reproductive performance are another concerning indication of the worsening prospects for this species and many others affected by environmental change, requiring a focus of conservation and management interventions on improving conditions that affect reproduction as well as reducing mortality,” wrote the study authors. 

Possible explanations

There are a couple of reasons why smaller size may impact the ability of North Atlantic right whales to reproduce. One is that smaller whales might be less healthy overall.

They might not have the strength or energy needed to carry and raise a baby. Having a calf takes a lot of energy, and their bodies might struggle to keep up.

Another reason is that smaller animals might not be able to have as many babies as bigger whales. Their reproductive organs might be smaller, or they might have other physical limitations that make getting pregnant or having healthy calves difficult.

It could also be harder for them to find a mate or for mating to be successful, making it even tougher for them to have offspring.

Human activities and North Atlantic right whales

Humans also play a role in the decline of North Atlantic right whales. When whales swim near fishing nets, lines, or traps, they can accidentally get stuck. 

The ropes can wrap around their bodies or even get stuck in their mouths, making it hard for them to move and eat. These deep cuts and infections can lead to death if the whales can’t get free or aren’t helped quickly.

Collisions with ships and boats are another big danger for these whales, especially in areas with heavy traffic.

The massive size and weight of the vessels can cause serious injuries like broken bones, internal bleeding, and death. Even if the whales aren’t killed right away, these injuries can make them sick and eventually lead to death.

Climate change and North Atlantic right whales

Climate change is making life harder for the creatures in several ways. As the ocean gets warmer, the balance of life in the water gets thrown off. This means the tiny animals the whales eat are showing up in different places, at different times, and there might not be as many of them. 

Ocean currents and North Atlantic right whales

Ocean currents are changing too, which also affects where the whales’ food goes and makes it harder for them to find enough to eat.

Because of this, the whales may not be getting the food they need to be healthy. In the worst cases, they might even starve. 

Sea level rise 

Climate change is also causing the sea level to rise and making the ocean more acidic, which harms the whales’ homes and food sources. Rising water levels could flood the areas where the whales raise their young, and the increased acidity could disrupt the entire food chain, making it even harder for the whales to find food.

Climate action

Protecting the whales requires tackling climate change on two fronts. First, we need to address the root causes by reducing greenhouse gas emissions.

Key strategies include switching to renewable energy, using less energy overall, and limiting pollution from industries, vehicles, and land use. 

By slowing down global warming, we can lessen the negative effects on ocean ecosystems, such as changes in temperature, acidity, and currents that affect the whales’ food supply.

Whale conservation 

To keep these magnificent creatures safe, we must tackle ongoing threats against them. 

Innovative fishing practices

This includes implementing breakaway ropes that release entangled whales, exploring alternative fishing methods that minimize entanglement risk, and temporarily restricting fishing activity in areas or during seasons crucial for whales, like calving periods.

Responsible navigation 

Additionally, responsible navigation is essential. By reducing ship speeds in known whale habitats, especially during vulnerable times, and utilizing advanced tracking systems, we can significantly decrease the risk of collisions.

Creating safe havens 

Establishing and expanding protected marine areas in critical whale habitats provides them with undisturbed spaces for vital activities like feeding, breeding, and raising young. 

Broader implications

Julia Singer, a marine scientist at Oceana, emphasized the implications of the concerning reproductive trend among North Atlantic right whales.

“This study reinforces the urgent need to reduce human-caused stressors, especially from boat strikes and fishing entanglements, to ensure mothers are healthy and strong enough to calve. For one of the most endangered large whales on the planet, every single North Atlantic right whale calf is vital to avoid extinction,” said Singer.

“This year alone, the U.S. East Coast has become a graveyard for North Atlantic right whales after two young whales were struck by boats, another juvenile died from a painful entanglement in fishing gear, and two newborn calves are presumed dead after going missing.” 

“This study shows the need for stronger protections to reduce the constant risks and stress North Atlantic right whales face every day from navigating a jungle of vertical fishing lines and speeding boats in their migration path.” 

“President Biden and Secretary of Commerce Gina Raimondo can stop whales washing up on our shores from boat strikes, and give North Atlantic right whales a chance at survival, if they stop delaying and finalize the updated vessel speed rule today.”

The study is published in the journal Royal Society Open Science

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