Evidence appears to be mounting that humpback whales are having problems. Signs of their stress include unusual whale beachings and a decline in their visibility that have marine biologists and other experts baffled about what might be happening. Are they responding to human-caused changes in their environment or is something else going on?
Unusual Stranded Carcass Highlights Humpback Whale Problems
It is never good to find a whale carcass lying lifeless on shore. However, it is especially perplexing to find a young whale lying tangled in a Brazilian mangrove brush, circled by vultures, and 4,000 miles from where it should have been swimming on the way to Antarctica. It is possible the whale died closer to open water and tides brought its body into shore, but the question still remains about what killed it and why it wasn’t further along on its journey to more southern waters. There’s also concern about the fact that the whale died so young and about the caused of its death.
Whale Sightings Are In Decline
Whatever problem affected the young whale that was found in Brazil might be impacting other whales as well. In recent years, there’s been a marked decline in humpback whale sightings and no one is quite sure why. In 2015, Pacific Ocean-based whale watchers, support networks, and scientists began to notice that whale sightings were in decline. The marine mammals were either late in their migration or were fewer in numbers.
More formal research supported casual observations. When experts compared a whale census conducted between 2008 and 2010 with a second census taken between 2013 and 2014 they noticed a decline. When compared again to data from 2016 to 2017, there was a 50 percent reduction in the number of same mother/calf pairings researchers identified in the first count. As another round of research began in 2018, an additional 35 percent reduction in paired sightings was beginning to show.
Theories On Possible Culprits
To try to help, scientists at the University of Hawaii are looking into the issue and planning to conduct some drone-based research to start to understand what may be happening. They plan to conduct measurements of the whales they find and to use other techniques to quantify the animals’ bioenergetic demands. They want to understand not only what whales need but how well these needs are being met.
It is also possible that whale populations are being affected by increased interactions with human-created ocean traffic. Though whale populations are currently in decline, they are still increased over where they were decades ago when whaling had decimated their numbers and modern conservation practices hadn’t yet kicked in. It’s possible that as conservation worked and whale numbers grew, conflicts with shipping and fishing traffic increased.
Statistics support this theory. Reports show that each year an estimated 300,000 whales and dolphins are killed when they are caught in fishing gear. Additionally, there have been more than 1,200 recorded whale/ship collisions since 2009.
Whales May Be Affected By Warming Oceans
As climate change occurs the oceans are one of the first areas to be affected. One example of these conditions, El Nino, creates patterns where warmer waters shift east in the Pacific Ocean. Scientists have identified at least two other patterns that are hitting at about the same time. The three impacts work together to dramatically change ocean temperatures.
What are the impacts of warmer oceans? Scientists believe there’s a strong chance they will affect krill, a primary food source for whales. As waters warm in the mid-Pacific, whales may be delaying their migration south to calving and breeding grounds so they can develop their fat stores more fully. While a lower amount of krill availability is just a theory at this time, it’s also possible that whale populations are simply declining so that they can balance out whatever numbers of krill happen to be available.
Experts also theorize that warmer waters can create conditions, like algae blooms, that are deadly to whales. This kind of mortality rate in whales would go along with other observations of temperature-related effects on other marine wildlife including sea bird die-offs, disease in Alaskan fish stocks, and a less plump, well-nourished whale population overall. If these kinds of problems are happening, they could be identified with the types of research conducted by the University of Hawaii Study.
How Whales Maintain Their Size
To try to understand what may be happening with whales, it is helpful to understand how they got so large— in the first place. Part of this answer has to do with the fact that they survive in a marine environment and without the constraints of the kinds of gravity humans have, they’re free to grow as large as evolution allows. Their watery habitat also allows them to swim freely and forage for unlimited amounts of food to support their growth. Thirdly, becoming larger is a way for mammals to maintain their body heat, protecting them against an ocean that’s colder than landed areas on earth. As the ocean changes, however, it is possible that the impacts of their size advantage will change.
How To Help Whales
Though it is still too early to know for sure that whale populations are under stress, it never hurts to do what we can to help them. One of the biggest things that experts recommend is to give whales more space in ocean waters. Large shipping and fishing traffic, as well as tourist traffic and even kayakers, can be stressful for them and keep them from resting or nursing. We can also do what we can to prevent the things that are causing warming waters in the first place. And researchers will continue to identify any specific problems so that targeted, supportive solutions can be developed. Hopefully, these kinds of solutions, when implemented consistently, can bring whale populations to their optimal levels and enhance ocean health.