The Safina Center

Jul 31st
2014

More Whales Means More Productive Oceans

As large whales – such as the sperm, humpback, gray, blue, and right – have started to slowly recover in recent years from centuries of overhunting, scientists are discovering that these large animals are very important to our oceans.

Previously there haven’t been enough whales in the oceans for scientists to study. This is because humans heavily hunted whales up until the 1970’s. By this time, we had removed 66-90% of whales from the oceans. They were hunted for their meat and for their blubber, which was turned to oil.

Thankfully, since that time, most countries have come to their senses and stopped whale hunting. And now, many large whale populations are slowly increasing. Humpback whales in the Southern Ocean and North Atlantic are on their way to increasing toward pre-hunting levels. The southern right whale is also showing good signs of recovery. Even blue whales are increasing, though they still remain at low numbers relative to their historic population size1.


Blue Whale- the largest animals ever known to have lived on earth.Photo by Diane Gendron and Sandy Lanham.

Blue Whale- the largest animals ever known to have lived on earth.

These growing whale numbers, along with new technological advances, are finally allowing scientists to study the roles whales play in our oceans. And what scientists are finding is that we have greatly underestimated the importance of whales.2

Scientists have discovered that whales facilitate the transport of nutrients around the ocean. When the whales feed at great depths and then return to the surface to breathe, they mix up the waters. And when the whales release urea and fecal plumes [or whale poop] this provides the surface layers of the ocean with important nutrients like Nitrogen and Iron. These nutrients act like fertilizers for plankton [small plants and animals that float in the upper layers of the ocean], spurring growth. Scientists are calling this the “whale pump”. Since plankton are the base of ocean food webs, enhanced plankton growth can increase the productivity of our fish and our entire ocean systems.

Whales also transport nutrients thousands of miles across the ocean when they migrate from high-latitudes where they feed to their lower-latitude breeding grounds. For instance, it is currently estimated that the blue whale transports 88 tons of Nitrogen per year from the Southern Ocean to its lower-latitude breeding grounds through the excretion of urea. Before commercial whaling it is estimated that they may have transported 2400 tons of Nitrogen to the lower-latitudes. Whale placentas may also provide other nutrients to these areas. Similar to the “whale pump”, this cross-ocean transport of nutrients called the “great whale conveyer belt” helps to increase plant and animal growth in lower-latitude areas, which are often devoid of nutrients.

Fishermen have often seen whales as competition, complaining that whales eat all the fish they are trying to catch. But this new scientific information suggests that having large whales around is likely to increase fish populations and help our fisheries.

 

Playful gray whale calf. Photo by Eddie Kisfaludy.

Playful gray whale calf.

Whale carcasses provide another unique service to our oceans. When whales die, their bodies fall to the ocean floor and provide organic nourishment and habitat for deep ocean creatures. Scientists have found dozens of species that are only associated with whale falls and believe at one time there were many more. When whales were hunted to near extermination, many species that specialize on whale falls likely went extinct before they were ever discovered.

As well, because of the large size of whales, they are capable of storing large amounts of Carbon. When whale carcasses fall to the deep ocean, this effectively transports Carbon from the atmosphere to the deep ocean, which can help to lessen the impacts of global warming and regulate our climate.

It is clear that having these large whales living in our oceans is much more valuable than any goods they provided during the whale hunting era.

Scientists say that as whales continue to increase in numbers, we can expect to see an increase in ocean productivity in many areas, and that having more of these large animals will help stabilize the oceans. Scientists also believe that as whale numbers continue to rise and they continue to study them, we are likely to uncover even more benefits that these magnificent creatures provide to our oceans.

 

Right Whale.Photo by Carl Safina

Right Whale.

Notes:

1.) Status of Whales from the International Whaling Commission

2.) Recent scientific review study on whales as marine ecosystem engineers, published in the journal Frontiers in Ecology and the Environment.

For more on whales, check out The Safina Center’s Ocean Wildlife section.

 

Elizabeth Brown is a research scientist at The Safina Center. 

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Posted in:   Climate, Whales

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