We nearly hunted blue whales to extinction. Now they're bouncing back.

[Buster's Uncle]

We nearly hunted blue whales to extinction. Now they're bouncing back.
Vox
Updated by Brad Plumer on September 8, 2014, 4:30 p.m. ET  @bradplumer  brad@vox.com



A blue whale spotted approximately 4 miles west/southwest of San Mateo Point, California.   Tom Benson/Flickr



It's easy to get pessimistic about the state of the oceans. Coral reefs are dying. Various fish species are being wiped out by overfishing. Jellyfish are taking over.


The blue whale recovery is a sign that ocean conservation measures really can work


But not all news is bad news. Case in point: A recent study published in Marine Mammal Science found that blue whale populations off the coast of California have almost entirely rebounded after being nearly hunted to extinction in the 20th century. (Many thanks to Andrew Revkin for the pointer.)

Unfortunately, the same can't yet be said for blue whale populations down near Antarctica — which have yet to fully recover from the massive whaling frenzy that only ended in the early 1970s. (Earlier estimates suggested that Antarctic blue whales, which used to be the most numerous of all, are still at just 1 percent of historic levels.) Still, the big blue whale rebound off the coast of California is a reminder that protections for threatened species really can make a difference.


How we nearly hunted blue whales to extinction

Blue whales are the largest, heaviest animals ever known to exist on this planet. Growing to nearly 100 feet and weighing more than 160 tons, they're far more massive than even the biggest land dinosaurs that have been discovered.

So it's amazing to think that humans nearly wiped the whales out entirely in the 20th century. The stunning animation below, made by Cole Monnahan, a PhD student at the University of Washington, tells the tale:



(Cole Monnahan)


Before the late 19th century, blue whales were simply too big and powerful to pursue. But the advent of steamboats and advanced harpoon guns made it easier to go after larger whales for oil and meat — and catches began surging, first in Iceland and Norway, then around the world.

By the time the International Whaling Commission banned blue-whale hunting in 1966 — and after illicit Soviet whaling finally tapered off in the 1970s — most of the damage was done. Roughly 380,000 blue whales had been killed, and the species was at 0.2 percent of its initial numbers.


But now there's recovery — at least off the California coast

A large blue whale off the coast of southern California. (D Ramey Logan/Wikipedia)


Now there's some excellent news. The latest paper, by Cole Monnahan, Trevor Branch and André Punt of the University of Washington, estimates that there are currently about 2,200 California blue whales in the eastern North Pacific — more or less the number that existed before the advent of whaling.


Figuring out the numbers involves some detective work


What's more, they argued that the blue whale population in this region has plateaued because it's nearly reached the maximum size that this region of the ocean will support — and not because too many whales are being killed by ship strikes, as some researchers thought.

How did they figure all this out? Calculating the precise numbers of whales (both now and historically) involves a lot of detective work, as this release from the University of Washington details. The total number of blue whales caught in the region wasn't even known until recently — because Soviet whaling figures were kept secret for so long. In a June paper for PLOS One, the researchers combined those numbers numbers with data on whale acoustic calls to estimate that roughly 3,400 blue whales were caught in the eastern North Pacific between 1905 and 1971.

In the latest paper, the researchers put all of that together to model a more precise population estimate over time. Among other things, they calculated that there are currently about 2,200 California blue whales today — and that's about 97 percent of the carrying capacity for the region.

Now, note that this is only one region of the ocean. Down in Antarctica, the situation is far more dire. An earlier paper by Branch, using a similar model, estimated that the blue-whale population there went from 239,000 down to about 360 in the 1970s, and was still only back up to around 1,700 by the late 1990s. Recovery there has been very, very slow.


Ship strikes are a problem — but they're not thwarting the recovery

(Britt Crawford/Flickr)


Another big concern about blue whales is that too many are being hit by large ocean vessels. In their paper, the authors agree this is a problem, but they find that this doesn't appear to be thwarting the overall recovery of California blue whales.


Some groups have estimated that a dozen blue whales a year are killed by ship strikes


Estimating the precise number of whales killed by ship strikes is also difficult — since, as Monnahan discusses in a blog post here, impacts aren't always recorded and carcasses aren't always recovered. Some groups have estimated that roughly a dozen California blue whales a year are killed.

In the Marine Mammal Science paper, the authors considered even higher-end estimates (35 per year) and found that ship-strike deaths still wouldn't prevent the California blue whale population from rebounding to historic levels.

This is in contrast to earlier research, which had suggested that blue whale populations in the area were stagnating because of ship strikes. The authors also estimate that it would take an 11-fold growth in ship strikes for their to be a 50 percent chance of long-term population depletion.

That said, the authors certainly don't condone ship strikes. The paper does note that current ship strike numbers "are likely above legal limits set by the U.S." and add that "ship strikes are currently a major concern for other endangered cetacean populations." For that reason, many researchers have argued for policies to reduce these strikes — say, by moving shipping lanes away from known feeding areas.


http://www.vox.com/2014/9/8/6122867/we-nearly-hunted-blue-whales-to-extinction-now-theyre-bouncing-back

[Buster's Uncle]

California blue whales, once nearly extinct, back at historical levels
Reuters
By Dan Whitcomb  8 hours ago



Blue Whales are seen in this undated handout photo courtesy of NOAA National Marine Fisheries Service. REUTERS/NOAA National Marine Fisheries Service/Handout



LOS ANGELES (Reuters) - California blue whales, the largest animals on Earth once driven to near extinction by whaling, have made a remarkable comeback to near historic, 19th-century levels, according to a University of Washington study released on Friday.

The recovery makes California blue whales - which study authors say now number about 2,200, or 97 percent of historical levels - the only population of blue whales known to have recovered from whaling.

"The recovery of California blue whales from whaling demonstrates the ability of blue whale populations to rebuild under careful management and conservation measures," said Cole Monnahan, a University of Washington doctoral student and lead author of the study.

Despite the comeback, the whales - which as adults can reach nearly 100 feet (30 meters) in length and weigh 190 tons (172 tonnes), twice as much as the largest known dinosaur - are still being struck by ships off the California coast at numbers above allowable U.S. limits, according to the study's authors

Conservation groups say at least 11 blue whales are struck each year along the U.S. West Coast, nearly four times the "potential biological removal" level of 3.1 permitted under the U.S. Marine Mammal Protection Act.

"Even accepting our results that the current level of ship strikes is not going to cause overall population declines, there is still going to be ongoing concern that we don't want these whales killed by ships," University of Washington assistant professor of aquatic and fishery sciences Trevor Branch said.

According to the University of Washington paper and a separate paper published earlier this year, some 3,400 blue whales were caught between 1905 and 1971, a number determined in part by examining once-secret Russian whaling archives.

The study's authors say that the population of California blue whales is now growing more slowly, partly due to ship strikes and also because numbers are reaching the habitat limit.

"Our findings aren't meant to deprive California blue whales of protections that they need going forward," Monnahan said.

"California blue whales are recovering because we took actions to stop catches and start monitoring. If we hadn't, the population might have been pushed to near extinction – an unfortunate fate suffered by other blue whale populations," he said. "It's a conservation success story."

(The first name of Trevor Branch has been corrected in paragraph six of this Sept.5 story)

(Reporting by Dan Whitcomb; Editing by Sandra Maler)


http://news.yahoo.com/california-blue-whales-once-nearly-extinct-back-historical-160435036.html