Sea otters, which were hunted to extinction in Southeast Alaska during the 18th and 19th century fur trade, were reintroduced in the 1960s. In this region, 403 animals were transplanted to six sites, predominantly on the outer coast. The population is now estimated at about 25,000 and ranges continuously along the outer coast of Southeast Alaska and interior areas including Glacier Bay. The Glacier Bay population is particularly interesting because it grew from 5 animals in 1995 to over 8000 in 2012. Such a dramatic increase is likely from both births and a movement of animals into Glacier Bay.
While this is an excellent example of exponential population growth, this growing sea otter population plays a large role in the marine ecosystem of Southeast Alaska. Sea otters are top predators, so called because they are at the top of the food chain. They have a disproportionately large role in the food chain and are designated as a keystone species. Like a keystone at the top of a stone arch that plays a critical role in holding up the arch, a keystone species play a critical role in an ecosystem.
Along rocky shores, sea otters eat sea urchins, and sea urchins eat kelp. So where there are sea otters, kelp is in high abundance. In the absence of sea otters, sea urchins can reach very high numbers and result in a barren area. Because kelp provides a place to live, hide and reproduce for many animals, for example rockfish and herring, the number of animals and plants in an area is usually higher in the presence of otters. By helping kelp forests to grow, sea otters may also indirectly help to reduce levels of atmospheric carbon dioxide, which is a major factor in climate change. A recent study showed that kelp forests play an important role in capturing carbon in coastal ecosystems.
Sea otters also eat a range of species important for commercial, subsistence, and sport fisheries. Declines in geoduck clams, abalone, sea urchins, Dungeness crab, and sea cucumber populations and fisheries have been attributed to sea otters. A recent study provides evidence that observed declines in sea cucumber populations resulted from sea otter predation over an extended period of time. Sea otters need to eat about one-quarter of their body weight per day, as they do not have blubber, like other marine mammals, to stay warm.
Although sea otters are doing well in the Southeast Alaska population stock, they are not increasing throughout their entire range. The global population has declined by more than 50 percent in the last 30 years and this pattern is expected to continue. In the US, two populations of sea otter are listed as threatened under the Endangered Species Act; the Southern sea otter in California and the Southwest stock of the Northern sea otter in Alaska. In Alaska, the population of sea otters in the Aleutian Islands (Southwest stock) declined dramatically, with declines up to 90 percent in the 1980s and 1990s.
From 6-10 p.m. on Thursday, Feb. 21 in the Egan Library, at the University of Alaska Southeast, a distinguished panel of experts on sea otters will present the latest scientific information on sea otters in Southeast Alaska, to include information on the current population status and their ecological role including foraging habits and impacts on kelp forests. A series of lectures will be followed by a question and answer session with the audience. On Friday, February 22 at 6:30 and 8pm, Jim Bodkin will present the Fireside lecture, “A Sea of Otters” at the Mendenhall Glacier Visitor Center. Both events are free and open to the public.
• Eckert is an Associate Professor of Fisheries at the Juneau Center of the School of Fisheries Sciences at the University of Alaska Fairbanks. Pearson is an Assistant Professor of Marine Biology at the University of Alaska Southeast in Juneau. Eckert may be reached at: 907-796-5450. Pearson may be reached at: 907-796-6271.
Comments (19)
Add commentLast time I dove in POW, it
Last time I dove in POW, it was like a moonscape. Yes otters are an important part of the ecosystem, but they are growing unchecked. An otter will eat anything that moves, and probably a few things that dont. They were a part of the ecosystem prior to being wiped out, but the ecosystem changed without them. We then reinsert them, and the balance is off. Their population is explosive and they are over exploiting their resources. It took tens of thousands of years for the ecosystem to balance out initially to having otters around. We cannot just thrust them back in and expect everything to work nice. The population needs controlled. I personally think that there needs to be a hunting season for anyone, not just natives, and the ability to sell the hides. That will keep the population from explosive growth. Yes they are cute and all, but they need some control or they will crash.
Wildlife Don't Overexploit Their Prey
Sea otters, like other animals, eat what they need to survive. They don't overexploit their resource. And, the biodiversity of the ecosystem they were a part of in Southeast Alaska as well as throughout their worldwide range suffered when sea otters were nearly wiped out by the fur trade. They returned to areas they historically occupied and the balance and biodiversity returned. They weren't "reinserted". And, lastly predator control is not the way to manage fisheries nor is it legal.
Kpawsuh - I'm not sure about all this but,
Years ago when the sea otter population was fairly low, Natives were allowed to hunt them as sea mammals. But part of the decision was that they had to use the pelts in traditional ways.
In the past, as far as I can tell, before the arrival or Euroamericans, some of the pelts were used to line robes and blankets, but many of the pelts were simply traded to others around them as whole pelts. The new interpretation of traditional ways was that the pelts had to be made into some wearable product like caps, gloves, mittens etc.
Perhaps if Natives, especially in rural villages were simply allowed to hunt sea otters and sell the pelts, the sea otter population might be controlled and rural people would have a source of income. Then furriers and industry could make the pelts into products that would sell world wide.
However, the fur market around the world has apparently decreased and there may not be a great market for wearable fur items.
If local folks haven't seen a tanned sea otter pelt, the State Museum does have one that they put on display at times. The fur is probably the finest fur in the world. Sea otters don't have a layer of fat under the skin, but the cold waters never really touch their skins. The fur is kept well oiled and is so thick that water is kept away.
Think of it this way. The average human with a full head of has something like 700,000 hairs. The sea otters have that many hairs in a square inch !
Just an opinion and a possibility
I keep hearing that story
That sea otters are growing unchecked like some sort of cancer and will eat everything down to bare rock.
I'm not buying it.
First, they're not at the top of the pyramid. Orcas eat them. So do sharks.
Second, if they're impacting their own food resource that heavily, they'll soon limit their own population. Nature abhors an imbalance.
All of this noise by the shellfish industry harkens back to the old days of the salmon fishery when they declared war on sea lions and eagles in an attempt to wipe out any competitors.
Thanks to Professor Eckerts for pointing out that otters fill an important niche in the ecosystem.
Maybe some limited harvesting is warranted, but to declare that humans need to "bring the system back into balance" is laughable. We'll grossly over-react, like we usually do.
One more thing - sea otters are highly valued by our visitor industry. They may be worth more swimming around than some geoducks are to the Asian seafood market.
Lat, I would suggest a trip
Lat, I would suggest a trip to POW. It's about more than them eating a few geoducks. It more like them eating all the geoducks. They eat everything. They are spreading like crazy. There have been reports of them in berners even.
I'm not advocating
I'm not advocating extirpation but having some mechanism to lower the population is needed. They are overtaxing the area yes but it isn't going to cause their population to crash. The excess otter just move on to the next bay and up the coast.
There were otters here...
...before we wiped them out. And yet the ecosystem somehow survived then. We don't need to screw with it - the system will balance back out.
Enough with the hyperbole.
Wildlife Don't Overexploit Their Prey
Animals don't extirpate their prey. We do and we have overexploited many animals sea otters eat. They eat what they need to survive. What is being requested by some is fisheries management through predator control, which is not legal. Sea otters were part of Southeast Alaska and many other parts of the historic range before we nearly wiped them out. When sea otters were present, balance and biodiversity existed. It isn't a matter of "reinserting them". They are reoccupying historic habitat and balancing the system.
It's a new balance with us (modern society) in the mix
and we're historically intolerant of competitors. With commercial interests attaching dollar amounts to sea otter impacts, I'm betting the gate-keepers, ADF&G and others, are going to bend to commercial pressures.
This article lists them as top predators in their food chain, Lat., which could be due to lazy research if, as you say, orcas eat them. Rogue mammal eating orcas...
What's interesting to me is their relationship with urchins. I haven't seen studies on this, but I've observed that our hatchery salmon runs, the chum salmon returning to southeast waters by the millions, with unharvested carcasses often littering the bottom of salt-water bays by the tens of thousands, seem to greatly encourage urchin populations---This could explain some of the attraction of the archipelago to these urchin-eating mammals, but it could also hint at a direction for assimilation into our commercial culture for these animals outside of the time-worn and probably out-moded method of simply killing them off to the point where we hope they survive but are nevertheless not impacting our commercial fisheries.
The scientifically established link between otters and kelp as a carbon-sink is a driver for exploring this link with commercial activity
Sitka Sound
The otters have eliminated the abalone and urchins in Sitka Sound, all of the outer coadts from Kruzof to Yakutat. as well as any Dungeness crabs. The otters have eliminated Dungeness inBartlett Cove Before otters Orca Inlet near Cordova had an annual harvest of 2.2 million Dungeness. By 1989 after the otters were introduced the harvest was zero.
How many...
...crabs and urchins were in these paces before the otters were wiped out? Maybe the crab populations in recent years have been unnaturally high due to the lack of their normal predators. At what cost to the ecosystem?
I'm not entirely opposed to any otter harvests, but there need to be more voices at the table than just the commercial fishermen.
Lat
Once again you seem to be commenting on a subject that you know little about. Sea otters completely eat them selves out of house and home. They start with the crab and work their way down to sea cucumbers. When everything is gone they move on. It does resemble a moonscape. And, the fisherman better have lots of "voices at the table" cause they are coming up against the Feds...and we all know what the current attitude in D.C. is like.
Crab
The otters have wiped out crab in Icy Straits and Glacier Bay and the Sea Lions are out of control as well. Re-introducing them was a bad idea. If the migrate back over time so be it. The problem is they have almost no predators because they are an orca's least favorite food. They have super dense fur and no fat. They could become the raw material for a high-end clothing industry in Southeast and people could become the predator that is missing right now.
hmmm...
How can we convince the sealions to eat the otters?
One of the greatest Dungeness
One of the greatest Dungeness crab fisheries (1960's) use to take place on the shores north of Cape Spencer in the gulf of Alaska.
Go set a pot there now and I bet you will catch zero.
Oh brother..
The leave them alone and nature will balance out theory. Ok, that is like saying no bag limits or closed seasons on charter and commercial trawler fishing anywhere, oh don't worry the stocks will return. Yeah right. Otter are traveling more inland because they consume everything they can dive down eat and move on...We do not need time to study this any longer, it is time to cull about half of the otter population.
Is there anything in the
Is there anything in the oceans the commercial fisherman don't want eliminated from Whales on down that might possibly compete? Fishermen like to complain about loggers but there's not much difference in attitudes. They don't own the oceans anymore than the loggers own the forests.
Not just crabs and urchins
Sea otters also eat mussels, clams, scallops, etc. It is a fallacy that killer whales and sea lions eat otters. While they might if desparate, the caloric value in a sea otter is very low (due to no fat) and not worth the effort it takes to chase and kill.
It's not just the commercial industry that will be hurt by the uncontrolled growth of the sea otters, it's private individuals who harvest just for ourselves that will be hurt too. No more clam gathering at the lowest tides of the year, no more scallops to dive for, etc.
And if you think otters are cute and cuddly and the tourist love them, that is true. But the tourists do not want to see the results of explosive growth. No one does.
A lot of misenformed comments...
Sea Otters do not 'eat themselves out of house and home' as 'dennyh' says - if anyone is guilty of that, it is the humans. It is well known in professional circles that Sea Otters are very selective. Their favorite food is the Sea Urchin, and studies have shown that their favorite Sea Urchins are the very same ones that the humans love to sell. They leave the smallest, because they do not provide the nutrients, and they leave the largest Sea Urchins because they are not prime sushi. They don't clean out the crab because they prefer a mixed diet and prefer Sea Urchins. Sea Otters do not benefit from over harvesting; they can expand their range as an option to 'eating themselves out of house and home' as 'dennyh' likes to say. Bottom line is, the best solution is a environment full of diversity, with kelp forests and no over harvesting by any species. But just try to tell the humans that. Remember, the humans are not just living off the resources, they are converting them all into money, then exchanging that for giant trucks, mortgaged homes, trips to Los Vegas, chicks, beers, and everything else. Don't worry about the Sea Otters eating all the seafood - there were lots of them here before humans came and wiped them out. There was plenty of food for the Sea Otters too, so they obviously didn't eat it all. The truth is, there are piggy humans that want it all for them selves, and they don't want to share anything with the Sea Otters - or anything else, either.
Don't you love it
Don't you just love it when humans get "involved" and reintroduce something into the ecosystem. It certainly feels like the right thing to do. Often times there is a reason that the species declined or was exterminated. Wolves were reintroduced in the Greater Yellowstone ecosystem in the 80's at a huge expense to the taxpayer. Now, the wolves are taking over some of the areas elk and moose herds, hate it when that happens. Next time before launching into some sort of reintroduction of a species give a little more long term thought to what the situation will look like 20 years down the road and while you are at it quit messing with Mother Nature.