Wednesday, September 9, 2009

Summer Adventures Part 1: Sea Lion Rescue

Aside from the random post about Chupacabras, I've been pretty silent the rest of the summer, for a few reasons. First and foremost, I was trying to catch up on thesis fieldwork, and also kept on finding some really great fossils (more on that later). I also went on a 5 day field trip with Dick Hilton of Sierra College to Plio-Pleistocene strata of southeastern Oregon and Northern California (part of my so-called North Coast Project). In addition to this, I also took a 5 day trip back up here to Montana for my girlfriend's older sister's wedding. Then, a week and a half at Lake Tahoe, and then more fieldwork. Oh, and a week long road trip back to Montana via Northern California and Oregon.

So, during my field work in the Santa Cruz region, I decided to head over to Pt. Santa Cruz and try out my new Canon EOS Rebel XS with a 300mm lens and photograph some of my favorite flippered friends: Zalophus californianus, the California Sea Lion. Now, last summer I spotted a couple Steller Sea Lion males (Eumetopias jubatus); it was obvious that they were Eumetopias and not Zalophus because of their lighter, hairier pelage, humongous size (nearly twice the size of obvious Zalophus males) and bearlike heads without a sagittal 'bump'.Zalophus yearlings at Point Santa Cruz, California

Anyway, I got a bunch of great photos of some of these guys. There were several dozen hauled out on the Point itselft as well as the rock offshore, mostly yearlings and the occasional subadult male, and a few pups (and lots of dead pups, in various states of decay; presumably starved to death). I saw a guy with a marine mammal center sweatshirt on, and I stroke up a conversation. Afterward, he asked me if I could help him capture a sea lion with an eye tumor. He pointed out the individual to me, and sure as hell, its left eye was in pretty bad shape.

Juvenile sea lion with eye infection.

So I naturally agreed, and he returned with a huge net and a dog crate built for a great dane. I was to bring the crate to him after he had netted the poor little guy; apparently the crate scares the sea lions away, and he suspects they may remember every time it appears, one of them gets abducted (yes, by aliens, just like in Happy Feet).

Marine mammal center 'Doug' capturing a juvenile sea lion with a very big net.

Well, let me tell you - I've had my fair share of vicious dog encounters, and I've seen big cats roar at the zoo, and seen pissed off bulls, and none of these were remotely as intimidating as this 80lb sea lion. This thing was biting at the net and shaking its head after it clamped down, all the while emitting the scariest growl/snarl I've heard from a vertebrate. Doug finally dragged it over to where I had placed the crate, and wrestled the sea lion into the opening. When it was nearly inside, a sea lion head with mouth agape and a beautiful set of (very sharp, unworn) homodont teeth with moderately developed lingual cingula and accessory cusps on the postcanines (yes, I had that much time to remark upon the dental morphology) found its way out of the crack between the net and the crate, and took a swipe at me, narrowly missing my hand by a couple of inches (I distinctly heard the teeth 'snap' just like when a dog shuts its mouth quickly).
The sea lion looks 'ok' from the right side...

...not so well from this side.

After we got 'her' in the crate, Doug informed me that California Sea Lions can easily bite through 1" thick plywood sheets with ease (and that their bites hurt like a *****). Based on canine size, it looked to be a 'she' - very skinny, narrow, canines are typical of otariid females. Doug informed me that Northern Fur Seals (Callorhinus ursinus, my favorite pinniped) are by far more aggressive and ferocious than any sea lion. This news warmed my heart, as Callorhinus actually has a pre-Pleistocene fossil record (and if you include its ancestor, Thalassoleon, the Callorhinus-Thalassoleon lineage is the best preserved otariid lineage in the fossil record).

The eye injury, according to Doug, was most likely an infection, as tumors are more typical of old adults. In this case, the eye had gotten infected, and the lids had more or less rotted away (very technical, I know), leaving the actual eye to prolapse (it was actually hanging out of the orbit a little bit). I can only assume that the marine mammal center will amputate the eye, and cauterize the orbit shut.
The female sea lion just before removing the crate from the Point.

In any event, a look at the last photo shows something interesting: this individual was pretty plump, and showed no signs of emaciation (most of the other yearlings looked pretty starved), and was slightly larger than the other yearlings in the vicinity. This eye infection was obviously more than a few days old, but it apparently didn't affect her ability to survive and forage. So, a happy ending - she will most likely survive to raise many pups.


"the Dude" said...

I recall reading of a mother east coast seal doing well though blind. Among the freediving-spearfishing community, seals and sea lions are well known for their curiosity, nibbling diving fins and swiping speared fish from a belt leader, but I haven't yet heard of any skin bites. Ashore is entirely another story.

Robert Boessenecker said...

I've heard about the curiousity of pinnipeds. Often when I am on the shore collecting data or fossils, harbor seals and california sea lions will swim up close and impolitely stare.

The only case (locally) that I've heard of a sea lion biting someone in the water was an adult male california sea lion that bit swimmers near Crissey Field in San Francisco about 2 or 3 years ago (roughly about the same time that a confused male elephant seal was attempting to mate with female harbor seals and accidentally killing them; and then it got into a fight with an english bulldog, who barely survived).

dross said...

Hi Robert, this is Doug Ross. Thanks for helping with the rescue, I couldn't have done it alone. Here is a medical report from the vet who treated this sea lion named Mombasa:
"Mombasa- 23 kg female CSL that presented with a large mass involving the entire left eye itself. Creepy is a good way to describe the appearance of this mass. The photographs don't do it justice. The origin of the mass was a diseased eyeball. The surrounding tissues of the lids, the conjunctiva, the orbit, etc. were normal, so when the animal looked around the mass moved along with the right eye- - creepy. The solution (we hope) for this animal was to remove the mass and the residual deformed eyeball
which was done on the 13th. This morning I looked at the animal on
rounds at it seems like it doesn't know anything at all happened-
stealing fish from it's enclosure-mates and gobbling them up. Stitches will be taken out in a week or so. (Aug 14 2009 Dr. Van Bonn)

Robert Boessenecker said...

Hi Doug! Glad to hear she pulled through! You were totally right, she did put up quite a fight - I presume she's already been back at sea for quite a while?

Glad to help!