Monthly Archives: March 2016

Steller Sea Lions, Part 3

Kodiak Wildlife, Steller Sea Lion, , , , , ,

100_1190

This week I will discuss recent and current research on Steller sea lions as well as theories to explain why their numbers have decreased so rapidly over the last several years.

Steller sea lion females live up to thirty years, while males have a maximum life span of twenty years.  Males have a much higher mortality rate than females, probably at least in part due to the stresses incurred by securing and maintaining territories.  By the time they are ten years old, there is a three to one ratio of females to males.

Stellers die from a number of causes; many are well-understood, but the underlying reasons for their dramatic population decline are still a mystery.  A high number of aborted Steller sea lion fetuses are found in the wild, and it is estimated that less than one-third of all pups reach sexual maturity.  Pups may be washed off the rookery by storm waves or killed by adults tossing, biting, or crushing them.  A pup may also be abandoned by his mother or die from disease or starvation.  Threats to Steller sea lions of all ages include disease, loss of habitat, contaminants and pollutants, boat strikes, shooting by humans, entanglement in fishing nets and ocean debris, and indirect impacts, such as competition with fisheries for important food sources, including walleye Pollock.

It is known that sea lions are preyed upon by killer whales and sharks, but a recent study by a biologist at Oregon State University and a biologist with the Alaska Sea Life Center pinpointed a surprising possible predator of sea lions.  Pacific sleeper sharks are a large, slow-moving species of shark that until recently were believed to be scavengers or to prey on fish.  Pacific sleepers can grow to twenty feet (6.1 m) long, and there is now evidence that they may prey upon sea lions, although the incidence of this predation is unknown.  Biologists inserted “life-history transmitters” into the abdomens of thirty-six juvenile Steller sea lions.  These transmitters record temperature, light, and other properties during the sea lions’ lives.  When a sea lion dies, the tags either float to the surface or fall out on shore and transmit the data by satellite to researchers.  Seventeen of the original thirty-six tagged sea lions have died.  Fifteen of the transmitters indicated the sea lions had been killed by predation.  Usually when a sea lion is killed, the tag is ripped out of the body and floats to the surface, recording a rapid temperature change and exposure to light.  Three of the predation deaths were different, though.  They recorded an abrupt drop in temperature, but they did not float to the surface and sense light, indicating that they were still surrounded by tissue.  The obvious explanation is that they were eaten by a cold-blooded animal such as a shark.  The only other possible shark candidates in the area are great white sharks and salmon sharks, both of which have counter-current heat exchangers in their bodies, giving them higher body temperatures than those recorded.  Biologists believe the only possible predator in the area that is large enough to eat a sea lion and has a body temperature as low as those recorded is a Pacific sleeper shark.

While still much more research is needed to definitively identify Pacific sleeper sharks as predators of sea lions and to understand how many sea lions sleeper sharks actually kill and eat, the possible ramifications are troubling.  Ground fish harvests in some area of the Gulf of Alaska have been limited in recent years to reduce competition for fish that are preferred by Steller sea lions.  It is possible, though, that limiting fishing has led to more fish, providing a food base for a larger population of Pacific sleeper sharks, and adult sleeper sharks may in turn prey on sea lions.  If this is true, then management directives may have harmed rather than helped the Steller sea lion population in the Gulf of Alaska.

The relationship between Pacific sleeper sharks, sea lions, and ground fish is still not well understood, and it is a good example of the complexities of the North Pacific food web.  Understanding why Steller sea lion populations, as well as populations of other pinnipeds, are decreasing in certain areas is not an easy undertaking.  Several factors have been suggested to explain the decline of the western Steller sea lion population in the last three to four decades.  Possible reasons are described as “top down” processes and “bottom up” processes.  Top down processes include predation by killer whales or sharks; killing by humans, either directly such as by shooting, or indirectly by entanglement in fishing gear or ocean debris; and harassment of sea lions, especially at rookeries.  Bottom-up processes include reduced prey quality and abundance, either due to competition with commercial fisheries or for some other reason; long-term shifts in their environment, such as changes in ocean temperature or an increase in contamination; and disease.  At the present time, no one or combination of these factors sufficiently explains the decline of the western population of Steller sea lions.

There are currently a number of scientific studies examining the nutritional and biological needs of Stellers.  An interesting result from a study by Carla Gerlinsky at the University of Washington showed that under-nourished sea lions are able to dive for a slightly longer period of time than unstressed sea lions when foraging for food.  However, while the nutritionally-stressed sea lions are able to dive and therefore forage longer, they need more time on the surface to recover between dives, leading to longer foraging trips requiring more energy.  These longer foraging trips also increase the risk of predation at sea and reduce the amount of time a female can spend feeding and taking care of her pup.

Biologists and fisheries managers are also working on practical solutions to decrease human/sea lion conflicts, such as non-lethal ways to deter sea lions from raiding commercial fishing nets, signage near harbors and fish-cleaning stations to remind people that feeding sea lions is a federal offense, and methods of keeping fish-cleaning stations tidy, so sea lions can’t help themselves to fish scraps.  In Kodiak, sea lions were hauling out on an old breakwater float in the boat harbor, causing continual conflicts with humans at the harbor.  When the old float was replaced with a new one, the old float was moved away from the dock, and the sea lions that had already staked claim to the float, moved with it, leaving the new float sea-lion free for human use.

Don’t forget to sign up for my Mystery Newsletter on my home page.  I will send you back issues  as soon as you join.

 

 

Steller Sea Lion, Part 2

Kodiak Wildlife, Steller Sea Lion, , , , ,

DSC_0117

This week I’ll tell you a little about Steller sea lion reproductive behavior and biology.

Steller sea lions use both haul-outs and rookeries.  Rookeries are breeding colonies where sea lions mate, and females give birth; and haul-outs are areas where sea lions rest.   Rookeries are used during the mating and pupping season by adults and pups.  Haul-outs are sites used by some non-breeding adults and sub-adults throughout the year and by adults during times other than the breeding season.

Female Steller sea lions reach sexual maturity between the ages of three and six, and most breed every year.  Males are sexually mature between the ages of three and seven, but they are not physically mature and large and strong enough to hold territories until they are nine to ten years old.  Male Stellers are very territorial, and holding and defending a territory is physically exhausting.  Not only must they sometimes engage in fierce, often bloody, fighting with other bulls, but a male often goes without eating for one to two months while he stays on the rookery to defend his territory.  Because of these exhaustive physical demands, males hold territories for an average of only two years, which means they only have a few mating seasons.  It is probable that most males never breed, but the largest, strongest, most successful bulls are those that hold territories, and they mate with many females, passing on their genes to the next generation.

Bulls come ashore at rookeries in mid-May, and they use vocal and visual displays to establish territories, sometimes fighting with other males.  Bulls defending a territory will remain on the rookery until mid-July without eating or drinking.  Females arrive soon after the males and give birth to a single pup within three days of their arrival.  Females remain with their pups for five to thirteen days before leaving the rookery every one to three days to feed, and feeding trips generally last less than 24 hours.  Pups usually nurse for one year, but unlike other pinnipeds for which weaning is predictable, Steller pups may continue to nurse for up to three years.  Mothers use smell and vocalizations to create a bond with a newborn pup.

Approximately two weeks after giving birth, a female Steller will mate again.  Like many other animals, Steller sea lions exhibit delayed implantation.  While a female breeds in June, the fertilized egg does not implant on the uterine wall until October, making the gestation period, from implantation until birth, approximately seven to eight months.    Pups are able to swim and crawl soon after they are born.  They are approximately 3.3 ft. (1 m) in length and weigh between 35 and 50 lbs. (16-22.5 kg). 

 Next week’s post will cover some surprising new research about Steller sea lions and a possible predator that may be at least partially responsible for the decrease in Steller populations in the North Pacific.

Once again, if you like mysteries and true crime, sign up for my Mystery Newsletter on my home page.

 

 

Hiking in New Zealand

Uncategorized, , , , , ,
Mt. Cook
Mt. Cook

Mike and I spent the last month traveling and hiking  in New Zealand, and it was quite an adventure. New Zealand is a gorgeous, vibrant country where even the land seems to be alive. With the Pacific tectonic plate colliding with the Australian plate, earthquakes are common in many areas of the country. We felt two good jolts while we were staying in Christchurch on the South Island. Five years ago, Christchurch suffered extensive damage from a 6.3 earthquake, and residents are still struggling to rebuild their downtown area.

Geyser
Geyser

In addition to earthquakes, New Zealand has active volcanoes, geysers, and hot springs. On the South Island, we saw glaciers and vivid blue and green glacial lakes with colors so pure; it was difficult to believe they were natural. We crossed many rivers in our travels, stared straight up at towering cliffs, and in some places, we were surrounded by waterfalls too numerous to count. In pouring rain, our bus pulled into a small area that was circled by steep mountains, and as water rushed down the cliffs and swirled around us, our guide told us that this area was called “the toilet bowl,” an accurate description, at least during a rain squall. Not all the terrain in New Zealand is dramatic. Much of both islands consists of beautiful, rolling hills and pastures full of sheep, cattle, and even deer, which are farmed for their meat.

IMG_0224Two weeks of our trip was a hiking tour with Active Adventures New Zealand, with the emphasis on “active!” Our first big hike began by climbing 1800 large steps carved into the side of a mountain. By the time I got down, my legs were shaking, and I began to wonder if I’d make it through the next two weeks.

Our guides on the trip were Gary and Holly. Since guiding is also my job, I am always intrigued to watch other guides at work, and I was very impressed with Gary and Holly. Not only did they guide us on our many, long hikes, but they cooked most of our meals, and Gary drove our small bus with a trailer in tow over narrow, winding roads and one-way bridges. Sometimes, when it was raining, the windows became so fogged that I don’t know how he could see where he was going. While Gary drove, both he and Holly regaled us with Maori legends about how various lakes, rivers, and glaciers were formed. Most of these tales involved, at least, one or two beautiful princesses. We learned such things as how the Fox Glacier was formed, why there are sand flies in Milford Sound, how the kiwi birds lost their wings, how Maui slowed the sun, and much, much more (click on any of the above to learn the details of each legend). On top of all of this, Gary and Holly went out of their way to make sure each of their 14 charges had everything he or she needed or wanted.

We traveled with 12 other adventurers on our trip. Phil and Sue were from Canada, and the rest of us were from the U.S. One thing we soon learned about our guide, Gary, was that he is a master of the Kiwi understatement, and it didn’t take us long to translate his words:IMG_0414

A wee hike meant, at least, 4 to 6 hours.

A wee bit of climbing meant, at least, a 45⁰ angle

A wee bit of undulating terrain meant a steep climb followed by a steep descent followed by another steep climb and another steep descent and on and on.

A wee bit technical – Uh oh, that meant serious rock climbing would be involved.

A wee hill meant a snow-capped mountain.

Our two-week adventure culminated in a three-day option of either a multi-day hiking trip, kayaking for three days, or biking for three days. Six of us chose the hike while the rest of the group opted to go kayaking. Of the six hikers, Debbie chose to do one day of hiking, while the rest of us (obviously not the brightest of the bunch) went hiking for the full three days on the Angelus Circuit. Since we could not stop to resupply, we had to carry everything we needed for three days on our backs in large packs, including our personal gear, a sleeping bag, hiking poles, water, a bowl, cup, spoon, and a portion of the food.

Debbie, Mike me, Tara, Mike and, Denny.

The first day we hiked 3 ½ hours along beautiful Lake Rotoiti. We stayed at Lakehead Hut that night. The huts are interesting places with bunks for 28 people, and they are available to anyone who makes a reservation. You share kitchen facilities with the other campers, and yes, you sleep next to strangers. The outhouses at Lakehead Hut were a bit dicey since they were full of with sand flies and bees. This on top of the issues that normally accompany outhouses made a trip to the bathroom a bit stressful and to be avoided if at all possible. The hike to Lakehead Hut was fairly easy, but we knew the following day would be anything but easy, and I was simply hoping I could make it up the mountain! For our dinner the first night, Holly made us a wonderful pasta and vegetable meal, accompanied by wine that our fellow hiker, Mike Hofmann thoughtfully packed with him. After dinner, we enjoyed a Tim Tam Slam, an interactive dessert demonstrated by Holly. It involved sucking hot cocoa through a Tim Tam (a chocolate-frosted, chocolate cookie) and then sucking the cookie into your mouth before it disintegrated. The process left us all sticky and giggling while the other hikers in the hut watched us warily.

Tara, Mike, Mike, Denny, Gary and Holly
Tara, Mike, Mike, Denny, Gary and Holly

The weather was perfect on day two, but the hike was a brutal ascent to 4800 ft. We began the day by hiking across two “wee” rivers up a steep “wee” bit of elevated path through the trees, and then we knew we were really in trouble when Gary told us, “I won’t lie to you. The rest of the trek is steep and difficult.” There was no “wee” in his description, and I half expected him to pull climbing ropes and pitons from his pack. It was a tough climb. I think I stopped at every single trail marker and sucked in air. As I craned my neck back and looked upward there, seemed no end to the trail, and the few times I thought I could see the last marker; the trail turned, and the markers continued upward. Gary told us it would take 8 to 9 hours to get to the top, and I was proud that I made it up there in just over 7 hours. Mike and Denny, two of the guys in our group, made it in 6 hours. We all agreed that the hike had been tough, but the view from the top was worth our effort. As we crested over the top near Angelus Hut, we were treated to the breathtaking (what little breath I had left) view of sapphire-blue Lake Angelus, its windswept waves sparkling in the sun. That is a sight I will remember for the rest of my life!

IMG_1196

Angelus Hut next to the lake was also a treat. It was very clean with large picture windows looking out on the lake. Its volunteer caretaker, Mary, saw to it that the windows were spotless so that the hikers could enjoy the view. The outhouses were also spotless and mostly bug-free. The only downside to Angelus Hut was that hikers appeared from every direction, and the hut was full – all 28 beds. The hut was noisy most of the night with doors banging and people shuffling in and out.   That evening for dinner, Holly and Gary served chicken curry with a dessert of deconstructed cheesecake. It was delicious, and the mood was light. After all, Mike, Denny, Tara, Mike and I had completed the toughest day of the hike – at least, we thought it was the toughest day.

IMG_1203After a fitful night’s sleep, we awoke at 6:00, ready to tackle the last section of our hike. This morning we would hike another 45 minutes up and along the ridgeline for 4 hours before dropping down below the tree line for the final hour of hiking down to the car park. Gary did mention something about large rocks and small loose rocks, but I admit I wasn’t listening very closely. I just wanted to get back to our bus, and I thought it sounded like an easy day once we got to the ridgeline. I couldn’t have been more wrong! The hike to the ridgeline was no problem, but once we got up there, we were buffeted by winds that were gusting to 50 mph. The ridge was fairly narrow, and we had big packs on our back. When the wind gusted, I staggered, hunkering down to hold my position. I admit I was terrified I would be blown off the mountain, and those large rocks Gary had briefly mentioned turned out to be more of a problem than I had anticipated. We had to hop from one to the next in the driving wind. Thankfully, Gary stayed with me all the way, because it was not easy. He was also there to help me through the “loose rock” section, and then when a huge gust knocked me over and nearly sent me tumbling down the mountain, Mike held my hand for the rest of the hike along the ridge. Not only was it windy, but clouds were settling on the mountain, and was starting to rain. As our visibility decreased and the wind increased, I could sense the strain in Gary’s demeanor. He told us to keep moving as fast as we could, and Mike said, “You want us off this ridgeline, and I couldn’t agree more.” IMG_0439

Tara and I needed no encouragement. We wanted off the mountain worse than anyone. Finally, we began to descend, and the minute we dropped below the tree line, the world changed. We were out of the clouds, the rain stopped, the wind calmed, and below us, we could see Lake Rotoiti, gleaming like a jewel. The lake was home that day to speed boat races, and we could hear the roaring engines from high on the mountain. As the participants and spectators enjoyed a beautiful, Saturday afternoon in the sun, we marveled that they had no idea what the weather conditions were like on the mountain that towered above them. We stepped out of a world filled with wind, rain, fog, and peril and into a beautiful weekend afternoon at the beach.

Once we reached the carpark, Holly greeted each of us with a beer, and I told her I loved her. Then, we were off to meet the rest of our group for a wine tasting at a nearby winery, and this action perfectly captured the essence of our tour. We had three days of rugged hiking and staying in bare-bones huts, followed by a civilized wine tasting. I did, note, though, that we hikers looked a bit less civilized at the winery than did our fellow kayakers.IMG_0213

That night at our farewell dinner, Denny, one of my fellow travelers, made an eloquent toast to our guides. He said, “We will soon fade from your memories, but you will never fade from ours.” So true!

If New Zealand isn’t on your travel wish-list, it should be. It is a clean, beautiful country with some of the friendliest people I’ve ever encountered. I can’t say enough good things about it!

We are now on our way back to Alaska, and I can’t wait to get home. If you haven’t already done so, sign up for my Mystery Newsletter. Due to my vacation, there will be no March Newsletter, but I am already working on my April Newsletter.

If any of my fellow hikers is reading this, thanks again for being a part of my very memorable New Zealand adventure!

 

Steller Sea Lion

Kodiak Wildlife, Steller Sea Lion, , , , ,

DSC_0157

Steller sea lions are impressive animals, and you wouldn’t want to run into one in a dark alley, or even on a fishing dock.  A large bull can way over a ton, and they have a have nasty attitudes to go along with all that blubber.  For all you Star Wars fans, I’ve always imagined that Jabba the Hutt was created with a Steller sea lion in mind.  For this post and the next two, I will write about Steller Sea lions, their biology, distribution, social structure, and some amazing new research pinpointing a surprising possible predator of Stellers.

The Steller or Northern sea lion (Eumetopias jubatus) is a member of the order Pinnipedia, which includes harbor seals and walruses, and it is the largest species in the family Otariidae, the “eared seals”.  This family also includes the California sea lion and the Northern fur seal. Otariids, unlike phocids (the “true seals”), have external ear flaps, an elongate neck, long fore flippers used for propulsion, and hind flippers that can rotate, allowing sea lions to use all four limbs for movement on land.  They are called sea “lions”, because adult males have thick necks with long fur on the neck, resembling a lion’s mane.  Steller sea lions were named after German physician Georg Steller, who was the naturalist on the 1741 Russian expedition led by Vitus Bering.

Steller sea lions are found from southern California, along the coastline of the Pacific rim to northern Japan, but most of the breeding rookeries are located from the Gulf of Alaska to the Aleutian Islands.

Steller sea lions exhibit marked sexual dimorphism.  Males, on the average, are 1.3 times longer than females, but they weigh 2.5 times more than females.  Adult male Stellers average 1500 lbs. (750 kg) and are 9 ft. (2.7 m) in length.  A maximum-sized male can weigh as much as 2500 lbs. (1120 kg) and be 10 -11 ft. (3-3.4 m) in length.  Females average 600 lbs. (272.7 kg) and are 7 ft (2.1 m) in length, but may weigh as much as 770 lbs. (350 kg).

A Steller sea lion has a hefty body and a blunt snout.   A male has a distinctive forehead and a mane of long hair on the back of his neck, shoulders, and chest.  This mane not only protects him from cold air and water temperatures and from jagged rocks on his haul-outs and rookeries, but it also protects him when fighting with other males.  Pups are dark brown at birth, and since the tips of their hair are colorless, they appear frosty.  Their hair lightens after their first molt.  Adults are blonde to reddish- brown with dark- chocolate-brown on their undersides and flippers.  Females are usually lighter in color than males.  A Steller’s fur is thick and coarse, and they shed or “molt” their fur every year.  The molt takes approximately four weeks and occurs in the late summer or early fall.

A sea lion has a streamlined body shaped like a torpedo, which reduces drag when moving through the water.  This streamlining is due to a thick layer of blubber under the skin.  Stellers have long, wing-like fore flippers that they stroke up and down to thrust themselves through the water in a movement that resembles flying.  They use their hind flippers for steering.  Unlike harbor seals, sea lions are able to fold their hind flippers under their bodies to walk on land.  They are quite agile on land, and an adult male Steller can easily out-run a human.

Stellers, like all eared seals, have small, external ear horns. Biologists believe that hearing is one of the most important senses for a sea lion, and they probably have acute hearing under water and fairly good hearing in air.

Steller sea lions are very vocal.  At a haul-out, you may hear growls, roars, and grumbles from the older sea lions, along with lamb-like vocalizations from young pups.  Unlike California sea lions, Stellers do not bark.

I’ll have more about Stellers next week. Meanwhile, if you haven’t already done so, visit my home page and sign up for my Mystery Newsletter.