Category Archives: Kodiak Wildlife

Wildlife of Kodiak Island including biology, behavior, and news

Steller Sea Lions, Part 3

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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.

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Steller Sea Lion, Part 2

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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.

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Steller Sea Lion

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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.

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Sea Otters Part 2

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Sea otters are well adapted to their marine environment.  Their nostrils and ears can close when diving, and they are able to change the refractive power of their lenses so they can see clearly in water as well as in air. The skeleton of a sea otter is loosely articulated and has no clavicle, allowing the animal a great deal of flexibility when swimming and grooming. A sea otter’s hind feet are flattened and webbed much like flippers, and the fifth digit on each foot is elongated, allowing the otter to swim more efficiently on its back. The front paws are short and have extendable claws and tough pads on the palms, enabling the otter to grip slippery prey, and the teeth are adapted for crushing hard-shelled invertebrates.  Sea otters have large, lobulated kidneys that allow them to conserve water and maintain water balance while living in a saltwater environment, Their kidneys efficiently absorb water and eliminate excess salt in urea, a waste product more concentrated than sea water. Sea otters are very buoyant due to their large lungs, which are two-and-one-half times bigger than those of a similar-sized land mammal.

Sea otters are not particularly streamlined, and because of this, they are the slowest swimming of all marine mammals. Top speed for a sea otter is 5.6 mph (9 km/hr), but speeds of 2 to 3 mph (3.2 to 4.8 km/hr) are more common. Sea otters usually swim on their backs while paddling with their hind flippers, but when an otter needs to travel quickly, it swims on its stomach and undulates its entire body. Sea otters are graceful in the ocean, but they aren’t built to travel on land.  It is rare to see a sea otter on land, but some like to haul out on rocks, and on Kodiak, we occasionally see sea otters resting on blocks of ice in the winter.  When they do travel on land, they travel at a clumsy, rolling gait or run in a bounding motion.

Otters generally dive and feed in fairly shallow water, less than 60 ft.(18.3 m), and they normally only stay under water for one to two minutes, but they have been known to dive as deep as 330 ft. (100.58 m) and remain submerged for as long as four to five minutes.  They are able to stay under water this long because of their large lungs that can store an abundant supply of oxygen, and because of their flexible ribs that allow their lungs to collapse under pressure.

Sea Otter eating an octopus
Sea Otter eating an octopus

A marine mammal must maintain a body temperature near 100° F (37.8° C), and in Alaska, where the water drops as low as 35° F (1.67° C), this can be a challenge.  Other marine mammals have a thick layer of blubber to insulate themselves from the cold, but sea otters have very little fat and depend mainly on their fur to keep them warm.  Sea otters have the thickest fur of any animal, with 850,000 to one million hairs per square inch (up to 150,000 per square centimeter). It is their dense, beautiful fur that made them so valuable to fur traders in the 1700’s and 1800’s.

 

The fur consists of two layers.  Long guard hairs form the outer layer, and these provide a protective coat that keeps the underfur dry.  It is this extremely dense underfur that keeps the otter warm, but to insulate efficiently, the fur must be clean, so sea otters spend a large portion of each day grooming and cleaning their fur.   In addition to cleaning his fur, an otter will somersault in the water and rub his body to trap air bubbles in his fur.  These bubbles not only provide insulation but also help to keep the skin dry. Since sea otters must have clean fur to stay warm, they are particularly susceptible to the ravages of an oil spill.  If their fur becomes oiled, it loses its insulating properties. And when an otter tries to clean his oiled fur, he ingests the toxins from the oil.  An otter’s underfur ranges from brown to black, with guard hairs that may be light brown, silver, or black. Alaskan sea otters often have lighter fur on their heads, and the fur usually lightens as an otter ages.

 

In addition to their warm fur, sea otters maintain their body heat by burning calories at a rapid rate.  A sea otter’s metabolism is two to three times higher than that of a similar-sized land mammal.  Because its metabolic rate is so high, a sea otter must eat 23 to 33 percent of its body weight each day.  That means that a fifty-pound otter will eat 11 to 16 lbs. (5 to 7.3 kg) of food every day.  Sea otters also maintain their body heat by keeping their forepaws out of the water and their hind flippers folded over their abdomens when resting and floating.  An otter’s paws are covered by very little fur and lose heat rapidly when submerged in cold water.

 

 

Sea Otters

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Sea otters evoke strong emotions in humans.  Most of us can’t help but say, “Ahhhh!” when we see a cute furry otter floating on its back or looking at us in surprise, front flippers held high in the air.  Watching a baby sea otter sitting on its mother’s stomach, or hearing one break open a clam on a rock makes most of us smile.  Many fishermen, though, are not fond of sea otters and for a good reason.  Sea otters are so efficient at finding and eating shellfish that they are able to reduce populations of abalones, clams, and sea urchins to the point where a commercial fishery for these species is not viable in areas with large sea otter populations.  In this post and my next two posts, I’ll discuss sea otters and their fascinating biology and behavior.

While sea otters are the second smallest marine mammal, they are the largest members of the mustelid family, which also includes freshwater otters, weasels, minks, skunks and badgers. Sea otters may weigh as much as 100 lbs (45.5 kg).  The average adult California female weighs 44 lbs. (20 kg), and the average male weighs 64 lbs. (29 kg).  In Alaska, the average adult female is 4 ft. (1.2 meters) long and weighs 60 lbs. (27.3 kg), while the average adult male is 5 ft. (1.5 meters) long and weighs 70 lbs. (31.8 kg).

River Otter

Sea otters are the only mustelid in the genus Enhydra, and they are significantly different from all other mustelids. Sea otters are one of nine to thirteen (taxonomists disagree on the exact number) species of otters found around the world. Except for sea otters and the endangered species of marine otters, all other otters live primarily in freshwater, although river otters (Lutra canadensis) travel freely between rivers and the ocean, and on Kodiak, it is common to see river otters swimming near shore in the ocean.  River otters and sea otters resemble each other, but sea otters are larger and weigh two to three times more than river otters.  Sea otters have adapted to a life in the ocean with hind feet that are webbed to the tips of their toes and resemble flippers.  River otters also have webbed feet, but they are small, making it easier for river otters to move on land, while sea otters are very clumsy out of water. A sea otter’s tail is flat and looks like a paddle, while a river otter has a long, round tail that tapers to a point. The claws in the forepaws of a sea otter can be extended, but those of a river otter cannot. River otters swim on their stomachs, and although sea otters can also swim on their stomachs, they usually swim on their backs while paddling with their hind flippers.  River otters give birth to litters of up to four pups, but sea otters, like other marine mammals, usually only give birth to a single pup.

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There are three subspecies of sea otters.  Enhydra lutris lutris ranges from the Kuril Islands to the Commander Islands in the western Pacific Ocean.  The sea otters in this subspecies are the largest and have a wide skull and short nasal bones. The Southern sea otters, or the California sea otters as they are commonly called (Enhydra lutris nereis), are found off the coast of central California.  Sea otters in this group are smaller and have a narrower skull with a long rostrum and small teeth.  The vast majority of sea otters belong to the subspecies Enhydra lutris kenyoni, the Northern sea otters.  This subspecies ranges from the Aleutian Islands to British Columbia, Washington, and northern Oregon.

Before the 1700’s, an estimated 150,000 to 300,000 sea otters inhabited the area from northern Japan to the Alaska Peninsula and along the Pacific coast of North America to southern California. Between 1741 and 1911 when sea otters were aggressively harvested for their luxurious furs, the population dropped to only 1000 to 2000 animals, and they had been eliminated from much of their original range. Many biologists believed the population was headed toward extinction. In 1911, the International Fur Seal Treaty was signed by the U.S., Russia, Great Britain, and Japan, stopping the commercial hunting of sea otters, and slowly, their numbers began to increase.  Sea otters began re-colonizing much of their former range and were reintroduced to other areas.  Sea otters now occupy about two-thirds of their historical range.

 Counts between 2004 and 2007 estimate the worldwide sea otter population at approximately 107,000 animals. Sea otter populations are considered stable in most areas, although California populations have plateaued or slightly decreased, and there has been a drastic decline in sea otter numbers in southwest Alaska, from Kodiak Island through the western Aleutian Islands.  This area once contained more than half of the world’s sea otters, but the population has declined by at least 55 to 67 percent since the mid 1980’s, and in 2005, the U.S. Fish and Wildlife Service listed this distinct population segment as Threatened under the Endangered Species Act. In 1973, the otter population in Alaska was estimated at between 100,000 and 125,000 animals, but by 2006, the population had fallen to approximately 73,000 animals, mainly due to declines in the Southwest Alaska District Population Segment. The cause of this decline is unclear, but evidence suggests that it may be due to increased predation by killer whales.

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Porpoises

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Two species of porpoises frequent the waters near Kodiak Island: The harbor porpoise and Dall’s porpoise. Our guests often ask if the terms dolphin and porpoise can be used interchangeably, and the answer is no! Porpoises and dolphins are as distinct as cats and dogs, and they belong to different taxonomic families. Porpoises are smaller than dolphins, and they are stockier and lack the characteristic “beak” of a dolphin. Porpoises have spade-shaped teeth while dolphins have conical teeth. Porpoises grow faster and reach sexual maturity at a younger age than most dolphin species. Most porpoise species are less social than dolphins, and porpoises usually hang out alone or in small, fluid groups.

Harbor, Porpoise

The harbor porpoise is one of the smallest oceanic cetaceans, and it is the smallest cetacean found in Alaska. The body of a harbor porpoise is stocky and rotund through the mid-section, tapering to a slender tail stock. An average harbor porpoise is five ft. (1.5 m) in length and weighs 130 lbs. (60 kg). The body is dark gray or dark brown on the back, fading to a lighter gray on the sides. The throat and belly are white, but there may be a streak of gray on the throat and a dark chin patch. The flippers are dark in color, and a dark stripe extends from the flipper to the eye

Harbor porpoises primarily eat fish, but they may also feed on squid, octopus, and crustaceans. In Alaska, they feed on fish such as cod, herring, and pollock, and it has been estimated that they eat approximately 10% of their body weight each day. They surface in a slow roll and rarely “porpoise” out of the water. They are shy and seldom approach vessels, and they never play in the bow wake like Dall’s porpoises do. Large sharks, dolphins, and killer whales all prey on harbor porpoises.

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Dall’s porpoise is easily identified by its striking black and white coloration that resembles the markings of a killer whale and the characteristic rooster-tail splash it often makes when surfacing. A Dall’s porpoise averages six ft. (1.8 m) in length and weighs approximately 270 lbs. (123 kg). It has a stocky, muscular body and is particularly robust through the mid-section. It has a small, round head that slopes steeply to a short, poorly defined beak. It has small teeth shaped like grains of rice. The teeth are the smallest of any cetacean species, and they often do not rise above the surface of the gums. The color pattern of Dall’s porpoises varies between individuals, but most are black on the upper sections of the body, with large oval-shaped white sides and white bellies. A band of white usually borders the flukes and the dorsal fin.

Dall’s porpoises forage at night, and they feed on small fishes and cephalopods. In Alaska, they eat squid and small schooling fishes such as capelin, lantern fish, and herring. A Dall’s porpoise consumes approximately 28 to 30 lbs. (12.7-13.6 kg) of food each day.

Dall’s porpoises are the fastest of the small cetaceans, reaching speeds of 35 mph ( 56.3 km/hr), which is a tie with killer whales for the fastest marine mammals. You can often see them from a distance, slicing through the water and creating a V-shaped splash called a rooster-tail splash. This splash creates a hollow cone that allows the porpoise to breathe under the surface of the water. Dall’s porpoises rarely engage in acrobatic behavior such as breaching or leaping out of the water, but they will charge a rapidly moving boat to ride the bow or stern waves, and they may remain in the bow wave for half an hour or more, darting in and out of the wake and making steep-angled turns.

Killer whales and sharks may prey on Dall’s porpoises, but because of their speed, agility, and fairly large body size, they often can escape predators. About 30 Dall’s porpoises per year die as a result of being caught in fishing nets in Alaska. It is unclear why they get caught in salmon nets, since they don’t feed on salmon, but many of the deep-sea species they do feed on come to the surface at night when these porpoises feed, making it more likely they will run into nets.

 

 

 

 

 

More About Toxic Algae

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Last week I discussed the toxic algae that cause paralytic shellfish poisoning, and this week, my post is about other species of toxic algae, the symptoms they cause and their impacts on humans and animals.

Amnesic Shellfish Poisoning (ASP) is caused by domoic acid, a biotoxin that is produced by the diatom Pseudo-nitzschia. Fish and shellfish, including bivalves and crab, can accumulate domoic acid with no ill effects, but when humans, other mammals, and birds consume the toxic fish and shellfish, they suffer the effects of ASP. As with paralytic shellfish poisoning (PSP), cooking or freezing the toxic organisms does not lessen the toxicity. This past summer, scientists estimated that the largest-ever bloom of Pseudo-Nitzchia occurred, stretching from California to Southeast Alaska and prompting Oregon and Washington to issue emergency closures for their commercial shellfish fisheries. The bloom was not obvious from sea level, but satellite images showed that a large swath of the ocean had been overtaken by the single-celled algae.

Domoic acid can be fatal if consumed in high doses. It is a neurotoxin that inhibits neurochemical process and can cause short-term memory loss and brain damage. Symptoms appear within 24 hours of ingesting the toxic organism, and they include vomiting, nausea, diarrhea, and abdominal cramps. In more severe cases, neurological symptoms such as a headache, dizziness, confusion, disorientation, vision disturbances, loss of short-term memory, motor weakness, seizures, profuse respiratory secretions, hiccups, unstable blood pressure, cardiac arrhythmia, and coma may occur within 48 hours or up to three days.

In 1987, ASP caused the deaths of three people on Prince Edward Island who ate infected mussels. There is no antidote for domoic acid. Of the 107 confirmed cases, there were four deaths and a few cases of permanent short-term memory loss. Since March 2007, the large increase in marine mammal and seabird strandings and deaths off Southern California has been linked to the recent blooms of toxic algae, and most of the dead animals tested positive for domoic acid.

Ciguatera is not something we worry about in Alaska. It is a foodborne illness caused by eating certain tropical and subtropical reef fish. Ciguatoxin has been found in over 400 species of reef fish, and it can also occur in farm-raised salmon. It is caused by several species of dinoflagellates such as Gambierdiscus toxicus that adhere to coral, algae, and seaweed. The toxic dinoflagellates are eaten by herbivorous fish that are in turn eaten by carnivorous fish that may then be eaten by larger carnivorous fish. The toxin is biomagnified as it moves up the food chain, so predators near the top of the food chain are likely to be the most toxic. Like the other toxins we have discussed, ciguatoxin is odorless, tasteless, and cannot be broken down or removed by cooking.

Symptoms of ciguatera in humans include nausea, vomiting, and diarrhea, usually followed by headaches, muscle aches, ataxia, numbness, vertigo, and hallucinations. These neurological symptoms can persist and are sometimes misdiagnosed as multiple sclerosis. Interestingly, some ciguatera toxins can be passed from an infected individual to a healthy individual through sexual intercourse, and diarrhea and facial rashes can occur through breast feeding in an infant whose mother has been poisoned. The symptoms of ciguatera can last from weeks to years, sometimes as long as 20 years. Most people do recover over time, but symptoms often reappear.

Cyanotoxins are produced by bacteria called cyanobacteria (blue-green algae). Cyanobacteria is found in both fresh and salt water, and blooms often form thick mats or scum over the surface of the water. Sometimes the blooms are such a bright green that they look like paint floating on the water. Cyanotoxins include neurotoxins, hepatotoxins, cytotoxins, and endotoxins. The cyanobacteria neurotoxin BMAA can cause neurodegenerative diseases such as ALS, Parkinson’s disease, and Alzheimer’s disease. Cyanotoxins are toxic to animals as well as humans.

I am intrigued by toxic algae, and I am concerned that as our oceans warm and receive more nutrients from man-made runoff, toxic algae blooms will plague not only humans but also fish, birds, and marine mammals. The dinoflagellates, diatoms, and bacteria that produce marine toxins are tiny organisms that we can’t even see, but their impacts are huge.

I promise a less-technical post next week, and please don’t hesitate to leave a comment telling me what you’d like me to write about. Also, if you are interested in true crime, don’t forget to sign up for my Mystery Newsletter. As soon as you sign up, I’ll send you my first newsletter.

Toxic Algae

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 Blooms of toxic algae are nothing new. Toxic algae occur naturally in both fresh and salt water, and algal poisonings have happened many times over the centuries. What is different is the frequency and magnitude of toxic blooms in some areas of the world. Environmental conditions such as changes in salinity, increasing water temperature, and an influx of nutrients can trigger an algal bloom, and once the bloom begins, it can increase exponentially in a short period. As our oceans get warmer, it is likely we will see even more of these toxic blooms in upcoming years. This past summer, a massive bloom of the algae Pseudo-nitzschia that produces domoic acid, a powerful neurotoxin, shut down the Washington state commercial fishing season for Dungeness crab, causing millions of dollars in lost revenue, and this toxic bloom possibly caused the deaths of at least 44 whales in Alaska.

In my next two posts, I will dive into the topic of toxic algae in more detail. There are several species of toxic algae, and I will discuss four types of algal poisonings caused by toxic blooms: Paralytic shellfish poisoning, amnesic shellfish poisoning, poisoning caused by ciguatera toxin, and cyanotoxic poisoning.

     Paralytic shellfish poisoning (PSP) is caused by a microscopic single-celled dinoflagellate algae in the genus Alexandrium. Bivalve shellfish, such as mussels and clams, may feed on these dinoflagellates and concentrate PSP toxins that are not harmful to the bivalves but are poisonous to humans, other mammals, and some birds that feed on these bivalves. Crab can also concentrate the toxin in their viscera.

In my novel, Murder Over Kodiak, Dr. Jane Marcus is working to develop a small, inexpensive kit that would allow a person to dig a bucket of clams and easily test them to make sure they aren’t toxic before eating them. She explains the difficulty of her research to FBI Agent Nick Morgan by telling him that PSP toxins are called saxitoxins, which are produced by dinoflagellate algae. These dinoflagellates do not produce just one toxin, but 21 molecular forms of saxitoxin, and these 21 forms can undergo transformations that can change one toxin into another. The forms vary in toxicity. A person’s stomach acid can change the original saxitoxin into another form that is six times more toxic. Furthermore, some species of bivalves can hold higher levels of the toxin than other species can, and some species, such as butter clams, have the ability to bind the most highly toxic forms of saxitoxin. Steamer clams, on the other hand, transform saxitoxin into one of its less toxic forms.

In my novel, a lady eats toxic clams for dinner and suffers the textbook symptoms of severe PSP. Twenty minutes after eating the infected bivalves, her lips begin to feel numb, and her fingers and toes start to tingle. Soon, she is dizzy and sick to her stomach, her breath coming in short gasps. Forty-five minutes later, she can’t walk or talk and is barely breathing. She stops breathing in the Coast Guard helicopter on the way to the hospital.

Saxitoxins are neurotoxins that block the movement of sodium through nerve-cell membranes, which stops the flow of nerve impulses, causing numbness, paralysis, and disorientation. The toxicity of saxitoxins is approximately 1000 times greater than cyanide, and the symptoms begin to appear soon after consuming the toxic shellfish. There is no antidote for PSP, and there is nothing that can be done to toxic shellfish to render them safe for consumption. Saxitoxins do not dissolve in water, and they are heat and acid-stable. In other words, cooking the bivalves will not break down the toxins. Some shellfish store the toxin for weeks, and others, such as butter clams, can store the toxin for as long as two years. All cases of PSP require immediate medical attention, and some may require life support equipment to save a victim’s life. If the dosage of PSP is low and if proper medical treatment is administered, the symptoms usually diminish in nine hours.

The worst historical account of PSP poisoning occurred in Southeast Alaska in July 1799 when more than 100 Russians and Aleuts died from eating clams and mussels gathered from Peril Straits near Sitka. The most recent cases occurred last summer when two people died in Southeast Alaska, one from eating a cockle and the other from eating a Dungeness crab, and three people became ill in Kodiak from eating butter clams. Cockles tested in Southeast Alaska last summer had a level of PSP that was 2,044 parts per million. Anything over 80 parts per million is considered unsafe for human consumption. PSP also kills sea otters, and it probably is toxic to other mammals. It is known to affect shags, common terns, common murres, Pacific loons, sooty shearwaters, and possibly many other bird species.

As a side note, I am not the first person to use algal toxins as part of the plot of a story, and I am in good company. In 1961, hundreds of crazed birds, mostly sooty shearwaters, attacked the town of Capitola, California, crashing into street lamps and through glass windows and attacking people. These birds normally live offshore, but it is assumed that they dined on small fish that had eaten toxic Pseudo-nitzchia algae, and the birds became disoriented after succumbing to amnesic shellfish poisoning. Alfred Hitchcock based his screenplay The Birds on this incident. I’ll discuss amnesic shellfish poisoning in more detail next week.

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Arctic Tern (Sterna paradisaea)

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The Arctic tern (Sterna paradisaea) is one of three species of terns found in Alaska. The other two species are the Aleutian tern (Onychoprion aleutica) and the Caspian tern (Sterna caspia). Terns belong to the family Laridae, which also includes gulls.

Arctic terns have a circumpolar range. They breed in the Arctic and subarctic regions of North America, Europe, and Asia, and they winter at the southern tips of Africa and South America, all the way to the edge of the Antarctic ice. In the United States, Arctic terns nest as far south as New England on the east coast and Washington State on the west coast. In Alaska, the Arctic tern has the largest breeding range of any Alaskan water bird. Arctic terns nest from Point Barrow through the Southeast Panhandle, and everywhere in between those two points.

Since Arctic terns breed in Arctic and subarctic areas and then migrate as far as the edge of the Antarctic ice to spend the winter, biologists believe they have the longest migration of any animal. The only animal whose migration may rival that of the Arctic tern is the sooty shearwater which migrates between New Zealand and the North Pacific. In a 2010 study, biologist Carsten Egevang and his colleagues fitted 11 Arctic terns with miniature geolocators, and they learned Arctic terns migrate even further than was previously believed. Some individual terns in the study traveled nearly 50,000 miles (more than 80,000 km) round trip. Because Arctic terns spend summer in the high latitudes of the northern hemisphere and then travel to the high latitudes of the southern hemisphere for the summer there, they see more sunlight every year than any other animal species on the planet.

Arctic terns measure 14 to 17 inches (36-43 cm) in length and have a wingspan of 29 to 33 inches (74-84 cm). Their bodies are white or gray during the breeding season, and a black patch covers the head and forehead. They have a sharply pointed red bill and short red legs. Their deeply forked tail resembles the tail of a swallow and is the reason for their nickname, “Sea swallow.” Terns are agile and quick in the air and can even hover above the water while searching for food. Because they have small, webbed feet, terns do not swim well and do not remain in the water any longer than it takes to catch their prey. A tern flies with its bill pointed down toward the water, and when it sees a fish or other prey, it dives into the water, grasps the prey, and flies away with the fish in its beak. During the non-breeding season, a tern’s legs and beak turn black, and the black patch on the head shrinks. Also during the non-breeding season, terns molt and lose most of their feathers. If they lose their feathers faster than they can be replaced, they may be flightless for a short period.

Arctic terns mate for life, and in Alaska, they arrive at their breeding areas in early to late May. During their courtship, the male performs a “fish flight.” He carries a fish in his bill and flies low over the female on the ground. If she sees him, she will join him in a high climb and flight. Terns nest in solitary pairs or colonies of a few to several hundred pairs. A tern’s nest is little more than a shallow depression in the ground, and nests usually have little or no lining material. Terns nest near fresh or salt water on beaches, spits, and small islands. The female lays one to three eggs that are brown or green and lightly speckled. Both sexes incubate the eggs, and the eggs hatch in about 23 days. The young terns immediately leave the nest and hide in nearby vegetation. The parents catch small fish to feed the chicks for the next 25 days until the chicks have fledged. Arctic terns are very aggressive during the breeding season, and they will attack intruders by crying loudly and repeatedly diving at the intruder’s head. Less than three months after they arrive at their breeding colonies, Arctic terns begin their long migration south.

Arctic terns eat small fish, insects, and invertebrates. During the non-breeding season, they are pelagic and forage at the edges of the pack ice, icebergs, and ice floes near shore.

The worldwide population of Arctic terns is between one and two million breeding pairs. Several hundred thousand pairs nest in Alaska. Because terns nest on the ground, their eggs, and chicks are susceptible to predation by foxes, rats, raccoons, gulls, and other seabirds. Arctic terns are also susceptible to pollution, human disturbance, and decreased food availability due to warming ocean temperatures. Arctic terns may live into their late twenties or early thirties.

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Dead Whales

Fin Whale, Humpback Whale, Kodiak Wildlife, Living in the wilderness on Kodiak Island, , , , , , , , ,

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This summer and fall several dead whales were spotted in the Western Gulf of Alaska, with the majority clustered around Kodiak Island. The number of deaths now stands at 43 whales, including fin whales, humpbacks, and, at least, one gray whale. So far, none of the whale carcasses that could be accessed have been in good enough shape to provide a clue to the cause of the deaths, but the National Oceanic and Atmospheric Administration (NOAA) is so concerned that they have classified the deaths an “unusual mortality event” (UME). A UME is defined as a significant die-off of a marine mammal population that demands an immediate response.  This designation triggers a focused, expert investigation into the cause.

At nearly the same time dead whales were being discovered in Alaska, whales were also dying off the coast of southern Chile. In November, biologists in Chile announced that in June, 337 sei whales were found beached in a region of southern Patagonia in Chile. This is one of the largest whale strandings ever recorded. While these whales were found beached, researchers think they died at sea and washed up on the beach.

What caused the deaths of the whales in Alaska and Chile, and did they all die from the same cause? Sadly, we may never know the answers to these questions, but biologists in both Alaska and Chile suspect a harmful algae bloom may be the culprit. Most of the dead whales are baleen whales that feed low on the food chain, making them highly susceptible to a toxic algae bloom. What makes this scenario even more believable is that abnormally warm water conditions in the Pacific Ocean this summer led to a massive toxic algae bloom of the single-celled algae Pseudo-nitzschia.

Pseudo-nitzschia produces domoic acid, a powerful neurotoxin. Under normal circumstances, a domoic acid concentration of 1,000 nanograms per liter is considered high, but in mid-May, concentrations 10 to 30 times this level were found in the North Pacific. Domoic acid accumulates in zooplankton, shellfish and fish, and when mammals and birds eat these organisms, the accumulated acid over-stimulates the predator’s nervous system, causing the animal to become disoriented and lethargic. Ingestion of high concentrations of domoic acid can lead to seizures and death.

In addition to Pseudo-nitzschia, the warm ocean water conditions in the Pacific also may have resulted in blooms of other toxic algae, but if toxic algae are the culprit, why aren’t other mammals or birds dying as a result? These are questions researchers are scrambling to answer, and recently they have been rechecking photos to see if there is evidence that the whales may have starved to death. Warmer ocean conditions could have led to a reduction in the prey of these huge whales that must eat  continuously all summer to build a blubber layer that will last them through the winter.

There is no time frame for when a UME must end, and biologists plan to keep researching the whale deaths for a while longer, but they admit the cause may never be known. One dead whale washed up a few miles from where we live, but we saw many other whales this summer that seemed to be feeding and acting normally, and I hope the whale deaths were an anomaly that won’t continue next spring and summer.

Next week I’ll go into more detail about toxic algae blooms. For those of you who have read my novel, Murder Over Kodiak, you may remember that Jane Marcus was studying paralytic shellfish poisoning, a condition caused by a poisonous algae bloom, and since toxic algae have been in the news this year, I think it will be an interesting topic to tackle.

I am FINALLY ready to send my first Mystery Newsletter to those who have signed up for my list. I plan to mail it on January 6th, so if you haven’t signed up for my list yet, do so soon on my home page. My first newsletter will chronicle the events of the McCarthy massacre of 1983. Thanks, and be sure to leave a comment to let me know what you think of my post!