Category Archives: Kodiak Wildlife

Wildlife of Kodiak Island including biology, behavior, and news

What Do Sea Otters Eat?

November 4, 2018Kodiak Wildlife, Sea OtterAlaskan Sea Otters, Do sea otters eat fish, Kodiak Wildlife, Robin Barefield, Sea Mammals of Alaska, sea otter, What Do Sea Otters Eatadmin

As I told you last week, a sea otter burns calories at a rapid rate to help maintain its body temperature in its home in the cold North Pacific. It consumes between 23 and 33 percent of its body weight per day, so a fifty-pound otter eats 11 to 16 lbs. (5 to 7.3 kg) of food every day. Where does a sea otter find this much food, and what do they eat?

Sea otters are known to consume more than 150 different prey species, mostly slow-moving benthic invertebrates such as mollusks, crustaceans, and echinoderms, but if they are hungry enough, they also sometimes eat fish and even seabirds. Sea otters are the only marine animals capable of lifting and turning over rocks in search of prey and the only marine mammal that catches fish with its forepaws rather than with its teeth.

Studies done in southeast Alaska, Prince William Sound, and near Kodiak Island indicate that clams are the primary and preferred prey of sea otters in these regions. Clams constituted anywhere from 34% to 100% of the diet of sea otters near Kodiak. In areas where clams are less plentiful, and in areas where otters have depleted the clam populations, mussels and sea urchins comprise a larger percentage of otters’ diets. Crabs are also important prey species where they are available. On the west side of Kodiak Island, we see otters eating clams, scallops, crab, and octopus. Sea otters’ diets vary not only from one location to another and in response to available prey species, but also because individual otters have different food preferences, and a mother often passes on her fondness for certain foods to her pup.

A sea otter has a loose pouch of skin under each foreleg where it can store food collected on a dive. When the otter returns to the surface, it can rest on its back and leisurely retrieve one piece of food after another from its pouch. In addition to food, the sea otter also stores a rock in one of its pouches. The otter can use the rock underwater to pry loose mussels or other attached bivalves or to dislodge sea urchins wedged in crevices. When floating on the surface, the otter places the rock on its chest and pounds crabs, snails, clams, and other prey against the rock to break through the tough shells. Sea otters are one of the few animals other than humans known to use tools.

Sea otters are very efficient at finding and eating shellfish, and where large groups of sea otters reside, they reduce populations of abalones, clams, and sea urchins to the point where a commercial fishery for these species in the area is not viable. This competition between sea otters and fishermen creates a conflict which cannot be easily resolved by fish and wildlife managers.

Sea otters are considered a “Keystone” species, meaning they affect the ecosystem to a much greater degree than their numbers would suggest. Sea otters protect kelp forests off Northern California by eating herbivores such as sea urchins that graze on the kelp. In turn, the kelp forests provide food and cover for many other species of animals, and kelp forests play an important role in capturing carbon and reducing atmospheric carbon dioxide levels. Without sea otters, urchins over-graze the kelp, throwing the ecosystem out of balance.

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Robin Barefield is the author of three Alaska wilderness mystery novels, Big Game, Murder Over Kodiak, and The Fisherman’s Daughter. To download a free copy of one of her novels, watch her webinar about how she became an author and why she writes Alaska wilderness mysteries. If you like audiobooks, check out her audiobook version of Murder Over Kodiak. Also, sign up below to subscribe to her free, monthly newsletter on true murder and mystery in Alaska.

Mystery Newsletter

How Do Sea Otters Stay Warm?

October 28, 2018Kodiak Wildlife, Sea OtterAlaskan Sea Otters, How Do Sea Otters Stay Warm, Northern Sea Otter, Robin Barefield, sea otter, Sea Otters near Kodiak Islandadmin

Northern sea otters (Enhydra lutris kenyoni) are common in the waters surrounding Kodiak Island. Our summer guests love watching and photographing these cute, curious animals as we pass by them in our boat. Some otters lie placidly on their backs and watch us motor past, and others dive from the perceived danger we create. A few otters repeatedly twist and turn in the water or turn summersaults, and we laugh at their comical antics. The truth is, though, sea otters don’t turn summersaults because they are having fun; these movements have the much more practical application of keeping the animals warm.

A marine mammal must maintain a body temperature near 100° F (37.8° C), and in Alaska, where the water temperature drops as low as 35° F (1.67° C), keeping warm 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 for insulation. 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.

A sea otter’s fur consists of two layers. Long guard hairs form the outer layer, providing a protective coat to keep the underfur dry. The extremely dense underfur provides warmth, but for the fur to insulate efficiently, it 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 his skin dry. An otter’s underfur ranges from brown to black, and the guard hairs vary from light brown to silver or black. Alaskan sea otters often have lighter fur on their heads, and the fur usually lightens as an otter gets older.

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 the metabolism 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. This means a fifty-pound otter will eat 11 to 16 lbs. (5 to 7.3 kg) of food every day.

Because very little fur covers an otter’s paws, they lose heat rapidly when submerged in cold water, otters conserve heat by keeping their forepaws out of the water and their hind flippers folded over their abdomens when resting and floating.

Since sea otters are dependent on their fur to keep them warm and insulated from the cold ocean water, and because they must continually groom their fur to maintain its insulating properties, they are extremely vulnerable to the effects of pollution. When oil or another pollutant soils an otter’s fur, the fur becomes matted, and it can no longer keep the animal warm. Matted fur can lead to hypothermia and death from exposure. When the otter tries to clean his fur to remove the pollutant, he ingests the toxin, which is also often fatal.

When the Exxon Valdez struck a reef in Prince William Sound in 1989 and spilled eleven million gallons of crude oil, nearly 1000 sea otter carcasses were recovered, and biologists estimated the actual number of sea otters killed by the oil spill was anywhere from 41% to 80% higher than the number of dead otters observed.

Sea otters have many interesting adaptations to a life spent in the ocean. In this post, I told you how much sea otters need to eat each day just to stay warm, and next week, I’ll write about what sea otters eat and how they catch and eat their prey.

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Mystery Newsletter

How Can You Tell if a Kodiak Bear is a Male or a Female?

October 7, 2018Kodiak Bear, Kodiak WildlifeAlaskan Brown Bears, Brown Bears, Clues to differentiate male and female Kodiak bears, How to tell whether a bear is male or female, Kodiak Bear, Kodiak Island, Robin Barefieldadmin

Unlike cartoon bears, female Kodiak bears don’t wear hair ribbons on their head, so you must depend on other factors when trying to differentiate a male from a female bear. Last week, when I wrote about how to judge the size of a bear, I covered some of the ways body shape and musculature vary between males and females, but I will cover body shape and other clues in more detail this week.

Does the Bear Have Cubs?

This statement seems so obvious to me that I almost forgot to mention it. I’m sure most of you know male bears do not hang around with cubs. Regardless of what you might have seen in the movies, a Kodiak bear accompanying cubs is always their mother.

Do you see sex organs?

Minus cubs, there are only two sure ways to determine the sex of a Kodiak bear. The first is the presence of either nipples or a penis sheath and testicles. Even if you don’t see her cubs, you might see nipples in the armpit area of a nursing female when she walks. While often not visible, you sometimes see the penis sheath and testicles on a male, especially on a large boar.

Have you seen the bear urinate?

The only other way to be certain of the sex of the bear is to watch it urinate. Females urinate outward and to the rear, while males urinate straight down or forward between the legs. Females also sometimes squat to urinate.

Head and Shoulders:

If you do not see cubs or sex organs, and if the bear is not cooperative enough to urinate in front of you, you will have to depend on other clues to make an educated guess at the sex of the bear. Some of these are the same body shape differences I covered last week when I discussed how to determine the size of a bear.

A female brown bear’s head is narrower than a male’s, and her muzzle tapers, giving her a pointy nose. A female also has narrow shoulders roughly the same size as the head. Male Kodiak bears are more muscular than females. A male has a wide head and a square face. A large male’s forehead muscles bulge, creating a furrow or valley down the center of the forehead, and his massive shoulders are noticeably wider than his head.

Body Shape and Legs:

An adult female brown bear’s legs are shorter and thinner than the legs of an adult male, but unless you are comparing two bears standing side by side, it is not easy to determine the sex of the bear by looking at its legs. Males have robust front legs, and they are heavy through the ankles, ending at their wide feet. A female’s legs taper slightly, giving her the appearance of thinner ankles. Also, because females have shorter legs, their bodies hang lower to the ground.

The body, legs, and mid-section of a male brown bear look heavy and bulky, but since females aren’t exactly dainty in appearance, it is difficult and often misleading to use body shape to determine the sex of a bear. My husband, who had been around Kodiak bears all his life and has been a guide most of his life, says he is still sometimes surprised when he watches a young bear he is certain is a female until the bear urinates, and he realizes it’s a male.

Conclusion:

Unless a bear has cubs, you see her nipples or his genitalia, or you see the bear urinate, it is impossible definitively to differentiate male and female Kodiak bears. A huge bear is probably a boar, but large sows can also look huge, especially after a summer gorging on fish and berries.
The body shape of a bear provides clues to its gender. A heavy, bulky bear with a wide head and shoulders and a furrow down the middle of its forehead, is likely a male. It is more difficult, though, to distinguish sub-adult males from females.

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I hope my posts on bear size and gender answer a few questions about identifying bears in the field. The bottom line is that it’s impossible to pin down the gender of a bear from a distance, but you should be able to tell whether the bear is small or large by looking at the shape of its body.

Next week, I have a treat in store for you. My friend and fellow author, Steve Levi, has agreed to write a guest post about his books and his background. Be sure to stop by next week and meet Steve.

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Robin Barefield is the author of three Alaska wilderness mystery novels, Big Game, Murder Over Kodiak, and The Fisherman’s Daughter. To download a free copy of one of her novels, watch her webinar about how she became an author and why she writes Alaska wilderness mysteries. If you like audiobooks, check out her audiobook version of Murder Over Kodiak. Also, sign up below to subscribe to her free, monthly newsletter on true murder and mystery in Alaska.

Mystery Newsletter

How Do You Estimate the Size of a Kodiak Bear?

September 30, 2018Kodiak Bear, Kodiak WildlifeBrown bear size, How to determine bear size, How to Estimate Bear Size, Kodiak Bear Size, Kodiak Brown Bearadmin

When our summer guests see a bear, they immediately want to know its size. They ask, “How much does it weigh?” or, “Is it a big bear or a small bear?” If you see a Kodiak bear ten feet in front of you on a trail, it looks huge, but the same bear walking along the beach a mile away appears small. Guides who have spent years watching bears can easily tell you whether a bear is big, small, or medium-sized, but it’s not easy even for an experienced guide to judge the exact size of a bear from a distance. In this week’s post, I will discuss the indicators a guide uses to judge the relative size of a bear, but first, let me share some facts about the weight of Kodiak bears at different ages as they grow.

Kodiak bears gain weight and add fat in the summer when food is abundant, and then they burn off this fat during hibernation, so their weights vary from fall to spring. Yearling cubs weigh approximately 135 lbs (61.36 kg). When they are two-and one-half-years old, males begin to outgrow the females, and weights vary greatly. Females reach their full adult size at approximately five years when they weigh between 350 and 500 lbs. (159.09 – 227.27 kg). Males continue to grow, gaining about 100 lbs. (45.45 kg) per year until they are eight to ten years old and weigh 500 to 1000 lbs. (227.27 – 454.54 kg). In the wild, an 800 lb. ( 362.87 kg) female would be a huge sow, and a 1500 lb. ( 680.39 kg) male is a maximum-sized Kodiak bear. The largest Kodiak bear on record lived in the Cheyenne Mountain Zoo and weighed 1670 lbs. (757 kg.).

When you see a bear on a salmon stream or watch him through binoculars, you might not be able to determine how big he is, but you should be able to tell whether he or she is relatively large or small.

Shape:

Look at the bear’s overall shape. Does the bear appear square or rectangular? Young, small bears look square from a distance, while larger Kodiak bears have a rectangular shape. A larger, older boar also appears bulky through the rump and midsection.

Legs:

Are the bear’s legs long or short, and thin or heavy?

Big males have long legs. The front legs on a large male appear heavy and do not taper at the ankles. A young male brown bear also has long legs, but they look lanky, not thick and heavy. A Female, even an old female, has shorter legs, making her body appear closer to the ground. A female’s front legs taper at the ankles.

Head Neck and Shoulders:

Note the size of the ears in relation to the rest of the head. The ears on a large male or female bear appear small compared to the rest of the head, and on a large male, the ears appear wide-set. The ears on a young, small bear look large in comparison to the rest of the head and seem closer together. Now, look at the shape of the head. A large boar has a wide, square face with a thick, heavy muzzle. A sow has a small, narrow head with a tapered muzzle, and a young bear has a long, triangular head.

The massive muscles on the head of a large boar create a furrow down the middle of the forehead, and its muscular shoulders are wider than its head. A female has narrow shoulders the same width as her head, and a young bear has a long, relatively thin neck.

Claws:

Old, big bears of either sex often have distinctive white claws, but a male can be big without being old, so a big boar might have dark claws, and occasionally, a younger, smaller bear has white claws.

Conclusion:

If you’ve never seen a Kodiak bear in the wild, how can you tell if it has small ears, broad shoulders, or tapered ankles? If you see several bears at once, you can study and note the physical differences between big bears and smaller, younger bears, but if you see a single bear walking the beach, these general clues to size might not help you. My husband has been a bear guide for most of his life, and he says the best clues are:

1. The shape: is the bear rectangular (large) or square (small)?
2. Does the bear appear bulky and muscular (large) or does it have long, lanky limbs (small)?
3. Finally, and this point is often overlooked, how does the bear move? Watch the bear awhile. Does he walk or run in jerky movements (small), or are his movements slow and deliberate (large)?

Examine the photos in this post. Can you tell which bears are large and which are small?

Next week, I’ll share some clues on how to differentiate between male and female Kodiak bears. It’s not as easy as you might think, and unlike in the cartoons, females don’t wear bows in their hair.

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Mystery Newsletter

Sablefish (Anoplopoma fimbria)

September 2, 2018Fish, Kodiak WildlifeBlack Cod, Robin Barefield, Sablefish, Sablefish in Alaskaadmin

Sablefish (Anoplopoma fimbria) or black cod, as they are commonly called, are not related to Pacific cod but are instead in the family Anoplopomatidae, a family with only one other species, the skilfish (Erilepis zonifer).

A sablefish is slim and long and covered with small scales. It is dark gray or grayish-green on its back and sides and light gray or white on its stomach. It has two widely separated dorsal fins and a tail which is lightly indented in the middle. Sablefish have large mouths with small teeth. They grow quite large and have been known to reach 45 inches (114 cm) in length and 50.5 lbs. (25 kg). An average-sized sablefish weighs 8.1 lbs, (3.7 kg) and is 27 inches (69.1cm) long.

Sablefish range from Alaska and British Columbia south to Baja, California, and west to Kamchatka and Japan, Alaska has the highest concentration of sablefish.

Adult sablefish live on the slopes of the continental shelf and are usually found at depths of 492 to 4921 ft. (150 – 1500 m), but they have been found as deep as 9842 ft. (3000 m). Juveniles live nearshore in much shallower water. Juveniles are pelagic, while adults live near the bottom.

Sablefish spawn in the winter, normally between January and March, but spawning is dependent upon location. They spawn along the continental shelf at depths greater than 3281 ft. (1000 m.) Sablefish become sexually mature between five and seven years, and once they reach sexual maturity, they spawn annually. A female lays 110 eggs per gram of body weight, so an average sized female weighing 3.7 kg will lay approximately 407,000 eggs.

Sablefish larvae drift inshore, and juveniles remain inshore until they reach a size of 12 to 16 inches (30 -40 cm) at the age of two to five years. They then begin to move into deeper water and settle near the bottom, where they continue to grow.

Juvenile sablefish eat zooplankton and small fish, and adults eat fish, squid, octopus, and crustaceans. Survival of juveniles varies greatly from year to year, and biologists believe this variability is linked to zooplankton abundance, which is in turn linked to environmental conditions. Zooplankton thrive during years when ocean temperatures and nutrients produce rich phytoplankton crops for them to eat, and juvenile sablefish then eat the zooplankton, such as krill. When conditions are not favorable, though, zooplankton numbers drop, and fewer sablefish survive.

Juvenile sablefish are prey for many fish species, including Chinook and coho salmon. Sperm whales are a major predator of adults. Sablefish often live as long as 40 years, and the oldest recorded in Alaska was 94-years-old.

Like halibut, sablefish bring a high price per pound to commercial fishermen, and the current value of sablefish in the U.S. fishery is approximately $50 million per year. Most of the commercial catch is exported to Asia, where it is considered a delicacy, but sablefish is gaining popularity in the U.S. Sablefish are primarily harvested by longline or trawling. A small but growing sport fishery for sablefish has developed in Southeast Alaska.
Sablefish abundance has dropped since the 1980s, but with stricter commercial regulations in place, fishery managers consider the population stable. Both state and federal agencies manage sablefish.

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Mystery Newsletter

Lingcod (Ophiodon elongatus)

August 26, 2018Fish, Kodiak WildlifeAlaskan Fish, Fishing in Alaska, Fishing on Kodiak Island, Greenling, Kodiak Island, Lingcod, Lingcod Biology, Robin Barefieldadmin

Lingcod are not true cod and are not related to Pacific cod or pollack. Instead, lingcod are the largest members of the greenling family. Adults average 10 lbs (4.5 kg), but they can grow to over 80 lbs. (35 kg) and measure 60 inches (150 cm) in length.

A lingcod has a long body and varies in coloration from gray to brown to green or even blue on the back and sides and lighter on the stomach. It is covered with dark brown or copper blotches arranged in clusters, and it has a prominent light-colored lateral line and large, cycloid scales. A long dorsal fin spans the distance from behind the head nearly to the tail. The front part of the fin is spiny, while the posterior portion consists of soft rays. A notch connects the two sections. The anal fin has three spines. The head and mouth of a lingcod are large, and the mouth holds 18 big, sharp teeth. The head does not have scales.

Lingcod are found only on the west coast of North America, from the Alaska Peninsula and Aleutian Islands south to Baja California. They are common throughout Southeast Alaska, along the outer reaches of the Kenai Peninsula, around Kodiak Island, and in Prince William Sound. They normally live nearshore around rocky reefs from depths of 30 to 330 ft. (10 – 100m), but they have been found as deep as 1000 ft. (300 m). Lingcod usually stay in the same area and often near the same reef for their entire lives, but researchers have tagged lingcod that have moved as far as 500 miles (800 km) from where they were first observed.

Female lingcod mature between three and five years of age at a length of 24 to 30 inches (61-75 cm). Males mature when they are two years old and approximately 20 inches (45 cm) long. Lingcod nest in rock crevices or ledges with strong currents. A male leads a female to the nesting area, and the female lays between 150,000 to 500,000 eggs. The number of eggs a female lays increases with both size and age. Once the female lays her eggs, she leaves the area, and then the male fertilizes the eggs and stays to guard the nest. In Alaska, lingcod begin spawning in early December, with peak spawning from mid-January to mid-March. The eggs hatch within 5 to 11 weeks, so most hatching takes place between mid-March and mid-May.

Male lingcod guard the egg nests until the eggs hatch. If left unguarded, egg nests are usually decimated within 48 hours by rockfish, starfish, sculpins, kelp greenling, and cod. The adult male must be aggressive to drive away invading fish and invertebrates, and if something happens to him, the eggs will not survive. Unfortunately, this aggressive behavior of the male makes him more vulnerable to predation by seals, sea lions, and anglers.

Lingcod larvae measure ¼ to ½ inch (7-10 mm) in length. They drift with the ocean currents and grow rapidly by eating copepods and small fish. By mid-summer, when they are 3-inches (150 cm) long, they settle on the bottom in kelp or eelgrass beds and feed on juvenile herring or other small fish. They remain in shallow water as they grow. Adult lingcod are voracious predators and grow rapidly. They feed on invertebrates and fish, including other lingcod who are nearly their same size. Lingcod continue growing until they are 12 to 14 years old. Male lingcod have a maximum lifespan of 14 years, while females can live as long as 20 years.

Lingcod are popular for both sport and food. Their flesh is white with a natural blue-green tint. The blue coloration disappears when cooked. The flesh is dense and mild tasting and is high in protein, minerals, vitamins, and omega-3 fatty acids. Lingcod are taken by subsistence, sport, and commercial fishermen. Because they are so aggressive, they are excellent fighters for sport anglers.

Lingcod are highly susceptible to overfishing. Anglers can easily find lingcod because they live nearshore in shallow, rocky areas, and since they are so aggressive, they readily hit a lure. Once a lingcod population is overfished, it doesn’t recover for a long time. Because lingcod can be easily over-harvested, the Alaska Department of Fish and Game conservatively manages the lingcod fishery. To protect spawning females and nest-guarding males, sport and commercial fisheries are closed during the spawning and nest-guarding periods. Also, minimum size limits have been established to protect immature fish, and finally, catch limits are restricted.

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Mystery Newsletter

Walleye Pollock (Gadus chalcogrammus)

July 29, 2018Fish, Kodiak WildlifeAlaska Fish, Alaska Pollock, Commercial Fishing, Gadus chalcogrammus, Pacific Cod, Pollock, Robin Barefield, Walleye Pollockadmin

The walleye or Alaska Pollock (Gadus chalcogrammus) is another species in the true cod family Gadidae. For a long time, taxonomists placed walleye pollock in a separate genus from Pacific cod, but researchers have recently shown pollock are closely related to Pacific and Atlantic cod, and most taxonomists now include walleye pollock in the genus Gadus.

Pollock are more streamlined than their gray cod cousins, but like cod, pollock have olive-green to tan mottled markings their backs. This coloration helps camouflage them from predators and prey when they rest and swim near the sandy ocean bottom. Pollock have silvery sides, white bellies, three dorsal fins, and two anal fins. Pollock have either no chin barbel or only a tiny barbel.

Pollock range from the Sea of Japan and the Sea of Okhotsk west to the Bering Sea and the Gulf of Alaska and south to Northern California. They migrate in a circular pattern, moving inshore to relatively shallow waters from 295 to 460 ft. (90 to 140 m) to breed and feed in March and then returning in December to the warmer, deeper waters of the continental shelf to 525 to 984 ft. (160 to 300 m). Pollock are semi-demersal (semi-bottom dwelling) but can be found anywhere from the surface to 1640 ft. (500 m).

Pollock spawn from March to mid-June. They form dense schools when spawning and broadcast eggs and sperm into the water. Fertilized eggs are planktonic, and depending on the temperature of the water, they incubate for approximately 10 to 27 days. When the larvae hatch, they have a yolk sac and float upside down at the water surface until the sac is absorbed.

Young pollock eat zooplankton, but as they grow, they begin adding fish to their diet. Adults feed on young pollock and other fish. Pollock grow rapidly and can reach a length of 3.4 ft. (105 cm) and a weight of 13.3 lbs. (6.05 kg). They usually don’t, live more than 10 years, but biologists in Alaska have recorded pollock as old as 22 years.

Alaska pollock is the largest fishery by volume in the United States and the second most important fishery in the world. The Alaska pollock has been called, “The largest remaining source of palatable fish in the world.”

From 1964 through 1980, only foreign vessels harvested Alaska pollock. U.S. vessels began to enter the fishery in 1980, and by 1987, U.S. boats harvested 99% of the quota. Since 1988, only U.S. vessels have operated in the Eastern Bering Sea pollock fishery. From 2002 to 2006, the Eastern Bering Sea pollock catch averaged 1.48 million metric tons worth $500 million annually.

While biologists do not believe pollock have been overfished, stocks have declined in recent years. The pollock fishery was originally a bottom fishery and trawls were dragged across the ocean bottom to catch the fish. As concerns about habitat degradation from bottom trawling grew, fishermen switched to pelagic trawl gear, which is deployed above the seabed. Controversy also swirls around the use of pelagic trawl gear, though, since the trawl is not specific to pollock but catches and often kills any fish it encounters.

Pollock is an important food for Steller sea lions, and when sea lion populations began decreasing, managers reduced fishery time and implemented area closures for pollock near critical sea lion habitat.

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Next week I plan to take a short break from fish and set the stage for a wonderful guest post from a fellow author the following week. Three weeks from now, I will write about lingcod. As always, thanks for visiting my blog.

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Robin Barefield is the author of three Alaska wilderness mystery novels, Big Game, Murder Over Kodiak, and The Fisherman’s Daughter. To download a free copy of one of her novels, watch her webinar about how she became an author and why she writes Alaska wilderness mysteries. If you like audiobooks, check out her audiobook version of Murder Over Kodiak. Also, sign up below to subscribe to her free, monthly newsletter on true murder and mystery in Alaska.

Mystery Newsletter

Pacific Cod Commercial Fishery

July 22, 2018Fish, Kodiak WildlifeAlaska Fishing, Atlantic Cod, Cod, Cod in Alaska, Pacific Cod, Robin Barefieldadmin

Three weeks ago, I wrote about the collapse of the Pacific cod population in central and southwestern Alaska. Over the course of two years, cod went from one of the most prolific fish species in the area to nearly non-existent. The Alaska Department of Fish and Game slashed commercial fishing quotas in 2017, but there were so few cod, commercial fishermen struggled even to catch the allowed poundage. The economic ramifications from the crash of the Pacific cod fishery are just beginning to affect Alaska’s ports, and biologists believe it will be years before the launch of another viable cod fishery.

This week, I’ll explain more about the history of the Pacific cod fishery and commercial methods for harvesting cod in Alaska. First, though, I want to emphasize the importance of Pacific cod not only to fishermen but also to consumers. Most of us at some point in our lives have eaten cod; whether it was a fish stick, a fish sandwich, fried fish, or baked white fish, cod is one of the most popular fish served by restaurants from fast-food drive-ins to diners to gourmet bistros. Cod has a mild flavor and a dense, flaky white flesh. It freezes well and can be shipped long distances. Cod liver oil is made from cod livers and is an important source of vitamin A, vitamin D, vitamin E, and omega-3-fatty acids.

The Pacific cod fishery gained traction just as the Atlantic cod fishery began to crash. The Atlantic cod fishery lasted for more than 1000 years and was popular even during the Viking period, around 800 AD. The fishery was vital to Europe, Canada, and the U.S., but this widespread popularity of Atlantic cod led to its downfall. Atlantic cod populations survived centuries of human strife, ranging from plagues to wars, only to be fished to the point of annihilation because the many countries that commercially fished cod couldn’t agree on regulations to protect this valuable resource. With Atlantic cod no longer available, fish buyers looked to the Pacific.

Pacific cod have been commercially fished on a small scale since the 19th century, but the modern commercial fishery began in the early 1960s with the Japanese longline fishery in the Bering Sea/ Aleutian Island (BSAI) region. Between 1980 and 1989, a U.S. trawl fishery and several joint venture fisheries began in both the BSAI and the Gulf of Alaska (GOA) regions, and by 1989 the U.S. commercial cod fishery overtook the foreign fishery in both the BSAI and GOA regions.

Multiple methods are now used to harvest Pacific cod, including trawl, longline, pot, and jigging. Between 1991 and 1999, trawl gear accounted for 52% of the cod catch, longline gear took 37% of the harvest, and pot gear caught 11%. After 2000, however, longline fishing became the most productive means of landing cod. Between 2000 and 2006, longline gear accounted for 46% of the catch, trawl gear 37%, and pot gear 16%.

According to recent NOAA Fisheries Service surveys of Pacific cod stocks taken only a few years before the population collapsed, the cod stocks in Alaskan waters were stable and were not being over-fished. In 2010, NOAA estimated the BSAI stock at 1 million metric tons and the GOA stock at 0.4 million tons. Biologists have closely regulated the Pacific cod fishery and have erred on the side of caution by setting strict quotas to protect not only the cod fishery but also marine mammals such as Steller sea lions that depend on cod for food.

Researchers are now working diligently to discover what happened to the Pacific cod. Why did the cod population crash in Alaska? The leading theory is the crash was caused by warmer-than-normal ocean temperatures which in turn caused a reduction in the biomass of phytoplankton and zooplankton in the North Pacific. Juvenile cod, like most young fish, depend on zooplankton as a food source. Because of the reduction of zooplankton in the North Pacific, juvenile cod had little to eat, and many starved to death.

If the zooplankton biomass in the North Pacific has decreased to the point where cod can’t find enough to eat, we should all be concerned, not only for cod but for all animals in this portion of the sea. Marine animals from the smallest fish and birds to the largest whales depend on phytoplankton and zooplankton to survive.

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Robin Barefield is the author of three Alaska wilderness mystery novels, Big Game, Murder Over Kodiak, and The Fisherman’s Daughter. To download a free copy of one of her novels, watch her webinar about how she became an author and why she writes Alaska wilderness mysteries. If you like audiobooks, check out her audiobook version of Murder Over Kodiak. Also, sign up below to subscribe to her free, monthly newsletter on true murder and mystery in Alaska.

Mystery Newsletter

Pacific Cod (Gadus macrocephalus)

July 15, 2018Fish, Kodiak WildlifeAlaska Fish, Cod, Cod Biology, Kodiak Fish, Pacific Cod, Robin Barefieldadmin

True cod belong to the genus Gadus. The two most common members of the genus Gadus are the Atlantic cod (Gadus morhua) and the Pacific cod (Gadus macrocephalus). These two species are similar in appearance, reproductive biology, and lifecycles. Pacific cod are also known as grey cod, gray cod, greyfish, or grayfish.

Pacific cod range from Japan to the Bering Strait and the Gulf of Alaska and south as far as Northern California. Pacific cod are bottom dwellers and are usually found between depths of 40 to 1800 ft. (12-549 m). They tend to move into deeper water in the fall and winter.

A Pacific cod’s body is elongate and ranges in color from grey to brown on the back and sides to a pale cream on the stomach. Mottled spots or pale areas cover the backs and sides. A cod has a triangular tail, three rounded dorsal fins, and two anal fins. The fins are dusky colored and have white edges. The upper jaw of a cod extends over the lower jaw, and it is easy to identify a Pacific cod by its single chin barbel, or whisker, that has a length nearly equal to its eye diameter. Female cod can grow to 58 inches (147 cm) in length and weigh 55 lbs. (25 kg) Males are slightly smaller and can reach a length of 55 inches (141 cm) and weigh 44 lbs. (20 kg).

Female cod reach sexual maturity when they are four to five years old at a length of 20 to 23 inches (50-58 cm). In Alaska, most spawning activity occurs in March. Males court females by displaying their fins and grunting. A male and female then pair, and the male swims upside down under the female while she releases her eggs and he releases his sperm. The fertilized eggs then sink to the bottom where they remain for eight to 23 days before the hatch. A newly-hatched cod enters a planktonic phase for the next ten weeks while its body weight increases by 40-fold. When it is approximately 0.79 inches (2 cm) the cod moves to the sea floor and begins eating benthic crustaceans, such as isopods and small crabs. After six months, the cod is approximately 3.1 inches (8 cm) long, and by the end of the first year, it has attained a length of 5.5 – 7.1 inches (14-18 cm). Small cod eat mostly invertebrates, while larger Pacific cod feed on invertebrates and fish.

Cod live a maximum of 18 years. They are plagued by parasites, including the cod worm, Lernaeocera branchialis. Cod worms have a complex lifecycle. They begin as free-swimming larvae but then hook to the front of a flatfish or a lumpsucker. The worms penetrate the flesh of the fish with a fine filament and suck the blood of their host. The worms then mate, and the female worm finds a cod and clings to the cod’s gills, where it then penetrates the body of the cod and enters its heart. The front part of the worm forms branches and burrows into the main artery of the cod and extracts nutrients for itself and its eggs from the cod’s blood. Other parasites also infect cod, and anglers commonly catch cod covered by sores.

Cod are important food fish for larger fish, sharks, and marine mammals, including the endangered Stellar sea lion. They are also a commercially valuable food fish for humans.
Next week, I’ll write more about the importance of cod as a commercial species, and I’ll discuss the various methods of harvesting them.

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Robin Barefield is the author of three Alaska wilderness mystery novels, Big Game, Murder Over Kodiak, and The Fisherman’s Daughter. To download a free copy of one of her novels, watch her webinar about how she became an author and why she writes Alaska wilderness mysteries. If you like audiobooks, check out her audiobook version of Murder Over Kodiak. Also, sign up below to subscribe to her free, monthly newsletter on true murder and mystery in Alaska.

Mystery Newsletter

What is a Cod?

July 8, 2018Fish, Kodiak WildlifeBlack Cod, Cod in Alaska, Lingcod, Pacific Cod, Pollock, Tomcodadmin

Four species of fish in the Gulf of Alaska have the common name “cod,” but only two of these species, the tomcod and Pacific grey cod, are true cod. Common fish names are often misleading and confusing. For example, brown trout (Salmo trutta) belong to the genus Salmo, while cutthroat trout (Oncorhynchus clarki) and rainbow trout (Oncorhynchus mykiss) are in the genus Oncorhynchus. To confuse the issue even more, brook trout (Salvelinus fontinalis), lake trout (Salvelinus namaycush), and Dolly Varden trout (Salvelinus malma) are char, not trout. Also, in the southern United States, bullheads are catfish, while in Alaska, we call sculpins bullheads.

True Cod and Imposter Cod

Lingcod (Ophiodon elongatus) and black cod (Anoplopoma fimbria) are not only unrelatedto Pacific grey cod (Gadus macrocephalus) and Pacific tomcod (Microgadus proximus), but they look quite different from the two “true” cod species. Pollock (Gadus chalcogrammus), though, a species closely related to a Pacific grey cod, isn’t even referred to as a cod. With these confusing common names, we can forgive an angler for not knowing whether he has caught a “true cod” or some unrelated fish.

Last week, I wrote about the crash of the Pacific cod population in the Gulf of Alaska. In that post, I was discussing only Pacific grey cod. Over the next few weeks, I’ll write posts about the true cod species as well as the cod imposters in Alaskan waters. I hope to clear up any confusion surrounding cod and their common names.

Pacific Tomcod

The Pacific tomcod (Microgadus proximus) is one of the smaller members of the cod family, reaching a maximum size of 12 inches (30.5 cm). Its body is slender and covered with small, thin scales, but it feels smooth to the touch. It ranges in color from olive green to brown on its dorsal surface and creamy white on its ventral surface. Like its cousin the grey cod, a tomcod has a barbel on its chin, three dorsal fins, two anal fins, a large head, and a large mouth with small teeth. A tomcod’s barbel is smaller than a Pacific grey cod’s barbel, and unlike a Pacific cod, a tomcod’s dorsal fins do not contain spines. Despite these differences, a tomcod looks very much like a small Pacific grey cod.

Tomcod range from central California to western Alaska and can be found anywhere from the surface to as deep as 700 feet. They feed on zooplankton, shrimp, worms, and small fish and in turn, are a food source for larger fish, seals, and sea lions. Because of their small size, tomcod are not an important species for either commercial or sport fishermen, but they are a good food fish and have a sweet, subtle flavor.

Next week, I’ll discuss grey cod. I have already posted about their declining numbers in Alaskan waters, but I’ll delve more into their biology, importance in the ecosystem, and their value as a human food source. The following week, I’ll point out the differences between Pacific and Atlantic cod.

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