Category Archives: Kodiak Wildlife

Wildlife of Kodiak Island including biology, behavior, and news

Tufted Puffins Warn Us of Our Changing Climate

June 30, 2019Birds, Kodiak WildlifeAlaska Birds, Melting Sea Ice, Puffin, Puffins warn us of our changing Climate, tufted puffin, Tufted Puffins Die in Alaska, Tufted Puffins Starving to Deathadmin

Tufted puffins are shouting a warning from the middle of the Bering Sea, and we need to listen to them. As our oceans warm, these beautiful birds are starving to death.

Alaska’s four Pribilof Islands sit between mainland Alaska and Russia. The islands support more than two million seabirds, which survive by feeding on plankton and fish in the nutrient-rich Bering Sea. With so many birds in one area, it’s not unusual to occasionally find dead ones, but alarm bells sounded when biologists learned more than 350 dead birds had washed up on the beaches of St. Paul Island, the largest of the Pribilof Islands. This number is seventy times higher than the annual average count of five bird carcasses. Stranger still, most of these dead birds were tufted puffins, a bird that rarely washes up on the beach after it dies.

Biologists knew the birds they’d found dead represented only a fraction of the total, so they applied a computer model using wind patterns and ocean currents to determine what percentage of the dead birds likely reached the shore. From this percentage, they calculated somewhere between 3,150 and 8,800 birds perished in late 2016. Even if you choose to believe the low end of this estimate, the numbers are astounding.

Two species of puffins live in Alaskan waters. The horned puffin (Fratercula corniculata) and the tufted puffin (Fratercula cirrhata) belong to the family Alcidae, which also includes guillemots, murres, murrelets, auklets, and auks. A tufted puffin has a black body, a white face, and a red and yellow bill. Its common name is derived from the long tufts of yellow feathers curling back from behind the eye on each side of the head. Adult tufted puffins measure 14 inches (36 cm) in length and weigh 1.7 lbs. (771 g).

What killed the puffins?

The dead birds recovered from the beach appeared emaciated with weak flight muscles and almost no body fat. The birds had starved to death, but why?

Puffins feed on small fish, and until recently, many resided in the Pribilof Islands so they could gorge themselves on the abundance of fish in the rich Bering Sea. The icy Bering Sea is rapidly changing, though, as the ocean warms. As the sea ice recedes and thins, pollock, cod, and other fish can no longer find the super-cooled water at the edges of the ice sheet where they like to congregate. Instead, the fish disperse, making them more difficult for puffins to find and catch. Puffins now must travel further to find food, burning precious calories.

Also, as the northern ocean warms, dominant plankton species have shifted from large, meaty forms to smaller less energy-rich species. In turn, the plankton-eating fish are also thinner and provide fewer nutrients to the animals that eat them.

Puffins molt from August to October, and as they replace their feathers, the birds can barely fly and dive, making it difficult to feed themselves unless prey species are plentiful. Biologists were not surprised to learn most of the dead puffins they found on the beaches were in the middle of molting. The birds couldn’t travel far to travel to find food while molting, and they starved to death.

Puffins are not the only species affected by the loss of sea ice in the Bering Sea, and the diminished food source is not the only issue related to the melting ice. Without sea ice clinging to the coast, winter storms now batter the rocky cliffs, causing erosion at an unprecedented rate. These cliffs provide homes for seabirds, and some of the rocky beaches are breeding sites for endangered Steller sea lions.

The Pribilof Islands are a distant place most humans will never visit, but the drama playing out on those remote islands demands our attention now. The puffins are trying to tell us our environment is changing at an alarming rate.

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. Also, sign up below to subscribe to her free, monthly newsletter on true murder and mystery in Alaska, and listen to her podcast Murder and Mystery in the Last Frontier.

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Commercial Herring Fishery in Alaska

May 26, 2019Fish, Kodiak WildlifeCommercial Herring Fishing, Herring, Herring Fishing in Alaska, Pacific Herring, Sac Roe Herring Fishery, Spawn-on-Kelp Herring Harvestadmin

Herring are valuable fish to commercial fishermen, and in Alaska, herring are mainly harvested for their eggs which are shipped to Japan.

In last week’s post, I wrote about the biology and life history of the Pacific herring, and I explained how important herring are to the diets of many birds, fish, and marine mammals, but herring is also a valuable commodity to humans. For hundreds of years, Alaska native populations have conducted subsistence fisheries for herring. In the spring, villagers from coastal communities harvested herring eggs on kelp or hemlock boughs, and traditional dried herring is still an important resource in Bering Sea villages near Nelson Island where salmon is not readily available.

The commercial herring fishery in Alaska began in 1878 when 30,000 lbs. were caught for human consumption. Early Alaskan settlers preserved herring by salting the fish and storing it in large, wooden barrels. Salted and pickled herring production peaked after WWI when 28 million pounds (12,700 mt) were produced annually.

Reduction fisheries, which are the production of fish oil and fish meal from ground-up fish, began in Southeast Alaska in Chatham Straight in 1882. Reduced herring became more popular in the 1920s, and reduction plants sprang up from Craig to Kodiak in areas with large herring stocks. Harvests during the 1920s and 1930s reached 250 million pounds (113,400 mt) per year, and herring stocks declined in response to this unsustainable harvest. During the 1950s, the low cost of reduced Peruvian anchovies caused the reduction market in Alaska to collapse, and the last herring reduction plant in Alaska closed in 1966.

The Alaska sac roe fishery for herring began in the 1970s when the demand for imported herring eggs in Japan increased after Japan’s herring fishery declined. The sac roe fishery targets female herring just before they spawn. Pre-spawn egg sacs are removed from the female herring and shipped to Asia where they are a highly prized delicacy called kazunoko. Most herring for this fishery are caught by purse seining with a smaller percentage caught by gill netting. Unlike any other fishery in Alaska, managers carefully monitor the quality of the herring during the fishery to obtain the highest-value product possible. Technicians periodically test the condition of the female herring as their eggs ripen, and fishery managers use this information to carefully time the opening of the fishery to within days or even hours before the females are ready to release their eggs. This scrutiny ensures the eggs are ripe and prime for the Japanese market.

Most herring fisheries in Alaska are regulated as management units or regulatory stocks, and these stocks are very specific, often to small geographical areas. While managers might open herring fishing in one bay, the fishery could be closed in an adjacent bay because the herring return to spawn in the second bay the previous year did not meet sustainable levels. The herring sac roe fishery is competitive and intense. Fishery managers often open fishing at noon and close it a few hours later when fishermen have reached the quota for the area. Herring purse seiners work together in groups called combines and hire spotter planes to search for large schools of herring. The purse seine boats stand by near a school of herring until managers declare the fishery open, and then they quickly deploy their nets to scoop up the fish.

Since fishermen are only after the eggs in a sac roe fishery, the carcasses of the females and males caught in the nets are either processed for fishmeal or are sold for bait to commercial and sport anglers. There also is still a smaller food and bait fishery for herring.

In addition to the sac roe fishery, there is another type of commercial harvest for herring eggs called a spawn-on-kelp harvest using floating pens. Herring are caught with purse seines and then confined in floating pens containing kelp. When the herring spawn, the eggs attach to the kelp and are harvested. The eggs from this type of fishery sell for a very high value.

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Pacific Herring (Clupea pallasii)

May 19, 2019Fish, Kodiak WildlifeAlaska Herring, Clupea pallasii, Herring biology, Herring on Kodiak Island, Kodiak Alaska, Pacific Herringadmin

Last week, I mentioned how the Pacific herring (Clupea pallasii) had returned to Uyak Bay on Kodiak Island this spring in such large numbers, even bears recently out of hibernation noticed and were feeding on them in the shallow estuaries where they spawn. Pacific herring are an essential food source for many animals living in or near the North Pacific, including birds such as cormorants, murres, auklets, puffins, and bald eagles; fish, such as salmon, halibut, cod, and pollock, and marine mammals, including harbor seals, Steller Sea Lions, fin whales, humpback whales, and orcas. When a pursuing predator forces a school of herring to the surface, seagulls take advantage of the situation and can often be spotted noisily diving and feeding on the fish. Herring are loaded with nutritious oil and nutrients and are an important forage fish for many species.

A herring has a blue-green upper body, silvery sides, and large eyes. Its body is laterally compressed with large scales, protruding in a serrated fashion. It has no scales on its head or gills. A herring has a deeply forked tail, a single dorsal fin located mid-body, and no adipose fin. Pacific herring can grow to 18 inches (45.7 cm) in length, but they are usually smaller than 9 inches (22.9 cm).

Pacific herring live throughout the coastal waters of the Pacific Ocean. In the eastern North Pacific, they range from Baja California north to the Beaufort Sea, and in the western North Pacific, they can be found in the western Bering Sea to Kamchatka, in the Okhotsk Sea and around Hokkaido, Japan southeast to the Yellow Sea.

^[Pacific herring reach sexual maturity when they are three to four years old, and they spawn each year after reaching sexual maturity. Spawning occurs in the spring in shallow nearshore areas in intertidal and subtidal zones. Females release eggs at the same time males release sperm into the water, and the eggs and sperm mix, fertilizing the eggs. A single female can lay 20,000 eggs.

Spawning is precise, and while the trigger is not well understood, researchers suggest the male initiates the process by releasing milt containing a pheromone which stimulates females to release eggs. The process seems to be synchronized, and an entire school spawns in a period of a few hours, producing an egg density of up to 6,000,000 eggs per square yard (square meter).The fertilized eggs then attach to vegetation such as eelgrass or kelp or to the bottom. Eggs hatch two weeks after they are fertilized, and the larvae drift in the ocean currents. As they grow, juvenile herring stay in sheltered bays until autumn and then move into deeper water where they spend the next two to three years. Juveniles remain separate from the adult population. Biologists estimate only one herring per ten thousand eggs reaches adulthood.

Juvenile herring feed on phytoplankton and zooplankton, and adults also eat bigger crustaceans and small fish. Pacific herring travel in large schools. They migrate inshore to the heads of shallow coves and bays to spawn and then offshore to feed. They also migrate vertically in response to their prey, remaining near the bottom during the day and rising toward the top of the water column at night.

Herring are susceptible to environmental changes. Since they depend on shallow, inshore habitats to reproduce, they are affected by storms, pollution, and warming water temperatures. The Pacific herring population in Prince William Sound collapsed in 1993, four years after the Exxon Valdez oil spill, and it has still not recovered.^[

The biggest threat to Pacific herring is a loss of their spawning grounds. Spawning habitat can be degraded or destroyed by construction, dredging, log storage, oil spills or other pollution, and by global warming.^[ If Pacific herring populations crash, their loss will affect the many species of fish, birds, and marine mammals which depend on them for food.

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Spring on Kodiak Island

May 12, 2019Fish, Kodiak Bear, Kodiak WildlifeKodiak Bear, Kodiak Island, Pacific Herring, Robin Barefield, What Do Bears atadmin

I love spring. It is my favorite season. As winter loosens its grip and the vegetation begins to grow again, the world seems to return to life. Foxes scream in the middle of the night in search of new mates; does arrive in our yard with their wobbly, newborn fawns; eagles soar in mating spirals and begin remodeling their nests for the arrival of their chicks; and bears leave their dens in search of food after a long winter of fasting.

Spring always brings unexpected joys, and no two springs are alike. This year, we have watched an abundance of herring enter Uyak Bay to spawn. Often when large schools of herring return, we see increased whale, seal, and sea lion activity in the bay, but this year we’ve observed something different and exciting. Bears are feeding on the herring in the tidal flats at the head of Uyak Bay where the herring spawn. While in the summer months, bears typically catch and eat salmon in this same area, they don’t usually congregate to feed on herring. Herring are rich, oily fish loaded with nutritional value, and they provide a great supplement to a bear’s diet.

Bears’ stomachs contract during hibernation, and when they first leave their dens, their appetites are suppressed, and they eat little, concentrating on emerging plants and their roots. As spring progresses, bears can be seen feeding in grassy meadows and look much like grazing cattle with their heads bent to the earth. We don’t usually see bears feeding on fish until summer when they chase and catch salmon, but bears are opportunistic feeders, and since the herring are here now, bears are taking advantage of their abundance.

Herring are smaller than salmon, making them more difficult for a bear to catch. The herring swim into the eelgrass in the tidal areas at the head of Uyak Bay where they lay their eggs. When the tide ebbs, the fish temporarily become stranded in the shallow tidal pools, and bears can chase down and pounce on the fish.

As with salmon fishing, older bears are better than younger bears at landing herring. Fishing is a skill bears learn with much practice over time, so young bears are often clumsy fishermen. A sub-adult bear might gallop back and forth for thirty minutes without successfully landing a fish, while an older bear walks deliberately through the water and pounces with little effort on a passing herring. Each bear develops his own, unique fishing technique.

In the long run, this early appetizer of herring probably will make little difference to the overall health of the bears, but if Kodiak has a poor berry crop and a poor salmon run, this early addition of herring could sustain the bears until the salmon arrive.

Spring is only beginning here on Kodiak Island, and I can’t wait to see what other surprises the season has in store for us.

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Marine Reserves for Rockfish

March 10, 2019Fish, Kodiak WildlifeMarine Protected Area, Marine Reserves, Marine Reserves for Rockfish, Rockfish Conservation, Rockfish in Alaskaadmin

Should fisheries managers implement marine reserves to protect fragile rockfish populations? This week, I’ll tackle the controversial subject of marine reserves. What are they; do they work; and should they be employed to protect rockfish populations and help already depleted populations recover?

Two weeks ago, I discussed rockfish conservation, and last week, I explained how to implement the deep-water release technique for rockfish. If you missed either of those two posts, I suggest you read them to understand the biology and physiology of rockfish and why rockfish populations are fragile and subject to overfishing.

Marine reserves have been developed in certain areas where rockfish have been over-harvested. Before I start discussing the pros and cons of marine reserves, though, I want to differentiate between a few ecological terms I find confusing.

Marine Protected Area (MPA): This broad term covers a variety of management areas, including marine sanctuaries, estuarine research reserves, ocean parks, and marine wildlife refuges. Some MPAs are established to protect ecosystems, while others preserve cultural resources such as shipwrecks and archaeological sites, and still others are established to sustain fisheries production. Nearly all MPAs in the United States allow a variety of human activities, including fishing.

Marine Reserve: A Marine Reserve is a special, restrictive type of MPA where either no or only limited fishing (sport or commercial) and development are allowed. Marine Reserves are sometimes further divided into “Marine Reserves,” and “No-Take Marine Reserves.” When used together, these two terms usually mean managers allow some fishing for certain species in a Marine Reserve but place a ban on all fishing in a No-Take Marine Reserve.

When you add terms such as Marine Parks, Marine Preserves, and National Marine Sanctuaries to the mix, you end up scratching your head, wondering what each designation means. In this post, when I discuss marine reserves, I am talking about the implementation of a distinct area closed to all fishing.

Fisheries managers in the eastern North Pacific have designated several marine reserves in critical rockfish habitat where rockfish have been overfished. By prohibiting fishing in these areas, managers hope to rebuild overfished populations and protect spawning and nursery habitat. By closing an area to all fishing, biologists can protect rockfish not only from anglers who target rockfish but also from anglers who fish for other species and harvest rockfish as by-catch.

Fishermen generally do not like marine reserves because they lose fishing areas. Reserves protecting rockfish are also controversial because studies suggest as much as 20% of rockfish habitat would have to be closed for a reserve to be effective. Also, reserves displace effort and place pressure on open areas.

Some reserves appear to have benefitted local rockfish populations, but biologists are still uncertain about the overall success of reserves for managing rockfish. Since rockfish do not reproduce until they are several years old, though, and since few larvae survive to reach adulthood, it could take years to realize the benefits of rockfish reserves. Are we willing to wait before we judge the efficacy of these protected areas?

I planned to write two posts on rockfish and ended up writing six. The more I learned about these interesting fish, the more questions I had. I hope I found a few readers who are as intrigued by rockfish as I am. Before tackling my next group of fish, I’ll write a few posts on other topics.

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Deepwater-Release Technique for Rockfish

March 3, 2019Fish, Kodiak WildlifeDeepwater Release, Deepwater-Release Technique for Rockfish, Protecting Rockfish, Robin Barefield, Rockfish Conservation, Rockfish in Alaskaadmin

This week, I ‘ll describe the deepwater-release technique developed for rockfish. In my last post, I wrote about rockfish conservation and talked about ways anglers can help preserve vulnerable rockfish populations. Due to their unvented swim bladder, rockfish are extremely sensitive to changes in water pressure. When an angler catches a rockfish in water deeper than 90 ft. (27.43 m) and reels it to the surface, the fish’s swim bladder rapidly expands, compressing internal organs and often pushing the stomach out through the mouth. These pressure change can also rupture blood vessels, tear the swim bladder, and cause bulging eyes or gas bubbles in the eyes.

Stomach protruding from yelloweye rockfish mouth — Distressed Rockfish

Sometimes rapid pressure changes cause physiological damage so severe it kills the fish, but in other instances, the fish can survive if the angler quickly returns it to the depth where it was caught.

Since a rockfish’s swim bladder rarely deflates on its own once the fish arrives at the surface, the fish cannot dive and instead floats until it dies or is eaten. Anglers sometimes mistakenly feel they can help the fish by either puncturing the stomach protruding from the fish’s mouth or puncturing the fish’s body to let air out of the swim bladder. This technique, called “fizzing” or “venting,” often leads to infection and eventual death.

Recently, biologists have developed a new deepwater-release technique to submerge rockfish as quickly as possible either to the depth where they were caught or 100 feet (30.5 m), whichever comes first. Research on this technique has shown a substantial increase in the survival of released rockfish. One laboratory study produced a survival rate of 96% for recompressed rockfish. Another study in the wild found only 22% of yelloweye rockfish released at the water’s surface managed to submerge, but 98% of yelloweyes survived when submerged to the depth where they were captured.

The Alaska Department of Fish and Game has now added the deepwater-release technique to its list of “best practices” for anglers to employ to minimize release mortality of rockfish. Biologists believe if they can convince anglers to use this technique, as well as follow other rockfish conservation methods, rockfish mortality will decrease significantly.

What is the deepwater-release technique? It is a simple procedure, but since time is critical, rockfish anglers should have the gear ready and be prepared to implement the technique as soon as the rockfish arrives at the surface.

Several deepwater-release devices, from simple to sophisticated, can be purchased, but you can also easily make your own deepwater-release device. Begin with a 3-lb. jig with a single hook and grind the barb off the hook. Next, take a fishing rod and attach the line to the bend of the hook. Assemble the device and have it ready to go before you start fishing. The fish is much more likely to survive if you minimize its time at the surface, so have the device assembled and make sure you know what to do before you catch a rockfish.

If you think you have a rockfish on the line, quickly reel the fish to the surface. The swim bladder will inflate regardless of your reeling speed. Remove the hook from the fish’s mouth and attach the release device. If using a homemade device, hook the barbless hook through the soft tissue of the jaw. Gently drop the fish back into the water and release the anti-reverse on the reel, allowing the line to free spool. Allow the fish to descend until either the jig hits bottom, or reaches 100 ft., whichever comes first. Then, give the rod a hard tug to release the fish. The faster you can perform this technique, the more likely the rockfish will survive.

Next week, I’ll discuss marine reserves as a possible management option to protect rockfish populations. Reserves are controversial because both sport and commercial fishing are prohibited in reserves, and many biologists question if reserves work as a form of conservation.

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Rockfish Conservation

February 24, 2019Fish, Kodiak WildlifeBlackRockfish, Robin Barefield, Rockfish, Rockfish Conservation, Yelloweye Rockfishadmin

This week, I want to discuss rockfish conservation. Over the past few weeks, I’ve discussed how rockfish are more vulnerable to overfishing than most species of fish, and non-pelagic rockfish populations are particularly fragile. Rockfish prefer rocky habitats where anglers can easily find and target them, and rockfish are quick to take a lure, making them easy to catch. Also, they grow quickly but mature slowly, so they are often caught before they can reproduce and sustain their population. It is their physiology, though, not their lifestyle which makes rockfish susceptible to annihilation by anglers.

Rockfish rarely survive catch-and-release fishing because they have an unvented swim bladder. The swim bladder is a balloon-like organ which adjusts the buoyancy of a fish. As the fish ascends toward the surface, the swim bladder inflates. If the swim bladder has a vent, it can easily again deflate when the fish dives, but a rockfish cannot quickly deflate its swim bladder, and since the fish normally remains in deep water, it has no need to make large adjustments in the inflation or deflation of its bladder. When an angler catches a rockfish, though, and reels it to the surface, the gasses in the swim bladder expand and compress internal organs. Often, by the time the fish reaches the surface, the stomach bulges into the mouth cavity. Other common pressure-change injuries include ruptured swim bladders, ruptured blood vessels in internal organs, and bulging eyes or gas bubbles in the eyes.

Once the swim bladder of a rockfish has completely expanded, it will not likely deflate on its own because it does not have a vent. If the angler releases a fish with an inflated swim bladder, the fish floats on the surface until it suffocates, or something eats it. Gulls often land near floating fish and peck out its eyes while the fish is still alive.

Rockfish are good to eat and are harvested in commercial, sport, and subsistence fisheries from California to Alaska. Anglers have depleted many rockfish populations from British Columbia to California, and even when fisheries managers enact strict regulations or completely ban fishing in certain areas, these populations are slow to recover. Only older rockfish can reproduce, and few rockfish larvae survive to reach maturity.

Rockfish are not easy to manage because they live in deep, rocky spots where biologists cannot employ traditional sampling techniques. In Alaska, researchers do not know the abundance of most rockfish stocks, so fisheries managers have elected to implement strict regulations for catching and retaining rockfish, especially for yelloweye and other non-pelagic rockfish. Since even the rockfish anglers release are likely to die, though, biologists now focus on informing anglers of the fragility of rockfish populations.

The Alaska Department of Fish and Game distributes literature to sportfishing guides and posts informational signs near boat ramps to encourage anglers to follow these guidelines to avoid catching rockfish or to at least minimize rockfish harvest.

Angler's Guide to the Rockfishes of Alaska

If you are not targeting rockfish, avoid fishing where you are likely to catch them. Rockfish inhabit the steep sides of rock piles and reefs. Lingcod are found at the top of rock piles and reefs, and halibut lie on the flat bottom near a reef.
If you are targeting lingcod or halibut, keep your jig 10-15 ft. (3-5 m) off the bottom. Researchers in Oregon found this technique significantly reduced rockfish bycatch but did not affect the odds of catching halibut and actually increased the success rate for landing lingcod.
If you want to retain a few rockfish along with other species, target the other species first and retain any incidental rockfish you catch.
Fish with a circle hook. Circle hooks stick in the mouth and are not ingested, so they are easier to release and less likely to cause a serious injury.
Remember, rockfish only have a freezer life of four months, so don’t catch more than you can eat.
If targeting rockfish, implement deep-water-release methods.

In my next post, I will discuss deep-water-release techniques in more detail. This simple concept produces surprisingly successful results.

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Black Rockfish

February 10, 2019Fish, Kodiak WildlifeBlack Rockfish, Black Rockfish in Alaska, Kodiak Fish, Robin Barefield, Rockfish, Rockfish of Alaska, Sebastes melonopsadmin

Black rockfish (Sebastes melonops) range from range from Amchitka Island, Alaska in the Aleutian Islands to California. Two weeks ago, I wrote about rockfish in Alaska, and I explained that biologists classify rockfish by dividing them into two groups: pelagic and non-pelagic. Last week, I wrote about yelloweye rockfish, a non-pelagic species. This week, I’ll write about black rockfish, a pelagic species and the most common rockfish in Alaskan waters.

Although not related to the bass family, anglers often refer to black rockfish as black bass because their shape resembles a bass. They have a mottled gray-black body, usually with dark stripes extending from the head to the gill cover. The sides are lighter than the back, and the stomach is pale gray. Black rockfish have a large mouth and a spiny dorsal fin. As with other rockfish, venom sacs lie at the base of each spine. The venom is only mildly toxic to humans, but it does cause pain and can lead to infection. Their light-colored stomach, the lack of pores or a knob on the lower jaw, black mottling on the dorsal fin, and their large mouth which extends past their eyes, are all features which distinguish black rockfish from similar species such as dark rockfish and dusky rockfish. Black rockfish grow to a maximum length of 29.6 inches (69 cm) and weigh up to 11 lbs. (5 kg).

Black rockfish are found anywhere from the surface to 1200 ft. (366 m) deep, but they usually inhabit water shallower than 492 ft. (150 m). They are sometimes seen in large schools at the surface when they are feeding, but they most commonly occur in rocky areas or remain above rocky pinnacles.

Black rockfish are much more mobile than yelloweye rockfish, but biologists in Oregon performed a tagging study and learned the average home range of a black rockfish is only .2 square miles (.55 sq. km). A rockfish sometimes travels outside its home range during the reproductive season or to feed.

Black rockfish reach sexual maturity between the ages of six and eight years. After mating, the female stores the male’s sperm for several months before fertilizing her eggs. Then, between January and May, she releases between 125,000 and 1,200,000 larvae. Black rockfish have a maximum lifespan of fifty years.

Black rockfish feed on zooplankton, crab larvae, and small fish species such as herring and sand lance. Predators of rockfish include sablefish, halibut, other fish species, and seabirds such as pigeon guillemots.

Black rockfish populations in Alaska are considered stable, but fisheries managers set conservative limits on all species of rockfish. Because black rockfish grow and mature slowly, live nearshore, and have small home ranges, they are susceptible to overfishing by sport and commercial fishermen. They are easy to find and easy to catch. Like other rockfish species, they have an unvented swim bladder, and when anglers reel them to the surface, they usually do not survive if released.

As I have mentioned several times over the past few posts, both pelagic and non-pelagic rockfish are highly susceptible to barotrauma, physical injuries due to rapid changes in pressure when an angler catches a rockfish and brings it to the surface. In my next post, I will discuss ways to spare rockfish from barotrauma and methods to protect fragile rockfish populations.

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Yelloweye Rockfish (Sebastes ruberrimus)

January 27, 2019Fish, Kodiak WildlifeFish of Alaska, Fish of Kodiak Island, Robin Barefield, Rockfish, Rockfish of Alaska, Sebaste ruberrimus, Yelloweye, Yelloweye Rockfishadmin

The brightly colored yelloweye rockfish looks like a fish you might expect to see swimming near a tropical reef, but yelloweyes live in the frigid waters of the northeastern Pacific Ocean, from Baja California to the Aleutian Islands in Alaska. Anglers sometimes call yelloweyes red snapper, but they are not snappers and are not related to the red snappers found in the Gulf of Mexico.

Yelloweyes are among the largest rockfish found in Alaska and can grow to 36 inches (91.44 cm) in length and weigh 24 lbs. (11 kg.). They vary in color from orange-yellow to orange-red, and they tend to become more yellow as they age. Juveniles are usually bright red and have two vertical stripes, one above and one below the lateral line. As they age, the stripes fade, and their color changes to a red-orange or orange. A very old rockfish might be yellow. While their fins tips of adults are usually black, the fins of juveniles are tipped either white or black. As their name suggests, their eyes gleam bright yellow, making them easy to identify. In addition to the spines found in their dorsal and anal fins, several small spines sprout from their head.

Adult yelloweyes are solitary fish and live in steep, rocky areas, where they can find shelter. They typically live on the ocean bottom, and they don’t venture far from their rocky homes. They usually live between 300 and 600 ft. (91.44 – 182.88 m), but they have been found in only 48 ft. (14.63 m) of water and as deep as 1,800 ft. (548.64 m). Because yelloweyes live in rocky areas near the bottom and have small ranges, biologists classify them as one of the species of non-pelagic rockfish.

Rockfish are long-lived and slow to mature. Yelloweyes can live over 100 years, and the oldest recorded was a 121-year-old individual caught in Southeast Alaska. Yelloweye males mature when they are approximately 18-years-old, while females do not reach sexual maturity until 22-years of age. Males fertilize a female’s eggs internally, and the female then carries and nourishes the eggs until they hatch into larvae. One female can give birth to as many as 2,700,00 larvae.

Since the female nourishes her eggs and gives birth to live organisms, you might expect rockfish to have a higher reproductive success rate than do other fish species where eggs receive little or no parental care, but unfortunately, only a small percentage of rockfish larvae survive to adulthood, and even fewer survive until they are sexually mature. As soon as they are released, ocean currents sweep most of the larvae out to sea, and the young fish die before they have a chance to feed and grow. Other larvae starve to death from a lack of food, while many fall prey to larger fish, seabirds, and other organisms. The few larvae that survive, drift with the ocean currents while they eat and grow into small fish. They then settle to the bottom where they can find protection from predators among rocks and under kelp. As the young grow, they move into deeper water.

Yelloweye populations are fragile and vulnerable to overfishing. Females do not reproduce until they are over twenty-years-old, and once the female releases her larvae, few of the young survive. Recruitment of young fish into the population is slow, and if a fish reaches sexual maturity and is then caught by an angler or eaten by a predator, the population suffers not only the loss of this one individual but also the loss of all the potential young this one fish could have produced during its long life.

Because yelloweyes seldom move from one area to another, they are easy targets for anglers, and they are easy to catch. Even strict regulations which prevent the retention of non-pelagic rockfish do not protect yelloweyes because when an angler reels a yelloweye to the surface from a depth greater than 90 ft., the fish usually cannot return to the bottom, and when released, it floats at the surface until it dies. Yelloweyes, like other rockfish, have an un-vented swim bladder, and as the swim bladder inflates when the fish is reeled to the surface, it compresses internal organs and often pushes the stomach out of the mouth. The fish cannot deflate its swim bladder at the surface, but the swim bladder will deflate to the normal size if the angler can return the fish to the bottom where it was caught. New deep-water release techniques have helped improve the survivability of released rockfish.

The best way to avoid killing a yelloweye is to avoid fishing in the rocky areas where they live. Fisheries biologists find it difficult and expensive to manage non-pelagic rockfish because hauling them to the surface to tag them would likely kill them. Researchers believe most yelloweye populations in Alaska remain stable, but they’ve enacted strict regulations to protect these beautiful fish.

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Mystery Newsletter

Rockfish of Alaska

January 20, 2019Fish, Kodiak Wildlife, UncategorizedBlack Rockfish, Fish of Alaska, Rockfish, Rockfish in Alaska, RockfishBiology, Yelloweye Rockfishadmin

Scientists have identified more than 102 species of rockfish belonging to the genus Sebastes, and over thirty species live in Alaskan waters.^] Although anglers sometimes refer to yelloweye rockfish as red snapper, and many call black rockfish black bass, there are no snapper or bass in Alaska.

Rockfish belong to the family Scorpaenidae, the “scorpionfishes.” Scorpionfish have venomous spines in their fins, and the venom in some species is extremely toxic. Rockfish venom is only mildly toxic, but it causes pain and swelling and can lead to infection. In most species of rockfish, the venom sacs are located at the base of the dorsal and anal fin spines, but in a few species, other fin spines are also venomous. They use their venom to defend themselves.

A rockfish has large scales, and in addition to its fin spines, it has smaller spines on its head and gill covers. Species range in color from bright reddish orange and yellow to gray and black. Individuals of some species grow to 40 inches (101.6 cm) in length.

Scientists divide rockfish species into two groups based upon their preferred habitats: Pelagic and Non-Pelagic. Pelagic species can be found at any depth and usually swim in large schools above rocky shelves. Pelagic species include black, dusky, dark, and yellowtail. Solitary non-pelagic rockfish remain near the bottom in rocky areas, sometimes hiding in cracks or under rocks. They usually live at a greater depth than pelagic species. Non-pelagic species include yelloweye, tiger, quillback, silvergray, China, copper, rougheye , and shortraker.

Rockfish are some of the longest living vertebrates. A yelloweye caught in Southeast Alaska was 121 years old, and shortraker rockfish can live over 150 years.^]

Some species of rockfish reach sexual maturity at five to seven years old, but others do not begin to reproduce until they 15 to 20 years of age. Most fish lay and fertilize eggs externally, but rockfish mate internally, and the female carries and nourishes the eggs for several months before giving birth to thousands or even millions of tiny larvae. The larvae are at the mercy of the ocean currents and wind, and most get swept out to sea and don’t survive. Those that do survive, are subject to predation. The larvae feed and grow in the ocean column for several months before they settle onto the ocean floor where they can seek protection in the kelp and rocks. As the young mature, they move into deeper water.

Researchers have found that while pelagic rockfish sometimes travel hundreds of miles, most maintain a range of only twenty miles. Non-pelagic species have very small ranges of only a few-hundred yards, and some spend their entire lives on the same rock pile.^] Because non-pelagic species do not travel far from their rocky homes, they are easy targets for anglers and are vulnerable to overfishing.

Rockfish eat plankton, crabs, shrimp, and small fish, including smaller rockfish. They are preyed upon by Pacific cod, lingcod, sablefish, other rockfish, halibut, king salmon, sculpins, sharks, seabirds, marine mammals, and humans.

Non-pelagic rockfish are more susceptible to overfishing than most fish species. Not only are they easy to find and catch, but they rarely survive catch-and-release fishing because their air bladder or swim bladder has no vent. A fish uses its swim bladder to adjust buoyancy, and when a rockfish is caught in its deep home and reeled to the surface, the balloon-like swim bladder rapidly expands and pushes against its internal organs. By the time the fish reaches the surface, the expanded swim bladder often shoves the stomach into the mouth. Once it is at the surface, the fish is unable to deflate the swim bladder, and if the angler releases it, the fish will float at the surface and die.

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In my next post, I will discuss yelloweye rockfish in more detail, and in the following post I’ll focus on black rockfish. Then, I’ll talk about rockfish management and techniques anglers can employ to preserve non-pelagic rockfish populations.

I have been traveling for the past two weeks and will be on the road for another three weeks, so my posts have been less frequent than usual, and I probably won’t return to a steady schedule until I get home. Thanks for reading, and I hope you are enjoying a great winter.

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