Tag Archives: Rockfish

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.

Stomach protruding from yelloweye rockfish mouth — Stomach protruding from mouth

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.

_________________________________________________________________________

Several weeks ago, I mentioned the Reader’s and Writer’s Book Club started by my publisher and some of my fellow authors. You can still claim your free lifetime membership to the club by following this link, but free membership will end within the next few weeks. I am currently writing a mystery with the aid of club members, and I invite you to join the fun!

As always, thanks for visiting my blog, and don’t forget to sign up for my free monthly mystery newsletter about true murder and mystery in Alaska.

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.

Mystery Newsletter

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.

_________________________________________________________________

Mystery Newsletter

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.

________________________________________________________________________

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.

_______________________________________________________________________

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.

_________________________________________________________________________