Monthly Archives: February 2019

Rockfish Conservation

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 swimming

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
  1. 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.
  2. 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.
  3. If you want to retain a few rockfish along with other species, target the other species first and retain any incidental rockfish you catch.
  4. 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.
  5. Remember, rockfish only have a freezer life of four months, so don’t catch more than you can eat.
  6. 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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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.

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Black Rockfish

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

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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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.

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Sign Up for my free, monthly Mystery Newsletter about true crime in Alaska.
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