Tag Archives: Cod

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.

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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.

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What Happened to the Pacific Grey Cod?

July 1, 2018Fish, Kodiak WildlifeCod, Cod Crash in Alaska, Cod in Alaska, Crash of Pacific Grey Cod, Grey Cod, Pacific Cod, Robin Barefield, The Blobadmin

In October 2017, the National Oceanic and Atmospheric Administration (NOAA) made a shocking announcement. Pacific cod (or grey cod) stocks in the Gulf of Alaska had declined 71% since 2015 and 83% since 2013. Cod, once one of the most plentiful fish in Alaskan waters, suddenly became a rare catch, devastating one of the most lucrative commercial fisheries in the state. Biologists scrambled to learn why cod were dying and why the few cod caught weighed less than normal and appeared malnourished.

While researchers yet do not have empirical evidence to support their theory, they have a good idea why cod populations have crashed. During the winter of 2013/2014, scientists mapped an unusually warm, large, circular body of seawater in the North Pacific Ocean. This mass of water didn’t cool as winter progressed but instead hovered several degrees above the normal winter temperature. Scientists nicknamed the mass of warm water the “Blob.” In February 2014, the Blob remained 4.5° F (2.5°C) warmer than the average February ocean temperature.

Warm water temperatures persisted throughout 2014, and oceanographers noted these were the warmest temperatures ever measured in the North Pacific Ocean since climatologists began recording ocean temperatures. Along with these warm water temperatures, a static high-pressure region in the atmosphere persisted throughout much of 2014, resulting in a lack of the normal wind-generated currents that stir the surface waters of the North Pacific.

This warm, calm mass of water produced far-reaching effects on the biology of the North Pacific. Without an upwelling of cooler water and nutrients, the surface waters of the warm Blob became stagnant, resulting in reduced phytoplankton production. Phytoplankton is the platform for the ocean food pyramid, and without a healthy supply of phytoplankton, the pyramid collapses. Zooplankton can’t survive unless they have phytoplankton to eat, and without zooplankton, many fish species, including the juveniles of most species, will starve. Plankton-eating fish provide the food supply for larger fish, and all fish, mammals, and birds dependent on marine life to survive will suffer from a reduction in phytoplankton productivity.

A lack of food was not the only problem Pacific cod faced, though. The increased ocean temperatures raised their metabolism while reducing the available food. With less food, the average size of the cod dropped. A 2015 NOAA survey showed cod were the skinniest ever recorded, and at this same time, mortality rates skyrocketed for the younger age classes of cod, an indication the cod population would not recover for many years. The warm water and lack of nutrients also negatively affected cod egg production.

Will the Pacific grey cod recover? Biologists don’t know the answer to this question, but even if cod populations begin to recover now, they will not be commercially viable until at least 2021. The crash of the cod fishery has had a negative impact on the economies of Alaska fishing ports, and the decline of cod is certain to impact the food web of the North Pacific.

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.