The Subtle Vices of Overfishing

Obviously, overfishing can kill too many adult fish to keep populations healthy. But overfishing has more subtle effects that conspire to cripple salmon recovery. The most important of these may be the gradual downsizing of salmon.

This results from well-intentioned regulation intended to avoid the waste associated with harvesting immature fish in the ocean. Fishery managers regulate the mesh size of nets used to catch salmon so as to allow smaller, immature salmon to escape. For fish caught in the troll fisheries, they have also established minimum size requirements. This promotes greater biological efficiency, but has a powerful side effect: size, an advantage in the natural system, becomes a disadvantage in the harvest system.

As a result, the size of salmon has been dropping rapidly. As recently as the 1940s, most of the salmon returning were the larger salmon that stayed out in the ocean as long as four or five years.84 Now they are much smaller. And they don’t stay out as long, because each year at sea exposes them to another fishing season. Harvest pressure has selectively eliminated the oldest, largest salmon. A 1980 study by renowned Canadian fish biologist W. E. Ricker concluded that the average size of chinook salmon “has been declining since at least 1920, and continues to decline. Present average weights are half or less than half of those obtained 50 years ago.”85 Another researcher reported a marked decrease in the average age of fall chinook caught in the ocean from 1919-30 to 1949-63, which he characterized as typical of an overexploited population.86 The same phenomenon has been observed in Norwegian cod, Atlantic salmon, red snapper, and red porgy.87

Size reductions may have a lot to do with the mysterious loss of “resilience” in overfished salmon populations. Fishery mismanagement can quickly select out the genes for large fish that took centuries (or longer) to develop, and no effort is made to put them back. Large fish got large for a reason. They avoid predators better, and each one of them has a lot more eggs per spawner. Yet it seems to take a very long time for animals to get larger naturally, so that when fishing restrictions are lifted, populations do not rebound. Fisheries scientist John Palmisano suggests that “[t]he failure of many of the Basin’s stocks to recover could be a result of the loss of genetic material that occurred during the periods of overharvest . . .“.88

Size could also explain disproportionately large reductions in upriver salmon runs. Fishermen have long recognized that salmon “destined for upriver areas are larger, as they need more stored fat to enable them to make the journey to their spawning grounds”.89 Size was also an advantage in surmounting obstacles to upstream migration, particularly forceful rapids and waterfalls. Before dams replaced a difficult rapids known as “Goblin’s Gate” on the Elwha River, had a reputation for enormous chinook salmon. Only the big ones could get up the rapids.90 On the Columbia and Snake, fish ladders have replaced the falls, but size may still be important in that larger fish may have greater stores of energy needed for the longer journey.

Many upriver salmon stocks, including Idaho’s salmon, have suffered rapid declines that are often blamed on dams. The endangered Snake River spring chinook and sockeye, because they go so far up into the headwaters of the Snake River Basin, have harder migration journeys than most other Columbia River Basin fish.

Smaller salmon are going to have a significant handicap, and the hardest part of their journey may be above the dams. That could be another reason why we have a good deal of high quality salmon habitat in Idaho, far up the tributaries of the Snake River, where salmon are no longer found.

Upriver stocks in the Columbia Basin must pass over many dams, but upriver stocks are declining faster on undammed rivers too. For all we know, the single most important reason for the comparatively greater declines in upriver stocks is the fact that the fish are no longer big enough to get back up there. When I offered this theory to Donna Darm of the National Marine Fisheries Service, who used to assist the Regional Director, Will Stelle, in resolving tough policy issues, she said “keep your day job”. Fishery scientists could explore and resolve this question, but the harvest interests and their fishery agencies are not interested in the answer. They would rather blame the dams. The Columbia River Alliance has asked NMFS to study these effects in the Environmental Impact statement it has been preparing pursuant to court order after a legal victory in Ramsey v. Kantor (see Chapter 10). NMFS refuses to do so.

The net-based harvest has a second effect, whose long-range implications are entirely unknown: decreasing the age at which salmon are sexually mature. For many years, fishery agencies have kept count of “jacks”, which are sexually precocious two-year old males. The proportion of jacks has been rising. This phenomenon was reproduced in a laboratory experiment with two tanks of water fleas. Researchers sieved the tanks every four days, killing all the big water fleas in one tank, and all the little ones in the other tank. After several generations, the fleas in the tanks where big fleas were removed grew more slowly, and began reproducing when they were smaller. In the other tank, the fleas grew faster and did not reproduce until they were larger. In guppies, this change takes about fifty guppy generations.91 Fishery managers don’t seem to be very interested in finding out what the rising proportion of jacks is doing for spawning success.

Another subtle effect comes from the fact that when salmon runs were huge, large numbers of salmon would die after spawning and their bodies would fertilize the streams, providing a reservoir of organic material much richer than rocks or wood. Tiny plankton-like organisms would feed on the dead salmon, and would in turn be eaten by the juvenile salmon overwintering the streams. Insect larvae would colonize the carcasses, then be eaten by fish or escape to the land, spreading the organic materials from the salmon’s body to the land itself. One river on the Olympic Peninsula was called the Hamma Hamma or “Stinky-Stinky” because of the magnitude of the rotting salmon bodies. Now that salmon runs have declined, the clarity of these streams may be a barrier to salmon recovery.

Fishery managers have ignored the fertilization phenomenon entirely in setting salmon fishing seasons. To them, any salmon that escapes the gauntlet of nets and hooks is wasted. Fishery managers do set "escapement goals" to allow some salmon to return to the spawning grounds, but the escapement goals are never high enough. Rather than simply manage to allow adequate escapement, the Oregon Department of Fish and Wildlife recently commenced a complicated process to obtain permission from water quality regulators to dump 300 dead fish in Still Creek, a tributary of the Sandy River, as well as several other Oregon rivers.92

Ironically, less than two months after the Oregon Department of Fish and Wildlife announced its plan to dump dead fish in the Sandy River, it was trying to keep dead fish out of another Oregon River. The problem arose when the state shut down Klaskanine Hatchery for lack of funding. Instead of letting the returning adult coho salmon spawn in the river, perhaps establishing a naturally-spawning run, the state killed all the salmon and fed them to the inmates at the Yamhill County Correction Center. According to the Hatchery manager, Bob Bivans, salmon carcasses rotting in the river posed a risk of spreading diseases to native cutthroat trout.93

Because the parasites are now plentiful in the Columbia River Basin, the best we can probably hope is that resistant strains of fish survive. The benefits of allowing the fish to return upstream to spawn seem pretty obvious; even throwing dead fish in the river probably won't do much harm. But it seems unlikely that hiring biologists to lard Northwest streams with dead fish is a particularly cost-effective means of recovering salmon. Especially if we have to sterilize the carcasses.

84 See R. Reuberger, "The Great Salmon Mystery", Saturday Evening Post, Sept. 13, 1941.

85 W.E. Ricker, “Causes of the Decrease in Age and Size of Chinook Salmon (Onchorhychus tshawytscha)”, Can. Tech. Rep. of Fish. & Aquat. Sci. No. 944 (May 1980).

86 J. Van Hyning, “Factors affecting the abundance of fall chinook salmon in the Columbia River” (Or. Fish Comm’n 1973), cited in “Complation of Information on Salmon and Steelhead Losses in the Columbia River Basin”, at 103

87 J. Weiner, The Beak of the Finch 264.

88 J. Palmisano, Informal Comments to the NWPPC on the ISG’s Report, April 15, 1997, at 13.

89 I. Martin, Legacy and Testament: The Story of the Columbia River Gillnetters 51.

90 M. Goodman, 20 Envt’l Law at 120.

91 These experiments are summarized in J. Weiner, The Beak of the Finch 263-64.

92 "Officials want permission to put dead fish in streams", The Oregonian, Sept. 27, 1996.

93 C. Hollander, “End of the line—Hatchery’s closure means returning salmon have nowhere to go”, The Daily Astorian, Nov. 1996.

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