First of all, fish and other organisms are killed by "entrainment" when they are drawn involuntarily into the cooling system. Especially vulnerable are the free-floating eggs of a number offish species, larval fish, fish smaller than 2½ inches and plankton, the microscopic plant and animal life on which many fish graze. Death by entrainment comes from the high velocity of the water flow, which smashes the fish into various parts of the system, and the sudden temperature rise of the cooling water, which causes thermal shock. Recent tests at the Pittsburg, Calif. oil-and gas-fired power plant on the Sacramento River estuary showed high inner-plant mortality of larval striped bass when the cooling water temperature was above 85° or 86°. Organisms that are not killed outright, say some authorities, may suffer delayed mortality—loss of equilibrium, coma, then death. Barton C. Marcy Jr., a biologist studying the Haddam Neck nuclear plant on the Connecticut River, discovered that no larval or juvenile fish of any species survived entrainment above 82°. He also reported that 80% of the dead specimens were mangled by the machinery. In 1969 and 1970 the Haddam Neck plant killed a total of 358 million larval fish.
Valuable species of shellfish are very vulnerable to entrainment at certain stages of their life cycle. Clark and Brownell predict that the Seabrook nuclear power plant, proposed for construction next to the Hampton-Seabrook marshes of New Hampshire, could do "massive damage" to clam populations even though the plant would draw its cooling waters not from the estuary but from the bottom of the ocean outside. "The ocean water in this area," they write, "has proved to be strongly estuarine because the estuary flushes out 85% of its high-tide volume on each ebb tide. Clam larvae, which transit to the ocean and back with each change of tide, are exposed in high concentration to entrainment by the offshore intake because they are non-buoyant and tend to sink toward the bottom once they are through the inlet and out in the ocean. All larvae entrained would be killed in passage through the plant." By one estimate the clams will be reduced by more than a third.
According to Clark and Brownell, "Inner-plant kill appears to be a most serious (if not the single most serious) impact of estuarine-sited power plants with once-through cooling." However, scientists have been slow to recognize this problem because the organisms are small and can float away with the current, unseen and unappreciated. The worst documented case on record is in an Environmental Protection Agency study of the oil-fired Brayton Point power plant on Mount Hope Bay, Mass. in 1971. The EPA scientists reported that "all larval menhaden are killed on passage through the Brayton Point Plant." The highest calculated kill there for a single day was 164.5 million menhaden on July 2, 1971. The cause of death appeared to be "hydrostatic, mechanical shearing forces." Dr. C. M. Tarzwell of EPA noted bluntly, "When you are in an estuary where there is a concentration of plank-tonic and larval forms, the more water you put through the plant the more harm you are going to do."
To keep debris from entering the plant innards with the cooling water, power plants have trashracks and intake screens. Juvenile fish of certain species from 2½ to five or six inches long are too large to go through the screens to become entrained, but they are also too small to swim against the flow and escape being caught and held against the screens. "It appears that most estuarine fish impinged on power-plant screens are killed outright or suffer mortal damage resulting in delayed death by exhaustion, suffocation or external and internal mechanical impact," Clark and Brownell write. The six million fish estimated killed at the Surry plant were screen-killed. The same applies to the menhaden, anchovies and croakers done in at the P. H. Robinson gas-fired power plant on Galveston Bay, Texas in 1969-70. The small Indian Point One nuclear plant on the Hudson River averaged a yearly kill of one million to 1.5 million fish from 1965 through 1972. The AEC predicts that when Indian Point Two goes into full operation shortly, it and the smaller plant will kill five million fish a year.
The hot water that flows from a power plant can kill fish outright or affect their behavior in several ways. The most common cause of death is thermal shock, although Clark and Brownell are somewhat dubious about high temperature shock kills, surmising that other factors are involved. The heated plume, however, may put what amounts to a thermal dam in a river that can prevent fish from migrating or getting to upstream spawning grounds. "A discharge plume would not have to block a whole passageway to interfere with fish migration," Clark and Brownell write. "For example, salmon and steelhead prefer to migrate in shoal water near the edge of a riverway apparently, rather than in the deeper channel. Consequently, they would be subject to blockage by a plume that occupies only the upper part of the water and does not extend all the way to the bottom."
Interestingly, cold shock kills, caused by plant shutdowns, have also been registered. The Smithsonian Institution reported on a huge kill offish, mostly menhaden, that died in January of 1972 following the shutdown of the Oyster Creek nuclear plant at Barnegat Bay. "Menhaden normally migrate to warm waters off North Carolina during the winter," the Smithsonian reported. "However, the heated waters discharged from the cooling system of the Oyster Creek plant appear to have created 'favorable temperatures and the fish—unaware of the changing season—did not migrate. When the plant shut down on Jan. 27, water temperatures in the creek returned to their normal winter low, and the menhaden died of thermal shock." Other enormous kills from similar causes have occurred since in New York and Florida.
Fish kills from supersaturation of nitrogen—the bends—in the discharged water also occur. "Although embolism kill from power-plant discharge had been reported for fresh water," Clark and Brownell write, "the first documented example of a probable nitrogen kill in an estuarine location occurred in and around the discharge canal of the Pilgrim power station on Cape Cod Bay in early April 1973. The Smithsonian Institution reported on the incident as follows: "Thousands of adult Atlantic menhaden (10" to 14" long) are dying near the warm water discharge of Boston Edison's nuclear power plant. The kill was reported by Edison officials late Monday afternoon (April 9, 1973). There are preliminary indications that the menhaden are dying from a gas bubble condition which is caused by supersaturation of nitrogen in the water naturally. However, the water taken by the plant at a low temperature is increased roughly 26-27° F. so that when it comes out of the plant it is supersaturated. The fish are hemorrhaging in the fins. They have numerous gas bubbles on their fins and in the membranes between the fin rays.' " Clark and Brownell add that it is likely that numerous nitrogen kills have occurred at other plants but were unrecognized or unreported: "The unsolved kill of many thousands of menhaden at the Millstone Point Plant [on Niantic Bay, Conn.] in the spring of 1972 was quite probably a nitrogen embolism kill."
After summing up the considerable dangers posed by poor power plant siting and design, Clark and Brownell make some specific recommendations on how to alleviate the problems the plants cause. Their recommendations are not likely to please various power companies that, despite the toll of dead and dying fish vomiting from their plants, like to plead for "more time for research programs." Briefly put, Clark and Brownell say that existing plants must be equipped with "closed" cooling systems, in which the cooling water is constantly recirculated and is itself cooled down by evaporation in huge towers. Further, they state flatly that no new power plants should be built on critical spawning and nursery grounds of tidal estuaries. These areas are too valuable to suffer any more damage, even with the use of closed-cycle systems, which still require a small daily "make up" refill of water drawn from the estuary. Some power companies have adopted closed-cycle cooling, for example, the two new Potomac Electric units of the Chalk Point station on the Patuxent River, but in far too many cases the utilities have balked, even though the potential for extensive damage is evident. As a case in point, Clark cites the Calvert Cliffs nuclear plant that Baltimore Gas and Electric is currently building directly on Chesapeake Bay. Clark says, "I predict this single plant may be the greatest environmental disaster to fish ever to go into operation. It will kill many millions of fish. It is a perfectly designed fish trap. Watch. I predict. Quote me."
Just over our offshore horizon lies another menace to our coastal fisheries—an enormous foreign fleet that is sucking up everything that swims. In July the National Marine Fisheries Service reported sighting 210 foreign fishing vessels and support ships off the mid-Atlantic and New England coasts—some of them right at the edge of the 12-mile fishing limit. From the air it looked like a D-day armada. There were 178 Soviet ships, 10 East German, seven Polish, seven Japanese, four West German, two Spanish and two Bulgarian. The Soviets had 111 of their ships working in a string from the tip of Cape Cod northeastward to Georges Bank. Most of them were factory stern trawlers.
Soviet vessels first appeared off the East Coast in 1961 to begin so-called "exploratory fishing" for sea herring on Georges Bank east of Cape Cod, a traditional U.S. fishing ground. They kept coming back with huge trawlers and factory ships, far in advance of any privately built U.S. fishing vessels, and in the late 1960s they were joined by vessels from Poland, West Germany, East Germany, Rumania, Bulgaria, Japan and Spain. The foreign fleets indulge in "pulse" fishing, which means directing fishing intensity upon a particular species or stock until it is exhausted. Special scout ships equipped with electronic sensors plot the movements or migrations of fish, and catch vessels move in for the kill. And kill it is. Foreign catches of cod, sea bass and porgies have depressed both U.S. sports and commercial catches. And in just a few years of intense fishing the once enormous stocks of sea herring have been diminished by 90%, and haddock have been reduced to such low numbers the species may become almost nonexistent in East Coast waters. Most of the haddock the Soviet fleet caught in the mid-1960s were immature fish that would have sustained the regular U.S. fishery into the 1970s.