Document LKBz4QmyrVN8vzRX86DYwBQjb

El|r jnanlitiwjtoit {luat WASHINGTON, D. C. D. SiS.m SUN. ilO.148 FEB 10 1976 / --, Outdoors/C. Boyd Pfeiffer Rock fish Decrease Called Cyclic A cyclic decline in the rate of rockfish reproduction, more than any chemical pollution of the Chesapeake Bay, has led to the fall-off in fishing there, according to two scientists who study the bay. Consequently, they say, rock fishing should improve in two to four years, although it likely won't reach the ab normally good levels of mid- 1960s through the early 1970s. Some groups of fishermen have claimed that --Polychlorinated biphenyl ^BTOTW05o*5T thenay Ka caused sterility in spawning rock and has killed the Just- hatched fry. But Dr. Ted S. Y. ' Kuo. chairman of the fisheries department of the University of Maryland's Chesapeake Biological Laboratory, and Dr. John Merriner, head of the ichthyology department of the Virginia Institute of Marine Science, have concluded that the decrease In the number of rock is due to e natural dip in the flsh'arateofspawning. Dr. Koo's studies have led him to think that every six years a "dominant-year class" of rock is hatched. The large numbers of fish spawned that year lead to good fishing two to four years later when the fry have grown to the IS- to 16-inch sise idoat for both sport and commercial fishing. Dominant-year classes, according to Dr. Koo, have been spawned in 1952. 1958. 1964 and lT9. and should occur again this year. Thus, rock fishing should continue to be poor until at least 1971 but then improve, says Dr. Koo. Dr. Merriner, whose department keeps a close watch on bay pollution, says, "Fluctuations of rockfish in the Chesapeake Bay are caused by environmental factors on the spawning and nursery grounds that affect year-class strength." Ben Florence, a biologist with (he Maryland Fisheries Administration, thinks the excellent fishing cycle now ended was caused by dominant-year classes plus abnormally large numbers of fish hatched in the normally "off" years of 1961,1962, and 1966. Surveys of commercial landings in Maryland confirm this. Catches of rockfish through I960 were at a peak. By comparison, the 1971 commercial catch was down 2.6 million pounds, the lowest U had been since 1958. Now the boom in rock fishing is over, the scientists .a say, as reproduction (rends return to normal levels. But Dr. Merriner is con cerned about the rock and other coastal fishes. He fears that increased sport fishing along the coast plus com* mercial fishing could ad? versely affect the future pf several species. . - Consequently, fishermen and biologists alike should continue to keep watch on tn rockfish; especially on the small fish that are tjpt barometersof the future. r- HONS 033047