McHUGH: MARINE FISHERIES OF DELAWARE 



of American oysters, and had substantial shad, 

 sturgeon, and other fisheries. A variety of factors, 

 including improper management of shellfish 

 beds (harvesting without replenishing equal 

 quantities of shell stock), development of the 

 watershed with attendant siltation, heavy indus- 

 trialization of the Delaware River, industrial 

 effluents and oil spills, mosquito control by ditch- 

 ing wetlands and spraying, and closure of harvest- 

 ing areas caused by sewage contamination, caused 

 American oyster production to decline to 4,082 t 

 (9 million lb) by 1954. By 1960 the American 

 oyster industry suffered a catastrophic collapse 

 caused by the pathogen MSX ( Minchinia nelsoni). 

 In Delaware, the value of American oyster land- 

 ings declined from almost $3 million to <$40,000 

 from 1954 to 1961. The fishery has not been re- 

 established to date (Maurer et al. 1971). 



Gunter (1975) claimed that American oyster 

 production in Delaware Bay as a whole (Delaware 

 and New Jersey) has declined in two vast steps, 

 from about 6,500 t (14,247,000 lb) from 1880 to 

 1931, to 3,600 t (7,951,000 lb) from 1932 to 1957, to 

 390 t (859,000 lb) from 1959 to 1970. He pointed 

 out that the two declines each occurred 3 yr after 

 diversions of Delaware River water to New York 

 City in 1929 and 1953. He did not offer other data 

 to substantiate cause and effect. 



Weakfish 



catch remains at over 1,360 t (3 million lb). 

 The resource obviously fluctuates widely in abun- 

 dance for environmental reasons, of which more 

 will be said later. It was relatively abundant in the 

 1950s and very low in abundance in the 1960's. 

 The decline of the commercial fishery was prob- 

 ably a combination of these natural fluctuations 

 and an increasing catch by the recreational fish- 

 ery. The estimated catch by sport fishermen in 

 1974 was 1,724 t (about 3.8 million lb). A.ssuming a 

 much smaller recreational catch in the 1880's, 

 this compares favorably or even exceeds earlier 

 catches. Some also have suggested that the decline 

 in abundance of weakfish after the Second World 

 War may have been caused by widespread use of 

 DDT on salt marshes (Joseph 1972). 



The gradual decline in the take of weakfish by 

 commercial fishermen probably contributed to 

 the virtual collapse of the commercial fisheries 

 generally in Delaware. Sturgeon, shad, and 

 croaker, the other major contributors to the in- 

 shore fishery, had already been reduced in abun- 

 dance much earlier, and with weakfish virtually 

 gone, there was little else to attract commercial 

 fishermen. This probably was hastened by recre- 

 ational fishermen, who discovered an old law some 

 time in the 1960's that prohibited trawling in 

 Delaware Bay and applied pressure to have it 

 observed. New Jersey fishermen have not been 

 allowed to trawl in the Bay for many years. 



There is little question that weakfish was 

 the "money" fish of the Delaware fishery. It has 

 fluctuated widely in abundance from time to time, 

 but has held up well, and may now be as abundant 

 or more so, than it ever was. Although the record 

 of commercial landings from 1880 to 1977 is in 

 general downward (Figure 11), this is a popular 

 sport fish, and recreational catches in recent 

 years, if they are at all accurate, suggest that the 



Alewives 



Except for a brief period in the early 1930's, 

 alewives were a relatively small and declining 

 resource in Delaware (Figure 12). Catches de- 

 clined fairly steadily, until by the 1960's they were 

 almost zero. The brief increase in alewife landings 

 in the early 1930's may have been caused by the 



Figure ll. — Commercial landings of 

 weakfish in Delaware, 1880-1977. 



585 



