McHUGH: MARINE FISHERIES OF DELAWARE 



commercial catch, and possibly more. This report 

 also gave estimated landings by recreational 

 fishermen for other years, 2.4 million fishes 

 in 1968 and 1.9 million in 1973. Using the same 

 average annual weights these amounted to 

 roughly 1.542 t (3.4 million lb) and 1,225 t (2.7 

 million lb), respectively. This was 21 times and 

 2.3 times the commercial catch of finfishes, re- 

 spectively. These are probably not very accurate, 

 but it is clear that sportfishermen in Delaware 

 caught more fishes than commerical fishermen. 



THE OCEANOGRAPHIC REGIME 



Parr (1933) found that through alternate 

 development and breakdown of temperature 

 barriers at Cape Cod-Nantucket Shoals and Cape 

 Hatteras, the shallow water belt along the Middle 

 Atlantic coast is in open-temperature continuity 

 with the waters north of Cape Cod in winter and 

 with waters south of Cape Hatteras in summer, 

 being barred in opposite directions during these 

 seasons. Temperatures in the Cape Cod region 

 develop slowly in winter, early spring, and late 

 fall, but show violent fluctuations in summer. In 

 the Cape Hatteras region the opposite succession 

 of conditions prevails, with relatively smooth 

 temperature changes in summer, but with violent 

 fluctuations in winter, early spring, and late 

 fall. Winter invasions of fishes from the north are 

 quantitatively poor and not very penetrating, but 

 visitors from south of Cape Hatteras are usually 

 complete. In the Delaware Bay region these 

 changes are at a maximum, and Delaware Bay has 

 the greatest difference between maximum 

 and minimum temperature whether at the 5 per- 



centile (Figure 5) or the 95 percentile (Figure 6) 

 level. This means that the temperature regime is 

 less variable to the north and south of Delaware, 

 and presumably the effect on migrations is less. 

 The data from which Figures 5 and 6 were taken 

 are from Waters ( 1967 ). This shows for a period of 

 over 100 yr the 5 percentile and 95 percentile iso- 

 therms of surface water temperatures along the 

 Atlantic coast of North America. The temperature 

 rises rapidly in spring and falls almost as rapidly 

 in fall, and also varies considerably from time to 

 time. For example, the 70° F isotherm penetrates 

 only to Virginia in cool years (Figure 5), but rises 

 as far north as Cape Cod in warm years (Figure 6) 

 in summer. Similarly, in winter the 42° F iso- 

 therm comes as far south as Cape Hatteras in cold 

 years, whereas in warm years it barely reaches 

 Cape Cod. 



This means that Delaware is in a region of 

 rather highly variable water temperature, which 

 will influence how far north southern species will 

 come in summer, and how far south boreal species 

 will come in winter. This is obviously not a favor- 

 able oceanographic regime for highly predictable 

 fisheries, even if their numbers did not fluctuate 

 greatly from time to time. 



FISHES AND SHELLFISHES 



Menhaden 



Although it undoubtedly was abundant in the 

 Delaware area, menhaden did not support a major 

 commercial fishery in the early days. Along many 

 parts of the coast it was originally used mainly as 

 fertilizer, applied directly to agi'icultural land. 



CAPE COD 

 LONG ISLAND 



CAPE MAY 

 CAPE CHARLES 



CAPE HATTERAS 

 CAPE LOOKOUT 

 CAPE FEAR 



O 



< 



I 



q: 

 O 





M J J A 

 MONTHS 



M J J A 

 MONTHS 



Figure 5. — Surface temperatures along the Middle Atlantic 

 coast, 5 percentiles, by months and degrees latitude. 



Figure 6.— Surface temperatures along the Middle Atlantic 

 coast, 95 percentiles, by months and degrees latitude. 



581 



