fluctuated between 0.7 and 2.5 million lbs/yr, with no downward trend, 

 but the fishery is approaching the point of maximum sustainable yield. 

 Limiting factors have been low levels of recruitment, and predation. No 

 known disease is prevalent. The report summarizes major fishery problems 

 in the Bay and offers 7 recommendations for fishery management generally. 

 - J.L.M. 



1180 



Lynch, M. P., and J. Claiborne Jones. 1977. 



Public health aspects of tropical storm Agnes in Virginia's portion of 

 Chesapeake Bay and its tributaries. in The Effects of Tropical Storm 

 Agnes on the Chesapeake Bay Estuarine System. Chesapeake Research Con- 

 sortium, Inc. Johns Hopkins Univ. Press, Baltimore, CRC Pub. 54: 625-635. 



On June 23, 1972, Virginia waters in Chesapeake Bay and its tributaries 

 were closed for the taking of shellfish for direct human consumption. Por- 

 tions of the Bay and tributaries were reopened on July 20, 1972, and by 

 October 5 all areas were opened except those permanently closed. Higher 

 than usual coliform levels in Virginia waters appeared to be primarily 

 associated with runoff from the initial rains. With the exception of eco- 

 nomic dislocations in the shellfish industry caused by the closings, the 

 public health ' impacts were minimal. - J.L.M. 



1181 



MacBride, E. W. 1912. 



Oyster culture and clam fishing, Prince Edward Island. Contr. Can. Biol. 

 Fish. 1906-1910(13): 217-220. 



Most of this paper deals with the oyster fisheries, to study which the 

 author had made a trip to the Island. He received complaints on arrival 

 about damage to oyster beds by fishing for Venus mercenaria. This was a 

 fairly new fishery, legal during the closed season for oysters. This clam 

 lies buried in the mud with the posterior surfaces of the edges of the 

 valves just showing above the silt. Harvesting was done with a large rake 

 with 9-inch teeth, which disturbs the bottom. There was no reason for 

 fishing hard clams on oyster beds because the characteristic bottom for 

 clams was blue mud, which is unsuitable for oysters. Large clams, called 

 "bulls", were found around the edges of oyster beds, but were not marketable. 

 The preference was for clams of intermediate size, which have tenderer foot 

 tissues. It was concluded that oysters may invade a clam bed and the • older 

 clams may survive. The author believed that new hard clams could not 

 establish themselves on an oyster bed. He stated that oyster and hard clam 

 fisheries could exist side by side if the areas for each are defined. 

 Considerable numbers of hard clams were opened, but none showed gonad 

 development. It was concluded that July is not part of the breeding season 

 in P.E.I. -J.L.M. 



1182 



MacClintock, Copeland, and Giorgio Pannella. 1969. 



Time of calcification in the bivalve mollusk Mercenaria meroenaria (Linnaeus) 

 during the 24-hour period. Geol. Soc. Am., Abstracts with programs for 1969, 

 Pt. 7: 140 (abstract) . 



An experiment in the natural environment, beginning in August, in which hard 

 clams were notched and one removed each hr for 52 consecutive hrs, showed that 

 all deposition takes place at nearly uniform rate at night. Very little shell 

 is deposited during the day. Major breaks marking increments were related to 

 the non-deposition period between the two low tides during daylight. It was 

 concluded that calcification is restricted to a few hrs of physiological 

 activity. A simple increment is deposited when this activity is not 

 interrupted by a low tide at night. Otherwise a complex increment with a 

 marked break inside is formed. Shifting of this line toward the margin in 

 adjacent increments parallels the 50-min daily tidal shift. - J.L.M. 



331 



