86 



BIOLOGICAL REPORT 31 



predominant in the watershed contributing to the 

 head of the bay (Fig. 5.2). Two primary methods 

 are used in cranberry harvest: water harvesting, 

 whereby bogs are flooded during the harvest sea- 

 son and the floating berries can easily be gathered 

 on the surface of the water, and dry harvest, where 

 the berries are mechanically scooped dry, which 

 tends to damage die vines. The disadvantage of wet 

 harvest is more rapid deterioration of the berries, 

 with these generally processed for juice or sauce 

 (90% of the national cranberry market). Dry-har- 

 vested berries are generally sold fresh or frozen, 

 making up the balance of the market. 



Cranberry cultivation has often been scrutinized 

 for its potential as a source of pollution to coastal 

 waters in that fertilization and pesticide application 

 are common practices in this agriculture (Fig. 5.3 ). 

 Increased demand for cranberry products has gen- 

 erally resulted in more efficient agricultural prac- 

 tices rather than overall areal growth, with chemical 

 application methods becoming increasingly sophis- 

 ticated to maximize yields. A constant concern has 

 been the potential for coastal eutrophication result- 

 ing from nutrient losses through runoff and ground- 

 water flow. However, measurements of inputs and 

 losses from a major cranberry bog into the head of 

 Buzzards Bay (Buttermilk Bay) indicate that losses 

 are small, comparable to those generated by low- 

 density (0.4 ha) residential development and cer- 

 tainly less than those of other dominant shoreline 

 uses around the bay (Howes and Teal 1 992). Nu- 

 trient retention by the bogs is consistent with crop 

 management practices to prevent overfertilization, 

 which tends to reduce yields by encouraging ex- 

 cessive vegetative growth. Generally, growers in the 

 Buzzards Bay watershed apply only enough fertil- 

 izer to compensate for the nitrogen lost in berry 

 harvest. Pesticides generally used in cranberry ag- 

 riculture have been approved by EPA for applica- 

 tion, and most have short life spans in the environ- 

 ment. With the increased use of recycled bog wa- 

 ter (primarily due to 1 iinited water supplies), residual 

 pesticides and nutrients are given additional oppor- 

 tunity to become sequestered within the bog before 

 the potential for loss to adjacent coastal waters. 

 Although fertilized, die bog loses about one-half to 



one-third of the amount of dissolved inorganic ni- 

 trogen (DIN, a readily bioavailable form of nitro- 

 gen) per unit area compared to detailed studies of a 

 natural wetland, Great Sippewissett Salt Marsh 

 (Valiela and Teal 1979). The pattern of loss is 

 roughly the same for both systems, with greatest 

 losses occurring during the coolest parts of the year 

 when the receiving coastal waters are less sensitive 

 to inputs. 



The dairy industry has been identified as a po- 

 tentially important source of agriculturally based 

 pollution to Buzzards Bay waters. The towns of 

 Carver, Rochester, and Westport are the primary 

 sites within the watershed, with only Westport lo- 

 cated directly on the bay. All of these towns have 

 seen a decrease in agricultural activities in recent 

 decades as residential development has replaced 

 farmland. Of the three towns, Westport supports 

 most of the dairy industry, although it has declined 

 by more than half in the past two decades. How- 

 ever, closures of shellfish areas because of bacte- 

 rial contamination have become more frequent even 

 while the total number of dairy cows has decreased 

 because the density of cattle per hectare in many 

 areas has increased. The greater density has in- 

 creased manure concentrations in some places, 

 causing higher inputs in runoff from pastures and 

 feedlots to streams entering the river and bay. As 

 more land is converted from agricultural to residen- 

 tial housing, pollutant inputs from the dairy industry 

 will be replaced, most likely with somewhat differ- 

 ent but nevertheless significant inputs from humans. 



Marine Economy. The marine economy in Buz- 

 zards Bay consists primarily of commercial finfishing 

 and shellfishing, although commercial finfishing is 

 prohibited in the central bay. Much of the com- 

 mercial fishing fleet is based out of New Bedford, 

 with most fishing activities concentrated offshore. 

 The shellfishing industry, however, is centered pri- 

 marily within Buzzards Bay. Four major species of 

 shellfish are harvested — quahogs (or hard-shelled 

 clams, Mercenaria mercenaria), oysters, soft- 

 shelled clams (or steamers), and bay scallops (see 

 also Chapter 4 ). Quahogs represent the largest por- 

 tion of the shellfishery, yet significant numbers of 

 the other major species are harvested each year. 



