destroy entire mussel mats in the intertidal zone. Consequently, on exposed 

 rocky shores, the majority of blue mussels are juveniles. 



Human Impacts 



Evidence indicates that mussel populations may be depleted if harvesting 

 continues at present or greater levels (Dow and Wallace 1954; and MARITEC 

 1978). Stocks of mussels are already depleted between the Damariscotta 

 estuary (region 3) and Rockland (region 4) according to MARITEC 's survey 

 (1978). Overharvesting and natural factors may have contributed to the 

 decline in abundance. 



Other human impacts on mussels include habitat destruction, oil spills, 

 dredging, and discharge of contaminants. Evidence of the effect of these 

 factors on populations of mussels in coastal Maine is lacking. 



Importance to Humanity 



The blue mussel once supported a part-time shell fishery in Maine but during 

 World War II the need for substitute sources of protein prompted an increase 

 in fishing effort. The harvest increased during the war and peaked at over 

 2.5 million pounds in 1944 (Maine Landings 1944). In 1947 the harvest 

 declined to approximately 40,000 lb (Maine Landings 1947). Dow and Wallace 

 (1954) feel that the decline was not only due to a decline in demand for 

 mussels but also due to the fact that readily available natural stocks of 

 mussels were no longer available. 



The landings of blue mussels have steadily risen since 1974 to almost 3.5 

 million pounds in 1978 (see figure 12-2). This increase is attributed to 

 growth in demand for inexpensive protein. 



Mussels infected by "red tide" are unfit for human consumption and in recent 

 years harvesting of mussels in infected areas has been temporarily banned. 

 Little effect of red tide on the distribution and abundance of mussels is 

 apparent; however, high levels of toxin can cause mortalities. 



A factor that limits commercial harvest of mussels is the presence of pearls 

 in the meat of the mussel. Mussels containing pearls are usually unacceptable 

 commercially. Evidence exists that pearls are the result of infestation by a 

 trematode ( Gymnophallus ; Lutz 1976), of which the life history is unknown. 

 Evidence also exists that the adult host is a sea duck (a scoter or an eider), 

 the blue mussel being the intermediate host (Stunkard and Uzmann 1958) . 

 Whether natural mechanisms of pearl formation exist is not known (Lutz 1976) . 



Management 



Management of mussel resources in the State of Maine is similar to that of 

 clam resources. Towns which have appropriated funds for shellfish management 

 are allowed by the State to regulate harvesting activities within their 

 jurisdictions. Most town ordinances, however, pertain to clams and do not 

 regulate mussels specifically. 



License fees are required from individuals landing more than 1/2 bushel of 

 mussels at one time. The Maine Department of Marine Resources regulates 



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