COMMERCIAL FISHERIES 



Excepting local harvest of eels and alewives in the riverine system, 

 commercial fishing in coastal Maine occurs only in the estuarine and marine 

 systems. Harvesting and processing of finfish and shellfish cause local and 

 regional ecological problems, through waste generation (from boats and 

 processing plants), habitat modification (piers, dockside facilities, and 

 processing plants), and reduction of populations. 



Processing fish produces waste that may contaminate local intertidal flats and 

 the water column. Thirty-four fish-processing plants in coastal Maine possess 

 waste water discharge permits (regulated by Maine Department of Environmental 

 Protection as of March, 1979; see atlas map 3). The impacts of water 

 pollution are discussed below under "Population and Industry." 



Commercial fish harvest, particularly the mechanized harvesting of scallops 

 and mussels, worm and clam digging, and lobster impounding, modifies the 

 marine and estuarine habitats and populations. Mechanized scallop harvesting 

 equipment traps and crushes benthic invertebrates in the trawls used to drag 

 for scallops. Drags also resuspend bottom sediments and nutrients, which 

 increases water turbidity, and results in (1) reduced light penetration, (2) 

 the smothering of benthic invertebrates, and, occasionally, (3) excessive 

 nutrient enrichment of surface waters. Worm and clam digging disrupt 

 intertidal flats and expose invertebrates to dessication, freezing, predation, 

 and physical damage. These effects may be most severe in winter when many 

 invertebrates burrow to deeper depths to escape the harsh surface conditions. 

 Impoundments for the storage of lobsters may (1) result in the loss of 

 intertidal habitats, (2) obstruct fish passage, and (3) alter sedimentation 

 patterns . 



Commercial fish harvest may disturb seal breeding areas, seabird breeding 

 sites, and bald eagle nesting sites. "Marine Mammals," chapter 13, 

 "Waterbirds," chapter 14, and "Terrestrial Birds," chapter 16, discuss the 

 effects of human disturbance of breeding locations on reproductive success. 



Fish weirs and stop seines may trap marine mammals (especially whales; see 

 chapter 13, "Marine Mammals"). Fish seines also may entrap and drown diving 

 seabirds. (No data are available on this problem in Maine but it has been 

 documented elsewhere.) 



Fish piers, breakwaters, boat launches, and docks constructed by the fishing 

 industry have ecological impacts. These are discussed below under "Port and 

 Navigation." Certain harbors that are important in commercial fishing (e.g., 

 Alley's Bay in region 6) are maintained through dredging operations, that have 

 adverse ecological effects (see "Port and Navigation" below, and atlas map 3). 



Stocks of shrimp, haddock, sturgeon, and other fishes, are currently low in 

 comparison to historic numbers. Declines in abundance are often unnoticeable 

 statistically (e.g., through catch trend analysis) until the decline has 

 reached an advanced stage. Intensified fishing efforts and utilization of 

 more selective equipment tend to counterbalance catch shortages temporarily. 



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