56 • Wetlands: Their Use and Regulation 



Crayfish. — Crayfish require the fluctuating 

 water levels found in wetlands for mating and egg 

 laying. Crayfish also feed primarily on wetland 

 vegetation (46). Although there are commercial 

 crayfish fisheries in Wisconsin and the Pacific 

 Northwest, the most valuable crop comes from the 

 Lower Mississippi River Basin, particularly Loui- 

 siana. Approximately 25 million lbs, representing 

 revenues of $11 million, are harvested annually.* 



Fish and Shellfish. — Many freshwater and salt- 

 water fish require wetlands at some stage of their 

 lifecycle.'^ Pike, pickerel, and muskellunge seem 

 to prefer vegetated shallow water for broadcasting 

 their eggs and may even spawn on land that is only 

 temporarily flooded in the spring. '^ Large mouth 

 bass spawn in the temporarily flooded zones of bot- 

 tom land hardwoods. An abundant supply of in- 

 vertebrates in these areas supply necessary food 

 during a critical period after the fish eggs hatch (38). 

 The alewife and the blueback herring spawn in 

 freshwater tidal marshes and flood plain forests 

 along the east coast (18). 



Members of the perch family (including wall- 

 eyes), the sunfish family (including bluegUl, bass, 

 and crappie), and the pike family (including pick- 

 erel and muskellunge) commonly are found in veg- 

 etated wetlands, owing to the protection from pred- 

 ators afforded by the vegetation, strong currents, 

 sunlight, and the fact that the prey of all these fish 

 often take refuge in the wetland. Grey snapper, 

 sheepshead, spotted sea trout, and red drum move 

 into mangroves after spending their first few weeks 

 in submerged seagrass beds. These fish feed heavily 

 on either small fishes or amphipods (86). 



Juvenile marine fish and shellfish also use coastal 

 marshes, particularly marshes of intermediate sa- 

 linity, because this salinity excludes both marine 

 and freshwater predators (2). (See table 5 for a list 

 of species.) Pacific coast wetlands probably do not 

 serve the same nursery function as do the Atlantic 

 coast and gulf coast wetlands (68). 



•Calculation of the crayfish catch ($11 million, 25 million lbs), based 

 on data supplied by Larry Delabreteonne. 



"Adamus and Stocl<well, op. cit. 



'^Information comes from two sources: 1) C. L. Hubbs and K. F, 

 Lagler, "Fishes of the Great Lakes Region," Cranbrook Institute of 

 Science, Bulletin No. 26, Bloomfield Hills, Mich., 1958; 2) M. B. 

 Trautman, "The Fishes of Ohio," Ohio State University Press, Col- 

 umbus, 1957. 



Table 5.— Selected Commercial or Sport Fish and 

 Shellfish Utilizing Coastal IVIarshes as Nurseries 



Sand seatrout 



Weakfish 



Croaker 



Spot 



Menhaden 



Striped mullet 



Bay anchovy 



Striped bass 



White perch 



Silver perch 



Summer flounder 



Brow^n and white shrimp _^__ 



SOURCE: Odum, et. al., 1979, op. cit., note 68. 



Endangered Species. — Approximately 20 per- 

 cent of all plant and animal species found on the 

 Federal Government's list of endangered or 

 threatened species heavily depend on wetlands for 

 food and/or habitat (table 6). Many other plant and 

 animal species not included on the Federal list are 

 found on State lists. A number of endangered 

 species not listed in table 6 also may use wedand 

 resources to a greater or lesser extent.'* 



Other Wildlife. — While relatively few animals 

 depend entirely on resources found only in 

 wetlands, many animals heavily exploit wedand 

 resources. Foxes and raccoons, for instance, may 

 prefer den sites in wedands, owing to their close 

 proximity to the water (72). In fact, the availabili- 

 ty of wetland resources may determine the health 

 and survival of many animals during critical times. 

 Wedands, for instance, are preferred by deer, 

 pheasants, and other animals as winter cover be- 

 cause of the presence and availability of food. Cedar 

 swamps, for example, are the only feeding grounds 

 that can sustain white-tailed deer through northern 

 Michigan winters. In Minnesota, white-tailed deer 

 spend 80 percent of their time in wedands between 

 December and April (79). 



During droughts and dry years, wetlands serve 

 as reservoirs that are extremely important to re- 

 gional wildlife stabUity. Southeastern swamps pro- 

 vide food resources when upland resources are un- 

 available (57). In a survey conducted by FWS, State 



"For a more complete review of the species that use wetlands, see 

 John Kusler, "Our National Wetland Heritage: A Protection Guide- 

 book," Environmental Institute, Washington, D.C., 1978, The table 

 was prepared by the Office of Endangered Species and subjected to 

 approximately 30 reviews. 



