Brook Silverside 137 



SURVEY AREA 

 The Waccamaw River originates at Lake Waccamaw in Columbus 

 County, North Carolina, and flows approximately 63 km south-southwest to the 

 North Carolina/South Carolina border (Fig. 1). The river has a total length of 

 approximately 225 km and joins the Pee Dee River at Winyah Bay, South Car- 

 olina (Shute et al. 1981). In North Carolina the Waccamaw River drains 3,255 

 km 2 of primarily forested land and has a relatively low ratio of base flow to 

 runoff (Bales and Pope 1996). Tributary streams in this system are generally 

 highly colored, low pH, low flow to stagnant, blackwater swamps. Many of 

 these streams exhibit large seasonal changes in depth and flow, with concomi- 

 tance changes in discharge. Recent studies of streamflow characteristics in this 

 drainage indicate that flow variability has increased the past decade (Bales and 

 Pope 1996). 



METHODS AND MATERIALS 



We sampled at 39 sites in the Waccamaw River drainage from May 

 1994-mid-November 1996. Standardized sampling was conducted at each site 

 using a backpack electroshocker, seine, and/or rotenone. For sites in North Car- 

 olina (n = 18), we used coated nylon nets (50 m, 1.3 cm-mesh) to block off a 33 

 m or 66 m reach. Three passes were made through the blocked off area using 

 either a backpack electroshocker or a 3 m x 1.2 m, 3.2-mm mesh seine. For 

 rotenone samples, fish were dipnetted for up to two hours following introduction 

 of rotenone at 1 ppm. Rotenone was then neutralized using a 1 ppm potassium 

 permanganate solution. South Carolina collections (n = 21) were made with a 3 

 m x 1.2 m, 3.2-mm mesh seine, except for one backpack electroshocker collec- 

 tion. Fishes taken, and data on habitat (stream depth, width, and substrate type; 

 current speed; air and water temperatures; pH; dissolved oxygen concentration) 

 were recorded at each site. 



All fishes were preserved in 10% formalin upon capture for subsequent 

 examination. Brook silversides were measured to the nearest mm standard 

 length (SL) and deposited at the North Carolina State Museum of Natural Sci- 

 ences in Raleigh. 



RESULTS AND DISCUSSION 



In North Carolina we collected 36 brook silversides. We took 18 spec- 

 imens in the Waccamaw River 50 m below the Lake Waccamaw dam, Columbus 

 County, on the 14th (5 specimens by electroshocker) and 18th (13 by rotenone) 

 of September 1995 (Fig. 1). Size range of these fish was 29-48 mm SL, and 2- 

 3 size classes were represented. Current velocity at this site was 0. 17 m/sec with 

 a pH of 6.4 and dissolved oxygen of 7.2 mg/L. We also took two specimens (34, 

 40 mm SL) by electroshocker in Wet Ash Swamp, a Waccamaw River tributary, 

 at a point 50 m below the State Route 1300 bridge in Brunswick County, on 14 

 September 1995 (Fig. 1). Current there was m/sec, pH 5.8, and dissolved oxy- 



