FISHERY BULLETIN: VOL. 77. NO, 2 



Table l. — Sampling localities and dates for collections of fishes and invertebrates, Cape Fear River estuary, N.C., including 

 physicochemical data. D = approximate distance from river mouth to creek entrance; SD = standard deviation; MPS - median 

 particle size; SC = sorting coefficient. 



SWfcfcl' NUMflER 



Figure 2. — Dutchman Creek. N.C., survey (October 1976) de- 

 signed to determine the number of seine sweeps required to pro- 

 duce a representative sample. Cumulative number of species 

 I ENS) and Shannon-Weaver diversity IH') are plotted on sepa- 

 rate axes. 



At rotenone sites, sufficient toxin was intro- 

 duced to kill all fishes present; this quantity was 

 determined by the presence of certain "indicator" 

 species in the collections, especially killifish 

 iFundulus spp.) and eels (e.g., speckled worm eel, 

 Myrophis piinclcifns; American eel, Anguilla ros- 

 trata) which are resistant to rotenone and may 



also burrow in the substrate. Stricken fishes were 

 dipnetted as long as they were visible on the sur- 

 face, and the downstream block nets were also 

 picked at the end of the survey. During winter, 

 additional rotenone was added to ensure that toxi- 

 city remained uniform, and in all months, potas- 

 sium permanganate (KMnO^) was added down- 

 stream to detoxify rotenone carried below the 

 sites. During this study, no attempt was made to 

 account for rotenone losses due to settling. 



All collections were initiated near low tide to 

 reduce the effects of current and to sample post- 

 larval fishes that were not swept downstream by 

 tidal flows. To ensure uniformity of water volume 

 between the block nets, staff gauges and land- 

 marks were used to standardize the volume/area 

 sampled. Throughout this paper, all catches will 

 be reported as the number of individuals per 400 

 m-, the average surface area of the stations. 



Temperature was recorded prior to each collec- 

 tion with a calibrated stick thermometer or tem- 

 perature mode on a Beckman (model RS 5-3) 

 salinometer; surface salinity was measured with 

 the same instrument. The salinometer was cali- 

 brated prior to each monthly sampling trip with a 



T.^BLE 2. — Comparison of length-frequency distributions from 6.5 and 1.0 mm mesh, seine collections. Cape Fear River estuary, 

 N.C. A = 6.5 mm mesh seine, seven sweeps; B = 1 .0 mm mesh seine, three sweeps. Lower one-tailed /-test; ** =P 0,01. ns = not 

 significant. Specimens '-28 mm are not included in mean values. 



Species 



Length (mm) 

 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 28 



Total 



Mugtl cephatus 

 Leiostomus xanthurus 

 Paralichthys spp 



4 36 37 62 41 20 15 13 7 1 



342 



