December 1974 provided the data for analyses of 

 distribution and food habits. An analysis of fish 

 community structure based on this data has been 

 reported by Colvocoresses (1975). 



The York River and its major tributaries 

 (Pamunkey and Mattaponi rivers) represent an 

 estuarine system which is relatively well known 

 biologically and is relatively undisturbed (Boesch 

 1971). The general trend of geomorphology, hy- 

 drography (salinity, dissolved oxygen, and tem- 

 perature), ecology, and alteration by man of the 

 area were described by McHugh (1967), Boesch 

 (1971), and Brehmer. 5 



MATERIALS AND METHODS 



Survey Programs 



Seven longitudinal strata (A, B, C, D, E, F, and 

 G) and three cross-sectional substrata (north 

 shoal, channel, and south shoal) within each 

 stratum were sampled monthly (Figure 1). Shoal 

 hauls were usually in water <4 m and channel 

 hauls in water >5 m deep. Randomly numbered 

 square grids (540 m on a side) were assigned as 

 trawl stations. In the lower 16 km (10 miles) of the 

 York River, strata A, B, C, and D were sampled 

 from March 1972 to December 1974. The upper 

 part of the York River was sampled from January 

 1972 to March 1974, but the random method was 

 not used until June 1972 and strata E, F, and G 

 were not designated until January 1973. Before 

 the random sampling program, fixed sampling 

 stations in the channel were assigned at 8-km 

 (5-mi) intervals from the mouth of the York River 

 (mile zero) up to 45 km (mile 28, also see Haven 

 1957; Markle 1976). Data from fixed station sam- 

 ples (January-May 1972) were combined within 

 the strata for analyses. Lower portions of the Mat- 

 taponi and Pamunkey rivers (strata: M and P) 

 were sampled after January 1973. Three sub- 

 strata (1, 2, and 3) were set at 8-km (5-mi) inter- 

 vals for the lower 24 km (15 mi) upstream from 

 their confluence with the York River (about 45 km 

 from the York River mouth). Each sampling 

 stratum was divided into station grids, each 

 measuring 540 m on a side; four to six grid stations 

 were sampled randomly from each stratum 

 monthly. 



FISHERY BULLETIN: VOL. 75, NO. 4 



Gear 



Bottom trawl tows were against the current, of 

 5-min duration on the bottom with a 4.9-m ( 16-ft) 

 semiballoon otter trawl (7-m rope, 1.9-cm bar 

 mesh, 0.63-cm bar mesh cod end liner), 7-m bridle, 

 and 0.6-m weighted otter doors at a speed of ap- 

 proximately 90 m/min. Nine stations were sam- 

 pled monthly with beach seines along the shores of 

 lower parts (strata A-D) of the York River (Figure 

 1) and three replicate hauls were made with a 

 15.25-m (50-ft) bag seine (1.8 m deep with a square 

 bag, 0.64-cm bar mesh in the wing and 0.48-cm bar 

 mesh in the bag). Thirteen beach seine stations 

 were selected along the shores of the upper part of 

 the York River (strata E-G, Figure 1). These sta- 

 tions were only sampled from July to October in 

 1972 and 1973 with a 30.5-m (100-ft) bag seine. 

 Beach seine data were used only for length fre- 

 quency analysis in the present study. Hy- 

 drographic (salinity, temperature, and dissolved 

 oxygen) data were collected from both surface and 

 bottom water. 



Sampling Procedure 



All fishes were identified, counted, and weighed 

 in the field or laboratory. Total length (TL), mea- 

 sured from snout to the posterior tip of the caudal 

 fin (on the midline), was taken to the nearest mil- 

 limeter. All individuals of each species were mea- 

 sured from each trawl haul. For very large 

 catches, at least 25 individuals were subsampled. 

 Specimens were randomly selected for stomach 

 analyses and preserved in 109c Formalin; 6 

 stomachs were dissected out and transferred to 

 409c isopropanol or 109c ethanol. Stomach con- 

 tents were identified to the lowest practical taxon 

 and frequency of occurrence of each item was re- 

 corded. 



The standard methods of Hubbs and Lagler 

 (1964) were used for all counts and measurements, 

 if applicable. Upper and lower jaw lengths were 

 measured from tips of the premaxilla and dentary, 

 respectively, to the symphysis at the posterior 

 corner of the mouth gape. Digestive tracts were 

 removed from the fish. The intestine was 

 straightened and measured from its junction with 

 the stomach to the anus. Osteological observations 



5 Brehmer, M. L. 1970. Biological and chemical studies of Vir- 

 ginia's estuaries. Unpubl. manuscr., 120 p. Va. Inst. Mar. Sci., 

 Gloucester Point. 



6 Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



658 



