FISHERY BULLETIN: VOL. 75, NO. 4 



~ 20- 

 x 



a 1-0- 

 o 



_i 



00— 



3.0- 

 x 2 0- 



3 i.o- 

 oo 



JULY 1973 



_E3_ 



M-2 



M-3 



I 



-r-^. O 



P-2 



P-3 



,^m 



OCT 1973 

 I 

 I 

 I 



M-2 



M-3 



m J 



p-i 



P-2 



P-3 



Cynoscion regain J Micropogon undulatus 



Bairdiella chysoura frS] Leiostomus xanthurus 



FIGURE 4. — Seasonal abundance of four juvenile sciaenids in the 

 Mattaponi and Pamunkey rivers. Mean numerical catch per tow 

 of each substratum expressed as log (x +1). Strata: M = Matta- 

 poni River, P = Pamunkey River. Substrata: 1, 2, and 3 desig- 

 nated by river distance upstream. 



abundant in the middle part of the river. Micro- 

 pogonias undulatus was more abundant in the 

 upper part of the river, and especially in the Mat- 

 taponi and Pamunkey rivers (Figures 4, 5). Mean 

 catch per tow increased up the estuary. Depth 

 distribution of these four species of sciaenids indi- 

 cated that they were more abundant in the chan- 

 nel stations (Figure 3). The relative abundance at 

 south shoal stations was higher than at north 

 shoal stations. The area was larger and the sam- 

 pling depth was greater in the south shoal than 

 the north shoal area (Colvocresses 1975; Chao 

 1976). Also, the average size of young sciaenids, 

 especially the young-of-the-year groups, was 

 larger in the channel than in the shoal stations 

 (see section on "Distribution and Size"). Larger 

 size juvenile sciaenids might use deeper areas to 

 seek food and shelter. 



cj - 



z: <a 



«3 



2.0 



00- 



n 



lc e> 

 0- o 



< - 1 0.0-™- 



CJ ■= 2 0- 



>'£ 



i.o- 



_l CD 

 Z> O 



-3 - 1 0.0 



to - 2 0- 



>-•£ i.o- 



-I o 

 Z) o 



-i 0.0-"=- 



N '* , «' 



(-S io " 



O O 



O - 1 



ro -2 0- 

 S- * - 



£»5 i.o- 



O jo.O- LiL 



_rD 



sH 



B 



at! 



JZL 



a 



n 



J 



ad 



n , - i-i 



£L 



mm 



ai 



Jl n : 



□£] 



I 



Cynoscion regalis 

 Bairdiella chysoura 

 J Micropogon undulatus 



■:'y.i Leiostomus xanthurus 



M 



M 



FIGURE 5. — Seasonal mean abundance of four juvenile sciaenids along the salinity gradient (strata) in the York River estuary. Grand 

 mean numerical catch of four juvenile sciaenids per tow of stratum expressed as log (x + 1). Strata: A-G in York River, M = Mattaponi 

 River, P= Pamunkey River. Grand means of January and April represent the average of 3 yr. (1972 to 1974). 



664 



