190 



Fishery Bulletin 89(2). 1991 



20 30 



APRIL 



20 20 30 10 20 30 10 20 



MAY APRIL MAY JUNE 



Figure 6 



Spatial and temporal abundance (numbers/lOOm 1 ) 

 of striped bass eggs and larvae in the James River, 

 1981. River miles are nautical miles above the river 

 mouth. 



peak spawning appeared to be bimodally distributed 

 along the river channel. Eggs were present in both 

 rivers on initial surveys of 1981 (21 April in the Chicka- 

 hominy River and 22 April in the James River) in fresh 

 to slightly brackish water and temperatures of 15.6- 

 18.7°C. Maximum egg densities in the James River 

 were only 46/100 m 3 in 1981 (13/100 m 3 in the Chicka- 

 hominy), compared with 195/100 m 3 in 1983. These 

 maxima occurred in both years during the first week 

 in May, in tidal freshwater and similar temperatures 

 (18.5-19.5°C), but at sites separated by 16km (Fig. 6). 

 In the Chickahominy River, eggs were restricted to the 

 river's junction with the James and found on only two 

 surveys, suggesting that eggs could have been spawned 

 in the James River and tidally advected into the 

 Chickahominy. 



Larval striped bass were not present in collections 

 from the Chickahominy River in 1981, and the river 

 was not sampled in 1983. James River collections in 

 1981 yielded primarily yolksac larvae, found in max- 

 imum densities similar to those of eggs (Fig. 6). The 

 modal length of larvae during the first 3 weeks of 

 surveys in 1981 was 5.0-5.9 mm, but a few smaller lar- 

 vae (4.0-4.9 mm) were hatched as late as 21-22 May. 

 The maximum size of larvae increased from 7.0-7.9mm 

 in late April to over 13 mm on 4-5 June, the last survey 

 in which striped bass larvae were captured. Only a 

 dozen larvae larger than 9 mm were collected. In 1983, 

 larvae from the early-May surveys attained densities 

 of 31/100m 3 . 



Figure 7 



Spatial extent of observed striped bass egg occurrence. Rap- 

 pahannock River, 1982 and 1983. Over 80% of eggs occurred 

 in solid black areas. Inset shows location in Chesapeake Bay 

 region. 



Rappahannock River, 1982 and 1983 



Eggs were found within the first 40 km of tidal fresh- 

 water in both 1982 and 1983 (Fig. 7). Peak spawning 

 was observed between river miles 51 and 62 in 1982 

 and miles 48 and 59 in 1983. Eggs occurred in densities 

 ranging between 1.4-330/100m 3 during April 1982 

 and 0.7-50/100 m 3 in May of that year. None were 

 found after the 1 1 May survey, and the maximum den- 

 sity occurred on 21 April in temperatures 15.7-16.6°C. 

 In 1983, eggs were collected in all weekly surveys from 

 9 April to 13 May, but increasing densities were re- 

 versed by a cold snap in the third week of April, when 

 only scattered eggs were found (water temperatures 

 had declined from 13-14°C to 11-12°C). Egg densities 

 peaked once water temperature rose in the last week 

 of April, when a maximum of 477 eggs/100 m 3 was 

 recorded. Eggs were rare by the final sampling date 

 (May 13). 



