Rotunno and Cowen: Temporal and spatial spawning patterns of Peprilus triacanthus 
787 
Table 1 
List of 1988 and 1989 cruises, sampling dates, number of fish collected, and locations. 
Atlantic Bight. 
SAB = South Atlantic Bight; MAB = Mid- 
Net 
Cruise 
Date 
No. of fish captured 
Location 
1988 
DEL88-5-2 
24 April-1 May 
71 
SAB 
Frame 
ATLANTIC TWIN 
21 May-23 May 
29 
SAB 
DEL88-7-1 
1 June-3 June 
3 
MAB 
DEL88-7-2 
11 June-16 June 
22 
MAB 
DEL88-7-3 
6 July-9 July 
4 
MAB 
DEL88-7-4 
16 July-22 July 
99 
MAB 
DEL88-7-5 
29 July-2 August 
50 
MAB 
DEL88-7-6 
8 August-12 August 
110 
MAB 
Tucker 
DEL88-7-3 
6 July-9 July 
188 
MAB 
DEL88-7-4 
16 July-22 July 
1,191 
MAB 
DEL88-7-5 
29 July-2 August 
514 
MAB 
1989 
DEL88-7-6 
8 August-12 August 
1,063 
MAB 
Frame 
FE1-89 
25 April-29 April 
158 
SAB 
ONR1-89 
30 May-2 June 
8 
MAB 
ONR2-89 
6 June-7 June 
4 
MAB 
FE2-89 
7 July-10 July 
2 
MAB 
ONR4-89 
18 July-2 August 
22 
MAB 
ONR5-89 
14 August-18 August 
170 
MAB 
Tucker 
FE1-89 
25 April-29 April 
201 
SAB 
FE2-89 
7 July- 10 July 
445 
MAB 
ONR4-89 
18 July-2 August 
89 
MAB 
ONR5-89 
14 August- 18 August 
146 
MAB 
inspection. Fish were x-rayed with a Kodak Faxitron 
at settings of 40 kilovolts, 20 milli-amperes and 30 sec- 
onds, which gave the best results with Kodak Industry 
X negatives. These negatives were placed in a Kodak 
GBX developer and replenisher solution for 2 to 3 min- 
utes, rinsed in water, placed in a Kodak GBX fixer so- 
lution for 5 minutes, rinsed for 15 minutes in water, 
and dried overnight. Caudal vertebrae were counted 
with the aid of a dissecting scope and included those 
vertebrae attached to the first fully formed hemal spine 
and extending to the urostyle (Gosline, 1960). 
Caudal vertebrae counts were made for larvae se- 
lected to cover the range of sizes (all were larger than 
7 mm, the size at which Ditty (1981) found most fish 
to have adult characters), body depth-standard 
length ratios (shallow and deep-bodied), and dates of 
capture (spring and summer) encountered. Caudal ver- 
tebrae were counted for a subsample of 34 cleared-and- 
stained fish and 64 x-rayed fish from the 1988 Frame 
trawls and 76 x-rayed fish from the 1989 Frame trawls. 
Ventral midline melanophores were counted for a 
subsample of 50 fish (25 from the spring and 25 from 
the summer) smaller than 4 mm SL (the size at which 
Ditty based his observations). These fish were ran- 
domly chosen from 1989 formalin-preserved collec- 
tions. Ventral midline melanophores were considered 
to be those located between the hindgut and noto- 
chord tip (Ditty, 1981). 
Otolith marking experiment 
Otoliths of 22 fish were marked with oxytetracycline 
hydrochloride (OTC) in August of 1991 to determine 
if Peprilus larvae and juveniles deposit daily rings. 
Sizes of fish ranged from 10 to 31 mm SL. Fish were 
acclimated for two days in a five-gallon bucket with 
built-in screening that allowed water to flow-through 
the bucket when it was placed in an aerated seawa- 
ter bath. Fish were fed twice daily with either live 
Artemia nauplii or live field-captured zooplankton 
during both acclimation and experimental periods. 
Experimental conditions were maintained as follows: 
temperature fluctuated between 12°C and 24°C, sa- 
linity ranged from 28 to 30 %o, pH varied from 7.6 to 
8.0 (however, during marking the pH dropped to 6.5 
and 6.6), and the photoperiod remained constant at 
a 14-h light and 10-h dark cycle. 
The marking procedure followed those for mass- 
marking larvae and juveniles (Hettler, 1984; Tsuka- 
moto, 1985; Muth et al., 1988). Briefly, fish were im- 
mersed in a 450 mg/L concentration of OTC for a six- 
hour period. Fish were covered during the marking 
period to decrease the amount of light because light 
may interfere with the effectiveness of tetracycline 
(Secor et al. 1 ). While immersed in the marking solu- 
tion, four fish died. The remaining 18 fish were trans- 
ferred from the marking solution and placed inside 
