Miller et al : Distribution, abundance, and growth o\ Miaopogonias undulatus 



109 



Delaware Bay Bottom Trawl Survey 



April-August 1997 and 1998 



CPUE of Atlantic croaker 



n = 5,178 



B 



</ Bottom Sediment Type 

 in Delaware Bay 



I I Gravely Sand 



CZIlSand 



I I Mud / Sand 



Mud 



Gravely Mud 



Figure 9 



(A) Catch per unit of effort (CPUE=fish/10 min. tow) of young-of-the-year Atlantic croaker (Micropogo- 

 nias undulatus) coWected by otter trawl (April to August in 1997 and 1998). Sediments containing mud 

 are indicated by shading. (B) The distribution of specific bottom sediment types in Delaware Bay is 

 modified from Sharp (personal commun. [J. H. Sharp. Marine Studies, Univ. Delaware, Lewes, DE.]). 



size or smaller than the ingressed fish collected during the 

 previous fall of all three years (Figs. 4 and 5). 



Consistent with the above fast growth rates. YOY Atlan- 

 tic croaker reached lengths of about 70-140 mm by July 

 and lengths ranging from 90 to 170 mm by August in the 

 marshes and slightly larger in the bay (Figs. 4 and 5). As a 

 result of these fast growth rates, the YOY attained a size of 

 approximately 125-250 mm by September, approximately 

 12 months after ingress into the bay and adjacent marsh- 

 es, and were distinctly larger than the next year class that 

 began ingressing during September of each year. 



Egress 



Young-of-the-year Atlantic croaker showed a relatively 

 consistent pattern of egress out of the marsh creeks in the 

 late summer and fall of each year, and as a result, there 

 was an increase in CPUE in the bay during October of 

 both years. The monthly CPUE in both upper and lower 

 bay marshes declined during the summer and were low by 

 August in all three years (Fig. 6), but the number of fish 

 present appeared to drop off more rapidly from August to 

 October in 1999 than in other years (Figs. 5 and 6). In the 

 bay, CPUE began to decrease somewhat later, after July 

 or August, but then increased to the yearly maximum for 

 the lower bay in October 1997 and 1998. By November of 

 each year, almost all YOY appeared to move out of the 

 marshes at sizes <200 mm, but in the bay there were large 



individuals >250 mm caught in October 1997 and 1998. 

 The baywide trawling survey did not provide samples in 

 November, so it was impossible to determine the timing of 

 egress of the remaining YOY out of the bay, but very few 

 age-1 fish were present in the bay or marshes by spring of 

 the next year. 



Discussion 



Ingress and settlement 



Young-of-the-year Atlantic croaker ingress into bay and 

 marsh nursery areas starting in the fall of each year in 

 Delaware Bay and in other estuaries along the Atlantic 

 coast. The majority appeared in September, October, and 

 November during our study and in previous collections 

 in Delaware Bay (Able and Fahay, 1998), Chesapeake 

 Bay (Haven, 1957; Chao and Musick, 1977), and North 

 Carolina (Ross, 1988). However, the fall ingress of this 

 cohort was not evident until October in Georgia (Dahlberg, 

 1972) and December in South Carolina iBearden, 1964). 

 The sudden appearance of significant numbers of larger 

 fish (50-75 mm) in September 1996 in both the bay and 

 marshes and to some extent in the marshes in 1999 sug- 

 gests that individuals that experienced different growth 

 rates or came from different spawning events sometimes 

 occurred simultaneously in Delaware Bay. 



