Fishery Bulletin 91 [I). 1993 



Figure 1 



Location of sampling sites for spot Leiostomus xanthurus larvae at Pivers Island near Beaufort Inlet and 

 ocean stations ("+") off the North Carolina coast. Surface-water temperatures are indicated for February 

 1988 stations. 



and 4 May 1988 (Fig. 2). The 4th of May was consid- 

 ered the virtual end of the recruitment period, since 

 spot densities had declined to <2 larvae/100 m 3 over 

 the last 2 weeks of sampling. The sum of the weekly 

 mean larval densities over all collections ( 1540 larvae/ 

 100 m 3 ) was used as the basis for determining the per- 

 centage of recruited larvae from each birthweek co- 

 hort. Larval density gradually increased during the 

 first 10 weeks of sampling, varying from to 40 lar- 

 vae/100m 3 (x=14.6). Approximately 9% of the larval 

 spot recruitment occurred during this period. The pe- 

 riod of highest density (x= 138.3 larvae/100 m 3 ) occurred 

 during 10 February-13 April, when 88% of the larvae 

 were recruited to the estuary. During this 10-week 

 period, there was wide variation in relative abundance 

 with four clear peaks, the largest occurring on 23 March 

 when 34% of all larvae were collected. During the last 

 3 weeks of sampling, larval density declined to very 

 low levels (x=3.7/100m 3 ) and represented less than 

 3% of the total spot larvae collected. There was varia- 

 tion in the catch densities among net sets on any given 



sampling night. Excluding the first 4 weeks when no 

 spot larvae were collected in 41% of the sets, the aver- 

 age nightly coefficient of variation was 65.3% (range 

 20.3-119.5%). 



We assumed that larvae caught each week were 

 newly recruited to the estuary and that they were in 

 transit to upper reaches of the estuary past Pivers 

 Island. These assumptions are supported by the gen- 

 erally small standard error in the age of larvae within 

 each collection (Fig. 3). The small observed within- 

 sample variation in age is probably due in part to 

 mixing of age cohorts in the ocean prior to estuarine 

 recruitment. Since larvae were not accumulating in 

 the lower estuary, there was no increase in standard 

 error of mean age over time. Also, in the week follow- 

 ing each of the four peaks (Fig. 2) densities were rela- 

 tively low, a pattern that did not suggest substantial 

 carryover offish from week to week. 



Age and length of larvae The weekly mean age of 

 spot larvae caught at Pivers Island fluctuated between 



