Rountree and Able Abundance, growth, and foraging habits of Mustelus cams 



525 



estuary (Table 1). Four replicate 2-min tows were made 

 at each location. One of the trawl stations was located 

 in Marshelder Channel in the vicinity of Foxboro and 

 Story Island creeks. Trawl samples were collected 

 monthly, except for fortnightly sampling during July, 

 August and September 1989 and 1990 (Szedlmayer et 

 al., 1992; Szedlmayer and Able, in press). 



Sex ratio patterns 



The sex ratio (percent female and male) was deter- 

 mined for each net check in which at least three fish 

 were collected. The sex ratio of smooth dogfish ob- 

 served at each net check was used as a proxy for the 

 sex ratio of smooth dogfish schools. If this assump- 

 tion is valid, then significant deviations from equal 



proportions would suggest that schools segregate by 

 sex. We also tested for temporal changes in sex ra- 

 tio, which would suggest differential timing of sea- 

 sonal movements by sex. Deviations from expected 

 ratios were tested by chi-square analysis (SAS Insti- 

 tute, Inc., 1988). 



Growth rate 



Temporal trends, and differences between sexes in 

 absolute growth rates were estimated by linear re- 

 gression offish size on date of capture. Length outli- 

 ers from each sampling period, which were assumed 

 to represent age-1 or older individuals from an ex- 

 amination of length-frequency distributions (Table 

 1; Fig. 2), were removed prior to the regression. An- 



