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



531 



have been reported elsewhere (Bigelow and Schroeder, 

 1948, 1953; Graham, 1967; Castro, 1983; Compagno, 

 1984; Hisaw and Abramowitz 1 ). 



Growth rate 



Our estimates of growth rates, based on length-fre- 

 quency analysis, suggest that smooth dogfish YOY 

 grow very fast during the nursery period (nearly 2 

 mm TL/day) and attain a size of 55-70 cm TL 

 (mean=63 cm) by the time they leave the estuary in 

 the fall. That such high growth rates are possible is 

 confirmed by a single tag return (out of 17 fish tagged 

 during 1989 weir sampling) in which a YOY male 

 grew 44 mm in 24 days, averaging 1.8 mm TL/day. 

 Similar growth-rate estimates have previously been 



reported. Hisaw and Abramowitz 1 suggested that 

 smooth dogfish females grow about 20-30 cm per 

 year, which corresponds to lengths of 48-70 cm TL 

 by their first year. Moss ( 1972 ) later used tooth width 

 and tooth replacement data to estimate a growth rate 

 of 1.4—1.7 mm TL/day for the first year, which over- 

 laps with our growth-rate estimates (Table 2). Ex- 

 trapolation from the von Bertalanffy growth curve 

 provided by Moss (1972) suggests that fish reach 

 about 60 cm by the end of their first six months of 

 life (roughly October). This estimate agrees well with 

 our estimate. Moss's ( 1972) growth estimate also re- 

 veals no difference in growth between sexes during 

 the first year, which agrees with our observations. 



The significant annual differences in our growth 

 rate estimates probably resulted from annual differ- 



