the bait of sport fishermen seeking other species. However, due to its 

 abundance and anatomical distinctiveness, the smooth dogfish is commonly used 

 by biological supply houses for dissection and study (Hi ldebrand and Schroeder 

 1928). 



The smooth dogfish is a viviparous shark and bears embryos which receive 

 nourishment from the mother by a yolk-sac placenta. Based on examinations of 

 smooth dogfish caught in the Woods Hole area, females reach sexual maturity by 

 the time they are 1.1m long and ovulate during the early part of July. 

 Presumably, mating also occurs at this time, when the sharks are found on 

 their summering grounds. The smooth dogfish has a gestation period of about 

 10 months, and young are therefore carried by the female during the fall 

 migration. Dogfish are typically born in litters of 15-16 "pups" (each fish 

 approximately 0.3 m in length) between May and mid-July, after the females 

 have returned northward (Bigelow and Schroeder 1953). 



Bottom Trawl Survey Results 



The cumulative distributions over the tii;;a series are shown for the 

 respective spring and autumn periods in Figures 1.1 and 1.2. The plots are an 

 excellent representation of what is known of smooth dogfish distribution and 

 movement. The spring plot (Figure 1.1) shows the shark occurring north of the 

 Virginia capes in waters less than 37 m. This inshore, northward distribution 

 would not be apparent if the timing of our spring cruises provided more 

 synoptic coverage (see "Methods"). In Figure 1.3, data have been plotted from 

 the last four spring surveys (1976-1979) only and thus produce an accurate 

 picture of spring distribution. The inshore concentrations determined from 

 surveys conducted during late April and May, remonstrate the rapidity of the 

 onshore and northward movement of smooth dogfii." in the spring (Figure 1.1). 



21 



