SMITH and MERRINER: REPRODUCTIVE BIOLOGY OF COWNOSE RAY 



S. Otwell 4 (Fig. 2). Only one embryo per gravid 



4 W. S. Otwell, formerly of North Carolina State University Food 

 Science Laboratory, Morehead City, NC; presently at University 

 of Florida, Food Science Department, Gainesville, FL 32611, pers. 

 commun. April and May 1978. 



female was observed. The overall sex ratio of em- 

 bryos (40o":439) did not differ significantly from 1:1. 

 Gravid female rays migrate into Chesapeake Bay 

 in spring with well-developed embryos that we 

 designated as approximately three-quarter term. 



44 -i 



Figure 1.— Relationship of clasper length 

 (mm) to disc width (cm) for 188 male Rhi- 

 noptera bonasus. 



12 - 



8 - 



4 

 



30 



• •• x 



•• • •• • 



• • xxm a • 



• • XXX* x« 



• •• • •• 



• •• mx* • X 

 •• • X» XX 



• • • 

 • • •• 



• x» 



XXX AM • 

 ••• X«5t •• • 

 •• ••«XX XX X 



• XX X «H«I. • 



i ' i  i  i ' r 



40 50 60 70 80 



DISC WIDTH (cm) 



90 



100 



450 



400 



350 



£300 



>- 

 cc 

 m 



u. 

 o 



x 

 t- 



Q 



? 



O 

 CO 



a 



250 



200 



150 



100 



50- 



N = 78 



•1 



iM 



I— Mean > Range 

 • One Value 

 + Two Volues 



SEPT ' OCT 



"jAN ' FEB ' MAR 



APR ' MAY ' JUNE ' JULY 



AUG 



NOV 



DEC 



Figure 2.— Relationship of disc width (mm) to date of capture for Rhinoptera bonasus embryos collected 1976 through 



1978. 



873 



