Figure 5.— Hinge and ligament of the sea scallop, (a) Outer layer of the ligament at hinge line, (b) resilifei, 

 (c) calcareous plates of the resilium, (d) compressible part of the resilium, and (e) surface view of calcareous 

 plate. 



VALIDATION OF THE METHOD 



In September of 1957, we had tagged and 

 released 5,375 sea scallops on the northeast peak 

 of Georges Bank. A fine hole is drilled in the ear 

 of the upper valve just over the byssal notch in 

 the lower valve. A stainless steel pin, bearing a 

 numbered Petersen disc and a 6-inch yellow plastic 

 streamer, is pushed through the hole and bent 

 over to hold the tag securely (fig. 12). The animal 

 is not wounded but the disturbance of dredging, 

 handling, and tagging is sufficient to put a strong 

 shock ring on the shell. The margin is nicked 

 with a triangular file so that this tagging shock 

 ring can be identified with certainty later. After 

 recapture it is simple to measure how much new 

 shell has been added since the date of tagging 

 and, with a large enough sample, calculate the 

 growth rule. 



This particular tagging experiment had been 

 very successful and we had a great many shells 

 from recaptured animals. One group of 411 had 

 been recaptured only a few weeks after release 

 and therefore bad added very little new shell. 



With the techniques described previously, the 

 annual rings on this group were located and the 

 shell lengths at the time of formation of each ring 

 measured (table 1). The Walford (1946) regres- 

 sion equation calculated from the average length 

 at the time of ring formation is: L,+i = 42.4 + 0.706 

 L t (equation 1). 



We also had 392 shells from animals that had 

 been captured, tagged, and released at the same 



Table 1. — Average length (mm.) at time of ring formation 

 for 8 year classes in sample of 411 sea scallops and aver- 

 age for all year classes combined 



304 



U.S. FISH AND WILDLIFE SERVICE 



