organics dissolve at different rates and 

 leave a distinct pattern. Peterson 

 describes the etched shell as "a relief 

 map almost like a fingerprint that 

 tells you the different areas and shows 

 you the growth lines." 



According to Peterson, the lines 

 revealed in the section display not only 

 annual features, but other 

 physiological and environmental 

 features as well. "You can see daily 

 growth lines on many mollusks, and 

 you can see sub-daily patterns," he ex- 

 plains. "You can even see the rise and 

 fall of the tides. There are lines 

 matching the lunar cycle of spring 

 tides and neap tides. And, there are an- 

 nual lines as well, coinciding with cer- 

 tain annual events the clam may ex- 

 perience, such as spawning. By 

 collecting at different times, we can 

 also identify the time of year that that 

 feature is laid down in the shell, and 

 that gives you an even more specific 

 marker." 



The aging technique used by Peter- 

 son is not new, however. It has been 

 used extensively on hard clams, but 



The man 

 Of 100,000 

 Seashells 



Across the country, when people cite 

 an expert on the subject of clams, 

 mussels or scallops, the expert's name 

 is likely to be Hugh Porter. This man 

 knows his mollusca. 



A native of Pennsylvania, Porter 

 came to North Carolina 25 years ago 

 to work on an oyster project under Al 

 Chestnut at the UNC Institute of 

 Marine Sciences in Morehead City. 

 There, Porter discovered some boxes of 

 shells, and his curiosity got the better 

 of him. 



"I quickly got interested in some 

 boxes of seashells that no one was pay- 

 ing any attention to," Porter says, 

 "and decided to put them into a collec- 

 tion before they got lost. There was a 

 lot of them I'd never seen before, Well, 

 it has just grown from a continuing 

 and developing interest. Now, I think 



Continued on next page 



only in northern areas. There the an- 

 nual feature, a cold check, is laid down 

 during harsh winter weather. It was 

 believed that aging hard clams 

 wouldn't be possible south of Cape 

 Hatteras in milder climates until 

 Peterson found a similar feature. 



"It turns out that we have a summer 

 feature here," the researcher says, 

 "that is an annual event — the heat 

 check. We've just recently collected 

 and analyzed our second-year collec- 

 tion, so we are now quite certain that 

 this is indeed annual and that it's go- 



ing to be a useful marker and aging 

 technique." It has also been deter- 

 mined that the summer feature is laid 

 down in the Carteret County clams be- 

 tween May and October. 



Peterson says his research is needed 

 because there is no basic biological 

 data available for managing hard clam 

 resources. "We've been working on 

 this aging technique so that we can 

 look at the natural populations that 

 are now being harvested by clammers 

 in the state and find out what their age 

 distribution is," he says. "In other 

 words, if people are hauling in, on the 

 average, three-year-old clams, that im- 

 plies that the renewal rate, the rate at 

 which those clams will replace them- 

 selves, is a great deal more rapid than 

 if they are harvesting twenty-year-old 

 clams. That," he continues, "is an im- 

 portant statistic that has been un- 

 available to people interested in 

 management of shellfisheries in the 

 state, and specifically of the hard clam 

 catch. It's just a question of how long 

 they need to grow into the size class 

 that is legal to harvest." 



Photo by Cassie Griffin 



Hugh Porter at the Institute of Marine Sciences 



