productive sequence. 



Besides laying down an annual line, 

 hard clams also record daily growth 

 lines and events in their shells. 

 "Reading the days in a clam shell is 

 like looking into a crystal ball," Peter- 

 son says. "You can see events like 

 storms or lunar tides recorded right in 

 the shell." 



In Core Sound Peterson found that 

 most hard clams reach legal harvest 

 size (one inch thick) in one-and-a-half 

 years. "But interestingly the clams 

 that have reached harvest size have 

 only had one reproductive season," 

 Peterson says. This means that the 

 clams have reproduced very few, if 

 any, baby clams, he says. 



Peterson found the average age of 

 clams in Core Sound to be nine years. 

 Ages among clams in the sample ran 

 from less than one year to the ripe old 

 age of 32. 



But the clams' long life spans worry 

 researchers like Peterson and also re- 

 source managers at the Division of 

 Marine Fisheries. A long-lived species 

 generally show lower levels of repro- 

 duction than annual species like 

 shrimp and scallops. This could mean 

 today's large harvests are feeding off of 

 several years of reproduction that can- 

 not be matched annually. 



"It has really become imperative," 

 Peterson says, "to address whether we 

 need to worry about managing the 

 stocks and whether we will be able to 

 continue the level of harvest we are 

 currently applying to the population." 



In another part of Peterson's pro- 

 ject, he and his graduate students com- 

 pared the harvest efficiency and envi- 

 ronmental impact of two hand- 

 operated clam rakes — the pea digger 

 and the bull rake. The pea digger, 

 traditional gear used by hand rakers in 

 North Carolina, resembles a garden 

 rake, having a wooden shaft leading to 

 a steel head with three to six prongs. 

 Rakers pull the pea digger back and 

 forth along the bottom waiting to hear 

 the scaping noise of metal hitting shell, 

 signaling a catch. 



The bull rake has only recently 

 made its debut in North Carolina after 

 being used in the Long Island Sound. 

 Its main feature, a cast iron basket, at- 

 taches to a metal shaft which ends in a 

 T-shaped handle. Fishermen push the 

 teeth of the basket about 5V2 inches 

 into the sediment and then pull the 

 rake in short, quick jerks. As it is 

 pulled along, clams, shells, seagrass 



and other debris are forced into the 

 basket. When the basket feels full, the 

 fisherman pulls up the rake and sorts 

 out the clams. 



Peterson tested the two rakes on a 

 sandy bottom. The pea digger dug up 

 more large clams than did the bull 

 rake. And with a pea digger, research- 

 ers were able to cover more area than 

 with the bull rake. 



In the seagrass bed the opposite oc- 

 curred. The bull rake captured more 

 clams and covered more area than the 

 pea digger. But the problem comes in 

 the amount of seagrass removed by 

 each rake. The bull rake removed, on 

 the average, more than twice as much 

 seagrass as the pea digger. It also had a 

 greater effect on roots and rhizomes, 

 important sources of seagrass survival 

 and reproduction. 



Peterson says his findings will sup- 

 port Marine Fisheries' restrictions on 

 the use of bull rakes in seagrass beds, 

 restrictions that have been under fire. 



Of particular interest to the Division 

 of Marine Fisheries, says Munden, has 

 been Peterson's work with clam kick- 

 ing. Kickers have long claimed that 

 kicking cultivates the bottom, making 

 better conditions for next year's baby 

 clams and increasing their numbers. 



But in an experiment where Peter- 

 son kicked and raked experimental 

 plots then compared them to areas left 

 untouched, he found no increase or 



A metal shed perches by the edge of 

 Core Sound in Atlantic. It might hold 

 fishing gear. But it doesn't. Eight 

 million baby clams are calling that 

 shed home until May. 



Monroe Willis, a native of Atlantic, 

 and his partner, Earl Huskey of New 

 Jersey, are gearing up what they hope 

 will be a lucrative business — a clam 

 hatchery. Clam hatcheries are new to 

 North Carolina. Most clam culture has 

 previously taken place in New 

 England and Long Island. But warm- 

 er waters and longer growing seasons 



decrease in baby clams. Even areas 

 kicked for two years showed no in- 

 crease in baby clam populations. 



As another part of the kicking ex- 

 periment, Peterson tested the recovery 

 rates of seagrass from raking and kick- 

 ing in seagrass beds. After raking and 

 kicking his experimental plots, Peter- 

 son waited a few months to see how the 

 grass fared. He found that the more in- 



tense the harvest (medium and high 

 kicking levels) the greater the damage 

 to the grass beds. Grass coverage was 

 cut to about half of the before-kicking 

 levels in the medium- and high-kicking 

 plots. 



After 10 months Peterson sampled 

 the grass beds again. Grass coverage in 

 the raked and low-kicking plots had 

 recovered, but the medium- and high- 

 kicking plots showed no tendency 

 toward seagrass recovery. 



Munden says Peterson's informa- 

 tion provides important scientific 

 proof of the long-lasting effects of clam 

 kicking in seagrass beds. 



While Peterson has gathered a lot of 

 information about hard clams and the 

 methods used to harvest them, he has 

 more work to do. He plans to measure 

 the effect of clam kicking on the sur- 

 vival of benthic invertebrates (food for 

 fishes) and on the turbidity of the 

 water. Peterson plans to compile his 

 information into proposed manage- 

 ment guidelines for the future. 



—Kathy Hart 



mean a marketable clam in fewer years 

 in the southeast. Add the shorter 

 growth period to the rising prices 

 clams bring from seafood dealers and it 

 equals more people interested in grow- 

 ing their own clams. 



But it takes more than interest to 

 get you started in clam culture. It 

 takes some knowledge of clam biology, 

 money to invest in equipment and lots 

 of patience, says Tony Capehart, a 

 Swansboro ice dealer. After reading up 

 on clam culture literature and talking 

 Continued on next page 



"Reading the days in a clam shell is like looking into a crystal 

 ball." 



— Charles Peterson 



To hatch a million eggs 



