est marine microorganism to the largest 

 fish. More directly stated: Seagrass 

 abundance can affect how many shrimp, 

 scallops and clams the consumer can 

 heap on his plate. Even for the clam 

 that is being harvested, seagrass is 

 important to the productivity of the 

 population. 



When it comes to refuge, grass beds 

 offer added protection. Peterson learn- 

 ed that the whelk, one of the clam's 

 life-long predators, can decimate a 

 clam population within five warm- 

 water months along sandy estuarine 

 bottoms. But among blades of sea- 

 grass, the hard clam can more easily 

 hide from its footed foe. 



In some cases, seagrass also may 

 help the clam in its procurement of 

 meals. Many biologists have long be- 

 lieved that growth rates were higher in 

 areas where strong currents delivered 

 more food. But Peterson found that the 

 reduced current flow caused by the 

 the presence of grass beds can deliver 

 more food, in some cases, to the clam's 

 sediment level and increase the bi- 

 valve's growth. 



To test the theory that seagrass cover 

 affected the abundance of other spe- 

 cies, Peterson examined populations 

 of bay scallops. He found that bay scal- 

 lop density dropped as seagrass de- 



clined as a result of clam kicking. But 

 the intensely kicked plots contained 

 even fewer scallops than expected. 

 Peterson suspects the greater decline is 

 caused by the patchy grass cover left 

 after kicking. If the remaining cover 

 were evenly distributed, scallop densi- 

 ties would be higher, he speculates. 



At N.C. State University, Sea Grant 

 researcher Jim Easley took an eco- 

 nomic approach to the question of 

 clam kicking's effects on bay scallops 

 in grass beds. Using a computer model, 

 Easley fed in a variety of economic, 

 biological and fishery information. 

 When the results were computed, Eas- 

 ley found that clam kicking and raking 

 had significant negative effects on the 

 number of scallops available for har- 

 vest in grass beds. 



Does clam kicking, in a seagrass bed 

 or out, increase next year's crop of 

 baby clams? This was a commonly 

 held belief among Carteret County 

 clam kickers. They thought that clear- 

 ing the estuarine bottom of larger 

 clams made more room for baby 

 clams. Peterson tested the notion. 



He learned that the removal of adult 

 hard clams by kicking did not enhance 

 the recruitment of baby clams. In fact, 

 in intensely kicked sand plots recruit- 

 ment was 50 percent lower than in the 



control plots. In intensely kicked sea- 

 grass beds, recruitment fell by 15 per- 

 cent. Peterson attributes the decline to 

 the disturbance of sediment caused by 

 the kicking. "Environmental damage 

 caused to seagrass beds and to depen- 

 dent fisheries production is not bal- 

 anced, even in part, by any increase in 

 local hard clam recruitment or by any 

 other obvious benefit," he says. 



The N.C. Division of Marine Fisher- 

 ies had suspected the beds' importance 

 and the adverse effects of kicking; 

 consequently they closed the beds to 

 mechanical harvest in 1978. "My 

 results added biological teeth to a pol- 

 icy that DMF had already been follow- 

 ing," Peterson says. "Now they can say 

 to the fisherman who wants a grass bed 

 open to harvest, we have scientific 

 proof that kicking harms the beds and 

 beds have advantageous impacts on 

 clams and other fisheries, especially 

 shrimp and bay scallops." 



But what of the clams nestled in 

 these grassy beds? Are they a resource 

 lost to the fisherman? No. Many of 

 these clams can still be harvested by 

 use of rakes. But more importantly, 

 Peterson believes these protected mol- 

 lusks, if left unharvested, can parent 

 the thousands of clams needed to re- 

 populate harvestable area tomorrow. 



Aging clams still active in bed 



A rumor circulating 

 among coastal fisher- 

 men had hard clams hid- 

 ing shamefully in their 

 beds. According to the 

 rumor, hard clams be- 

 came, how should we 

 say, sexually inactive, or 

 more delicately stated, 

 reproductively senile, as 

 they became older and 

 bigger. No wonder these 

 soft-bodied mollusks 

 had withdrawn into their 

 shells. 



Already large clams had been labeled as tough, fit only 

 for a pot of clam chowder. But as the rumor of their inabili- 

 ties spread, fishermen lost even more respect for the larger 

 mollusks. Clammers complained that the chowders occu- 

 pied valuable bed space that would be better used by a 

 younger, more productive set. 



But Sea Grant researcher Charles "Pete" Peterson made a 

 discovery that will gain the chowder clam new respect. He 



learned that older, larger 

 hard clams aren't repro- 

 ductively senile at all. In 

 fact, the number of gam- 

 etes, or reproductive 

 cells, a clam produces is 

 directly proportional to 

 its size. 



In Johnson Creek in 

 Core Sound, Peterson 

 dug out one large clam 

 that turned out to be 46 

 years old. "It was the 

 oldest mercenaria ever 

 recorded, and it had gam- 

 etes to beat the band," Peterson says. 



"This is important information because if we argue that 

 undamaged seagrass beds play a significant role as natural 

 predation refuges for a breeding stock of older adult clams, 

 it is critical to show that they do continue to reproduce with 

 age," he says. "Not only does the hard clam continue to 

 produce gametes as it ages, but also the number of gametes 

 produced increases dramatically with size and age." 



