THE BACK PACE 



"The Back Page" is an update 

 on Sea Grant activities — on 

 research, marine education and 

 advisory services. It's also a good 

 place to find out about meetings, 

 workshops and new publications. 

 For more information on any of 

 the projects described , contact the 

 Sea Grant offices in Raleigh 

 (919/737-2454). 



The headline reads: 

 North Carolina hard 

 clams murdered in Back 

 Sound bed. Suspects in- 

 clude members of two 

 underwater gangs — the 

 blue crabs and the 

 whelks. But detective Charles Peter- 

 son, a University of North Carolina 

 (UNC) Sea Grant researcher and biol- 

 ogist at the UNC Institute of Marine 

 Sciences in Morehead City, turned up 

 the real culprits — snapping shrimp. 

 The snapping shrimp (Alpheus), still 

 on the scene, gave themselves away by 

 snapping their small lobster-like claws. 



The shrimp produce a noise much 

 like a person snapping his fingers as 

 they clamp together their powerful 

 claws — claws capable of crushing a 

 small hard clam. Until Peterson's dis- 

 covery, most scientists thought snap- 

 ping shrimp used their claws primarily 

 to attract mates. Scientific literature 

 contains no reports of snapping shrimp 

 preying on hard clams, Peterson said. 



Peterson did his detective work as 

 part of a UNC Sea Grant research pro- 

 ject. Peterson is studying the hard 

 clam, a bivalve mollusk common to 

 North Carolina and large portions of 

 the East Coast, and the effects of har- 

 vest methods on the clams and their 

 environment. 



Peterson made his discovery when 

 Brian Beal, a graduate student work- 

 ing on the project, checked a seed-clam 

 experiment in Back Sound, where he 

 was monitoring clam growth and sur- 

 vival. To keep out the predators, Beal 

 had enclosed the clams in a wire cage. 

 Instead of finding healthy clams, Beal 

 was greeted by piles of crushed 



mollusks and a chorus of snapping 

 shrimp. 



Suspecting the one-and-a-half inch 

 shrimp may be responsible for the 

 clams' demise, Peterson and Beal set 

 up a laboratory experiment. Their 

 suspicions proved correct as the snap- 

 ping shrimp cracked as many as three 

 clams a day. Peterson says the shrimp 

 can crush clams up to two centimeters 

 long (about one year old). 



The snapping shrimp are abundant 

 in Back, Bogue and Core Sounds, 

 where populations run as high as 10 

 snapping shrimp per square meter, 

 Peterson says. And, the shrimp aren't 

 particularly choosy about their 

 habitat. They're just as likely to be 

 found tucked away in a sea grass bed 

 as hiding among the oyster rocks. 



According to Beal, in light of the 

 findings, previous studies may have 

 overestimated the predation rates of 

 blue crabs. The crushed clam shell left 

 behind by the snapping shrimp looks 

 identical to the crushed shell left by 

 the blue crab. Peterson says he doesn't 

 know what percentage of the hard 

 clam resource is being taken by snap- 

 ping shrimp, but he believes it may be 

 substantial. 



With the preliminary investigation 

 behind them, Peterson and Beal are 

 writing their report on the case of the 

 crushed clams, charging the snapping 

 shrimp with the clams' demise. And 

 what will the snapping shrimp plead. 

 Guilty by reason of hunger. 



Are you interested in 

 learning how to raise 

 crayfish, start a bait 

 business or produce fish 

 in your farm pond for 

 profit? The answers are 

 in a series of newspaper 

 columns written by one of UNC Sea 

 Grant's aquaculture experts, Johnny 

 Foster. 



Foster, a marine advisory agent at 

 the NCSU Aquaculture Demonstra- 

 tion Project, began the columns last 

 spring in response to numerous re- 

 quests for information. Several 

 newspapers in eastern North Carolina 



currently are running the biweekly 

 columns which report on the latest 

 research in aquaculture. Topics in- 

 clude catfish farming, soft-shell crabs, 

 eels, bait fish, prawn farming, striped 

 bass, pond construction, cage culture 

 and more. 



For a set of the aquaculture 

 columns, write yNC Sea Grant, Box 

 5001, Raleigh, N.C. 27650-5001. And, 

 for more information on aquaculture, 

 contact Foster at the NCSU 

 Aquaculture Demonstration Project, 

 Route 2, Box 305, Aurora, N. C. 27806 

 or call (919) 322-4054. 



Fishermen in Bruns- 

 wick, New Hanover and 

 Pender Counties will 

 have a new source of in- 

 formation waiting in 

 their mail boxes soon. 

 Jim Bahen, the Sea 

 Grant marine advisory agent in the 

 Wilmington area, has published the 

 first issue of his newsletter, Light 

 Line, designed for commercial 

 fishermen — gill netters, shrimpers, 

 charter boat captains and more. The 

 newsletter will offer news about 

 research, advances in gear and 

 methods, regulations, and programs 

 and events of interest. If you don't 

 receive a copy of Light Line, but 

 would like to be added to the list, write 

 the UNC Sea Grant Advisory Services, 

 General Delivery, Kure Beach, N. C. 

 28449 or call (919) 458-5498. 



Sea Grant agents Bob Hines and 

 Larry Giardina also publish a newslet- 

 ter for fishermen, marina operators, 

 seafood dealers and others along the 

 central North Carolina coast. To be in- 

 cluded on their mailing list, contact 

 the UNC Sea Grant Advisory Services, 

 P. O. Box 896, Atlantic Beach, N. C. 

 28512, or call (919) 726-0125. 



UNC Sea Grant will host a visit 

 from Neil Armstrong, director of the 

 Center for Water Resources Research 

 at the University of Texas in Austin, 

 to the North Carolina State Univer- 

 sity campus November 18 and 19. 

 Continued on next page 



