fisheries 



If you happen to catch a blue crab 

 wearing a backpack in the Pamlico 

 Sound, don't worry. The crabby crusta- 

 cean is part of a scientific study, and 

 he's wired for information. ■ In 

 1986, fishermen harvested over 23 million 

 pounds of hard blue crabs valued at 

 almost $5.5 million. In their soft postmolt 

 state, the crustaceans brought crabbers 

 another $700,000— a seven-fold increase 

 since 1981. ■ The crab harvest 



dropped from the more abundant 30 mil- 

 lion pounds of the early 1980s. And 

 fisheries managers are concerned that 

 development along the coast may affect 

 vital crab habitat. ■ Tom Wolcott, a 

 North Carolina State University zoologist, 

 will examine the blue crab and its habitat. 

 He is one of 12 Sea Grant investigators 

 probing fisheries questions about popula- 

 tion fluctuations, disease, pollution and 

 recreational fishing. ■ Wolcott will 



investigate blue crab hideouts— places 

 where the cranky crustaceans go to molt 

 and mate. He wants to know what kind of 

 habitat crabs prefer during these critical 

 life stages. ■ To monitor the crabs, 

 Wolcott will strap ultrasonic transmitters on 

 their backs and track their paths with 

 receivers and hydrophones. When the 

 crabs molt, they'll leave behind their 

 backpacks and clues to their habitat 

 preferences. 



Scallops are a valuable winter fishery; 

 clams a year-round gold mine. ■ In 



fact, since the price for small hard clams 

 rocketed from two cents apiece in 1975 to 

 an occasional 24 cents apiece in 1987, 

 clammers have plied the waters in record 

 numbers, fi But there may be trouble 

 ahead. Hard clams are being over- 

 harvested, and state resource managers 

 need information to make wise manage- 

 ment decisions. ■ To define the prob- 

 lem, researchers must first define the 



areas clams call home. That is the work of 

 Pete Peterson, a biologist at the University 

 of North Carolina Institute of Marine 

 Sciences. He'll also test a proposed rota- 

 tion system for harvest areas to see if the 

 mollusks increase in abundance. ■ As 

 for the bay scallop, Peterson plans to learn 

 more about the sweet mollusks' survival 

 rate. Using the results, resource managers 

 can determine whether it's feasible to in- 

 crease populations by dispersing "seed" 

 scallops in the estuaries. 



Photo by jim Strickland 



Pete Peterson will sieve the sound far answers 

 about hard dam and scallop populations 



One year, thick schools of spot darken 

 North Carolina coastal waters. The 

 next year catching a spot may be 

 likened to finding the proverbial needle 

 in the haystack. ■ The exact causes 

 for the fluctuations have eluded scientists. 

 But Sea Grant scientists will test some 

 theories. ■ NCSU zoologist John Miller 

 and oceanographer Len Pietrafesa think 

 the answer may lie in the fish's migration 

 path from their spawning grounds to the 



estuarine nurseries. They believe that the 

 ocean, inlet and estuarine currents play a 

 role in the fish's migration and ultimately 

 their survival. ■ To test their theory, 

 Miller and Pietrafesa will use dye, floats 

 and small plastic particles to simulate the 

 path of fish carried in the currents. And 

 they'll sample the path of fish at different 

 points in their journey. ■ NCSU 

 zoologists Jim Rice and Larry Crowder 



believe the population fluctuations may be 

 linked to the size of larval fish as they enter 

 the estuary. Their size could well deter- 

 mine how susceptible the fish are to 

 predation and starvation— the most fre- 

 quent causes of death in baby fish. ■ 

 To test the theory, Rice and Crowder will 

 use field and laboratory experiments to 

 design a computer model that can predict 

 how fish size affects the survival of larvae. 



David Checkley will soon be getting an 

 earful from the Atlantic menhaden. 

 Checkley, an NCSU oceanographer, 

 will examine the ear bones of larval 

 menhaden to learn more about the 

 fish's early development. ■ Larval 

 fish add a protein layer to their ear each 

 day the way a tree adds a yearly ring of 

 growth. By using sophisticated equipment 

 to examine the ear bone, Checkley can 

 determine the menhaden's age and the 



water temperature at which it developed. 

 ■ Water temperatures affect when and 

 where the menhaden are spawned, when 

 they begin to feed, what they eat and how 

 they are transported to the estuary. ■ 

 With Checkley's data, scientists can more 

 readily predict the location of menhaden 

 spawning and development. And fisheries 

 managers will have a better understanding 

 of the habitat needs of this economically 

 important fish (see story, page 5). 



Photo by Scott Taylor 



Researchers will delve into the mysteries oj 

 fishery stock fluctuations 



