right times. And this sense of timing may be one of the 

 reasons why croaker are so abundant. Croaker, along with 

 spot, menhaden, and two species of flounder, follow a 

 similar time schedule for spawning, transport back to the 

 coast and arrival in the estuary. These five species make up 

 85 percent of the state's commercial catch by weight. 



Unable to swim, the larval croaker hitch a ride westward 

 on the ocean express. Miller and other scientists believe the 

 larvae ride an intermediate layer of warm ocean water that 

 flows shoreward during the winter. If croaker spawned any 

 other time of the year, their ride to the estuary might not be 

 available. 



About January, millions of baby croakers bom- 

 bard the coastline in search of an inlet to the es- 

 tuary. Once in areas like Pamilico Sound, the larvae 

 settle to the bottom for another ride to the nursery. 

 Winter winds blow surface waters against the 

 barrier islands. Gravity pulls bottom waters in the 

 opposite direction. By settling to the bottom, the 

 larvae are driven westward into nursery areas like 

 Rose Bay. 



Again, time is on the side of the croaker. The lar- 

 val croaker settle into the nursery between 

 February and May, just in time to catch the es- 

 tuary's peak productivity during the late spring. 



"The croaker grow like crazy in this environment," 

 Miller says. The larval croaker quickly become juveniles, 

 growing from 25 millimeters to five inches during their five- 

 month stay. The juveniles eat clam siphons, copepods, 

 benthic worms and mysid shrimp. 



And the estuarine nursery seems to provide some protec- 

 tion from predators. Miller has learned the nursery can be 

 an inhospitable place for adult fish who might prey on 

 juvenile croakers. Temperatures and salinity levels fluc- 

 tuate. As long as the fluctuations aren't too drastic, young 

 fishes, such as the croaker, can withstand the changes. But 

 adult fish aren't as tolerant of environmental stresses, 

 Miller says. Adult fish tend to avoid the nursery areas, 

 choosing deeper waters. 



After completing their growth spurt, juvenile croaker 

 leave the nursery behind about August, graduating to the 

 deeper waters of the estuary or the nearshore ocean waters 

 beyond. 



Of the 100,000 eggs the mother croaker 

 spawns, odds are, only one will survive 

 to become an adult. 



Percentages aren't on the side of the newborn croaker. 

 UNC Sea Grant Director B.J. Copeland, an estuarine 

 ecologist, estimates that 98 to 99 percent of the croaker die 

 between the time they are spawned and the time they reach 

 the estuary (about two months). Scientists believe a variety 

 of factors contribute to the high mortality rate. 



As eggs and young larvae, the baby croaker float among 

 the plankton, becoming prime targets for hungry fish. 

 Many die from natural causes — genetic deficiencies, defor- 

 mities. Others die from environmental stresses. Some never 

 find the right currents to carry them shoreward. And the 

 croaker are so tiny, scientists have a hard time tracking 



them through their early days to learn exactly what hap- 

 pens to the baby croaker. 



The estuarine nursery offers the baby croaker a better 

 chance. In Rose Bay, three percent of each day's remaining 

 balance of croaker die, says John Miller. Again, factors like 

 predation and environmental stresses such as salinity and 

 temperature changes contribute to the croaker's demise. 



But for the croaker who survives to leave the nursery, the 

 odds are favorable. The croaker, now about five inches long, 

 has fewer predators and has moved to the deeper, more 

 stable waters. 



Nearly 17,000 years ago, stone-age 

 fishermen would have been living in 

 their villages at the outer continental shelf 

 edge, about 25 miles east of Cape 

 Hatteras. 



When the last major ice age began about 35,000 years 

 ago, the North Carolina coastal and estuarine system would 

 have been in a geographic position similar to today. But, it 

 didn't stay there, says Sea Grant researcher Stan Riggs. 



Within 17,000 years, glacial ice extended into the 

 northern United States and sea level had dropped about 400 

 feet. Riggs says the entire North Carolina continental shelf 

 would have been exposed and the estuarine system would 

 have been near the edge of the shelf. 



Thousands of years later, the climate warmed again, sea 

 levels rose and waters flooded the river basins, forming to- 

 day's estuaries. 



Such warming and cooling trends take thousands of 

 years, says Sea Grant researcher Scott Snyder. Right now, 

 the earth is in a warming trend, he says. 



If that trend were to continue and all the glacial ice in 

 Greenland and Antarctica were to melt, the world's 

 shorelines would eventually be about 200 feet higher than 

 they are now, says Riggs. "This would put the entire coastal 

 plain of North Carolina under water with the shoreline oc- 

 curring approximately along Interstate 95 between 

 Roanoke Rapids and Fayetteville." 



But coastal residents don't have to pack up and move 

 yet, says Snyder. He says most geologists estimate that sea 

 level is rising a half a foot per century. So, we can expect the 

 estuaries to stay put for a while. 



