SEA 



SCIENCE 



and a Sea Grant fellow, also found a large 

 number of juvenile blue crabs in an 

 exotic species of submerged grass in the 

 mouth of the Albemarle and Currituck 

 sounds behind Kitty Hawk. The thick, 

 bushy grass, called Eurasian water-milfoil 

 or Myriophylum spicatum, grows so fast 

 that it can be a nuisance for boaters. 



"These alternative nursery areas 

 mainly blink on after hurricanes," says 

 Eggleston. "They have the potential to 

 increase the nursery capabilities of the 

 entire sound system." 



The Eurasian grass also serves as a 

 habitat for finfish, including the juvenile 

 red drum. "Red drum, which is fished 

 almost exclusively by recreational 

 fishers, has been overexploited," he says. 



However, the most critical habitat 

 for juvenile crabs is sea-grass beds along 

 the sound side of the Outer Banks. The 

 beds consistently receive post-larval crabs 

 during stormy and non-stormy periods. 



Eggleston says these nursery 

 grounds — which are vital to fishery 

 health — are vulnerable to human impact 

 and must command a high priority in terms 

 of conservation. "They can be threatened 

 by leaking septic waste from soundside 

 development and by Jet Skis and small 

 boats cutting through them," he says. 



These findings are part of 

 Eggleston' s ongoing blue crab study. 

 With initial funding from Sea Grant, he 

 began a large study of recruitment of 

 juvenile blue crabs in North Carolina 

 more than four years ago. The N.C. 

 Division of Marine Fisheries, National 

 Science Foundation and Z. Smith 

 Reynolds Foundation have also sup- 

 ported his research. 



Although the hurricanes may offer a 

 bounty of crabs, there are other concerns 

 about the health of the blue crab fishery. 

 Eggleston has studied overfishing in the 

 Pamlico and Albemarle sounds as well as 

 habitat changes from building jetties 

 outside Oregon Inlet. 



Eggleston found that blue crab 

 harvests in the Pamlico and Albemarle 



sounds are at or above sustainable limits 

 and should be capped or cut back to 

 protect the fishery's continued health and 

 productivity. 



"During the past three years, 

 crabbers have harvested between 54 and 

 67 million pounds a year in our sounds," 

 says Eggleston. "Based on our research, 

 which includes an analysis of multiple 

 sets of N.C. Division of Marine Fisheries 

 crab-harvest data dating back to 1 972, 

 we calculate the maximum sustainable 

 yield at between 48 and 60 million pounds." 



As oyster, flounder and other 

 species become overfished, more fishers 

 are turning to blue crabs, Eggleston says. 

 "No one wants to deny anyone this right. 

 However, if blue crab harvests continue 

 to exceed sustainable levels, the long-term 

 outlook for the fishery may be a concern." 



Blue crabs are North Carolina's top 

 commercial fishery species, worth about 

 $40.5 million in 1998, according to the 

 N.C. Division of Marine Fisheries. 

 About 800,000 crab pots are fished on 

 the sounds each year. The season tradition- 

 ally runs from March to November. 



In 1994, the N.C. General Assembly 

 issued a moratorium that placed a 

 temporary cap on commercial crab 

 licenses through July 1999. Legislation 

 that extends the crab moratorium to 

 October 2000 passed the General 

 Assembly in June. 



This year, the Division of Marine 

 Fisheries will come up with a new plan 

 for managing the number of fishers and 

 gear in the blue crab fishery, Eggleston says. 



In May, the Marine Fisheries Com- 

 mission adopted several temporary rules 

 for crab harvest and created management 

 regions for the blue crab fishery. 



"The Marine Fisheries Commis- 

 sion's regional advisory committees will 

 be developing effort-management options 

 for North Carolina's diverse crab fishery 

 prior to October 2000," says Nancy Fish, 

 spokesperson for the Division of Marine 

 Fisheries. 



One factor critical to the health of blue 



crab stock is the ratio of adult females, 

 called spawners, to recruits, or 

 juveniles less than 

 one year old. 



'The 

 number of 

 recruits in a population 

 depends in large part on the number of 

 spawners," Eggleston says. "The more 

 spawners, the more recruits. At too-low 

 population densities, the overfished 

 population begins to lose its ability to 

 build itself backup." 



Such a decline would affect the 

 blue crab's important role 



as a predator, 

 help- 



ing to 

 control the 

 abundance of clams, 

 worms and other soft-bottom prey that 

 live in the sand or mud. 



In his research, Eggleston also 

 found that Oregon Inlet is a critical 

 ocean-to-estuary link through which 

 millions of post-larval crabs enter the 

 North Carolina sounds. 



"We need to be careful about 

 possibly altering water exchange 

 through this vital link," he says. "Recent 

 proposals to build jetties outside the 

 inlet would be great for boating and 

 fishing, but the impact on crabs is 

 unclear. Jetties may actually enhance the 

 transport of crabs from offshore into the 

 sound or they may reduce transport or 

 have no effect at all. We need further 

 study before we build jetties." 



To get the most up-to-date informa- 

 tion on Eggleston' s blue crab research, 

 visit the Web at http://www2.ncsu.edu/ 

 eos/info/mea/mea469_info/bluecrab/. □ 



COASTWATCH 33 



