e t w o r k news 



Researchers Don't Count 

 Out Horseshoe Crabs — 

 Count Them Instead 



As hordes of horseshoe crabs 

 amassed on Delaware's Eastern Shore 

 last month for an annual mating spree, 

 scientists and volunteers took advan- 

 tage of the lovesick creatures to 

 conduct an important poll. 



Although it will take time to 

 reach definitive conclusions based on 

 this year's count, Delaware Sea Grant 

 scientist Joe Farrell says, "Numbers 

 from previous studies suggest a 

 decline in the last 10 years." 



Habitat loss explains the decline, 

 but a steadily increasing harvest is 

 also a contributor. Horseshoe crabs are 

 taken primarily for their meat, which 

 serves as bait for eel, conch and 

 catfish. Additionally, crab blood is 

 used for processing substances that 



detect bacterial contamination in 

 pharmaceuticals and surgical im- 

 plants. 



In February, Farrell brought 

 industry leaders together to discuss the 

 importance of wise management of 

 horseshoe crabs in Delaware and to 

 raise awareness of conservation 

 efforts. 



With an aim to reduce harvesting 

 pressure on the species, Farrell and 

 other scientists are seeking funding to 

 develop an artificial bait with all the 

 luring attributes of crabmeat. 



Strange Sounds May 

 Shoo Birds from Gill Nets 



In Washington's Puget Sound, 

 gill nets often ensnare more than fish, 

 and environmentalists have long 

 called for a better method to catch fish 

 without catching fish-eating birds. 

 Scientists participating in a Washing- 

 ton Sea Grant-led effort, funded by the 

 National Marine Fisheries Service, are 

 studying a way to make gill nets less 

 lethal for birds. 



The researchers are experiment- 

 ing with underwater sounds that alert 

 common murres and other fish-eating 

 birds to the presence of gill nets. 

 Initial tests began at the Oregon Coast 

 Aquarium, where scientists exposed 

 the birds to a variety of sounds at 

 different frequencies and intervals and 

 observed the birds' responses. 



According to University of 

 Washington zoologist Julia Parrish, 

 "The sounds tested included a random 

 series of beeps at different frequen- 

 cies. Most importantly, we had to 

 make sure the sounds did not attract 

 the birds." 



Results from the aquarium study 

 suggest that the birds can hear 

 manufactured sounds but are not 

 attracted to them — at least not at the 

 aquarium. 



The next round of tests will take 

 place in the Puget Sound sockeye 

 fishery. In a cooperative effort among 



industry and state and federal regula- 

 tory agencies, several gear modifica- 

 tions, including pingers, will be tested. 

 Gear modifications found most effec- 

 tive will be phased into the fishery. 



Keeping Sturgeon Stocks 

 Distinct Is Key to Their 

 Comeback 



Species on Earth come and go, but 

 sturgeon have managed to endure for 

 millions of years. When humans in 

 recent centuries developed a taste for 

 the strange-looking, prehistoric fish and 

 its eggs, however, that survival streak 

 appeared doomed to end. 



Restocking the fish seems a 

 sensible idea, but New York Sea Grant 

 researchers are finding they need more 

 information about the species before a 

 rehabilitation program can get under 

 way. 



Through a genetic study of 

 sturgeon, Isaac Wirgin, associate 

 professor of environmental medicine at 

 New York University Medical Center, 

 and John Waldman, a research associate 

 at the Hudson River Foundation, 

 confirmed that the Atlantic sturgeon 

 (Acipenser oxyrinchus) and the Gulf 

 sturgeon (A. oxyrhincus desotoi) are 

 distinct subspecies. They also found 

 regional distinctions among fish taken 

 from different environments within the 

 range of each. 



These findings are important 

 because the success of any recovery 

 effort would depend upon the ability of 

 the released fish to survive in a particu- 

 lar environment. According to 

 Waldman, introducing a fish from one 

 river into another could corrupt the 

 genetic pool, leading to a decreased 

 survival potential for offspring. 



The researchers have identified 

 three distinct Atlantic sturgeon stocks 

 based on genetic differences: Canada, 

 New York (Hudson River) and South- 

 eastern states. 



A recent moratorium on Atlantic 

 sturgeon fishing in New York will 



22 SEPTEMBER/OCTOBER 1996 



