Navigation Links
Decline of shorebird linked to bait use of horseshoe crabs
Date:2/17/2009

Declining numbers of a shorebird called the red knot have been linked to bait use of horseshoe crabs.

Long-term surveys of red knots showed that the average weight of red knots when they leave Delaware Bay has declined significantly since their primary food source, eggs of horseshoe crabs, has been reduced. The study also revealed that red knot survivorship is related to departure weight, and that the population size of red knots has declined by more than 75 percent.

"We concluded that the increased harvest of horseshoe crabs led to a reduction in the food supply for red knots at a critical period in their annual cycle, and this led to a dramatic decline in population size," said USGS scientist, Jon Bart, one of the authors of the study.

There is a long tradition in Delaware Bay of harvesting horseshoe crabs for use as bait in various fisheries. In the years from 1992 to 1997, reported harvest of crabs grew 20 fold from about 100,000 individuals harvested to more than 2 million. This newly released study shows that this increase in horseshoe crab harvest has led to a dramatic decrease in the number of spawning crabs and to a 90 percent decline in crab eggs available for shorebirds to eat.

Delaware Bay is globally recognized as an important feeding stopover for migrating shorebirds, especially red knots. Each year, red knots migrate from Arctic breeding grounds to the southern tip of South America and back, covering more than 18,600 miles. In May, large numbers of red knots congregate in the bay during their northward migration where they gorge on horseshoe crab eggs in preparation for their continued migration to the Arctic.

Concern over red knot populations led to restrictions in horseshoe crab harvest starting in 1997. But as Lawrence Niles, a biologist with the Conserve Wildlife Foundation of New Jersey and senior author of the new study says, "Despite restrictions, the 2007 horseshoe crab harvest was still well above that of 1990, and no recovery of knots was detectable. Recovery of both horseshoe crabs and red knots may require more restrictions on horseshoe crab harvest, possibly even a complete moratorium for some period. We've proposed a program of adaptive management, including monitoring, that should result in the information managers need to find the right balance."

Fifteen scientists participated in the study, from a wide variety of federal, state, and nongovernmental entities. The results are published in the February edition of the science journal Bioscience. The title of the article is, "Effects of horseshoe crab harvest in Delaware Bay on red knots: Are harvest restrictions working?"


'/>"/>

Contact: Jon Bart
jon_bart@usgs.gov
208-426-5216
United States Geological Survey
Source:Eurekalert

Related biology news :

1. Films of Mitchell and Kenyon illuminate lefties decline in Victorian England
2. Decline in uptake of carbon emissions confirmed
3. No convincing evidence for decline in tropical forests
4. Changes in ocean conditions in Sargasso Sea potential cause for decline in eel fishery
5. NOAA reports coastal waters show decline in contaminants
6. Understanding autumn rain decline in SE Australia
7. Great Ape Trusts Wich lead author of Oryx paper on continuing orangutan population declines
8. River damming leads to dramatic decline in native fish numbers
9. In scientific first, Einstein researchers correct decline in organ function associated with old age
10. Decline in Alaskan sea otters affects bald eagles diet
11. In a last stronghold for endangered chimpanzees, survey finds drastic decline
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/1/2016)... , June 1, 2016 ... in Election Administration and Criminal Identification to Boost Global ... a recently released TechSci Research report, " Global Biometrics ... Region, Competition Forecast and Opportunities, 2011 - 2021", the ... billion by 2021, on account of growing security concerns ...
(Date:5/20/2016)... 2016  VoiceIt is excited to announce its ... By working together, VoiceIt and VoicePass will ... VoicePass take slightly different approaches to voice biometrics, ... and usability. ... partnership. "This marketing and technology partnership ...
(Date:5/12/2016)... , May 12, 2016 WearablesResearch.com , ... published the overview results from the Q1 wave of ... recent wave was consumers, receptivity to a program where ... with a health insurance company. "We were ... share," says Michael LaColla , CEO of Troubadour ...
Breaking Biology News(10 mins):
(Date:6/23/2016)... Prostate Cancer Foundation (PCF) is pleased to announce 24 new Young ... cancer. Members of the Class of 2016 were selected from a pool of ... More About the Class of 2016 PCF Young Investigators ... ... ...
(Date:6/23/2016)... ... June 23, 2016 , ... STACS DNA Inc., the ... at the Arkansas State Crime Laboratory, has joined STACS DNA as a Field Application ... team,” said Jocelyn Tremblay, President and COO of STACS DNA. β€œIn further expanding our ...
(Date:6/23/2016)... , June 23, 2016 ... Hematology Review, 2016;12(1):22-8 http://doi.org/10.17925/OHR.2016.12.01.22 ... , the peer-reviewed journal from touchONCOLOGY, Andrew ... escalating cost of cancer care is placing an ... result of expensive biologic therapies. With the patents ...
(Date:6/23/2016)... (PRWEB) , ... June 23, 2016 , ... ... a new line of intelligent tools designed, tuned and optimized exclusively for Okuma ... 12–17 in Chicago. The result of a collaboration among several companies with expertise ...
Breaking Biology Technology: