Red Knot Background and Recovery
The red knot is a remarkable migratory shorebird. In the U.S., the shores of Delaware Bay provide a critical stopover area. The birds, many of which winter as far south as the southern tip of South America, arrive at the Bay to coincide with the spawning of horseshoe crabs in late May and early June, producing one of the most dramatic natural phenomena anywhere in the world. Feeding on fat-rich eggs of the horseshoe crab, the birds refuel and continue their journey to Arctic breeding grounds. At one time, more than 100,000 once stopped at the Bay. Today, that number is just over 13,000.
The decline is attributed to a serious drop in the number of horseshoe crabs, which began in 1989 and is now at the lowest point in the history of population surveys for this species. Lower egg numbers mean that birds cannot find food easily and must concentrate in limited areas where crabs are spawning. By tracking with radio-telemetry, biologists found that birds crossed the bay frequently, apparently searching for food. This extends the time necessary to gain weight, and may have consequences for their tight nesting schedule when they finally reach Arctic nesting areas.
A report to the New Jersey Department of Environmental Protection valued the annual Delaware Bay ecotourism at $34 million. Horseshoe crabs blood is also collected non-lethally from adult crabs for the biomedical industry. The U.S. Fish & Wildlife Service values this industry as providing $150 million per year. The Service similarly values the horseshoe crab fishery at $11 million per year, and eel and conch fisheries which use the crab as bait at $21 million per year. Therefore, the non-lethal ecotourism and biomedical industries out value the fisheries 6 to 1. Summary of this study.
The red knot stopover on the Delaware Bay is the most heavily studied in the world and the resulting analysis of the data is not encouraging. Experts predict that unless serious conservation strategies are funded and implemented immediately, the western hemisphere population of red knots is expected to become extinct as soon as 2010.
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