The highlight event of Delaware’s wildlife calendar, the spring stopover of shorebirds along the Delaware Bay, was once again a disappointing experience for visitors hoping to witness the epic wonder of migration this past spring.
Although shorebirds reliably showed up on the beaches, the star attraction, the red knot, was conspicuously scarce at the prime locations it historically appears. The visible absence of horseshoe crab eggs on the beach explains why red knots apparently are bypassing the Delaware Bay. To complete their migration, red knots are now replenishing at other locations on food that is less nutrient-rich than horseshoe crab eggs, increasing the risk of failing to complete the final leg of their migration to the high Arctic.
The dearth of suitable resources for migrating shorebirds on Delaware Bay beaches is the result of the environmentally menacing horseshoe crab harvest that the state of Delaware still allows, in sharp contrast to New Jersey’s full harvest moratorium.
Delaware uses the recommendations of the Atlantic States Marine Fisheries Commission, an agency set up to promote the interests of the fishing industry, to determine its horseshoe crab policy. Delaware does not take into account the overall economic picture, as New Jersey did when it implemented its moratorium in 2008.
The number of red knots observed during annual aerial surveys is currently a small fraction of the numbers observed during the 1990s, indicating that the red knot has made no recovery from that period of horseshoe crab exploitation. The scarcity of red knots corresponds to the visible absence of horseshoe crab eggs on the beach, compared to the baywide abundance in the 1980s. The obvious reason for this is the decline of spawning female horseshoe crabs.
In spite of these undisputed facts, the commission is now proposing to recommend the harvest of female horseshoe crabs, based on numbers generated by its new computer model. The model does not take into account egg density data, the most reliable indicator of the horseshoe crab population. It also does not include field survey data for red knots but makes its estimate of the red knot population using an algorithm that cannot be field-verified.
At the recent meeting of the commission’s Horseshoe Crab Management Board, a board member stated that individual states are not obligated to adhere to the recommendations the commission makes, as New Jersey has clearly demonstrated. Indeed, the states have a wider range of concerns beyond accommodating the interests of the fishing industry. The state of Delaware certainly does not want to be held responsible if the red knot becomes the next Carolina parakeet or passenger pigeon, both of which became extinct very rapidly. With the red knot population currently at a precariously low level, extinction is now a real possibility unless consequential action is taken by Delaware.
Several species of birds that were in decline in the last century as a result of human activity, including the osprey and the eastern bluebird, have made dramatic recoveries due to human intervention on their behalf. Due to the loss of its critical food source brought on by the fishing industry, the current outlook for the red knot is grim.
The only possibility for red knot recovery is for the Delaware legislature to take the responsible course of action and restrict the harvest of horseshoe crabs until the red knot is removed as a threatened species under the Endangered Species Act.
Steve Cottrell
President, Delaware Audubon
