Friday, Dec 25–Horseshoe Crab Study Suggests Future Changes

BERLIN – An eight-year study of the spawning habits of local horseshoe crabs by the Maryland Fisheries Service and Maryland Coastal Bays Program could prompt a change in horseshoe crab harvesting dates to allow the sea creatures to reproduce before capture.

The coastal bays horseshoe crab study, begun in 2002 and concluding early last summer, has determined that horseshoe crabs in Maryland spawn later than horseshoe crabs in the Delaware Bay.

Horseshoe crab spawning in Maryland’s coastal bays, the study revealed, reaches its height in June, which could, according to the study, be a result of water temperature.

Harvesting should then take place later in Maryland waters if harvest practices require waiting for the end of spawning to take horseshoe crabs, the study concluded.

The study also concluded that the increase in spawning males shown by the extensive study seems to show that the horseshoe crab population is increasing, since male horseshoe crabs mature at a greater clip than females by a few years.

The Maryland horseshoe crab population is more closely connected to the horseshoe crabs in Virginia waters than Delaware Bay, the study also showed.

Horseshoe crabs are harvested for biomedical uses and are subsequently returned to the sea. A clotting agent in the horseshoe crab’s blood is used in a test for bacteria in injectable medications.

The coastal bays spawning study, conducted by the Maryland Coastal Bays Program and the Maryland Fisheries Service, used volunteers to identify spawning beaches and gather data for a baseline number of spawning horseshoe crabs.

Until 2007, volunteers counted and gathered other data during the May and June spawning season from spawning sites on Assateague Island up to Isle of Wight Bay, a 10-kilometer span.

Researchers then realized that most of the spawning horseshoe crabs were concentrated around the Ocean City Inlet, and beginning in 2008 research concentrated on spawning areas near the Inlet, which were also sampled in 2009.

The Maryland horseshoe crab study was prompted by earlier horseshoe crab surveys in Delaware Bay attempting to determine the level of horseshoe crab eggs available to migrating Red Knots, a threatened species of sandpiper. 

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