Each year the Maryland Department of Natural Resources, in partnership with UMCES and VIMS, conducts a winter dredge survey to estimate blue crab population numbers in the Chesapeake Bay. The survey gathers information on the total number of crabs, as well as the number of adult males, female crabs of spawning age, and juveniles. Total numbers give an indication of the current health of the blue crab population; the number of juvenile and female crabs of spawning age give an indication of future conditions. Spawning age females impact the beginning of the coming harvest season (April to July, now ongoing); juvenile crabs impact the harvest further down the line.
The 2017 survey brought mixed results. Total population decreased in number from last year’s 553 million count to 455 million.
Population numbers of spawning age females must meet a certain threshold to be considered sustainable (70 million). Virginia and Maryland have also adopted a population target of 215 million. This year’s count of females of spawning age was the highest since the survey was first undertaken in 1988, with a number of 254 million, well above the target number. This number increased from last year’s count of 194 million.
Survey results were not so good for adult males – which decreased by 16% – nor for juveniles. The number of juvenile crabs estimated in this year’s dredge survey was the fourth lowest number ever recorded. This decrease could impact the second half of this year’s harvest (Maryland’s crabbing season runs until December 15; Virginia’s season closes November 30). Scientists on the Chesapeake Bay Stock Assessment Committee are likely to release updated management recommendations to Maryland and Virginia later this summer.
Note: To read more about where the winter dredge survey takes place, and how the survey is conducted, please read this piece from Maryland’s Department of Natural Resources.