On April 27, 2015, the Virginia Marine Resources Commission (VMRC), the Maryland Department of Natural Resources (Md. DNR), and the Virginia Institute of Marine Science (VIMS) reported the results of the latest winter dredge survey of Blue Crab populations in the Chesapeake Bay. Since 1990, the survey has been conducted each year from December to March by VIMS and the Md. DNR. The report for Winter 2015 showed increases in overall Bay-wide crab abundance and in several age categories.
The information from the winter dredge survey was an important factor in decisions about Blue Crab regulations made by the VMRC at its May 26, 2015, monthly meeting. According to the meeting summary, available online at http://www.mrc.virginia.gov/Commission_Summaries/cs0515.shtm, the Commission voted to continue the “seasonal management approach,” starting the next crab-management season on July 5, 2015 and ending July 4, 2016, and opening the commercial crab pot season March 17 and closing the commercial crab pot season November 30; continue the current bushel limit management measures and dates for upcoming season; adjust the closure dates for the non-crab pot gear season, closing on September 26 instead of September 16 and reopening the non-crab pot gear season on April 21 instead of May 1; nade it unlawful for any vessel to act as both a crab harvester and a crab buyer on the same trip; made it unlawful for any person to possess dark sponge crabs from March 17 through June 15; and deferred until October 2015 any decision on whether to continue in 2015-16 the closure of the winter crab dredge fishery from December 1—March 31 (the current practice). The Crab Management Advisory Committee is to continue working with staff and the Virginia Institute of Marine Science “to find the best measures to reopen this fishery.”
Following is an excerpt from the VMRC’s April 27 news release on the 2015 winter survey:
“This year’s overall Bay-wide crab abundance increased from 297 million crabs to 411 million crabs, a 38-percent increase. Juvenile crabs jumped from 199 million to 269 million, a 35-percent increase, and now comprise the bulk of the crab stock. Spawning-age female crab levels emerged from depleted status, increasing from 69 million to 101 million, a 46-percent increase, but remained well below the healthy-stock target of 215 million. Spawning-age females are the cornerstone of stock rebuilding. Spawning-age males increased from last year but their abundance of nearly 44 million remains the third lowest in the past 25 years. Although the overall number of crabs in the Bay improved, the stock remains just above pre-2008 levels, when a coordinated bay-wide stock-rebuilding program kicked off…
“Crab spawning naturally fluctuates and can be affected by wind, tide, weather, cannibalism, and increased predation on crabs by other species. Over the past two years, unexpected predation events and abnormally harsh winters have negatively impacted the crab stock and have highlighted the need for fishery managers to enhance resilience of the stock through adaptive management to compensate for unusual or extreme environmental stresses.
“The annual Winter Dredge Survey is the primary assessment of the Bay’s blue crab population… The survey employs crab dredges to sample blue crabs at 1,500 sites throughout the Chesapeake Bay from December through March. Sampling during winter when blue crabs are usually buried in the mud and stationary, allows scientists to develop, with good precision, estimates of the number of crabs present in the Bay.”
Following are the lowest and highest estimates of key parts of the Bay crab population since 1990:
Total (both sexes and all ages) – low of 251 million in 2007; high of 852 million in 1993.
Spawning-age females – low of 53 million in 1999; high of 246 million in 2010.
Juvenile-age (both sexes): low of 105 million in 1992; high of 581 million in 2012.
A table of all the results since 1990 is available in both of the sources listed below:
Scientific survey shows modest improvement in blue crab stock, Virginia Institute of Marine Science News Release, 4/27/15; and
Scientific Survey Shows Modest Blue Crab Stock Improvement, Virginia Marine Resources Commission News Release, 4/27/15.