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.
We’ve seen reports that the blue crab population is up this season, and activity has certainly increased in Antipoison Creek compared to recent years. We have at least three crabbers with pots at the mouth of the creek, collecting bushels of crabs in the double digits many days. We’re about halfway through the crabbing season, which is when the Chesapeake Bay Stock Assessment Committee (CBSAC) releases their advisory report each summer on blue crabs. Made up of state agencies and scientists from Maryland and Virginia, the most recent publication, issued June 30, echoes other recent reports we’ve read about crab population abundance.
One thing the CBSAC highlights is the abundance of female crabs in the Bay (which gives an indication of how the overall population will look in the next year). The committee keeps track of population estimates for adult female crabs, juvenile crabs, and male crabs in the Bay. The committee also sets threshold limits and targets for adult female population numbers. The threshold limit, the point at which the adult female population should not fall below, is set at 70 million; the target is set at 215 million.
This year at the beginning of the harvest season, the committee counted an estimated 194 million spawning age female crabs, which is a 92% rise from last spring’s count. Because only 15% of adult females were harvested last year, which was below the 25.5% harvest target, and given that 194 million adult females is well above the 70 million threshold, the Stock Assessment Committee has declared that overfishing is not occurring in the Bay.
However, the count of adult females is still something to look out for, regardless of how well the population is doing this year, especially as the current season continues. The CBSAC points out that it was only two years ago when the adult female crab population dropped below the 70 million-threshold mark. Blue crab population numbers can be extremely variable, so a good harvest and population one year does not ensure healthy numbers for the next season.
The CBSAC report includes a list of recommendations to continue to support and increase the blue crab population, which includes expanding blue crab sanctuaries in Virginia (Lower Bay), Maryland (Upper Bay), and parts of the Potomac River (overseen by the Potomac River Fisheries Commission) to protect females of spawning age. The CBSAC also calls for improvements in surveys and data acquisition needed to make more informed estimates of current population numbers. One other recommendation made by the commission, dependent on further assessment, is instating an annual total allowable catch (TAC), which is a fisheries method we will go into more detail on here shortly.
You can check out the full CBSAC 2016 report here.
Check out today’s front page article, “There’s Always a Catch,” on Chesapeake blue crabs in the Washington Post. Improvements in Bay water quality this year has had a positive impact on underwater grasses and blue crabs, but what does this mean for the Bay’s watermen? Journalist Steve Hendrix spent a day with a commercial crabber and found out temporary crab abundance doesn’t necessarily result in positive outcomes for our local watermen.
This spring we’ve read reports from the Virginia Institute of Marine Science (VIMS) on the recent resurgence of submerged aquatic vegetation in the Bay; we’ve seen the latest survey from VIMS and the Maryland Department of Natural Resources showing that blue crab populations are higher this year than in several years past; and we’ve seen the University of Maryland (UMCES) report on the overall improving water quality in the Bay watershed. We’ve noticed some of these improvements firsthand in Antipoison Creek, on Virginia’s Northern Neck. Gary Greenwood shares his observations below:
We just spent three days at our place in White Stone. The weather was terrific, but better than that, we saw things in and around the water that we haven’t seen in the 10 years we have been visiting.
Walking out our dock on Antipoison Creek we noticed a lot of underwater grasses growing on both sides. I understand from our neighbor who has lived on the creek for decades that there used to be a lot of underwater grasses in the creek, but it has been gone for a long time.
The grasses must be providing good habitat for young crabs. We have seen lots of skate in the shallows near the grass, and further out we see crab pots set by five different watermen, based on the colors of the buoys. We have always had crabs of course, but seldom a population to support this many pots.
We visited Mike next door at his oyster farm (www.windmilloysters.com). He was too busy getting a shipment of 5,000 oysters out the door, but he did give us some baby oysters so we can start the next generation in the cage under our dock. Mike said he is shipping more than 15,000 oysters a week, which is great for him and his small operation.
In addition to being a good business, Mike’s oyster farm, with a couple of million oysters in the creek and out in Little Bay, is probably one of the reasons the underwater grasses are returning. (See the earlier post about recent water quality in the creek and Little Bay.)
In the evenings I have been reading Kate Livie’s very enjoyable book, Chesapeake Oysters, about the oysters in the Bay and the people who have made a living from them. She does a great job recounting the history of the oyster from the 1600’s to the present. I hope to finish it this weekend.
One of our goals each time we visit is to eat local seafood whenever we can. This weekend we enjoyed roast oysters at Merroir across the river in Topping, and local rockfish from our fishmonger, Blue Water Seafood in Kilmarnock.
The efforts to clean up the Bay certainly need to continue. We plan to continue monitoring the water quality and donating our information and other resources where we think we can make a difference. This weekend has given us a little optimism that the things everyone does to help the Bay can make a difference.
Surveys for both blue crabs and underwater seagrass found increases in population levels and acreage in the Chesapeake Bay this year.
The 2016 joint survey between the Maryland Department of Natural Resources and the Virginia Institute of Marine Science (VIMS) found that there are 35% more blue crabs in the Bay than this time last year. More specifically, the female population reached 194 million individuals, with overall numbers reaching 553 million.
Crab population numbers tend to fluctuate year-to-year, based on a number of factors, such as habitat loss, water temperatures, and harvest levels. The past two years have seen improvements to population numbers, but the blue crab is still considered to be in a state of recovery. Numbers have not reached 800 million, the number of blue crabs found after the first survey in 1988, in many years. With population fluctuation in mind, experts at the Smithsonian Environmental Research Center stated that this year’s good news does not necessarily mean that stricter harvest restrictions in Virginia and Maryland should be lifted. (SERC, 2016).
Crab population levels can be linked to seagrass acreage in the Bay. Seagrass provides habitat and protection for juvenile blue crabs. In past years, seagrass loss has been one predicted cause for blue crab population declines. The most recent survey from VIMS found that Bay seagrass acreage in 2015 was the highest it has been in 30 years. Perhaps these increases correlate to blue crab numbers.
The VIMS survey counted 91,631 acres of seagrass, up 21% from the 2014 survey, and 140% from the first survey in 1984. For more information on growth rates in specific regions (Upper Bay, Mid Bay, Lower Bay), please see the Bay Journal.
The Virginia Marine Resources Commission (VMRC) issued their decision on October 27 concerning the winter dredging of blue crabs in state waters. The VMRC has elected to close winter dredging for the seventh year in a row, to protect the Chesapeake Bay crab population.
The VMRC must decide on a year-to-year basis whether or not to open winter dredging, based on what they call ‘trigger values,’or crab population numbers deemed high enough for winter harvesting. Trigger values for juvenile abundance of crabs must be at 291 million or higher; crabs of spawning age, or female abundance must be at 125 million for winter harvesting to occur. However, estimates made earlier this year for juvenile abundance of blue crabs was only at 269 million, and crabs of spawning age at 101 million. Both juvenile and female crab abundance were well below trigger values, leading to the recommendation to close winter dredging again this year. The VMRC took this recommendation into account, and elected to restrict dredging once again.
The full audio recording of the VMRC meeting concerning crab management can be found here.
By Gary Greenwood
As Katie pointed out in a previous post, some restaurants in the Washington area were reporting a shortage of crabs. When I was down at our house on Antipoison Creek, I stopped by to see Glenn, one of the local crabbers, to see how many crabs he was catching.
On July 2, Glenn brought in nine bushels of crabs from more than 150 pots. He considered that a good day, and said he had had a pretty good June as well. I rode with him as he delivered the crabs to his buyer and then picked up bait for his next trip out. Glenn had four bushels of #1s, three bushels of #2 and 2 bushels of #3 crabs.
The first picture shows the buyer weighing the four bushels of #1 jimmy crabs. Each bushel is marked as to the type of crab it contains. #1 are mature jimmy (male) crabs. These are often sold intact for steamed crabs. #2 jimmy crabs are younger male crabs, probably used for crabmeat. The #3 crabs are mature sooks (females). The price paid for a bushel depends on the type of crab, as well as the time of year and market.
The buyer was waiting for one more waterman to drop off his crabs, and then he would load the day’s catch into a refrigerated truck to take to the Little River Seafood processing plant up in Reedville.
After the bushels were weighed, Glenn picked up nine empty baskets, and we headed back to White Stone to pick up bait at a local fish warehouse. Glenn uses menhaden to bait his crab pots, and we picked up five 50-pound boxes of frozen menhaden. We stored those in an insulated box on the dock, ready to be loaded on the boat for the next trip out. Buddy, the blue heron that hangs out at Glenn’s fish house talked us into giving him one of the menhaden, which he promptly stabbed with his beak.