{"id":40914,"date":"2024-02-26T10:30:58","date_gmt":"2024-02-26T15:30:58","guid":{"rendered":"https:\/\/news.maryland.gov\/dnr\/?p=40914"},"modified":"2024-02-26T16:49:59","modified_gmt":"2024-02-26T21:49:59","slug":"winter-survey-takes-stock-of-the-chesapeake-bays-blue-crabs","status":"publish","type":"post","link":"https:\/\/news.maryland.gov\/dnr\/2024\/02\/26\/winter-survey-takes-stock-of-the-chesapeake-bays-blue-crabs\/","title":{"rendered":"Winter Survey Takes Stock of the Chesapeake Bay\u2019s Blue Crabs"},"content":{"rendered":"<p style=\"text-align: center\"><i><span style=\"font-weight: 400\">DNR measures hundreds of sites to help provide a snapshot of the crab population<\/span><\/i><\/p>\n<div style=\"max-width: 80%\">\n<p><iframe loading=\"lazy\" title=\"DNR&#039;s Blue Crab Winter Survey in the Chesapeake Bay\" width=\"540\" height=\"304\" src=\"https:\/\/www.youtube.com\/embed\/oRrsw1k3XCM?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen><\/iframe><\/p>\n<\/div>\n<p><span style=\"font-weight: 400\">At a nondescript spot in the middle of the Choptank River, the Mydra Ann slowed to a crawl.<\/span><\/p>\n<p><span style=\"font-weight: 400\">The crew aboard the crabbing boat, a mix of Maryland Department of Natural Resources (DNR) scientists and commercial watermen, readied the gear. With a thud, the large, steel-toothed dredge met the water of the Choptank, its chain whirring along the center of the boat as the metal bars lined with netting descended to the river bottom.<\/span><\/p>\n<p><span style=\"font-weight: 400\">After a one-minute drag traveling at 3 knots, the crew pulled up the dredge and emptied its contents onto the deck. Among the leaf litter, small rocks, and chunks of ice, small crustaceans shifted groggily\u2014juvenile blue crabs.<\/span><\/p>\n<p><span style=\"font-weight: 400\">\u201cIt\u2019s Christmas every day,\u201d said Chris Walstrum, a DNR natural resource biologist. \u201cYou don\u2019t know what you\u2019re gonna get.\u201d<\/span><\/p>\n<p><!--more--><\/p>\n<p><span style=\"font-weight: 400\">Walstrum leads the department\u2019s annual blue crab winter dredge survey, which provides an estimate of the size of the population of Maryland\u2019s state crustacean in the Chesapeake Bay and its tributaries. A coordinated effort between Maryland and Virginia since 1989, this survey helps assess how blue crabs are doing in the Bay and how much of the population is removed by harvest.<\/span><\/p>\n<p><span style=\"font-weight: 400\">Picking through the detritus, Heather Hayden, a DNR biologist, and John Murphy, the first mate of the Mydra Ann, set aside the crabs to be measured and logged. The survey takes place in the winter because crabs are more dormant during the colder months. Though they\u2019re not technically hibernating, the crabs are largely inactive and bury themselves in mud.<\/span><\/p>\n<p><span style=\"font-weight: 400\">The trip to the surface is a temporary awakening for the arthropods. Most only just begin to rouse to the change in temperature and scenery before Walstrum measures them, records their sex, notes any abnormalities (like a missing claw), and casts them back into the chilly waters, where they swim down, disappearing under the surface to resume their slumber.<\/span><\/p>\n<p><span style=\"font-weight: 400\">But the smaller crabs tend to be a bit quicker to adjust. They stretched their tiny claws skyward, pinch-ready.<\/span><\/p>\n<p><span style=\"font-weight: 400\">\u201cThey\u2019re a little slower this time of year,\u201d Hayden said. \u201cWhen you feel them start to reach, you just have to move.\u201d<\/span><\/p>\n<p><span style=\"font-weight: 400\">\u201cThey\u2019ll hurt you in the summertime,\u201d said Murphy, who crabs commercially for much of the year. \u201cIn the summer, they\u2019re moving and biting all over the place.\u201d<\/span><\/p>\n<p><span style=\"font-weight: 400\">The smallest crabs are the representatives of the latest spawn, known as the young-of-the-year, and are important to the future crab stock of the Bay. Those larger than 2.4 inches across the carapace will grow throughout the summer season\u2014by shedding their exoskeletons every month\u2014and will be able to spawn themselves.\u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400\">The survey also takes stock of female crabs, or sooks, which are more abundant than male crabs and important to a sustainable population. Easily identified by the Capitol-dome shape of their aprons, female blue crabs mate only once, in their final molt to maturity.<\/span><\/p>\n<p><span style=\"font-weight: 400\">Once the dredge\u2019s pull was accounted for, the team set off to the next location. Roger Morris, the captain of the Mydra Ann and a commercial crabber, entered the GPS coordinates and monitored the depth and temperature of the water on display screens.<\/span><\/p>\n<div id=\"attachment_40919\" style=\"width: 253px\" class=\"wp-caption alignleft\"><a href=\"http:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/dredge_sites.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-40919\" class=\"size-medium wp-image-40919\" src=\"http:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/dredge_sites-243x300.jpg\" alt=\"Map of sites surveyed in the Chesapeake Bay for the winter blue crab survey\" width=\"243\" height=\"300\" srcset=\"https:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/dredge_sites-243x300.jpg 243w, https:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/dredge_sites.jpg 300w\" sizes=\"auto, (max-width: 243px) 100vw, 243px\" \/><\/a><p id=\"caption-attachment-40919\" class=\"wp-caption-text\">For the survey, the Bay is divided into three strata, with each assigned a number of sites proportional to its area.<\/p><\/div>\n<p><span style=\"font-weight: 400\">The survey samples 1,500 sites, which are randomly assigned with a statistical analysis. Both states split them evenly, so Maryland monitors 750 sites through the course of the winter, hitting around 30 each day.<\/span><\/p>\n<p><span style=\"font-weight: 400\">Morris, who named his boat after his grandmother and daughter, both named Mydra, and his wife Ann, said they try to save the rivers for a windy day and tackle the open Bay when the wind is moderate, but they\u2019re out pretty much every weekday regardless.<\/span><\/p>\n<p><span style=\"font-weight: 400\">\u201cIt\u2019s no fair weather game, I\u2019ll tell you that,\u201d Morris said.<\/span><\/p>\n<p><span style=\"font-weight: 400\">Each dredge follows a familiar pattern. After a pull, the team analyzes the crabs. They also clear out the bycatch, which can be anything from sea squirts and small clams to the occasional beer can. The crew returns organic material back into the Bay, while they throw away the litter.\u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400\">At each site, scientists also collect a water sample to measure salinity and temperature.<\/span><\/p>\n<p><span style=\"font-weight: 400\">In the end, the data collected will help DNR and the Virginia Institute of Marine Science come up with an estimate of the total crab population in the Bay. The population<\/span> <a href=\"https:\/\/dnr.maryland.gov\/fisheries\/pages\/blue-crab\/dredge.aspx\/#:~:text=for%20each%20year%20of%20the%20survey\" target=\"_blank\" rel=\"noopener\"><span style=\"font-weight: 400\">varies from year to year<\/span><\/a><span style=\"font-weight: 400\">, though recent years have raised concern.\u00a0<\/span><\/p>\n<p><span style=\"font-weight: 400\">The<\/span><a href=\"https:\/\/news.maryland.gov\/dnr\/2022\/05\/19\/chesapeake-bay-blue-crab-winter-dredge-survey-results-released\/\" target=\"_blank\" rel=\"noopener\"> <span style=\"font-weight: 400\">2022 survey<\/span><\/a><span style=\"font-weight: 400\"> estimated 227 million crabs, the lowest ever recorded in the survey. In 2023, the population bounced back<\/span> <a href=\"https:\/\/news.maryland.gov\/dnr\/2023\/05\/18\/maryland-department-of-natural-resources-reports-encouraging-results-from-the-chesapeake-bay-blue-crab-winter-dredge-survey\/\" target=\"_blank\" rel=\"noopener\"><span style=\"font-weight: 400\">to 323 million<\/span><\/a><span style=\"font-weight: 400\">, an encouraging improvement, although scientists urged continued vigilance based on low juvenile abundance.<\/span><\/p>\n<div id=\"attachment_40918\" style=\"width: 770px\" class=\"wp-caption alignnone\"><a href=\"http:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/winterdredge-totalestimate.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-40918\" class=\"wp-image-40918 size-large\" src=\"http:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/winterdredge-totalestimate-1024x596.jpg\" alt=\"Graph of winter dredge survey results over time\" width=\"760\" height=\"442\" srcset=\"https:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/winterdredge-totalestimate-1024x596.jpg 1024w, https:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/winterdredge-totalestimate-300x175.jpg 300w, https:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/winterdredge-totalestimate-768x447.jpg 768w, https:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/winterdredge-totalestimate-1536x894.jpg 1536w, https:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/winterdredge-totalestimate.jpg 1974w\" sizes=\"auto, (max-width: 760px) 100vw, 760px\" \/><\/a><p id=\"caption-attachment-40918\" class=\"wp-caption-text\">The results of the winter dredge survey from 1990 to 2023. Estimates of blue crabs have been below average for the past four years, though fluctuations are common over time.<\/p><\/div>\n<p><span style=\"font-weight: 400\">Predation, water quality issues, and habitat loss likely contribute to diminished blue crab populations. A 2023 study found that<\/span> <a href=\"https:\/\/afspubs.onlinelibrary.wiley.com\/doi\/epdf\/10.1002\/mcf2.10261\" target=\"_blank\" rel=\"noopener\"><span style=\"font-weight: 400\">invasive blue catfish ate 440 tons of blue crab<\/span><\/a><span style=\"font-weight: 400\"> in the James River in Virginia.<\/span><\/p>\n<p><span style=\"font-weight: 400\">The 2024 blue crab winter dredge survey results won\u2019t be released until May. After completing the 750 sites, the team returns to high density sites and pulls again there, to make note of mortality. By comparing the number there at the first and second pull, they can get a sense of how intense the winter was for the crabs.<\/span><\/p>\n<p><span style=\"font-weight: 400\">Despite the crew&#8217;s 45 days on the water through the coldest weather of the year, there was a light mood on the boat. Between pulls, the team joked around with each other and played guessing games at the number of crabs that day or the number of cars leaving Tilghman Island that morning.<\/span><\/p>\n<p><span style=\"font-weight: 400\">Walstrum stays positive about Maryland\u2019s state crustacean too.<\/span><\/p>\n<p><span style=\"font-weight: 400\">\u201cThey\u2019re resilient; you can\u2019t look at one year to determine how they\u2019re doing,\u201d he said. \u201cThere have been some noticeable drops, but we have to keep on the up.\u201d<\/span><\/p>\n<div id=\"attachment_40920\" style=\"width: 770px\" class=\"wp-caption alignnone\"><a href=\"http:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/Blue-crab-2024-winter-survey-scaled.jpg\"><img loading=\"lazy\" decoding=\"async\" aria-describedby=\"caption-attachment-40920\" class=\"wp-image-40920 size-large\" src=\"http:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/Blue-crab-2024-winter-survey-1024x768.jpg\" alt=\"Blue crabs sitting next to a measuring ruler.\" width=\"760\" height=\"570\" srcset=\"https:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/Blue-crab-2024-winter-survey-1024x768.jpg 1024w, https:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/Blue-crab-2024-winter-survey-300x225.jpg 300w, https:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/Blue-crab-2024-winter-survey-768x576.jpg 768w, https:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/Blue-crab-2024-winter-survey-1536x1152.jpg 1536w, https:\/\/news.maryland.gov\/dnr\/wp-content\/uploads\/sites\/2\/2024\/02\/Blue-crab-2024-winter-survey-2048x1536.jpg 2048w\" sizes=\"auto, (max-width: 760px) 100vw, 760px\" \/><\/a><p id=\"caption-attachment-40920\" class=\"wp-caption-text\">Blue crabs await measurement during the 2024 winter dredge survey. Photo by Joe Zimmermann<\/p><\/div>\n<p><em><span style=\"font-weight: 400\">By Joe Zimmermann, science writer with the Maryland Department of Natural Resources.<\/span><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>DNR measures hundreds of sites to help provide a snapshot of the crab population At a nondescript spot in the middle of the Choptank River, the Mydra Ann slowed to a crawl. The crew aboard the crabbing boat, a mix of Maryland Department of Natural Resources (DNR) scientists and commercial watermen, readied the gear. With<a href=\"https:\/\/news.maryland.gov\/dnr\/2024\/02\/26\/winter-survey-takes-stock-of-the-chesapeake-bays-blue-crabs\/\">&nbsp;&nbsp;Read the Rest&#8230;<\/a><\/p>\n","protected":false},"author":250,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[957,11,33],"tags":[3905,2982,3182],"class_list":["post-40914","post","type-post","status-publish","format-standard","hentry","category-appnews","category-fisheries","category-the-bay","tag-blue-crab","tag-chesapeake-bay","tag-winter-dredge-survey"],"acf":[],"_links":{"self":[{"href":"https:\/\/news.maryland.gov\/dnr\/wp-json\/wp\/v2\/posts\/40914","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/news.maryland.gov\/dnr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/news.maryland.gov\/dnr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/news.maryland.gov\/dnr\/wp-json\/wp\/v2\/users\/250"}],"replies":[{"embeddable":true,"href":"https:\/\/news.maryland.gov\/dnr\/wp-json\/wp\/v2\/comments?post=40914"}],"version-history":[{"count":10,"href":"https:\/\/news.maryland.gov\/dnr\/wp-json\/wp\/v2\/posts\/40914\/revisions"}],"predecessor-version":[{"id":40941,"href":"https:\/\/news.maryland.gov\/dnr\/wp-json\/wp\/v2\/posts\/40914\/revisions\/40941"}],"wp:attachment":[{"href":"https:\/\/news.maryland.gov\/dnr\/wp-json\/wp\/v2\/media?parent=40914"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/news.maryland.gov\/dnr\/wp-json\/wp\/v2\/categories?post=40914"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/news.maryland.gov\/dnr\/wp-json\/wp\/v2\/tags?post=40914"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}