Horseshoe Crab Spawning Survey
The AACC Horseshoe Crab Survey of 2024
The goal of this project is to involve citizen scientists in mapping the spawning beaches of horseshoe crabs throughout the Chesapeake Bay. While there is anecdotal information concerning spawning beaches in the Chesapeake, there has not been any systematic effort to map all beaches and determine how heavily each beach is utilized. Without this information it is difficult to manage the Chesapeake horseshoe crab population.
All you need to conduct a survey is a smartphone. The information you send using your phone will be sent directly to a larger database of all spawning for a given year.
If you'd like to participate, you are welcome to survey any beach near you where you have access.
To do this:
1) Decide which beach you would like to survey. Any sandy beach, of any size, is a potential spawning beach. It could be at a park, or it could be a neighborhood beach where you have access.
Once you have chosen a beach, decide if you would like to go at night or during the day (or both). More crabs spawn at night, however some beaches are only available during the daytime.
2) Decide on a day, and time. The best time to look for horseshoe crabs is at a spring (high) tide in late May or June. This means a full or new moon. We usually survey a beach about an hour before the high tide time. That’s when female crabs emerge from the water with their males for spawning. The chart below lists the days and times for high tides during this period. The information can also be found using the "tide finder" on the Maryland DNR website.
3)Download the free "Anecdata" app onto your smartphone. Once you have entered your email address, you can search for our project. We are called “Chesapeake Horseshoe Crab Survey”.
4) Walk the beach within an hour of high tide. The app will ask for "weather" - enter conditions. It will also ask for "beach" - type the name of the beach you are surveying. You can enter this information just once, if you like, at the beginning of the survey.
5) If you see a spawning female crab, enter that as an observation. The app will ask you for #females and #males. For example, if you were to see one female with three associated males, you would enter "1" for females and "3" for males. There is a picture below, which shows what a spawning group looks like. The larger female is typically buried in the sand, with one or more smaller males over her. The first shows one female with four males, the second shows a group of three females, each with a single male.
6. Take a picture, and submit that as well. There are also data prompts for tag# and carapace width. If you see a crab with a small white circular tag attached (very unlikely), enter the tag number. Don't worry about carapace width.
7. Continue down the beach, and submit each spawning female/male group as a new observation until you've completed a single pass. Done! The program automatically submits username, time, date, and GPS coordinates.
If you have questions or comments, email me pjbushmann@aacc.edu.
At the end of the summer, all participants will receive a report showing the results of the year's work!
The chart below shows the best days to look for spawning. These days wrap around a full or new moon, and thus high spring tides. The best time on a given day is about an hour before high tide. Although the days are correct, the times shown are for Cove Point beach. High tide further up the Chesapeake will be later. Check the DNR website https://dnr.maryland.gov/Fisheries/Pages/Tide-Finder.aspx to find the best high tide time your chosen beach.
Best Spawning Horseshoe Crab Spawning May and June Dates and Times
Tides for Annapolis (US Naval Academy) starting with May 22, 2024.
Day High Tide Height Sunrise Moon Time % Moon
/Low Time Feet Sunset Visible
W 22 High 5:14 AM 1.7 5:47 AM Set 4:52 AM 96
22 Low 12:23 PM 0.5 8:18 PM Rise 7:49 PM
22 High 5:18 PM 1.0
22 Low 10:37 PM 0.3
Th 23 High 5:49 AM 1.8 5:47 AM Set 5:25 AM 99
23 Low 1:08 PM 0.5 8:19 PM Rise 8:56 PM
23 High 6:04 PM 0.9
23 Low 11:13 PM 0.4
F 24 High 6:24 AM 1.8 5:46 AM Set 6:05 AM 99
24 Low 1:51 PM 0.5 8:20 PM Rise 10:02 PM
24 High 6:50 PM 0.9
24 Low 11:54 PM 0.4
Sa 25 High 7:03 AM 1.8 5:45 AM Set 6:56 AM 98
25 Low 2:33 PM 0.4 8:21 PM Rise 11:03 PM
25 High 7:37 PM 1.0
Tides for Annapolis (US Naval Academy) starting with June 21, 2024.
Day High Tide Height Sunrise Moon Time % Moon
/Low Time Feet Sunset Visible
F 21 High 5:20 AM 1.8 5:41 AM Set 4:47 AM 98
21 Low 12:50 PM 0.5 8:35 PM Rise 8:52 PM
21 High 5:38 PM 0.9
21 Low 10:46 PM 0.4
Sa 22 High 6:02 AM 1.8 5:41 AM Set 5:45 AM 99
22 Low 1:30 PM 0.5 8:35 PM Rise 9:48 PM
22 High 6:28 PM 1.0
22 Low 11:38 PM 0.4
Su 23 High 6:46 AM 1.8 5:41 AM Set 6:52 AM 99
23 Low 2:09 PM 0.4 8:35 PM Rise 10:36 PM
23 High 7:17 PM 1.1
M 24 Low 12:33 AM 0.4 5:42 AM Set 8:05 AM 96
24 High 7:33 AM 1.8 8:35 PM Rise 11:14 PM
24 Low 2:48 PM 0.4
24 High 8:06 PM 1.1