More about Horseshoe
Crab Biology
Survey Instructions
Surveying Horseshoe Crabs at Other BeachesCONTENTS: Make sure you get all of the following!
1) This sheet of instructions.
2) Date and time of survey.
4) Tally sheets for recording data.
5) Beach site sheet for recording physical information about the survey location.
6) Instructions for classification of groups of crabs
7) Pacing trial instructions
8) The time of the higher high tide at your siteRecall that the target dates are:
May 30th through June 3rd
June 13th through 17th
June 28th through July 2nd
PREPARATION FOR THE SURVEY:
Clothing and accessories
- Wear appropriate clothing for weather and wet conditions at the water's edge. Consider sunscreen during the day and insect repellent when needed. If thunderstorms are present do no go onto beach.
- Bring a flashlight, clipboard or hard surface to write on, and a couple of pencils and a means to sharpen the pencils.
- Shoes are a necessity. We recommend watershoes, old sneakers, or boots. Do not go barefoot.
- An accurate wristwatch is needed for recording arrival time, as well as time survey is begun and finished.
SURVEY PROTOCOL:
- Arrive at beach at least 15 minutes before survey time.
- Ignoring the crabs for the moment, pace out a length of the beach. Your survey area should be as long as practicable -lengths over 550 meter, or 1580 are ideal, but your beach may be shorter. Place a marker of some sort at the each end of the survey area so you will know when you reach it while performing the count.
- While waiting for high tide, complete the Beach Site Sheet. Addresses and phone numbers of each survey team member are important in case we have questions about the data. Even if the weather prevents you from doing the survey, please complete the Beach Site Sheet and explain why the survey could not be completed.
- When it is time for high tide, go to your marked starting point (see corresponding beach map) and begin survey. As you walk towards the other end of the beach, count and record on the Tally Sheet all horseshoe crabs within a 1 meter transect, extending from the water's edge into the water 1 meter along the entire length of the survey area.
- If any tagged horseshoe crabs are observed, please record the tag number and condition of animal on the Tally Sheet.
- Record the time when the survey is completed on the Tally Sheet.
COUNTING AND RECORDING HORSESHOE CRABS:
- The gender of an adult horseshoe crab can be determined by:
- Size - Females tend to be approximately 25% larger than males at maturity. After examining a few horseshoe crabs you will be able to differentiate males from females by sight.
- Claws - Males develop a specialized reproductive claw at maturity. This claw enables the male to attach to the female. Turn over a male and notice how the first claw is different than all the other claws. The female lacks this type of claw.
- If you have difficulty determining gender, turn the horseshoe crab over and examine the claws.
- Use the following categories to record horseshoe crabs (see also the classification diagram):
- Solitary - Lone horseshoe crabs (usually males).
- Clasping pair - When the male is attached to the female. The clasping pair will either be burrowed into the substrate or swimming.
- Satellite - Male horseshoe crabs surrounding the clasping burrowed pair.
- Recording clasping and satellite crabs
- Burrowed pair or group and swimming pair.
- Record the number of males and enclose this number with a circle for each female. Sometimes it will not be possible to separate multiple spawning groups so it becomes necessary to record the multiple groups as one which may include more than one female.
Once you are done surveying:Send all of the following to the address below:
Completed Beach Site Sheet.
Completed Tally Sheet.Bennie Williams
Maryland Department of Natural Resources Fisheries Services
Tawes State Office Building, Floor B-2
580 Taylor Avenue
Annapolis, MD 21401Phone No. (410)260-8272
Toll Free Phone No. (800)688-FINS ext. 8272
Fax No. (410)260-8278
email: bwilliams@dnr.state.md.us