Surveying Horseshoe Crabs at Flag Pond, Selby
Beach, or Turkey Point
CONTENTS: Make sure you print a copy of each of the following!
1) This sheet of instructions.
2) Date and time of survey (see the
tidal tables for survey times).
3) Map of survey location (Flag Pond,
Selby Beach, or Turkey
Point (Eastern Shore).
4) Tally sheets for recording
5) Beach site sheet for recording
physical and environmental information about the survey location.
6) Instructions for identification
of groups of crabs
Recall that the survey target dates are:
May 30th through June 3rd
June 13th through 17th
June 28th through July 2nd
Make sure you contact the survey coordinator Bennie Williams
to confirm your date and location.
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.
- Arrive at beach at least 15 minutes before survey time.
- Walk to the location of the tide meter stick and monitor the tide
height (see corresponding beach map for location of tide meter stick).
- 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 the height of the tide on the meter stick remains constant
for 15 minutes or begins to decrease, go to the designated 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 1 meter (approx. 3 feet) of the water's
edge on land and 1 meter into the water 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, size,
- 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 or are unsure, turn
the horseshoe crab over and examine the claws.
- Use the following categories to record horseshoe crabs (also see
the classification diagram):
- Solitary - Lone horseshoe crabs (usually males) not associated
with any other crab.
- Clasping pair - When the male is attached to the female.
The clasping pair will either be burrowed into the substrate or
- Satellite - Male horseshoe crabs surrounding the clasping burrowed
- 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 the following to the address below:
Completed Beach Site
Completed Tally Sheet.
Maryland Department of Natural Resources Fisheries Services
Tawes State Office Building, Floor B-2
580 Taylor Avenue
Annapolis, MD 21401
Phone No. (410)260-8272
Toll Free Phone No. (800)688-FINS ext. 8272
Fax No. (410)260-8278