Saturday, September 8, 2012

Project Limulus: 2012 Horseshoe Crab Population Survey Summary


I am sorry to report that it was a disappointing spring for Menunkatuck’s Project Limulus  volunteers, especially after last year when we tagged 975 crabs.  Our total tagged for this year was only 240.  The crabs just weren’t there!  This would have been of greater concern to us had we not learned that Short Beach in Branford was crawling with them!  Heather Smiarowski, a Beach Captain for The Branford Land Trust, reported that they almost had more crabs than they could handle.  I wondered if Guilford’s lack of crabs could have been due to reconfiguration of the bottom of the Sound caused by Hurricane Irene.  I asked Dr. Mark Beekey, one of the Sacred Heart professors in charge of Project Limulus, and he said that it is not unusual for the crabs to show up in an area one year and then go somewhere else the next year.  We don’t know why this happens. Finding answers to questions like this is one of the reasons we are doing the study.
Recapture numbers were considerably less in Guilford as well.  A recapture is a crab which has already been tagged.  We found only 61 recaptures compared to 262 found last year.

Guilford’s Project Limulus team surveyed the two beaches at Indian Cove a total of 21 times.  We also met on two extra days for tagging only.  Crabs were tagged at the following Guilford beaches: Indian Cove Public, Indian Cove Private, Shell Beach, Joshua Cove, and Grass Island.  Our 2012 survey period began on May 3rd. and ended on July 1st.  We found the greatest number of crabs on May18th.  It is interesting to note that horseshoe crabs were sighted by volunteers as early as April 15th.   This was approximately one month earlier than the past 3 years and was probably related to the mild winter and warmer than average spring temperatures.  One hypotheses to explain our lower crab numbers this year was that we had missed a couple of weeks of tagging because the tags weren’t available until the beginning of May.  This idea, however, seemed to be negated by the fact that Branford continued to find large numbers of crabs throughout May and June. 

I think it is also interesting to note that during the actual beach surveys, which follow a prescribed protocol according to specific dates and tides, the number of crabs counted,(165), was not significantly different from last year’s count of 171.  I don’t know how to explain this.  All of my seasoned volunteers agreed that we really did see less crabs this year. 

New this year, were two visits to local schools.  Accompanied by a pair of live horseshoe crabs,my husband, Vaughn, and I gave presentations about Project Limulus to the students at the King-Robinson Magnet School in New Haven and at Rockville High School in Vernon.  It was great to see the students "getting up close and personal" with the horseshoe crabs! 
  
I can’t say thank you enough to my great team of volunteers for their time, enthusiasm, and dedication.  Here’s hoping that the crabs will decide to come back to Guilford next year!   I look forward to seeing you then.

We are always happy to have new volunteers.  If you are interested, please contact judy@menunkatuck.org.  For more information about Project Limulus, go to info@projectlimulus.org. 



                                       2010                     2011                  2012

Total crabs tagged-       370                       975                    240
Total recaptures-             26                        262                      61



                                        2010                    2011                  2012

Total crabs counted 
during surveys -              151                      171                    165                   


2010

Indian Cove Public Beach              Indian Cove Private Beach    

Single males-4                                  Single males-13
Single females-1                               Single females- 4
Pairs-30                                              Pairs-19
Female with 2 males-2                    Female with 2 males-3
Female with 3 males-0                    Female with 3 males-4
Total crabs-71                                   Total crabs-80


2011

Single males-19                              Single males-6
Single females-9                             Single females-1
Pairs-41                                            Pairs-13
Female with 2 males-7                  Female with 2 males-1
Female with 3 males-1                  Female with 3 males-0                                                                                                                 Total crabs-135                               Total crabs-36
                                                                                                                                                              
                                                                                                                                                      
2012

Single males-15                               Single males-7
Single females-4                              Single females-3
Pairs-27                                             Pairs-31                      
Female with 2 males-5                   Female with 2 males-0
Female with 3 males-0                   Female with 3 males-0
Females with 4 males-1                 Female with 4 males-0
Total crabs-93                                  Total crabs-72

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