The horseshoe crab is an ancient creature. Fossil records suggest it has been around for at least 400 million years. Today there are four species left on the planet, the one found in the United States is Limulus polyphemus and it can be found along the east and Gulf coasts. In recent years there has been a decline in this ancient creature across its range. In Pensacola Bay, they were once common but, like seagrass and scallops, began to decline in the 1960s and 70s. In recent years there seems to be more encounters with them. The Florida Fish and Wildlife Conservation Commission, in partnership with Florida Sea Grant, has been conducting statewide surveys and tagging programs using community science volunteers. The project is called The Florida Horseshoe Crab Watch. However, to participate in this program you must know the location of their nesting beaches, and in Pensacola we have not done that yet. So, our volunteers conduct Horseshoe Crab Searches to try and find such beaches.
Horseshoe crabs lay their eggs along the shoreline during the spring high tides of both the spring and fall seasons. Nesting typically occurs very close to the time of high tide. Over the past few years, we have been logging sightings of horseshoe crabs in the bay area. From these reports we have defined nine beaches where encounters occur frequently and have set those up as transects to be surveyed by volunteers for nesting activity. Those locations include:
- Kees Bayou near Perdido Key
- Park West on Pensacola Beach (2 transects here)
- Little Sabine on Pensacola Beach (2 transects here)
- Morgan Park on Pensacola Beach
- “Baby Beach” on Pensacola Beach
- Sharp Point on Pensacola Beach
- Big Sabine on Pensacola Beach
The spring high tide occurs twice a month and the spring season runs from March through June. Each high tide can occur more than one day during the spring high tide period (tidal range greater than 1.2 feet for our location) giving volunteers several days to survey their beaches.
For the 2023 Spring Season Florida Sea Grant trained 18 volunteers; 8 of those (44%) participated in a survey. Four of the nine defined transect beaches were surveyed (44%). Those included Park West (20 surveys), Little Sabine (17 surveys), Big Sabine (4 surveys), and Baby Beach (2 surveys).
Volunteers asked to survey beaches not part of the original nine, and five of those were surveyed. Those included Navy Point (1 survey), Shoreline Park (2 surveys), Galvez Landing (30 surveys), and Gulf Breeze just north and east of the Chappie James Bridge (3 surveys).
Four members of the public who were not part of the team did report horseshoe crab encounters during the spring. Mating pairs of horseshoe crabs were seen several times by locals near Baby Beach. Molts were found by beach combers at Baby Beach and Park West. And a biologist from Fish and Wildlife Research Institute, while floundering, witnessed our first nesting event! This occurred near Ft. Pickens gate on the Sound side. It occurred 12 hours AFTER the spring high tide.
|Location||No. of surveys||Miles searched||No. of encounters||Notes|
|Navy Point||1||1.5||0|| |
|17||8.5||0||This is a location where paired males and females have been found in the past.|
|20||17.0||2||1st nesting event reported here.|
|Baby Beach||2||0.6||2||Local swimmer reported several just offshore more than once.|
|Galvez Landing||30||3.0||0|| |
|4||4.8||2||Many live HCs and molts have been found here.|
|North shore of Gulf Breeze||3||0.9||3||Numerous molts are found on this beach and encounters are frequent.|
|TOTAL||79||39.1||21||HCs encountered 24% of the survey time.|
Beaches that were not survey this spring:
- Kees Bayou
- Park West – east walk
- Little Sabine – south
- Morgan Park
- Sharp Point
Eight trained volunteers conducted 79 surveys at eight different transects covering almost 40 miles.
21 horseshoe crab encounters occurred. These included live HCs and/or their molts.
The north shore of Gulf Breeze had NUMEROUS molts suggesting nesting may be occurring somewhere nearby, but those locations where not discovered.
NUMEROUS reports came from the Baby Beach area on Pensacola Beach. One volunteer followed them as they headed east and found most of the beach between Baby Beach and Portofino was armored (seawall or riprap) replacing potential nesting beach habitat for the HCs.
The FWRI biologist who witnessed the nesting event at Park West (closer to Ft. Pickens gate) indicated that there were 8-9 pairs on the beach around 10:30pm. This was 12 hours AFTER the spring high tide for the day. Suggesting that they may prefer nesting under the cover of darkness. The team discussed nighttime surveys, however, due to safety issues, and that they were not supported by FWC nor the University of Florida, evening surveys were not conducted. Discussion on this topic will be had by the team before we begin our fall surveys.
We will not begin the full tagging program until we witness nesting occurring more than once in a season.
The fall nesting season is approaching. This will run from October through December. If you are interested in volunteering contact Rick O’Connor at the Escambia County Extension Office (850-475-5230 ext.1111, email@example.com)
Source: UF/IFAS Pest Alert
Note: All images and contents are the property of UF/IFAS.