Introduction

The bay scallop (Argopecten irradians) was once common in the lower portions of the Pensacola Bay system.  However, by 1970 they were all but gone.  Closely associated with seagrass, especially turtle grass (Thalassia testudinum), some suggested the decline was connected to the decline of seagrass beds in this part of the bay.  Decline in water quality and overharvesting by humans may have also been a contributor.  It was most likely a combination of these factors.

 

Scalloping is a popular activity in our state.  It can be done with a simple mask and snorkel, in relatively shallow water, and is very family friendly.  The decline witnessed in the lower Pensacola Bay system was witnessed in other estuaries along Florida’s Gulf coast as well.  Today commercial harvest is banned, and recreational harvest is restricted to specific months and to the Big Bend region of the state.  With the improvements in water quality and natural seagrass restoration, it is hoped that the bay scallop may return to lower Pensacola Bay.

 

Since 2015 Florida Sea Grant has held the annual Pensacola Bay Scallop Search.  Trained volunteers survey pre-determined grids within Big Lagoon and Santa Rosa Sound.  Below is the report for both the 2024 survey and the overall results since 2015.

 

Methods

Scallop searchers are volunteers trained by Florida Sea Grant.  Teams are made up of at least three members.  Two snorkel while one is the data recorder.  More than three can be on a team.  Some pre-determined grids require a boat to access, others can be reached by paddle craft or on foot.

 

Once on site the volunteers extend a 50-meter transect line that is weighted on each end.  Also attached is a white buoy to mark the end of the line.  The two snorkelers survey the length of the transect, one on each side, using a 1-meter PVC pipe to determine where the area of the transect ends.  This transect thus covers 100m².  The surveyors record the number of live scallops they find within this area, measure the height of the first five found in millimeters using a small caliper, which species of seagrass are within the transect, the percent coverage of the seagrass, whether macroalgae are present or not, and any other notes of interest – such as the presence of scallop shells or scallop predators (such as conchs and blue crabs).  Three more transects are conducted within the grid before returning.

 

The Pensacola Scallop Search occurs during the month of July.

 

2024 Results

A record 168 volunteers surveyed 15 of the 66 1-nautical mile grids (23%) between Big Lagoon State Park and Navarre Beach.  152 transects (15,200m²) were surveyed logging 133 scallops.  An additional 50 scallops were found outside the official transect for a total of 183 scallops for 2024.

 

 

 

2024 Big Lagoon Results

75 volunteers surveyed 7 of the 11 grids (64%) within the Big Lagoon.  67 transects were conducted covering 6,700m².

101 scallops were logged with an additional 42 found outside the official transects.  This equates to 3.02 scallops/200m².  Scallop searchers reported blue crabs and conchs, both scallop predators, as well as some sea urchins.  All three species of seagrass were found (Thalassia, Halodule, and Syringodium).  Seagrass densities ranged from 5-100%.  Macroalgae was present in six of the seven grids (86%) but was never abundant.

 

2024 Santa Rosa Sound Results

93 volunteers surveyed 8 of the 55 grids (14%) in Santa Rosa Sound.  85 transects were conducted covering 8,500m².

32 scallops were logged with an additional 8 found outside the official transects.  This equates to 0.76 scallops/200m².  Scallop searchers reported blue crabs, conchs, and sand dollars.  All three species of seagrass were found.  Seagrass densities ranged from 50-100%.  Macroalgae was present in five of the eight grids (62%) and was abundant in grids surveyed on the eastern end of the survey area.

 

2015 – 2024 Big Lagoon Results

 

Year	No. of Transects	No. of Scallops	Scallops/200m2
2015	33	0	0.00
2016	47	0	0.00
2017	16	0	0.00
2018	28	0	0.00
2019	17	0	0.00
2020	16	1	0.12
2021	18	0	0.00
2022	38	0	0.00
2023	43	2	0.09
2024	67	101	3.02
Big Lagoon Overall	323	104	0.64

 

 

 

 

2015 – 2024 Santa Rosa Sound Results

 

Year	No. of Transects	No. of Scallops	Scallops/200m2
2015	01	0	0.00
2016	01	0	0.00
2017	01	0	0.00
2018	01	0	0.00
2019	01	0	0.00
2020	01	0	0.00
2021	20	0	0.00
2022	40	2	0.11
2023	28	2	0.14
2024	85	32	0.76
Santa Rosa Sound Overall	1731	36	0.42

 

¹ Transects were conducted during these years but data for Santa Rosa Sound was logged by an intern with the Santa Rosa County Extension Office and is currently unavailable.

 

Discussion

Based on a Florida Fish and Wildlife Research Institute publication in 2018, the final criteria are used to classify scallop populations in Florida.

 

Scallop Population / 200m2	Classification
0-2	Collapsed
2-20	Vulnerable
20-200	Stable

 

Based on this, over the last nine years we have surveyed, the populations in lower Pensacola Bay are still collapsed.  However, you will notice that in 2024 the population in Big Lagoon moved from collapsed to vulnerable for this year alone.

 

There are some possible explanations for this.

• The survey effort in Big Lagoon was stronger than Santa Rosa Sound. 75 volunteers surveyed 7 of the 11 grids.  This equates to 11 volunteers / grid surveyed and 64% of the survey area was covered.  With Santa Rosa Sound there were 93 volunteers who surveyed 8 of the 55 grids.  This equates to 12 volunteers / grid surveyed but only 14% of the survey area was covered.  Most of the SRS grids surveyed were in the Gulf Breeze/Pensacola Beach area.  More effort east of Big Sabine may yield more scallops found.
• There is the possibility of different teams counting the same scallops. Each grid is 1-nautical mile, so the probability of one team laying their transect over an area another team did is low, but not zero.
• It is known that scallops have periodic population booms. Our search this year may have witnessed this.  We will know if encounters significantly decrease in 2025.

Whether there was double counting this year or not, the frequency of encounter was much higher than in previous years.  There were multiple reports from the public on social media about scallop encounters as well, and in some places we did not survey.  It is also understood that scallops mass spawn.  So, high density populations are required for reproductive success.  The “boom” we witnessed this year suggests that there is a population of scallops – albeit a collapsed one – in our bay.  It is important for locals NOT to harvest scallops from either body of water.  First, it is illegal.  Second, any chance of recovering this lost population will be lost if the adult population densities are not high enough for reproductive success.

 

Acknowledgements

We would like to thank ALL 168 volunteers who surveyed this year.  We obviously could not have done this without you.

Below are the “team captains”.

 

Harbor Amiss                                              Glen Grant                       Eric Stone

David Anderson                                          Phil Harter                       Neil Tucker

Laura Baker                                                 Gina Hertz                       Christian Wagley

Melinda Bennett                                         Sean Hickey                    Jaden Wielhouwer

Samantha Bergeron (USM class)           John Imhof                      Keith Wilkins

Cheri Bone                                                   Jason Mellos                   Christy Woodring

Cindi Cagle                                                  Greg Patterson

Cher Clary                                                    Kelly Rysula

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Rick O’Connor                Florida Sea Grant; Escambia County

Thomas Derbes II          Florida Sea Grant; Santa Rosa County