Western Dry Rocks Research

Underwater fish counts allow us to understand changes in reef fish communities. We conduct these surveys both inside the seasonal closure and in surrounding waters. When conducting these surveys, we record the number and species of fish present, lengths of fish, and habitat measurements.  

What this will tell us: 

• Changes in reef fish communities over time, both inside and outside of the seasonal closure. 
• The timing of the reef fish aggregation formations. 
• Patterns of habitat use within the seasonal closure area

To learn more about this research from our scientists, view the video Western Dry Rocks Research: Reef Visual Census.

Acoustic telemetry is when animals tagged with special transmitters are tracked through the environment using an array of listening devices. We use these transmitting tags to follow reef fish over several years to evaluate the effect of the spatial closure on their movement patterns. 

What this will tell us:

• The timing of reef fish movements in the Western Dry Rocks area.
• The range of habitats that the reef fish use.
• When they arrive at a spawning site.
• How long they stay.
• How often they come back.

Angler Participation Program

When fishing near Western Dry Rocks, be on the lookout for tagged grey snapper and mutton snapper. They can be identified by an orange external tag located near their dorsal fin and/or by a black internal acoustic tag located inside their belly. If you catch one of these fish, report your findings to (786) 647-8908 or keys.fish@MyFWC.com and collect your reward.

To learn more about this research from our scientists, view the video Western Dry Rocks Research: Acoustic Tagging and Telemetry.

FWC researchers have partnered with scientists from Florida Atlantic University’s Harbor Branch Oceanographic Institute to conduct surveys using an unmanned underwater vehicle (UUV) to understand what is happening below the surface during the time of the closure. This equipment uses side-scan sonar to map the habitat and water column to locate masses of fish, similar to a fish finder on a recreational boat. High-definition cameras are also used to record and identify what type of reef fish are present as the UUV passes through the water column.

What this will tell us: 

• How large the fish aggregations are within the seasonal closure.
• What habitat features they are using.
• What species are present within the aggregations.

To learn more about this research from our scientists, view the video Western Dry Rocks Research: Autonomous Underwater Vehicle.

We have built specialized underwater cameras that can be deployed for weeks at a time at specific known spawning locations. These cameras have an extended battery life that allows them to capture multiple weeks of video when divers are not present.  

What this will tell us:  

• Capture behaviors associated with these aggregations.
• Document timing of spawning events.
• Quantify numbers of fish associated with these aggregations.

To learn more about this research from our scientists, view the video Western Dry Rocks Research: Underwater Camera Arrays.

Current speed, direction, and temperature, can influence reef fish behavior at spawning aggregation sites. To better understand how the currents within the seasonal closure influence reef fish behavior we deploy current meters during the time of the closure.   

What this will tell us:  

• The current speed and direction associated with reef fish behaviors.
• Water temperature influencing presence of reef fish.
• This information, coupled with acoustic telemetry data, can verify the timing of spawning aggregations. 

To learn more about this research from our scientists, view the video Western Dry Rocks Research: Current Meter.

Otoliths are the inner ear bones of fish and can be used to age an animal similarly to the way the rings in a tree trunk can age a tree. Species of snapper otoliths are being collected in and around the Western Dry Rocks seasonal closure to understand how the ages of reef fish change with this management decision.  

What this will tell us: 

• The ages of the fish collected.
• How these ages change over multiple years at these aggregation sites.

The reproductive organs of sampled fish are removed and preserved. These tissues are used to create microscope slides that we study to understand their stages of sexual maturity. We are interested in tracking how reproduction and egg quality and quantity change over time.. 

What this will tell us: 

• How many of the collected fish are actively spawning.
• What is the timing of their spawning.
• If reef fish at these aggregations are able to spawn multiple times in a season.
• If the total egg output of individuals changes over time.

Economic Studies

We are using in-person surveys and fish harvest data to document any economic changes for various user groups, such as: commercial fishers, charter boat operators, and recreational anglers. This information will be collected again several years from now to better understand these changes over time.  

What this tells us: 

• Costs of associated fishing.
• Effects of the seasonal closure on fishing habits.
• Participants’ knowledge of Western Dry Rocks.

Social Science Interviews

We are using anonymous in-depth interviews with members of key stakeholder groups (i.e., charter fishers, commercial fishers, dive shops, NGOs, general public) to gain insights in their awareness, opinions, and anticipated impacts of the seasonal closure. In addition, qualitative information gathered and collected from the public prior to the closure will be analyzed to assess changes over time.

What this tells us: 

• People’s awareness of the closure.
• Their viewpoints regarding this regulation, their opinion about the process by which the closure was established, their perception of the anticipated/realized impacts of the closure, and more.
• How these perceptions might change over time.

To learn more about this research from our scientists, view the video Western Dry Rocks: Social and Economic Science.

The Florida Keys Reef Tract is a heavily used marine ecosystem. Protecting multi-species spawning aggregations will encourage resilience for reef fish communities. Understanding how boating pressure changes due to the seasonal closure will provide information for how the closure will affect the broader ecosystem.  

FWC scientists have several projects that collect information to help us monitor these changes:

Passive Acoustic Hydrophones

Passive acoustic hydrophones are large microphones that record underwater sound. These hydrophones can be deployed for several months at a time and can detect not only fish sounds but also boat traffic. Boats that are rapidly moving through the area sound different than boats that are slowly maneuvering. We have placed several hydrophones within the Western Dry Rocks seasonal closure throughout the year. This will provide information on how boating patterns change during and after the closure.  

What this will tell us: 

• This will give us an understanding of relative boat activity in the Western Dry Rocks area. 
• How this boating activity changes during the months of the closure and other times of the year. 
• This will give managers an understanding of how boat traffic is changing and a relative estimate of compliance to the regulations. 

To learn more about this research from our scientists, view the video Western Dry Rocks Research: Passive Acoustic Hydrophones.

Aerial Surveys

We conduct two aerial surveys a month from April – July to record boat locations throughout the Lower Florida Keys reef tract. We collect data during the aerial survey using a specialized app. With this app we can record the number of boats at a location, document the GPS location of boats, as well as categorize the activity of those boats. 

What this tells us:  

• These surveys can provide understanding of boating pressure during the months of the closure and determine if pressure shifts to other sites when the closure is in effect. 

To learn more about this research from our scientists, view the video Western Dry Rocks Research: Aerial Surveys.