JUVENILE FISH TRAWLING SURVEY

Researchers pulling trawl net in Santa Rosa Sound

Funding: PPBEP EPA Grant $15,000 (2022); Florida State Appropriation $14,881 (2023)
Years: Reoccurring annually, 2022 - present
Partner Lead: Dauphin Island Sea Lab

Seagrass beds serve as critical nurseries for many species of fish that provide food and shelter from predators. Popular sport fish (e.g., Gray Snapper and Gag Grouper) spend their early lives in seagrass habitats when they are small before moving offshore as they get older and larger. Some species are lifelong seagrass residents (e.g., Red Drum, Speckled Trout, and Gulf Flounder).

It is important to monitor seagrass and fish communities consistently to track changes over time which we can use to inform future condition assessments of our bays and inform important management decisions. Researchers have been surveying our bays since the early 2000s with a historical dataset dating back to the 1970s.

2022 Map of Trawling Locations

To assess the fish communities within seagrass beds across Pensacola and Perdido Bay Systems, PPBEP partnered with researchers from the Dauphin Island Sea lab to conduct an annual trawl survey in October of 2022 and 2023 at 13 sites. The catch is sorted by species, fish are counted, and economically important species are measured before being released back into the water. The number of fish collected is standardized across sites by calculating the catch per unit effort which is the number of fish caught per km trawled/towed. 

Graph of Mean Catch per Unit Effort from 2006 to 2023

• Over the last 15-20 years from 2006 – 2018, there have been decreases in total fish catch at some sites, but recently (2022 to 2023) we observed increases in total fish abundance.
• Drought, rainfall, intense storms, water temperatures, habitat changes or alterations, and other environmental factors can affect fish abundances from year to year.
• In the last 40-50 years, researchers have observed an increase in tropical fish species abundance in our local bays and lagoons likely due to the impacts of climate change (i.e., increase sea surface temperatures).

 Pufferfish (left) and Burrfish (right)

• A total of 24-25 species were collected during the 2022 and 2023 surveys 
• There are significant differences between Perdido Bay and Pensacola Bay fish communities due to differing dominant seagrass communities.
• Pinfish was the abundant species collected from 2006-2023 with other schooling bait fish species making up large proportions of the catch, including Mojarra, Silver Perch, and Scaled Sardine.
• More unique species that were collected during the surveys include Spotted Scorpionfish, Striped Burrfish, Emerald Parrotfish, Planehead Filefish, and Lane Snapper.