REGIME SHIFT OF COMMON FORAGE FISH SPECIES IN BOCA CIEGA BAY

Forage fish make up a critical link in marine food webs, and are key food resources for several sportfish species whose fisheries have economic significance in Boca Ciega Bay. The purpose of this research was to study the seasonal variation in the abundance of forage fish Anchoa spp., Bairdiella chrysoura, Eucinostomus spp., Lagodon rhomboides, Menidia spp., and family Dorosomatidae (sardines) in Boca Ciega Bay, Florida, from May 2025 to January 2026. To do so, a ~5625 ft2 section of water was sampled every Wednesday at 1:30pm and 10:00pm off of the seawall at Eckerd College using a 75ft seine net. All fish collected were photographed and later identified.

Anchoa spp., Bairdiella chrysoura, Lagodon rhomboides, and Menidia spp. all had peak abundances earlier in the data set from May 2025 to July 2025. However, Eucinostomus spp. and family Dorosomatidae had peak abundance much later, from September 2025 to November 2025.

Starting in August 2025, there was an observed shift in the dominant species present in the area. Prior to this, Anchoa spp., Bairdiella chrysoura, Lagodon rhomboides, and Menidia spp. were the most abundant, and their declines were aligned with the dominance of Eucinostomus spp. and family Dorosomatidae.

Besides providing a better insight into the local fish community, understanding the shifts in dominance may provide insight into how environmental conditions influenced by climate change, such as water temperature, may affect the marine food web.

For more information: mtzimmer@eckerd.edu

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