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Northeast Florida Blue Crab Fisheries Independent Monitoring (FIM)

map showing blue crab sampling locations

In 2015, the Fish and Wildlife Research institute (FWRI) Crustacean Research Program began studying blue crab spawning stock populations, with a focus on female reproductive characteristics.  One of the four regions of focus was near the mouth of the St. Johns River, in northeast Jacksonville. In this region, four locations consisting of five traps were fished weekly. In 2019, the researchers expanded upon their initial objectives and added eight additional locations that extend south to encompass seventy miles of the St. Johns River. Currently, there are 9 locations, with five traps per location, monitored weekly. The 9 trap sampling locations are divided into 3 sub-regions throughout the river; JV, JG and JR.

Each week, FWRI biologists retrieve every trap and collect data for every blue crab in the trap. The traps are then re-baited and returned to the water. Measurements are taken of the carapace (top shell) and other physical attributes (carapace width, body width, carapace length, carapace height, and weight), various health metrics (missing legs, fouling, disease or parasites), stages of molt (exoskeleton condition), and reproductive state.

Temperature, salinity, dissolved oxygen, conductivity, and depth are recorded at each location.  Bycatch is also documented, as well as how many other blue crab traps are being fished in the immediate area, tidal stage, and moon phase. 

The data collected provides insights into shifts in sex composition over time, relationships between juvenile and adult populations, fluctuations in catch, as well as shed light on the spawning habits of females.  With this data, FWC can better manage and understand Florida’s largest blue crab fishery. 

The following tables summarize monthly blue crab catch data in the three regions. JV (2 locations), JG (4 locations), JR (3 locations)*.

*All data is considered preliminary and subject to change. Not for re-distribution.

2020 Blue Crab Catch

image showing the four different locations measurements are taken on a blue crab

Location points for measurements of carapace width, length, and height and body width.

 

image showing four different life stages of blue crabs as shown on their underside

Stages of molting (exoskeleton condition) for a male, immature female, mature female, and a female carrying eggs.