Sea Turtles in Sebastian, Florida

Loggerheads, green turtles and leatherbacks are the three sea turtles that typically nest on the beaches around Sebastian Inlet, and the Sebastian Inlet District says Kemp's ridleys, although rare, have been documented on occasion.

Loggerheads dominate the count. Florida State Parks says Sebastian Inlet State Park and the surrounding beaches have the largest nesting assemblage of sea turtles in the United States, and in June and July the park runs ranger-led walks to watch nesting loggerheads, with reservations made through Friends of Sebastian Inlet State Park (Florida State Parks).

Green turtles are the second species and the one that also lives in the lagoon. Leatherbacks are the largest and the scarcest: the FWC says about 50 percent of Florida's leatherback nesting occurs in Palm Beach County, well south of Sebastian, and that adults weigh between 700 and 2,000 pounds (FWC). The Sebastian Inlet District says leatherbacks are typically the earliest nesters on area beaches and that their overall numbers are very low.

The FWC puts loggerhead nesting near Sebastian in a global frame. It says the Northwest Atlantic loggerhead aggregation is considered the largest in the world, that Florida hosts about 90 percent of its nests, and that most of that nesting takes place in five east coast counties, Brevard, Indian River, St. Lucie, Martin and Palm Beach (FWC). Sebastian Inlet separates the first two.

In 2025 the FWC's Statewide Nesting Beach Survey counted 6,630 loggerhead nests, 4,598 green turtle nests and 78 leatherback nests on 36.0 kilometers of Indian River County beach, the county south of Sebastian Inlet.

Across the inlet, Brevard County surveyed 115.2 kilometers and recorded 22,716 loggerhead, 30,431 green and 129 leatherback nests (FWC 2025 statewide totals). The survey also counts non-nesting emergences, crawls where a turtle came ashore but left without laying; Indian River County logged 11,102 of those for loggerheads and 8,245 for green turtles in 2025, more than the nests themselves.

Those county totals cover every surveyed beach, not a sample. Indian River County's 36.0 kilometers, roughly 2.7 percent of the surveyed beach in Florida, held about 6.6 percent of the state's loggerhead nests and about 6.9 percent of its green turtle nests in 2025, by the arithmetic of the FWC table.

The statewide trend that frames the Sebastian counts comes from a smaller sample. The FWC's Index Nesting Beach Survey, run since 1989 on 27 core index beaches during a fixed May 15 to August 31 window, recorded over 50,000 loggerhead nests and nearly 50,000 green turtle nests in 2025. Loggerhead index counts have ranged from 28,876 in 2007 to a record 71,009 in 2023, and green turtle counts from under 300 to over 61,000 in 2023.

Near Sebastian, leatherbacks nest first, mainly March through July, loggerheads follow from April to September, and green turtles nest mainly from June through late September, according to the FWC.

Loggerheads that nest on the beaches either side of Sebastian Inlet return to their nesting beach every two or more years, 2.7 years on average, and lay an average of 4.1 clutches about every 14 days, each averaging 114 eggs (FWC). Green turtles return every two to three years and lay an average of 3.6 clutches of about 128 eggs; their name comes from the greenish color of their body fat, not their shell (FWC).

Leatherback nests are the easiest to spot on the beach south of Sebastian Inlet. The Sebastian Inlet District describes a large nest footprint with a lot of moved sand, an average of 80 to 120 eggs, an egg chamber about 3 feet deep and an incubation period typically 60 to 70 days (Sebastian Inlet District). The FWC counts the clutch differently, as an average of 73 fertilized eggs plus about 25 yolkless eggs (FWC).

March 1 is the official start of nesting season on the beaches at Sebastian Inlet, the date the district's monitoring crews begin, and the FWC's index window of May 15 to August 31 covers the peak for loggerheads and greens. The beachfront lighting and conduct rules for that season are covered on the Digital Towns page on sea turtle nesting rules near Sebastian.

South of Sebastian Inlet, contract biologists survey the beach every morning from March 1, mark nests with GPS, stakes and flagging tape, and send the data to the FWC's statewide database.

The Sebastian Inlet District describes biologists from Ecological Associates, Inc. heading out at first light on ATVs, walking up each crawl to decide whether the turtle nested or made a false crawl, and checking marked nests daily until hatchlings emerge. Under the protocol the district described, then pending final FWC approval, biologists marked every leatherback nest, every green turtle nest and 1 of every 4 loggerhead nests, and excavated unsuccessful nests after a waiting period to calculate reproductive success.

The monitoring is tied to sand. The district placed 113,000 cubic yards of sand on the beach south of the inlet between January and March 2019, and its permit requires nest monitoring on that 1.5 mile stretch between FDEP R-monuments R-10 and R-17, from the McLarty Treasure Museum south to the Ambersand beach access. The first season after the project, March to October 2019, documented 1 leatherback nest, 492 loggerhead nests and 101 green turtle nests on that stretch alone.

The district's stated reason is its legal job. It is mandated by the Florida Beach and Shore Preservation Act to bypass sand that migrates into the Sebastian Inlet system to downdrift beaches, and it monitors so that the work does not harm nesting on the beaches south of the inlet (Sebastian Inlet District).

Juvenile green sea turtles feed in the Indian River Lagoon seagrass near Sebastian and can be seen on the reefs off the McLarty Treasure Museum and along the rocks on the south side of Sebastian Inlet, according to Florida State Parks.

That makes the green turtle the one sea turtle the park describes feeding inside the lagoon at Sebastian (Florida State Parks). The U.S. Fish and Wildlife Service lists the green sea turtle among the federally protected species of the brackish Indian River Lagoon at Pelican Island National Wildlife Refuge, alongside the Florida manatee and the wood stork (USFWS).

The inlet is the doorway between the two habitats. The Sebastian Inlet District wildlife page includes a photograph of a green sea turtle swimming east through Sebastian Inlet to the Atlantic Ocean and another of a sea turtle hatchling. Inside Sebastian Inlet State Park, Florida State Parks keeps sea turtle exhibits near BG's Surfside Grill on the north side of the park and near the entrance to the Inlet Marina (Florida State Parks).