Mid-October is the start of the Florida stone crab season (ending mid-May). A unique fishery, Florida stone crabs are harvested only for their claws and live crabs are returned to the water with claws regenerating in 1-2 years (varies based on size of crab and time of harvest relative to molting cycle). Florida stone crab meat is flaky and white to off-white with a sweet taste. Claws are either cooked right on crabbing boats or dockside, and are available either fresh or frozen. Claws should be cooked right after they are removed from the crab so the meat doesn’t get stuck to the shell. Approximately 2.5 lbs. of claws yield 1 lb. of meat. Stone crab have a shelf life of 3-5 days so they need to be sold quickly, which can make it challenging to ship out of state. Claws past their shelf life will have an ammonia smell and slippery shells. Meat with black discoloration is a sign of poor handling. Beware imposters: Stone crab from Florida is larger, smoother, and more orange than rougher-shelled, duller-colored Chilean and Mexican rock crab and these imported cooked claws from crabs that look similar to stone crab claws are available frozen.
Based on average landings of Florida stone crab from 2016-17 and the most recent Seafood Watch ratings as of October 2019, the sustainability breakdown of Florida stone crab is as follows:
~90% of Florida stone crab landings globally meet a Seafood Watch "Avoid (red)" rating (~99% from the Florida Gulf)
~10% of Florida stone crab landings globally are unrated/unknown (from Cuba, The Bahamas, and Belize)
Global landings of Florida stone crab in 2017 compared to 2016 saw a decrease of about ~15%, and compared to 2012 saw a decrease of ~50%
In October 2019, the Seafood Watch rating for Florida stone crab changed from a "Best Choice (green)" to an "Avoid (red)" because of concerns about overfishing, mortality of stone crabs released after their claw is removed, and interactions with bottlenose dolphins
Florida stone crabs are closely related to Gulf stone crab (Menippe adina) and can interbreed with them. Florida stone crabs are a brownish red color with grey spots, and have unequally sized claws with black tips. Male Florida stone crabs have a larger pincher claw than females, who usually grow larger than males. They live up to eight years old.
Females reach maturity at about two years old. Males wait until the female molts before they can mate, after which the male stays to protect the female for up to several days. Spawning season lasts from April through September. Females retain the sperm received until their next molt, up to a year later. Sperm is stored in two sacs over the winter, and used in the spring or summer for internal fertilization of the eggs, which are deposited on the female’s underside in a bright orange or red egg sac, called a sponge. Females carrying eggs are called ovigerous. They can lay up to one million eggs at a time, several times during a spawning season, which hatch within two weeks. The larvae undergo six stages of molting and development in four weeks before emerging as juveniles. Juveniles tend to be darker in color than adults.
Florida stone crabs can lose their limbs easily to escape from predators or maneuver through tight spaces. The limbs can grow back within a year, including their claws, with little loss of blood if the joint linking the claw to the body is left intact. Every time the crab molts, their claws grow larger. Molting only occurs at night or in dark spaces, due to the extreme vulnerability of the crab to predators during the molt.
Florida stone crabs feed on oysters and other small mollusks, worms, and crustaceans. They also eat seagrass. Grouper, sea turtles, octopuses, and horse conch prey on Florida stone crab.
Florida stone crabs are found from the west central part of Florida south to the Florida Keys and around the peninsula to Atlantic central Florida. They are also found in parts of South and North Carolina. The species often co-occurs with Gulf stone crabs (Menippe adina) in between this area along the Atlantic and in parts of the Florida Panhandle – even interbreeding and producing hybrids in these regions. Florida stone crab larvae are planktonic and inhabit nearshore coastal waters and estuaries. Juveniles inhabit hiding places such as crevices near or under rocks, shells, and sponges. Adult Florida stone crab live in burrows and can be found in seagrass beds, on mud and sand bottoms, and on or near rocky substrates. Adults inhabit both near and offshore habitats up to depths of 200 feet (61 meters). Little is known about the migration habits of stone crabs, but it is believed they move in response to environmental factors and seasons. Both males and females have been observed moving inshore during the fall to mate.
Science & Management
The Crustacean Fisheries Group at Florida’s Fish and Wildlife Conservation Commission’s (FWC) Fish and Wildlife Research Institute (FWRI) has been studying Florida stone crab and the Gulf stone crab since 1988. Every two weeks FWRI scientists pull trap lines baited with fish. The number of traps used varies by location. The captured crabs are measured, checked for injuries or regeneration of limbs, reproductive state, and molt condition. Bycatch, trap condition, and water qualities are also recorded, such as bottom-water temperature, salinity, dissolved oxygen, and pH levels. The data collected provides new insight into the population biology of the stone crab fishery and helps with development of future management goals.
A 2015 study published in the North American Journal of Fisheries Management looked at the consequences of claw removal in the stone crab fishery. Stone crabs with only one claw removed, usually the crusher, were observed eating fewer bivalves, which are otherwise an important prey resource. Crabs with no claws could only scavenge for food or eat fish flesh. No stone crabs regenerated a legal-size claw upon their first molt after claw removal. Return to the fishery of once-harvested stone crabs is, therefore, unlikely. The study also saw that 20 percent of the claws examined exhibited breakage consistent with high levels of short-term mortality, suggesting that stone crab survival rates rely, at least partially, on the fisherman’s claw removal skills. New knowledge of long-term effects is necessary to properly manage the fishery and provide information and education on claw removal technique.
Mass culture of larval stone crabs and blue crabs at the University of Miami was successful; however, techniques need to be improved upon in order to reduce and control instances of cannibalism that occur naturally with most crustaceans. Research is underway to improve techniques of larval culture, and to test the feasibility of rearing crabs to marketable size in cages placed in natural waters.
The Florida stone crab fishery is managed by the Florida Fish and Wildlife Conservation Commission (FFWCC) in Florida state waters and in federal waters adjacent to state waters. The state of Florida has managed the stone crab fishery since 1929 with a fishery management plan (FMP) being implemented in 1979 to manage the fishery. The FMP was repealed in 2011, as it was redundant to management measures already in place by the FFWCC. The vast majority (98 percent) of the commercial harvest takes place in Florida and is under the management of the FFWCC. The FFWCC conducts population surveys through its research organization, the Fish and Wildlife Research Institute.
The stone crab fishery is unique as only the claws are harvested and the crab is returned to the water alive. If removed accurately, Florida stone crabs can regenerate their claws – that can then be harvested again in the future. Fishers can remove both claws if they are of legal size (2 ¾ inches); however, the FFWCC encourages the removal of only one claw, as it takes longer for the crab to regenerate both claws. It is also thought that the removal of both claws can lead to a higher mortality risk post release. Mortality rates post release vary and are dependent on whether both claws are removed, if the claws are removed incorrectly (with muscle tissue still attached), or if crabs are exposed to air for long periods of time.
Among other measures the FFWCC uses to manage the Florida stone crab fishery are:
A seasonal closure from May 16 to October 14 each year
Prohibiting the taking of claws from egg-bearing females
Handling requirements once crabs are on vessels
Gear restrictions and requirements – traps may be constructed from wood, plastic, or wire and must have a volume of eight feet or less
Efforts to reduce the capture of undersized crabs and prevent ghost fishing (all wire traps must have escape rings and have biodegradable panels)
In order to fish commercially for stone crab, fishers must have a Saltwater Products License, a Restricted Species Endorsement, and a Stone Crab Endorsement. Each trap in the commercial fishery needs to have a trap tag that corresponds to a trap certificate issued by the FFWCC. The issue of trap certificates is part of a 2000 effort reduction program looking to control the number of traps in the fishery and reduce fishing effort over a 30-year period. Since 2000, the FFWCC has allocated annual certificates to commercial stone crab fishers. The certificates can either be used to set traps or can be sold to other commercial fishers. To reduce the number of traps in the fishery, each sale between fishers involves a mandatory reduction in the number of certificates being transferred.
Fishery landings for Florida stone crab have fluctuated over the years, but have remained stable over the past decades. The life history of stone crabs (fast-maturing, highly fecund) and the nature of the fishery, make Florida stone crabs relatively resistant to fishing pressures. Female stone crabs generally enter the fishery after reproducing at least once.
Stone crabs have extremely high reproductive rates, making them less vulnerable to fishing pressure. When stone crabs are caught, fishermen twist off a claw and the crab is returned to the sea. Each crab can regenerate a new claw up to four times in its lifetime. Regenerated claws are easily identifiable.
Population levels of stone crab are estimated to be high and overfishing isn’t occurring, according to the U.S. National Marine Fisheries Service. While a monitoring program was being established in 2004, there has remained a lack of authoritative, scientifically-based assessment of stone crab abundance.
Habitat impacts (Wild)
The majority of stone crab come from Florida and are primarily caught using plastic or wooden traps. Some wire traps are used. Ghost traps are problematic for ocean habitat because the biodegradable panel takes months to a year to fully disintegrate, and the traps themselves can cover a natural marine substrate. Traps can also potentially damage coral reefs, seagrasses, and live hardbottom, according to the U.S. National Marine Fisheries Service.
Most of the bycatch in the fishery consists of nonlegal stone crabs that get released alive. Other bycatch includes mollusks, other crabs, and small finfish. Starting in 1979, the traps used to catch stone crab were required to have a biodegradable escape panel to reduce bycatch. Wire traps must have several unobstructed escape rings to prevent finfish bycatch.
According to the Monterey Bay Aquarium, stone crab fishermen and managers have created a plan to gradually reduce fishing efforts over the next 30 years to protect the population and maintain the fishery. Some institutions laud stone crab fishery management for trap design and gear control measures, seasonal closures, and minimum size restrictions on claws but note a lack of peer-reviewed scientific population assessments.