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Author Topic: Blue Crabs in the Chesapeake Bay "Facts"  (Read 1859 times)
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Balad1
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« on: July 23, 2016, 09:57:12 AM »

Probably posted before but good info.

Link: http://chesapeakebay.noaa.gov/fish-facts/blue-crab


Blue Crab

The blue crab's scientific name—Callinectes sapidus—translated from Latin means 'beautiful savory swimmer.'
Blue crabs not only comprise the most valuable fishery in the Chesapeake Bay, but are major predators of benthic communities and are prey for many other fish species.
Blue crabs are sexually dimorphic, meaning sexes occur in distinct forms. Males have blue claws and a narrow abdominal apron (referred to as the Washington Monument). Females have red-tipped claws ("painted fingernails") and a broad abdominal apron (referred to as the Capitol dome).
Status

Biomass: Approximately 194 million female adult (age 1+) crabs were estimated to be present in the Bay at the start of the 2016 crabbing season. This number is below the recommended target of 215 million female spawning-age crabs and above the recommended threshold number of 70 million female spawning-age crabs. This 2016 estimated abundance increased from the 2015 estimate of 101 million female spawning-age crabs.

The Chesapeake Bay blue crab stock is not depleted, and overfishing is not occurring.

Overfishing: No

Overfished: No

Fishing and habitat: The blue crab is perhaps the most sought-after shellfish in the mid-Atlantic region, and is caught both commercially and recreationally. The majority of the catch is commercial. Blue crabs are usually harvested with simple gear: pot, trotline, handline, dip net, scrape, or dredge. Crab abundance tends to be higher in areas with ample cover, such as submerged aquatic vegetation. Most fishing gear used to catch crabs has little to no effect on habitat.

Male and female blue crabs have different life histories, and this affects the catch of blue crabs around the Bay. More female crabs are caught in the lower part of the Bay because they stay in higher-salinity water when they spawn. Males tend to stay in lower-salinity water.

By-catch: Sublegal-sized blue crabs, various finfish, turtles, and even some mammals are considered by-catch in the blue crab fishery. Perch and Atlantic croaker are prominent finfish caught in crab pots, while diamondback terrapins, river otters, and raccoons have been found in lost and/or discarded traps.

Aquaculture: Blue crabs must shed their hard carapace shell in order to grow, and experienced crabbers can quickly spot signs that the crab is about to molt. These 'peeler' crabs are held for a short time in shedding tanks until they molt. After molting, the soft-shell crabs are removed from the water and sold. These shedding tanks are monitored continuously through the day and night. The Blue Crab Advanced Research Consortium is a multidisciplinary research and development program that focuses on hatchery technologies to produce juvenile crabs for potential enhancement of the wild stock and the development of aquaculture techniques for the year-round production of soft-shell blue crabs.

Life History and Habitat

Life history, including information on habitat, growth, feeding, and reproduction of a species, is important because it affects how a fishery is managed. The blue crab uses multiple habitats in the Bay throughout its life. Blue crab distribution varies with age, sex, and season: Blue crabs tend to be abundant in shallow-water areas during warm weather; in winter they are plentiful in the Bay's deeper portions. Males range farther up into the fresher waters of the Bay and its rivers than females, who congregate in saltier waters. Blue crabs are bottom-dwellers that use beds of submerged aquatic grasses as sources of food, nursery habitat for young, and shelter during mating, and molting.

Geographic range: Along the Atlantic Coast, the blue crab ranges from Nova Scotia to Argentina. Within the Chesapeake Bay, male crabs tend to prefer fresher waters in Maryland and upper tributaries, while females like the saltier waters in the mainstem and Virginia.

Habitat: Blue crabs occupy a wide variety of habitats throughout their life history. Offshore, high-salinity waters are used during early larval stages. Larvae move into the estuary and use intertidal marshes, seagrass beds, and soft-sediment shorelines as they grow. Crabs are highly tolerant of temperature and salinity variations and can live in just about any region of the Bay. Habitat loss and increased nutrient loading present the greatest threats to the population.

Life Span: Crabs generally live three to four years in the Chesapeake Bay and reach maturity in approximately 12-18 months. Determining age is extremely difficult due to the loss of hard parts during the molting process.

Food: Crabs are voracious predators and are considered scavengers, eating just about anything they can including fish, clams, oysters, mussels, snails, worms, and insects. They are extremely cannibalistic and are most vulnerable while in the soft-shell stage of molting.

Growth Rate: Growth of blue crabs is strongly affected by temperature. For example, up to 18 months is necessary for maturation in the Chesapeake Bay, while blue crabs in the warmer Gulf of Mexico may reach maturity within a year. In laboratory studies, growth virtually ceased at temperatures below 13° C (55° F), while the growth per molt was reduced above 20° C (68° F).

Maximum Size: The largest blue crab caught in the Chesapeake Bay was 10.72 inches and weighed 1.1 pounds.

Reproduction: Blue crabs mate and spawn from spring to fall (May to October) in the Chesapeake Bay. Male crabs tend to molt throughout their lives, while females have just the one 'terminal' or 'maturity' molt. Female crabs can mate only once during their lives (during their terminal molt when in the soft-shell stage), but store sperm for multiple spawnings. The male crab may cradle the female—a pose in which the two crabs are referred to as doublers—for a few days prior to her terminal molt to maturity, and may stay with her after mating while her shell hardens and to ensure another male doesn't mate with her. Females migrate to the mouth of the Chesapeake Bay to spawn and can produce between 750,000 and 3,200,000 eggs per brood. Eggs hatch into larvae and undergo a series of molts offshore in high-salinity waters. The larvae then migrate into the Bay, and a majority grow and mature in beds of submerged aquatic vegetation. Small crabs molt frequently, but molting decreases in frequency as crabs grow bigger.

Migrations: In general, males remain in lower-salinity waters. Females migrate to higher-salinity water to spawn. The creation of 'corridors' or 'sanctuaries' has been instrumental in protecting crabs as they travel among nursery, feeding, and spawning grounds.

Predators: Predation may play a major role in influencing the size of populations. Blue crabs are preyed upon by red drum, croaker, striped bass, and other blue crabs.

Commercial and Recreational Fishing Interest: Both

Distinguishing Characteristics: Five sets of legs, with major front claw and rear swimmeret. Males have blue claws and a narrow abdominal apron (referred to as the Washington Monument). Females have red-tipped claws ("painted fingernails") and a broad abdominal apron (referred to as the Capitol dome). Immature females have a triangular or V-shaped apron, narrower than the dome shape of the sook's apron.

Role in the Ecosystem

The blue crab is an integral player in the Chesapeake Bay ecosystem. Scientists continue to study the effects of predation on blue crab populations; the effect of blue crab on populations of their benthic prey species, such as soft clam; and the effect on the fishery as well as the effect of the fishery on the blue crab population itself. Due to the economic and iconic value of the blue crab, it is considered a keystone species influencing many aspects of the Bay's ecosystem.

Did You Know?

Blue crabs may be referred to as hard-shells (not molting), peelers (crabs about to molt), busters (crabs that have started to shed their old shell or molt), soft-shells (crabs that just molted and their shell has not yet hardened), jimmies (adult males), sooks (adult female hard crabs), she-crabs or sallies (immature females), and sponges or sponge crabs (adult females carrying eggs).
The blue crab is the Maryland state crustacean.
 

Updated June 2016

 
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I want too catch the crabs.
jack1747
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« Reply #1 on: July 23, 2016, 10:55:02 AM »

Click on the little crab at the bottom of any page.  The Info site will open up..

They probably got their info from us as it has been posted here for over a decade.  Wink
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