Blue crab

1. Winter · dormant
   0.15
2. Spring warm-up
   0.45
3. Summer
   0.80
4. ● Fall · heavy crabs
   0.90
5. Spring · warm water
   0.7566–86°F

1. 1

   dead fish (scavenged) · crab bait

   primary · finfish

   Diet share

   —

   In season

   Bait equivalents

   chicken necks, fish heads and racks, cut mullet, menhaden (pogy)

   Season

   Peak May–Oct · lull Dec–Feb

   Vulnerable when

   • High on rising / falling tide
   • Moderate on high slack / low slack tide

   Ranked for the angler model: dead, oily fish is what crabs come to on a trap or drop net. Natural-diet volume is led by bivalves (rank 2). — Laughlin 1982 (fish in diet); standard crabbing practice

2. 2

   oysters, mussels & estuarine clams · shellfish

   secondary · mollusk · Crassostrea virginica; Rangia cuneata; Ischadium recurvum · panhandle

   Diet share

   —

   No season data

   Bait equivalents

   fresh clam, fresh dead shrimp, shucked oyster, Fishbites clam

   Season

   No peak months on file

   Vulnerable when

   • High on rising / falling tide in calm-to-moderate surf
   • Moderate on high slack / low slack tide

   The leading natural food in the Apalachicola estuary (Rangia clams, oysters, mussels). Percentages not retrieved. — Laughlin 1982

3. 3

   mud crabs & fiddler crabs · fiddlers

   tertiary · crustacean · Panopeidae (mud crabs); Minuca, Leptuca and Uca spp. (fiddler crabs)

   Diet share

   —

   In season

   Bait equivalents

   fiddler crab, cut blue crab, sand flea

   Season

   Peak Apr–Oct · lull Dec–Feb

   Vulnerable when

   • High on rising / high slack tide in calm-to-moderate surf
   • Low on low slack tide

   Crabs, smaller blue crabs included, are a regular part of the diet. Cannibalism rises when crabs are crowded. — Laughlin 1982

Water temp

52–92°F

optimum 78°F

Salinity

3–30 PSU

Feeding

opportunistic

Typical size

5–7"

max 9.4" carapace width

Lifespan

3 yr

mature at 1 yr

Group feeding

none documented

Omnivorous scavenger and predator. Crushes clams and oysters, takes live and dead fish, eats other crabs (its own kind included) and detritus. Feeds day and night, more in the shallows after dark, and finds food by scent carried on moving water.

Field notes

• Growth and feeding stall once the water falls below about 51°F. Crabs move deep and bury, and traps go quiet until the spring warm-up.

  • water temp ≤ 52°F

  — Brylawski & Miller 2006

• Mature females leave low-salinity mating grounds for saltier bay mouths and nearshore water to spawn. Gulf-coast females move north toward the panhandle.

  • migration phase: fall run

  — FWC/FWRI blue crab life cycle

• Crabs crowd the shallow shore zone more at night than by day, so dock and seawall lines fish best at dusk and after dark.

  • time of day: {"in":["dusk","night"]}

  — Torre et al. 2017, Fishery Bulletin 115:556-565 (Delaware Bay; applied by analogy)

• Natural diet in the Apalachicola estuary is bivalves, fish, crabs (cannibalism included) and detritus. A scent-led scavenger, it comes to almost any oily dead bait.

  — Laughlin 1982

• A rain or river pulse that freshens the bay pushes crabs toward the lower bay and river mouths. Lines set at the salinity edge outfish last week's spot.

  • river pulse ≥ 0.2

  — angler heuristic, consistent with salinity-driven distribution — unverified

• Egg-bearing ('sponge') females must be released immediately. They gather near high-salinity bay mouths in spring and summer.

  — FWC recreational blue crab rules; FWC/FWRI blue crab life cycle

Schooling by phase

winter dormant

Buried in mud in deeper channels; few crabs come to bait

spring warm up

Emerging and molting; light 'paper-shell' crabs common

summer

Spread across flats and grass; heavy feeding, midday heat pushes crabs deeper

fall run

Full, heavy crabs; females moving toward the bay mouths

Citations

1. [1]Brylawski & Miller 2006 · torpor temperature 10.8°C
2. [2]Torre et al. 2017, Fishery Bulletin 115:556-565 · night shore zone
3. [3]FWC/FWRI blue crab life cycle · female migration
4. [4]Laughlin 1982 · diet apalachicola
5. [5]FWC blue crab species profile (myfwc.com/wildlifehabitats/profiles/invertebrates/blue-crab/) · lifespan female 1-2 yr, male 1-3 yr
6. [6]FWC/FWRI blue crab life cycle · adult size 3.9-9.4 in carapace width after 18-20 molts
7. [7]FWRI blue crab spawning survey · maturity size females mature at ~116-130 mm CW (4.6-5.1 in) across four Florida estuaries
8. [8]FWC/FWRI blue crab life cycle · gulf spawning March-December on the Gulf coast, peak early-late spring; extra fall spawn in St. Andrews Bay
9. [9]Brylawski & Miller 2006 (Maryland Sea Grant UM-SG-RS-2006-06) · torpor temperature growth-based torpor 10.8°C (51.4°F)
10. [10]Laughlin 1982, Bull. Mar. Sci. 32(4):807-822 · diet apalachicola bivalves, fish, crabs and detritus; percentages not retrieved
11. [11]general estuarine literature · salinity band unverified — 3-30 psu is a working band, not a cited range