Deep sea red crabs (Chaceon quinquedens,
for the five spines on the carapace, formerly Geryon quinquedens)
are distributed on and along the edge of the continental shelf
of the Northwest Atlantic Ocean and in the Gulf of Maine and the
Gulf of Mexico. They inhabit mud, sand, and hard bottom at depths
from 200 to 1800+ meters, at water temperatures between 5-8°
C (Wigley et al. 1975). In the Gulf of Maine, red crabs are found
in waters as shallow as 75 m. Male red crabs are believed to require
5-6 years to attain commercial size, and more than 15 years to
reach a maximum size of about 180 mm carapace width (Haefner 1977).
Female red crabs only grow to a maximum size of about 120 mm.
During mating, the larger male crab forms a protective “cage”
around the female, carrying her until she molts and becomes ready
to copulate. Female deep sea red crabs brood their eggs under
their abdominal flap for up to nine months. After the larvae hatch,
they remain in the plankton for 23-125 days. Larval settlement
is believed to occur near the base of the continental slope, and
the young crabs move up the slope as they mature. Male and juvenile
crabs are commonly found in deeper water than females.
2002, the New England Fishery Management Council implemented the
Deep Sea Red Crab Fishery Management Plan. Under the plan, a limited
access fishery was implemented with the fishery authorized to operate
with a target TAC of 2688 mt (5.928 million pounds), a 780 days-at-sea
allocation, and a trip limit of 34 mt (75,000 pounds). As well,
only male crabs are allowed to be landed. There are 5 boats currently
participating in the fishery. Red crab fishing occurs year round
along the shelf edge from the southern edge of Georges Bank south
to Cape Hatteras using square and conical pots as the principal
37.1). The red crab population in US north Atlantic
waters between Georges Bank and Cape Hatteras is managed as a single
Annual US commercial landings
of deep sea red crab during 1982 to 2005 ranged from 466 mt (1996)
to 4,000 mt (2001); no fishery occurred in 1994. Since 2002 when
the fishery management plan was implemented, landings have been
stable at about 2000 mt per year (Table 37.1,
37.2 Data]). A small portion of red crab landings are taken
as bycatch in the offshore lobster fishery. There is no recreational
fishery.Discards consist of female crabs (which cannot be landed
by regulation) and male crabs too small to sell (current fishery
selectivity curves indicate that 50% of red crabs are fully available
to the fishery by 92 mm carapace width). Discards have not been
well quantified but are likely substantial for both males and females
in the red crab fishery. Mortality rates for discarded red crabs
Vessel Survey Indices
The NEFSC winter, spring
and fall bottom trawl surveys cover only the inner edge of the deep
sea red crab’s depth range (200m+), so few red crabs are caught
and a meaningful numerical index of abundance cannot be calculated.The
main sources of fishery-independent data for red crab have been
two camera/trawl surveys designed specifically for red crabs and
operating completely within the species’ depth range. The
first targeted survey was conducted in 1974 using sled-mounted camera
gear to count the crabs on the bottom and an otter trawl to catch,
measure and sex the crabs (Wigley et al. 1975). A second survey,
using comparable gear, was conducted between 2003 and 2005 as a
cooperative research project led by industry-scientist partners.
The recent survey, conducted to assess changes in the red crab population
since 1974, indicated that both abundance and size structure of
the population had changed over time. Small crabs were relatively
abundant during 2003-2005, but the average size of male crabs was
smaller than in 1974 while the average size of females was the same
37.3 Data]). Overall red crab biomass is estimated to have increased
since 1974, most likely because of a larger numbers of small crabs.
Despite the overall increase in crab abundance, the biomass of large
males (114mm+) is currently lower than in 1974, most likely as a
result of fishery removals.
Results from the 2003-2005
survey served as the basis for the 2006 deep sea red crab stock
assessment. Fishable biomass of male deep-sea red crab was estimated
from this survey to be (+1SE) 36,250 + 5,460 mt (80 million pounds).
Fishable biomass in the 1974 survey was estimated to be about 34,000
mt (76 million pounds). However, the current fishery harvests smaller
red crabs (70-114mm CW) than in 1974 (114mm+).
biomass of mature female red crabs (70+ mm carapace width) from
the 2003-2005 survey was 67,900 mt (149.7 million lbs), compared
to an estimate of 19,700 mt (43.4 million lbs) from the 1974 survey.
Mature male biomass (75+ mm) was estimated to be 47,800 mt (105.4
million lbs) during 2003-2005 vs. 37,200 mt (82.0 million lbs) in
Based on the ratio of landings
to fishable biomass (males only), the average fishing mortality
rate for deep sea red crab during 2003-2005 was estimated to be
0.055 + 0.008 y-1. This estimate does not include any
discard mortality of undersized male or female crabs. If a significant
number of red crabs do not survive the discard process, then the
actual F will be much higher.
Biological Reference Points
No reliable biological reference
points are available for assessing the deep sea red crab resource
as so little is known about growth, natural mortality, longevity
and other vital stock parameters. An assessment conducted in 1977
(Serchuk 1977) estimated MSY for deep sea red crabs (males only)
at 1/2 M B0 = 2,494 mt (5.5 million lbs.) assuming
natural mortality M=0.2y-1, minimum market
size was 4.5 inches (114 mm), and the estimate of biomass from the
1974 survey represented virgin biomass (B0).
The 2002 FMP includes a preferred MSY estimate of 2,830 mt (6.24
million lbs) calculated using the same model as Serchuk (1977) but
assuming a natural mortality M = 0.15, a minimum market
size of 4 inches (101mm) and an expanded fishing area. Due to uncertainty
about the biological parameters mentioned above and the model used
to calculate MSY, none of the MSY estimates are now considered to
Commercial landings of deep sea
red crab have been stable at about 2,000 mt/yr since the FMP was
implemented in 2002. Fishable male biomass was estimated to be 36,300
mt in 2003-2005. As no reliable estimate of MSY or Fmsy
exist, the status of the red crab resource with respect to overfishing
or being overfished is unknown.
Table 37.1 Recreational
and commercial landings of deep sea red crab (thousand metric
For further information
Elner, R. W., S. Koshio,
and G. V. Hurley. 1987. Mating behavior of the deep-sea red crab,
Geryon quinquedens, Smith (Decapoda, Brachyura, Geryonidae).
Haefner, Jr., P. A. 1978. Seasonal
aspects of the biology, distribution, and relative abundance of
the deep-sea red crab, Geryon quinquedens Smith, in the
vicinity of the Norfolk Canyon, Western North Atlantic. Proceeding
of the National Shellfisheries Association 68:49-62.
Serchuk, F.M. 1977. Assessment
of red crab (Geryon quinquedens) populations in the Northwest
Atlantic. September 1977. Woods Hole Lab. Ref. Doc. 72-23:15 p.
Steimle, F. W., C. A. Zetlin,
and S. Chang. 2001. Essential Fish Habitat Source Document: Red
Deepsea Crab, Chaceon (Geryon) quinquedens, Life
History and Habitat Characteristics. NOAA Tech. Memo, Northeast
Fisheries Science Center NMFS-NE-163, Woods Hole, MA., 27 p.
Weinberg, J. R., and C. Keith.
2003. Population size-structure of harvested deep-sea red crabs
(Chaceon quinquedens) in the Northwest Atlantic Ocean.
Wigley, R. L., R. B. Theroux,
and H. E. Murray. 1975. Deep-sea red crab, Geryon quinquedens,
survey off northeastern United States. Marine Fisheries Review 37:1-21.