For golden crab, Chaceon fenneri, and red crab, Chaceon quinquedens, numbers per trap, sex, and crab size were tested for broad bathymetric, geographic, and seasonal patterns on the upper continental slope, northeastern Gulf of Mexico. Red crab occupied only the deepest of three sampled depths (i.e. 677 m vs. 494 and 311 m) while golden crab predominated at the upper two. Golden crab occurred adjacent to peninsular Florida, but not along the northern Gulf slope, while red crab occurred across the geographic arc sampled. Relative abundance increased southward for golden crab and northwestward for red crab, while the proportion of females increased counter-clockwise within the sampled range of each species. Golden crab exhibited a Chaceon-typical bathymetric pattern of partial sex segregation and size inversely related to depth, but male and female bathymetric patterns shifted seasonally with lags between geographic areas. Interspecific competition cannot explain the species depth zonation, while geographic and seasonal patterns may relate to Loop Current–Florida Current circulation.
Harvest potential, relative abundance, and geographic and bathymetric distribution are discussed for the red crab, Chaceon quinquedens, in the northcentral Gulf of Mexico. Harvest potential is expressed as the number of trapable crabs present on fishing grounds defined as depths ranging from 677 m to 1043 m between 87.5O and 88.5OW longitude. Using various estimates of the effective fiihing area (€PA) of a trap, the number oftrapableredcrabsonthefishinggroundsrangedfrom 3 . 7~ 10sto 1 0 . 7~ lo6. Estimatesofcrabnumberssuggest there is a potential for commercial harvest in the northcentral Gulf of Mexico, east of the Mississippi River.However, fishery development must take into consideration the preponderance of females on the defined fishing grounds (MF ratio= 1:2.1) and the high incidence of ovigerous females (-20%) during much of theyear. Females generally dominated at all depth strata, but the proportion of males to females increased with depth. Reduced numbers of red crabs were collected off the western Louisiana coast and a shift in depth distribution was found. Minimum upper depth limit for red crabs west of the Mississippi River was 860 m as compared to 677 m east of the River. The known range of C. femeri is extended to 92O12W longitude.
Bycatch associated with deepwater trapping of Chaceon is reported for outer shelf and slope waters of thenorthcentralGulfofMexico. Bycatch wasdominated by theisopod,Bathynomusgiganteus. Other crustacean megafauna consisted of the majid crab, Rochinia crassa, and the portunid crabs, Benthochascon schmitti and Bathynectes longispina. Finfish bycatch included hagfish, Eptatretus springeri, deepwater shark, Centrophorus uyatoand hake, Urophyciscirrata.
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