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The geographical spreading of new fishing activities and the increasingly deeper locations of these activities have shown the worldwide distribution of gerionid crabs and new descriptions of Chaceon taxa. However, incomplete penetrance, variable expressivity, and phenotypic overlap make the morphometric identification of these species difficult. In this study, partial sequences of the cytochrome c oxidase subunit 1 (COI) and 16S mitochondrial ribosomal RNA (16S rRNA) genes have been analyzed in Chaceon species from the Eastern Central and South Atlantic and compared with sequences of species from Western Atlantic. Our results corroborate the proposed morphological species and highlight the significant separation of the Eastern Atlantic species and those from Atlantic coasts of South America for both markers (97% Bayesian posterior probability, BPP / 83% Bootstrap replicates, BT). Interestingly, Chaceon sanctaehelenae shows a closer relationship with the species of the American coast than with those from the Eastern Atlantic. On the other hand, while COI marker clearly separates Chaceon atopus and Chaceon erytheiae species (99 BPP / 91% BT), these species share haplotypes for the 16S rRNA marker, pointing to a recent speciation process. Moreover, a close relationship was observed between Chaceon maritae and Chaceon affinis (94% BPP / 77% BT). The topologies of the trees obtained indicate that the ancestor of this genus was closer related to those species from South America than to those from the Eastern Atlantic. [ABSTRACT FROM AUTHOR]

Benthesicymus tanneri Faxon, 1893 (Benthesicymidae) is a poorly known benthopelagic shrimp dominant in the lower oxygen minimum zone (OMZ) boundary in the Mexican Pacific. Its bathymetric distribution and diet were studied off the Mexican Pacific continental slope at depths of 710-2309 m, and the potential environmental drivers were analyzed. A total of 187 specimens were collected between 772 and 2010 m, although most were found between 1008 and 1620 m. This represents a wide bathymetric distribution compared to other species inhabiting lower OMZ boundaries. The size of individuals (carapace length, CL) ranged from 11.2 to 53.3 mm with no clear bathymetric patterns in the size distribution of the species. The sex ratio (males:females, M:F) changed with depth from M:F = 1:1 at 700-1000 m to M:F = 1:5 at 1300-1600 m. The main prey of B. tanneri in all the samples analyzed was the pelagic red crab Pleuroncodes planipes (Munididae Ahyong, Baba, Macpherson and Poore, 2010), and secondary preys were benthopelagic and bathypelagic fishes and shrimp-like decapod crustaceans. Only 15% of the stomachs were empty. Specimens of P. planipes captured simultaneously to B. tanneri were measured as an indicator of the size of available prey and 90% of individuals measured 11.1-14.8 mm CL. Benthesicymus tanneri was collected within wide ranges of values of the different environmental variables considered, and statistical analyses did not provide solid relationships between the patterns of distribution and the environmental factors (Spearman R and Generalized Linear Models). We hypothesize that B. tanneri is a eurytopic species whose swimming capacity allows for temporal vertical migrations into the water column. [ABSTRACT FROM AUTHOR]

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Changes in enzymatic activities and protein content of leg muscle and hepatopancreas tissue of two deep-sea crabs were studied after 34 days of food deprivation. Geryon longipes and Bythograea thermydron are the most abundant deep-sea crab species in their respective environment. Geryon longipes dwells on the middle and lower slope of the northwestern Mediterranean Sea and has a bathymetric range between 450 and 1950 m depth. Bythograea thermydron dwells in Pacific hydrothermal vent sites and has a bathymetric range between 2000 and 3000 m depth. After 34 days under laboratory conditions, citrate synthase activities in the hepatopancreas of G. longipes and B. thermydron were found to be much lower in food-deprived crabs compared to fed crabs. In both species, no lactate dehydrogenase activity was detected in hepatopancreas tissue, and no food deprivation effects were observed for either lactate dehydrogenase or citrate synthase activities in leg muscle tissue. No changes in protein were found after 34 days of food deprivation, either. Enzyme activities of fed and food-deprived specimens maintained in the laboratory encompassed the natural range of variation measured in freshly caught crabs of both species. Lactate dehydrogenase, citrate synthase, and protein content of freshly caught specimens of G. longipes were significantly lower than in freshly caught specimens of B. thermydron. The results are discussed taking into account the surrounding environmental features both species encounter and from the point of view of the potential use of citrate synthase activity as an indicator of nutritional condition in deep-sea crustaceans. [ABSTRACT FROM AUTHOR]

A preliminary economic evaluation of the feasibility of establishing a fishery to process red crab meal (Pleuroncodes planipes) was conducted. Risk assessment indicated that a fishery of nine boats could operate with an average 1.53 benefit-cost ratio (B C-1) and annual net revenues (NR) of US$427?840, and that there is certainty of obtaining economic profit in every season, with a?B?C-1 > 1 and NR?> 0. Total catch and average catch per trip could be reduced from a total baseline catch of 10?328?tons (1735?t?meal) to 6061 (1844?t?meal), and from a baseline catch per trip of 11.4?t (4.78?t?meal) to 6.73?tons (4.85?t?meal) without economic losses. There was no possibility for profit when total catch and average catch per trip were, respectively, lower than 5365?t (1648?t?meal) and 5.96?t (4.71?t?meal). For a single-fishing trip operation, average B C-1 was 1.5 and NR was US$480. We determined that there was a confidence level of 84% to generate profits. To guarantee profits, a catch of 13.5?t?per?trip (1.35?t?meal) should be obtained. Single trips catching less than 3.3?t (0.94?t?meal) cannot make a profit. Sensitivity analysis indicated that plant processing efficiency for converting fresh red crab to meal, catch per trip, and sales price of red crab meal were most important in determining B C-1 and NR values. Plant efficiency constitutes the main element that needs to be optimized, particularly management practices to preserve fresh catch quality. A low sensitivity to costs for processing suggests the possibility of negotiating a higher price and the opportunity for processing plants to venture into processing of red crab meal. [ABSTRACT FROM AUTHOR]

A large number of specimens of Geryon longipes and Chaceon mediterraneus were collected by a series of baited traps deployed at 11 stations in the Cretan sea and the Levantine basin, covering a depth range of 1511 to 3080 m. The two crab species were not trapped together in any of the traps, however. Stomach content analysis of both species revealed a rather wide variety of prey categories (excluding the bait), such as Ascidiacea, Alcyonaria, Decapoda, Mysidacea, Amphipoda, and Polychaeta. C. mediterraneus showed a highly diversified diet with Crustacea, Alcyonaria, and Ascidiacea being the most dominant prey categories. The diet variability of G. longipes is less than that of C. mediterraneus, but Alcyonaria and Ascidiacea appeared again to be the two most abundant prey categories. However, the diet compositions of these two species appear to be different, with only few prey categories in common. The vacuity coefficient value was lower in C. mediterraneus than in G. longipes, which seems to have a lower feeding activity. Both species seem to exploit a variety of food resources. This makes living possible in the bathyal zone of the oligotrophic eastern Mediterranean. [ABSTRACT FROM AUTHOR]

This article focuses on the revisiting population size-structure of the deep-sea red crab, chaceon quinquedens. A fishery for the male deep-sea red crab, Chaceon quinquedens, developed off southern New England, U.S., in 1974 and has continued to the present day. Thus far, there have only been two published studies about red crab population size-structure in this area, based on surveys carried out in 1974. It is assumed that commercial harvesting of male crabs had taken place at depths shallower than 500 m during the period 1974-2001.