The development of management options for the black land crab (Gecarcinus ruricola) catchery in the San Andres Archipelago, Colombia

Population Structure of the Christmas Island Blue Crab, Discoplax hirtipes (Decapoda: Brachyura: Gecarcinidae) on Christmas Island, Indian Ocean

“…Lopez-Victoria and Werding, 2008)] have been the subject of traditional morphological allometric studies. In recent years, the value of this information for gecarcinid catchery management has been recognised, i.e., as an efficient and inexpensive strategy for the regular assessment of fishery stocks, thus ensuring future sustainability (Foale, 1999;Akin-Oriola et al, 2005;Baine et al, 2007).…”

“…Therefore, to further investigate sex ratio in D. hirtipes on Christmas Island a further study should now also be made at Ross Hill Gardens as well as at the other known residential areas inhabited by this species, both outside of the breeding season and during the breeding migration of both resident and migrating crabs. Previous studies have sampled land crabs to examine sex ratio at different stages of the seaward breeding migration (Hartnoll et al, 2006a;Hartnoll et al, 2006b;Hartnoll et al, 2007;Hartnoll et al, 2009). This has revealed that sex ratio of the resident population at this time can favour males, e.g., J. lagostoma (Hartnoll et al, 2006b;Hartnoll et al, 2009;Hartnoll et al, 2010).…”

“…This has revealed that sex ratio of the resident population at this time can favour males, e.g., J. lagostoma (Hartnoll et al, 2006b;Hartnoll et al, 2009;Hartnoll et al, 2010). The sex ratio of crabs during the migration is variable; it can be skewed towards males at the beginning, e.g., G. ruricola (Hartnoll et al, 2007), G. natalis (Hicks, 1985), and D. hirtipes (Foale, 1999), but be close to unity during the migration itself, e.g., J. lagostoma (Hartnoll et al, 2009;Hartnoll et al, 2010), and later be dominated by females, e.g., G. natalis (Hicks, 1985), especially at the shoreline, e.g., J. lagostoma (Hartnoll et al, 2006b;Hartnoll et al, 2009;Hartnoll et al, 2010). This change in sex ratio during the migration period has been explained in J. lagostoma by the fact that a greater proportion of females compared to males migrate (or participate in the migration for longer periods) and that as expected a greater proportion of females reach the shoreline to deposit their fertilised eggs into the ocean (Hartnoll et al, 2009).…”

“…The data for size at sexual maturity of gecarcinids is somewhat scarce and a range of methods have been previously utilised. For G. natalis (Hicks, 1985), G. ruricola (Hartnoll et al, 2007), and J. lagostoma (Hartnoll et al, 2010) size at sexual maturity was estimated to be 50% maximum carapace width for both sexes based on the minimum size of crabs with mature reproductive organs and/or which participated in the migration, and for females which produced eggs; for other gecarcinids size at sexual maturity was also estimated to be approximately 50% maximum carapace width for females based on pleon size and the smallest size of the ovigerous females, e.g., G. lalandii (Liu and Jeng, 2007) and E. notatus (Liu and Jeng, 2005). For G. lateralis (Bliss et al, 1978) and C. guanhumi (Gifford, 1962;Herreid, 1967) sexual maturity was also estimated to be in a range approximately equivalent to 50% maximum carapace width [33 mm (Bliss et al, 1978) based on a maximum carapace width of , 60-66 mm (Britton et al, 1982)].…”

“…These data will contribute towards the accurate assessment of the reproductive status of the various populations of D. hirtipes on Christmas Island which will be useful in the forming of efficient conservation strategies for this crab (Akin-Oriola et al, 2005;Baine et al, 2007).…”