Growth and Size of the Tropical Sea Cucumber Holothuria (Halodeima) atra Jager at Enewetak Atoll, Marshall Islands!

In September 1975, 5031 sea cucumbers (Holothuria atra Jager) were tagged with tetracycline and returned to a gutter on the seaward reef bench of Ananij Island, Enewetak Atoll, Marshall Islands. A sample of 184 individuals was collected in September 1976. Animals were dissected and plates of the calcareous ring were examined with ultraviolet radiation for tetracycline lines. Based on 18 tagged individuals, the Brody-Bertalanffy growth constants are: K = 0.11 and P00 = 0.89 cm (for interradial plates). Length (L, cm) and weight (W, g) of individuals are related to plate size: L = 36.35P and W = 1950P3, giving maximum size as 32 cm and 1352 g. Length frequency distributions for the population did not change from 1975 to 1976. A preliminary estimate of annual loss is 50 to 70 percent of the total population based on the growth parameters and population size structure. Holothuria atra shows asexual reproduction by transverse fission, which appears to be the major source of recruitment at Ananij rather than from the plankton. ON MANY TROPICAL REEFS, sea cucumbers are tion to a technique that shows some promise abundant and may attain densities in excess as a means ofstudying growth ofholothurians of 200/m2 (Bakus 1968). But they are very and so, somewhat indirectly, of estimating difficult to study as populations and very few mortality and population turnover. The estimates of growth and death rates of holoexperimental animal was Holothuria (Halothurians are in the literature. Edwards (1908) deima) atra Jager, an abundant and widely presents growth data for newly metamordistributed Indo-Pacific aspidochirote, which phosed Holothuria floridana Pourtales, but was studied at Ananij Island, Enewetak Atoll only up to a size of 4 mm and an age of 75 (11°28' N, 162°24' E). A second purpose of days under laboratory conditions. Rutherthis paper is to present information about ford (1973) presents growth data of newly growth, death, and size for this species. recruited Cucumaria pseudocurata to an age Holothuria atra is very abundant at certain of 1 year and gives estimates of loss rate for areas of Enewetak Atoll. Bakus (1973) shows animals less than I year old. Fish (1967) and a picture with a density of 5 to 35 individuals Buchanan (1967) discuss growth and mor1m at what he calls Anayaanii Island. This tality of Cucumaria elongata and calculate is the same island Johannes et al. (1972) call rates based on data for animals of many Japtan and which is now called Ananij. ages. Military charts list this island as Bruce. The ___--"T~h=e_I2UrI2_QSLQLthis-papeLis-to-cal-l-att~n-aFl'}a-w-hefe-eueumbers-were-studtetl seems to be the same area illustrated by Bakus (1973); it is a reef gutter on the seaward side of Ananij. The vegetated portion of Ananij is narrow at the southern end and has an enclosed inlet on the seaward side bordered by the main part of the island on the north and by a narrow peninsula of vegetated land (covered nearly exclusively by Pemphis aci-