The objective of the study was to investigate if reproductive characteristics of Pandalus eous affect the depth distribution in the East Sea of Korea. P. eous was found at depths of 500Á900 m in the East Sea of Korea, with the highest percentage occurrence (34%) at 500 m. A negative correlation was observed between the number of individuals and the depth. The overall sex ratio also turned out to be significantly correlated with depth. On average, the larger individuals (bigger than 26.37 cm), which included transitional, female, and ovigerous females, were mostly distributed at 700 m depth. The percentage of males increased by depth and ovigerous females were mainly distributed in the shallow water (300 m) during winter.Ovigerous females were not found at 900 m, which is the deepest depth range in this study. The percentage of transitional individuals was greatest at 500 m and decreased gradually with depth. All ovigerous female individuals were of the spent ovarian stage in winter. Female numbers in the ripe ovarian stage increased with depth and immature females rarely appeared. The gonadosomatic indices of the nonovigerous females and ovigerous females were highest at 700 m in depth. The mean egg size of P. eous was 0.8390.11 mm 3 in the nonÁeyed stage and 0.9390.17 mm 3 in the eyed stage.

In this study, we investigated the distribution patterns of two crangonid shrimps in the East Sea of Korea. The distributions of the shrimps differed significantly with depth. Neocrangon communis (Rathbun, 1899) was found at depths of 300-900 m throughout the survey area, with the greatest number of individuals at 300 m depth in the total sampling period. Argis toyamaensis (Yokoya, 1933) occurred over the entire depth range (300-900 m), with the greatest numbers of individuals at 800 m depth in the total sampling period. On average, the large females and ovigerous females of N. communis and A. toyamaensis were mainly distributed in shallow waters (300-400 m depth). The ovigerous females of the shallow-dwelling species A' , communis mainly occurred in shallow waters. The deep-dwelling species, A. toyamaensis, differed slightly from M communis in terms of the distribution of its ovigerous females. The ovigerous females of A. toyamaensis were widely distributed at all depths, and the gonadosomatic index did not differ significantly with depth. However, the deep-dwelling species, A. toyamaensis, had larger eggs than had N. communis. We suggest that life-history strategies are determined by many environmental factors, including depth, in the deep-water environment. The optimal distribution depths of these two species were closely related to their reproductive strategies. RÉSUMÉDans cette étude, nous avons étudié le modèle de distribution de deux crevettes crangonidés de la mer de l'Est de Corée. La distribution des crevettes diffère significativement avec la profondeur. Neocrangon communis (Rathbun, 1899) a été trouvée à des profondeurs de 300-900 m sur toute la zone examinée, avec le plus grand nombre d'individus à une profondeur de 300 m stir la )