The emergence success rates of loggerhead turtle hatchlings on Inakahama beach, Yakushima Island, Japan are decreasing. This phenomenon seems to be related to human interference on the beach. In order to investigate this relationship, locations and numbers of loggerhead turtle nests were recorded as well as the numbers of visitors to the beach. Furthermore, pressure, temperature, and CO₂ concentrations were measured in the nests and some were excavated to check the developmental stage of the embryos. Mean emergence success rates in nests located in “high traffic” areas proved lower than those in more remote areas. In addition, these rates were negatively correlated with accumulated pressure from trampling during the period from nesting to emergence. This suggests that the trampling of nests by visitors negatively affects the emergence of turtle hatchlings and our results show that trampling of a nest by more than 650 people could lead to a 50% reduction of hatchlings, and that more than 1200 people could lead to the complete mortality of the hatchlings of the nest. Lowered heat conductivity of their nests due to visitor’s trampling effect led to overheating of the nests because of their metabolic heat production and resulted in a retardation of hatchling emergence. Therefore, it is proposed that beach visitors should be prohibited from entering the conserved loggerhead nesting area during the nesting season in order to ensure a high emergence rate of hatchlings from their nests.

Age and growth of Sebastes schlegeli collected from the coastal waters of the Shiribeshi subprefecture in Hokkaido were studied. Observations of the otolith margin verified that annuli (outer margins of the opaque zone) were formed chiefly in June. This period accorded approximately with the parturition season (late May-mid-June) that was judged from the seasonal change in gonadosomatic index, occurrence of eyed eggs and histological observations of ovaries. The surface method of otolith aging was found to be inadequate for aging of S. schlegeli older than 7 years because of the underestimation of age. A significant difference was found in the parameters of the growth equations between females and males. Growth of S. schlegeli was expressed by the von Bertalanffy asymptotic growth function as TL_t=633.1(1–exp ^{-0.160(t+0.965)}) for females and TL_t=417.7(1–exp^{-0.363(t+0.368)}) for males, where TL, is the total length (mm) at age t (after parturition in years). Based on previously published data, the growth rate of S. schlegeli in this region was relatively low, especially in males, because of low temperatures during the winter and spring and the shortness of the high growth period of 10-20°C.

We examined distribution and feeding habits of adults (150-216mm SL) and subadults (70-149mm SL) and distribution of larvae and juveniles (9-69mm SL) of Nealotus tripes in the Kuroshio-Oyashio Transition Zone (KOTZ) and Kuroshio Extension (KE) in spring obtained by a midwater trawl survey at night. Adults and subadults rarely occurred in KE but were abundant in KOTZ with the concentrated area north of KE axis with sen surface temperature of about 17°C and 100m depth temperature of 12-14°C. Larvae and juveniles had slightly wider distribution in KOTZ. Stomach content index (SCI-stomach content weight per body weight) was not statistically different by time of day or by body size of adults and subadults. According to the index of relative importance (IRI), euphausiids (IRI-2.399) were most important prey of adults followed by myctophids (1,767), unidentified fishes (1,699), miscellaneous (702) and anchovy larvae (543). In subadults, unidentified fishes (mainly mesopelagics excluding myctophids, (1,862) and euphausiids (1,826) were major prey followed by miscellaneous (1,009), squids (209) and myctophids (164). These diet compositions were distinct from those reported for larvae and juveniles of N. tripes which heavily preyed upon anchovy larvae in KOTZ. The ontogenetic descent and diel vertical migration of N. tripes suggest a diet shift from anchovy larvae to micronektons.