Distribution and some biological features of skate Bathyraja parmifera (Rajidae, Rajiformes) in the northwestern part of the Sea of Japan
In the northwestern part of the Sea of Japan, skate Bathyraja parmifera in catches of the bottom trawl occurs at depths of 40 to 830 m at the near-bottom temperature of 0.4–4.9°C. Throughout the year, the skate performs migrations within the continental slope and, in the feeding period, inhabits mainly the depth range of 300 to 500 m. Maximal average density of aggregations of B. parmifera is observed in waters of northern Primorye; minimal average density is observed in Peter the Great Bay and on the Yamato Bank. In catches, skates with a length of 17–130 cm and a weight of 0.5–18.8 kg are recorded; however, fish with a length of 80–115 cm dominate. Individuals with a length of up to 40 cm feed mainly on amphipods, and larger immature and adult individuals feed on decapods, cephalopods, and fish. The value of the daily ration of B. parmifera with its growth decreases from 2.4 to 0.9% of the body weight. Specific ecological features of B. parmifera are a cause of its considerable underfishing by the bottom trawl; therefore, the total resource of this species in the considered region may be at the level of maximal estimates obtained during surveys and comprise no less than 20000 t.
Distribution and some traits of biology of Lycodes tanakae (Perciformes: Zoarcidae) in Primor’e waters (Sea of Japan)
With consideration of investigations made in 2004–2010, the spatial distribution of Lycodes tanakae, as well as some traits of its biology in Primor’e waters, is described. This species occurs all over the investigated region—from 42° to 49°N as explained by hydrological properties of bottom waters and by the bottom relief of this water area. In Promor’e waters, Lycodes tanakae occurs at depths of 87–1034 m. However, the majority of specimens (90%) prefers depths of 200–700 m. Thus, it can be attributed to the mesobathial ecological fish group. In spring and summer, juveniles of L. tanakae live at similar depths (200–350 m) where this species seems to spawn. In catches, L. tanakae is represented by specimens 11–90 cm in length, 0.1–4.9 kg in weight, and age from 1 to 10 years. The bulk of catches consists of specimens 40–70 cm long (62%), up to 2.2 kg in weight (90%), and of the age 4–7 years (72%). Sexual dimorphism in linear dimensions is not determined in L. tanakae. In summer, the ration of L. tanakae in Primor’e waters consists predominantly of cephalopods (on average, 59.4% of food weight). A noticeable part belongs to decapods (19.8%) and fish juveniles (16.6%). The smallest analyzed specimens consume small decapods and polychaetes. At the body length over 40 cm, L. tanakae pass over to predation. The value of the daily ration of Lycodes tanakae is, on average, 1.5% of the body weight.
Study of External Parasites Infesting Carcharhinus Melanopterus Fish From The Red Sea In Jeddah, Saudi Arabia
Parasitic diseases are harmful and limiting factors in breeding and rearing ornamental fish industry, such as the Monogenea ( Dactylogyrus sp and Erpocotyletiburonis ) and copepod ( Pandarus sinuatus  and Anchistrotostangi ). The copepod and the monogenean are gill parasites found on the shark; CarcharhinusMelanopterus . The primary purpose of this study was to determine the parasitic infections of sharks in red sea in Jeddah. For this purpose, 19 female C. Melanopterus and 14 male C. Melanopterus were first examined for ectoparasites using wet mount under a light microscope. All male sharks had Monogenea and/or copepod in their gill and only 3 females haven’t infections. Then, we aimed to find a combination of copepod and monogenea infection in C. Melanopterus gills. 50% of male and 42% of female were infected by copepod and monogenea. Our findings revealed that the protozoan infections are very common among sharks. Although, no gross pathology was observed among infected shark, but it is likely that in case of any changes in the environment, then parasitic infections could be harmful.