Distribution of jack mackerel (Trachurus japonicus) larvae and juveniles in the East China Sea, with special reference to the larval transport by the Kuroshio Current

2006 ◽  
Vol 15 (6) ◽  
pp. 508-518 ◽  
Author(s):  
CHIYUKI SASSA ◽  
YOSHINOBU KONISHI ◽  
KEN MORI
Keyword(s):  
Special Reference ◽  
East China Sea ◽  
Kuroshio Current ◽  
Larval Transport ◽  
East China ◽  
Jack Mackerel ◽  
The East China Sea ◽  
Trachurus Japonicus ◽  
China Sea ◽  
The Kuroshio

Collection of spawning-condition eels of Ariosoma meeki in the Kuroshio Current in the East China Sea

2016 ◽  
Vol 96 (8) ◽  
pp. 1701-1707 ◽  
Author(s):  
Shun Watanabe ◽  
Seishi Hagihara ◽  
Michael J. Miller ◽  
Masamichi Machida ◽  
Kosei Komatsu ◽  
...  
Keyword(s):  
Continental Shelf ◽  
East China Sea ◽  
Seminal Fluid ◽  
Kuroshio Current ◽  
East China ◽  
The East China Sea ◽  
Reproductive Condition ◽  
China Sea ◽  
Gonad Somatic Index ◽  
The Kuroshio

When and where marine eels spawn is poorly known even though species such as those of the family Congridae, Muraenidae and Ophichthidae can be caught in continental shelf habitats. The congrid genus Ariosoma includes small continental shelf eel species whose life histories are not yet known. Mature male and female eels of Ariosoma meeki were observed and captured on 17 August 2009 at the surface at night in the western side of the Kuroshio Current in the East China Sea close to new moon, while they were swimming slowly at the surface and exhibiting apparent reproduction-related behaviour. One male and one sex-unidentified eel (seemingly a male based on body shape) were observed to be chasing one larger female with their heads located near her urogenital pore area. The gonads of the female (540 mm) and the male (410 mm) that were caught by a long-handled dip net were in reproductive condition, because some eggs or seminal fluid were released during handling of the two specimens and high gonad-somatic index (GSI) values of 53 in the female and 20 in the male were recorded. This is one of the few cases in which fully ripe reproductive-condition marine eels have been observed or collected and it provides rare information about the spawning location and timing of this eel species.

scholarly journals Interannual variations in distribution and abundance of Japanese jack mackerel Trachurus japonicus larvae in the East China Sea

2016 ◽  
Vol 73 (4) ◽  
pp. 1170-1185 ◽  
Author(s):  
Chiyuki Sassa ◽  
Motomitsu Takahashi ◽  
Yoshinobu Konishi ◽  
Youichi Tsukamoto
Keyword(s):  
East China Sea ◽  
East China ◽  
Late Winter ◽  
Larval Abundance ◽  
Interannual Variations ◽  
Jack Mackerel ◽  
The East China Sea ◽  
Trachurus Japonicus ◽  
China Sea ◽  
Japanese Jack Mackerel

Abstract We examined the interannual variations in distribution and abundance of Japanese jack mackerel Trachurus japonicus larvae <5 mm standard length (SL), based on sampling surveys over a broad area of the shelf break region of the East China Sea (ECS) during late winter and spring for 12 years from 2001 to 2012. Larval abundances in late winter were higher than those in spring. In late winter, ratios (expressed as %) of larval abundance in the southern ECS south of 28°N to the whole study area were highest during the study period, with values ranging from 80.0 to 95.8%. In spring, the ratios in the southern ECS were still high (34.3–88.8%), although the values increased slightly in the northern and central ECS. There was no significant interannual variation in the centre of distribution of the larvae, suggesting that the formation of spawning grounds would be related to topographic rather than hydrographic conditions. Habitat temperature of larvae in the central and southern ECS was ∼3–5°C higher than that in the northern ECS throughout the study period, indicating that larval growth and survival processes may differ between the two areas. In the southern ECS, larval abundances fluctuated largely from year-to-year, and the interannual variations were closely correlated with water temperature and chlorophyll a concentration. However, larval abundance did not correlate with an index of recruited juveniles (∼50–75 mm SL) in the ECS, suggesting that mortality during the late larval and early juvenile stages is responsible for recruitment success or failure.

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