Japanese Journal of Ichthyology
Online ISSN : 1884-7374
Print ISSN : 0021-5090
ISSN-L : 0021-5090
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Volume 59, Issue 2
Displaying 1-8 of 8 articles from this issue
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  • Involvement of olfaction in spawning success of medaka Oryzias latipes
    Youichi Hayakawa, Shinpei Takita, Kazuya Kikuchi, Ayaka Yoshida, Makit ...
    2012 Volume 59 Issue 2 Pages 111-124
    Published: November 05, 2012
    Released on J-STAGE: December 02, 2014
    DOIhttps://doi.org/10.11369/jji.59.111
    JOURNAL FREE ACCESS
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    The importance of olfaction in spawning of medaka Oryzias latipes was established for the first time by observation of spawning behavior by fish subjected to an olfactory blockage. Experimental fish were prepared by (1) covering the nostrils on both sides (bilateral treatment), thereby excluding all olfactory stimuli, and (2) covering nostrils on one side only (unilateral treatment), thereby giving partial exclusion. A control group comprised untreated (intact). Experiments conducted for both males (bilateral male-intact female, unilateral male-intact female and intact male-intact female) and females (bilateral female-intact male, unilateral female-intact male and intact female-intact male) resulted in no spawning by intact females paired with bilateral males, whereas spawning occurred in intact females paired with both unilateral and intact males. Spawning also occurred when intact males were paired with intact, unilateral or bilateral females, indicating that olfactory stimuli were necessary for males to complete spawning, but not so for females. Spawning acts exhibited from pairing started by bilateral males-intact female pairs included “following” (initial act of following female), “positioning” (lateral courtship display), and “quick circle” (turning in front of female), but they did not include “contact” (bodies in contact posteriorly prior to gamete release), “wrapping” (male embracing female using their dorsal and anal fins during gamete release). On the other hand, intact and unilateral males participated in all of the above spawning acts, indicating that olfactory stimuli are indispensable for behavior concerning emitting semen.
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  • First Japanese record of an engraulid fish, Encrasicholina devisi (Clupeiformes), collected from Kagoshima Prefecture, southern Japan and comparisons with congeners
    Harutaka Hata, Hiroyuki Motomura, Hiro Ishimori
    2012 Volume 59 Issue 2 Pages 125-134
    Published: November 05, 2012
    Released on J-STAGE: December 02, 2014
    DOIhttps://doi.org/10.11369/jji.59.125
    JOURNAL FREE ACCESS
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    A single specimen of an engraulid fish, Encrasicholina devisi (Whitley, 1940) as collected from Uchinoura Bay, Kagoshima Prefecture, southern Japan, in January 011. The previously reported northernmost record of the species being as Taiwan, the agoshima specimen is described here as the northernmost (and first Japanese) record nown of E. devisi. Although the species is similar to E. heteroloba in having the maxilla osteriorly reaching to the subopercle, differences between the species have been unclear, ue to a lack of detailed comparisons. Comparisons of E. devisi with E. heteroloba based n 29 and 32 specimens, respectively, from the Indo-West Pacific revealed the former to ave 3 unbranched rays in the dorsal and anal fins [vs. 2 or (rarely) 1 in E. heteroloba]. ncrasicholina devisi also differs from E. heteroloba in having relatively fewer gill rakers: 6–46 (mode 40) on the first gill arch [vs. 44–51 (46)], 30–37 (34) on the second gill rch [vs. 33–42 (38–40)], 15–22 (19) on the fourth gill arch [vs. 19–25 (21)] and 3–7 (6) n the posterior face of the third gill arch [vs. 5–8 (7)]. Morphometrically, E. devisi is eparable from E. heteroloba in head length [25.8–27.5% (mean 26.7%) of standard length s. 22.8–25.5% (24.3%)], first unbranched dorsal-fin ray length [0.4–1.8% (1.0%) vs. 4.1– .7% (5.6%)], second unbranched dorsal-fin ray length [5.3–7.5% (6.7%) vs. 12.3–15.2% 13.5%)], first unbranched anal-fin ray length [0.3–2.1% (1.0%) vs. 2.5–5.0% (3.6%)] and econd unbranched dorsal-fin ray length [2.3–4.9% (3.9%) vs. 7.3–11.0% (9.6%)], and in aving the third or fourth soft ray in the dorsal fin longest (vs. second to fourth), and third o fifth soft ray in the anal fin longest (vs. second or third).
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