Although ex situ target strength (TS) measurements using dual- and split-beam systems have become the primary approach of estimating fish abundance, theoretical model estimation is a powerful tool for verifying the measurements, as well as for providing values when making direct measurements is difficult. TS values for 20 samples of live bambooleaf wrasse (Pseudolabrus japonicus) whose target length (TL) ranged between 13.7 and 21.3 cm were estimated theoretically using the Kirchhoff-ray mode model, and the TS values for 18 live fish samples were additionally measured at ~0° tilt angle to the swimming aspect using a tethered method at a frequency of 120 kHz to verify the theoretical values. The digitizing intervals used to extract the fish body and swim bladder morphology in the X-ray photographs significantly affected the calculated TS patterns, but variations based on the speed of sound and density ratio values for the general range of fish flesh were relatively small (within 1 dB). Close agreement was observed between the measured and theoretical TS values, and the correlation between the average TS and body length of the fish could be calculated accurately as <TS120kHz>= 20logTL (cm) –71.6 using the theoretical method.

제주 연안에 서식하는 용치놀래기, 어렝놀래기, 황놀래기, 놀래기를 대상으로 체장에 따른 성 분포와 생식소의 성 특성을 조직학적으로 탐색하여 성 전환 양상을 조사 비교하였다. 용치놀래기, 어렝놀래가, 황놀래기, 놀래기는 자성선숙형 자웅동체어로 조직학적 관찰 결과 정소조직(정자형성부위)이 퇴화기 난소의 전역에 출현하는 혼재형 2에 속하는 어종이었다. 용치놀래기, 황놀래기 그리고 놀래기는 1차 수컷과 2차 수컷이 존재하는 복웅성 어류이고, 조사된 어렝놀래기는

Eleven wrasse species inhabit the coastal waters of Jeju Island, Korea. They are the target of leisure fishing and are considered good eating. We investigated the distribution of standard length (SL) by sex of wrasse in Jeju coastal waters for Halichores poecilopterus, H. tenuispinis, Pseudolabrus japonicus, and Pteragogus flagellifera. A cross-section of the ovary showed the ovarian cavity and ovarian lamellae containing oocytes. A cross-section of the testis showed many lobules containing spermatogonia and spermatocytes. A cross-section of a gonad undergoing sex reversal showed the regression or reduction of oocytes and some spermatocytes located in the ovarian lamellae. A cross-section of a sex-reversed testis showed the primary structure of the ovary, with spermatocytes distributed in the epithelium of the lamellae, and reformed seminiferous ducts in the basement lamellae. (중략)

The sex differentiation of fishes occurs under the control of genetic and various environmental factors. DM-domain containing genes are novel zinc finger transcription factors and play key roles in sex determination. In order to isolate the wrasse DMRT (wDMRT) cDNA from the protogynous wrasse (Halichoeres tenuispinnis), the wrasse testis cDNA library was screened using the P-labeled PCR products, which were amplified with the degenerate primers from conserved DM-domain regions of several DMRT genes. Among a few positives obtained through screening, the full length wDMRT cDNA of 2.9kb size encoding a predicted 300 amino acid residues was isolated. The sequence analysis exhibited 60%, 43% sequence identity with rainbow trout and tilapia DMRT1, respectively. RT-PCR assay showed that wDMRT was expressed specifically in male testis. Also, wDMRT gene was strongly expressed in May during reproductive season, when the reproductivity of wrasse is most active. This results suggested that wDMRT gene function in testis differentiation The conserved DM-domain regions were amplified using PCR from DMRT genes of several species among Labridae, and their sequences were determined. The sequence of DM-domain region of Halichoeres. tenuispinis was identical to those of Pseudolabrus japonicus, Pteragogus flagellifera, and showed 94% identity with that of Halichoeres poecioptrerus.