흰베도라치, Pholis fangi의 초기 생활사를 밝히기 위해 한국 서해의 대천 연안에서 1988년 3월에서 6월 사이와 1989년 2월에 흰베도라치 치어를 채집하였다. 성장에 따라 외부형태 변화와 이석을 관찰, 측정함으로써 출현양상과 산란시기 및 초기성장 등을 조사하였다. 또한, 1998년 5월부터 1999년 11월 사이에 매월 대천 해역에서 채집된 흰베도라치의 생식소 관찰로 산란기를 추정하였다. 2월에는 흰베도라치 치어가 천수만 안팎에서 넓게 분포하였다. 3월에서 4월 사이에 만 안쪽에서 주로 출현하였고, 5월에는 만밖에서 주로 나타났으며, 6월 이후에는 본 연구 해역에서는 채집이 되지 않았다. 이석은 초기에 둥근 모양에서 체장이 30~40 mm 정도 성장하면 타원형으로 변하며, 일륜으로 볼 수 있는 미세 성장선이 나타났다. 또한, 핵으로부터 30개의 미세성장선 이후에 깊게 파인 불연속선이 나타나는데, 체장 10 mm 이하의 자어 형태에서는 성장 정지선이 나타나지 않았다. 이 불연속선은 연안측으로 회유하는 동안에 신진대사의 변화에 따라 형성된 것으로 판단된다. 흰베도라치의 초기성장은 다음과 같은 Gomertz식 TL = 6.702 exp {2.925 "1-exp (-0.0076 t)"} ($r^2=0.94$, N = 92)에 의해 추산되었다. 흰베도라치 이석에 처음으로 미세 성장선이 형성된 시기는 12월에서 1월 사이로 보여지며, 흰베도라치 성어의 생식소는 10월부터 성숙하기 시작하며 11월에서 12월 사이에 주로 산란하고 1월에는 산란을 마치는 것으로 나타남으로써 흰베도라치의 부화시간은 한 달 정도인 것으로 판단된다.
흰베도라치, Pholis fangi의 초기 생활사를 밝히기 위해 한국 서해의 대천 연안에서 1988년 3월에서 6월 사이와 1989년 2월에 흰베도라치 치어를 채집하였다. 성장에 따라 외부형태 변화와 이석을 관찰, 측정함으로써 출현양상과 산란시기 및 초기성장 등을 조사하였다. 또한, 1998년 5월부터 1999년 11월 사이에 매월 대천 해역에서 채집된 흰베도라치의 생식소 관찰로 산란기를 추정하였다. 2월에는 흰베도라치 치어가 천수만 안팎에서 넓게 분포하였다. 3월에서 4월 사이에 만 안쪽에서 주로 출현하였고, 5월에는 만밖에서 주로 나타났으며, 6월 이후에는 본 연구 해역에서는 채집이 되지 않았다. 이석은 초기에 둥근 모양에서 체장이 30~40 mm 정도 성장하면 타원형으로 변하며, 일륜으로 볼 수 있는 미세 성장선이 나타났다. 또한, 핵으로부터 30개의 미세성장선 이후에 깊게 파인 불연속선이 나타나는데, 체장 10 mm 이하의 자어 형태에서는 성장 정지선이 나타나지 않았다. 이 불연속선은 연안측으로 회유하는 동안에 신진대사의 변화에 따라 형성된 것으로 판단된다. 흰베도라치의 초기성장은 다음과 같은 Gomertz식 TL = 6.702 exp {2.925 "1-exp (-0.0076 t)"} ($r^2=0.94$, N = 92)에 의해 추산되었다. 흰베도라치 이석에 처음으로 미세 성장선이 형성된 시기는 12월에서 1월 사이로 보여지며, 흰베도라치 성어의 생식소는 10월부터 성숙하기 시작하며 11월에서 12월 사이에 주로 산란하고 1월에는 산란을 마치는 것으로 나타남으로써 흰베도라치의 부화시간은 한 달 정도인 것으로 판단된다.
Larvae of the gunnel Pholis fangi were collected in coastal waters off Daecheon with a bag net from March to June, 1988, and with a ring larva net in February 1989. Maturity and spawning period were analyzed by examination of the gonads of adult fish collected with a bag net from May 1998 through No...
Larvae of the gunnel Pholis fangi were collected in coastal waters off Daecheon with a bag net from March to June, 1988, and with a ring larva net in February 1989. Maturity and spawning period were analyzed by examination of the gonads of adult fish collected with a bag net from May 1998 through November 1999. In February, the larvae were widely distributed in the outer and inner Cheonsu Bay. From March to April the larvae were present mainly the inner bay; they were absent there in May and found mainly in the outer bay. After June, few gunnel larvae were collected in the study area. This suggests a seaward movement of gunnel from the nursery grounds of the bay to offshore feeding grounds. The otolith of larvae smaller than 10 mm in total length did not show a distinct growth stop. The growth stop is believed to be formed in the early larval stage when the total length is about 10 mm. This period coincides with the time of shoreward migration, suggesting a metabolic change during this period. At a total length of 30 to 40 mm, the shape of the otolith changes from spherical to elongate. Daily growth rate in length was estimated by the Gompertz equation, which is represented as follows: TL = 6.702exp{2.925"1-exp (-0.008 t)"} ($r^2=0.94$, N = 92) Assuming daily deposition of growth increments in the otolith, the time of first growth increment formation was shown to be from December to January. Gonad observations show that Pholis fangi spawns from November to December. So, the hatching time is thought to be about one month.
Larvae of the gunnel Pholis fangi were collected in coastal waters off Daecheon with a bag net from March to June, 1988, and with a ring larva net in February 1989. Maturity and spawning period were analyzed by examination of the gonads of adult fish collected with a bag net from May 1998 through November 1999. In February, the larvae were widely distributed in the outer and inner Cheonsu Bay. From March to April the larvae were present mainly the inner bay; they were absent there in May and found mainly in the outer bay. After June, few gunnel larvae were collected in the study area. This suggests a seaward movement of gunnel from the nursery grounds of the bay to offshore feeding grounds. The otolith of larvae smaller than 10 mm in total length did not show a distinct growth stop. The growth stop is believed to be formed in the early larval stage when the total length is about 10 mm. This period coincides with the time of shoreward migration, suggesting a metabolic change during this period. At a total length of 30 to 40 mm, the shape of the otolith changes from spherical to elongate. Daily growth rate in length was estimated by the Gompertz equation, which is represented as follows: TL = 6.702exp{2.925"1-exp (-0.008 t)"} ($r^2=0.94$, N = 92) Assuming daily deposition of growth increments in the otolith, the time of first growth increment formation was shown to be from December to January. Gonad observations show that Pholis fangi spawns from November to December. So, the hatching time is thought to be about one month.
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가설 설정
fangi. A. Otolith of a larva (30.7 mm TL) under transmitted light (left) and reflected dark field. Bar : 50µm B.
제안 방법
Objectives of this study are to describe the spatio-temporal appearance patterns of larval P. fangi in the coastal waters off Daecheon, Korea from 1988 to 1989, and to analyze the relationship between larval morphologic changes and otolith growths observing the microstructures in otoliths. Also, the spawning time and the patterns of early growth are estimated.
3 µm alumina powders. Prepared otoliths were examined and photographed at 200×, 400×, 500× magnification under a light microscope (Leitz diaplan) using transmitted and/or reflected dark -field illuminations. This method of examination permitted observation of not only growth increments but also the optical density that is determined by organic contents of the otolith.
The otoliths of larvae were extracted, brushed free of tissue and rinsed with distilled water under a dissecting microscope. The otoliths were prepared for observation by embedding them in the unsaturated polyester resin, by hand grinding them to the proximal surface of sagittal plane passing through the otolith center with a series of graded silicon carbide papers (400, 800 and 1,200 grits) and by polishing with 0.3 µm alumina powders. Prepared otoliths were examined and photographed at 200×, 400×, 500× magnification under a light microscope (Leitz diaplan) using transmitted and/or reflected dark -field illuminations.
대상 데이터
P. fangi larvae and adults were collected in the coastal waters off Daecheon, Korea with a bag net (mesh size: 0.33~1 mm) from March to June 1988 (st. 7), a 1 m ring net with 0.33 mm mesh in February 1989 (st. 1~8) and a bag net from May 1998 to November 1999 (open circles), respectively (Fig. 1). In addition, the surface water temperature was measured daily at a fixed station off Daecheon during the sampling.
이론/모형
The relationship between total length of larvae, radius of the otoliths and number of otolith increments was established by the least square method with the SPSS/PC± (Norusis, 1986) program. The total length was estimated by back-calculation (Fraser-Lee method in Bagenal and Tesch, 1978) from otolith radii.
The relationship between total length of larvae, radius of the otoliths and number of otolith increments was established by the least square method with the SPSS/PC± (Norusis, 1986) program. The total length was estimated by back-calculation (Fraser-Lee method in Bagenal and Tesch, 1978) from otolith radii. The growth formula was calculated following Gompertz growth function using Basic Fishery Science Programs (Saila et al.
성능/효과
In this experiment, supposedly, the ring in otolith of P. fangi larvae was a daily growth increment, and the time of the initial incremental deposition of P. fangi appeared in the coastal waters off Daecheon was estimated as the period from early November through next Februray, mainly December~January at the water temperature 3~8℃. However, the birth dates must be taken into consideration by adding the time from spawning to the first increment formation to the period of the initial increment deposition above-mentioned.
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