• 한국수산과학회지
• /
• 제53권1호
• /
• pp.19-26
• /
• 2020

The maturity and spawning of pacific sand eels Ammodytes japonicus, was investigated using samples collected by gill net in coastal waters near Donghae, Gangwon-do, from January 2017 to December 2018. Monthly changes were analyzed in maturity stage, gonadosomatic index (GSI), egg diameter, fecundity (F), and total length (TL) at 50% group maturity. The average TLs of female and male A. japonicus were 18.5 and 18.1 cm, respectively. The spawning period was from November to March, with the peak from December to February based on monthly changes in GSI and maturity stages. The egg diameter during the spawning-capable stage was 300-1000 (main mode 500-600) ㎛. Fecundity ranged from 6,411 eggs at 16.7 cm fork length to 45,771 eggs at 24.7 cm fork length. The relationship between TL and F was F=0.00005TL^4.2715 (R²=0.7216), such that F increased with TL. TL at 50% group maturity was estimated to be 15.1 cm for both sexes.

• 한국수산과학회지
• /
• 제53권1호
• /
• pp.74-82
• /
• 2020

Dragonet fish (Callionymidae), living in benthic upper 900 m of all subtropical, tropical and temperate oceans, comprises 200 species in 20 genera worldwide, of which 18 species in 6 genera occur in Korea. Although dragonet fish plays an important role in linking between top predators and lower trophic levels, there are only few studies about their early life history. Herein, we present molecular and morphological data on larvae and juveniles of Bathycallionymus kaianus (Günther, 1880) collected from the Korean waters. During 2016 to 2018, one preflexion larvae [2.69 in total length (TL)], three flexion larvae (3.65 and 4.77 mm TL), six postflexion larvae (6.07 and 7.94 mm TL), and three juveniles (10.81 and 12.26 mm TL) were collected in the East Sea, Korea Strait, and Jeju Island using Bongo net. Of them, 13 individuals were identified through molecular markers (COI or 16S rRNA) and morphologically described. The larvae of B. kaianus are well distinguished from other species of Callionymidae in melanophore distribution, body shape and development of preopercular spine. It was very similar to larvae of two Repomucenus species, R. valenciennei and R. virgis, but was clearly distinguished in melanophore distribution, preopercular spine development, and head shape.

• Fisheries and Aquatic Sciences
• /
• 제13권4호
• /
• pp.332-339
• /
• 2010

Maturity and spawning of the snailfish, Liparis ochotensis was investigated based on samples collected by gill net in the East Sea of Korea from December 2008 to December 2009. The average total length of L. ochotensis was 63.4 cm and 64.1 cm for females and males, respectively. Gonadosomatic index (GSI) began to increase in July, reaching a maximum in November, then began to decrease in December. Monthly changes in the GSI values of L. ochotensis were similar for females and males. Annual reproductive cycle of this species can be divided into five successive stages in females: early growing stage (May), late growing stage (June to July), mature stage (August to September), ripe and spent stage (September to December), and recovery and resting stage (January to April). Males show four successive stages; growing stage (May to July), mature stage (August to September), ripe and spent stage (September to December), and recovery and resting stage (January to April). Relationship between total length (TL) and fecundity (F) was F=$0.00003TL^{4.002}$ ($R^2$ = 0.703), and F increased with TL. Total length at 50% group maturity was estimated to be 55.8 cm. Our findings suggest that the spawning period takes place from September to December, with the main spawning period occurring from October to December.

• 한국수산과학회지
• /
• 제39권5호
• /
• pp.419-426
• /
• 2006

This study investigated the ecology and growth of Monostroma nitidum Wittrock in both its natural habitat and the laboratory. The maximum length, width, and weight of M. nitidum in March were 9.0$\pm$4.7 cm, 9.6$\pm$3.6 cm, and 1.52$\pm$1.13 g, respectively. Yellowish-green or yellowish-brown reproductive thalli began to appear in January, and over 80% of the thalli matured by March. The male and female spores were ca. 6 $\mu$m long, and elongate and ovoid in shape. The spores had two flagella and one-eye spot, and tended to swim toward light. Maximum number of spores released from matured thalli was 236 cells/mL after 70 minutes at a light intensity of 100 $\mu$mol/m$^2$/s. The zygote diameter ranged from 3.4-6.0 $\mu$m (mean 4.2 $$m) and increased to 69.8 $\mu$m 14 weeks after culture. The mass release of zoospores was observed from thalli in the dark (3 to 12 days), after 30 min under dry conditions in the shade, at 25$^{\circ}C$, and a light intensity of 100 $\mu$mol/m$^2$/s. The maximum number of zoospores released was 109.8 cells/mL after 60 min of induction. M. nitidum fronds on the net increased to 6.8-7.2 cm in length, and 6.6-8.9 cm in width during the winter.

• 한국수산과학회지
• /
• 제46권3호
• /
• pp.287-295
• /
• 2013

The growth, respiration, ingestion, and ecological efficiencies of Hexagrammos otakii larvae and juveniles reared on different diets and temperatures were estimated. A factorial experiment using two diets [non-enriched hatched Artemia nauplii (NEA) and enriched Artemia nauplii (EA)] crossed with two temperatures [natural seawater temperature (NT, $5.1-8.5^{\circ}C$) and heated seawater (HT, $13{\pm}0.5^{\circ}C$)] was conducted to investigate growth and energy budgets of Hexagrammos otakii larvae and juveniles. The energy used by larvae and juveniles for 6 weeks was calculated using data on ingestion, growth, respiration, excretion, and egestion. In the NT trials, the energy used for growth by larvae and juveniles was 0.121 and 0.129 Kcal in the NEA and EA treatments, respectively. Assimilation efficiency at NT were 78.0% and 80.2% in the NEA and EA trials, respectively. Gross growth efficiency ($K_1$) were 60.5% and 62.3% and net growth efficiency ($K_2$) was 77.56% and 77.71% in the NEA and EA trials, respectively. In the HT trials, the energy used for growth by juveniles was 0.189 and 0.212 Kcal in the NEA and EA trials, respectively. Assimilation efficiency at HT was 86.4% and 95.1% in the NEA and EA trials, respectively. Values of $K_1$ and $K_2$ at HT were 69.5% and 80.43%, respectively, in the NEA trials, and 73.9% and 77.66%, respectively, in the EA trials. These results suggest that enriched Artemia nauplii and higher temperatures ($13{\pm}0.5^{\circ}C$) are effective for rearing larvae and juveniles of H. otakii.

• 한국수산과학회지
• /
• 제31권5호
• /
• pp.654-664
• /
• 1998

1992년 3월에서 1993년 1월 사이 만입구에 설치된 소형정치망 어획 자료를 수집하여 천수만 부어류 종조성의 계절변동을 분석하고, 1981$\~$82년 자료와 비교하였다. 조사기간 동안 출현한 63종의 어류가 출현하였고, 멸치(Engraulis japonicus), 까나리 (Ammodytes penonatus), 횐베도라치 (Enedrias fangi) 및 밴댕이 (Sardinella zunasi)가 우점하였다. 봄에는 횐베도라치의 치어와 멸치, 까나리, 밴댕이 등의 성어가 대량 가입되었으며, 이 어종들은 이른 여름에 그 수가 감소하였다. 8월부터 봄에 산란부화한 부어류들의 유어가 가입하여 높은 생체량을 보였으며, 늦가을부터는 이 어류들이 월동하기 위하여 외해로 빠져나가 생체량이 감소하였다. 본 조사의 종조성의 계절변동은 1981$\~$82년과 비슷한 경향을 보였으나, 양적으로는 1981$\~$82년에 비하여 높았다. 이것은 1992년 봄과 가을에는 평년 수온에 비하여 약 $2^{\circ}C$ 정도가 높은데 기인된 것으로 판단된다. 주둥치 (Leiogathus nuchalis)의 증가는 수질의 변화와 관계가 있는 것으로 추정된다.

• 한국수산과학회지
• /
• 제34권6호
• /
• pp.594-599
• /
• 2001

돌산도 모래해안 쇄파대에서 셀매네트를 사용하여 1 m 수심의 표층, 저층 그리고 바닷가에서 주야, 조석 계절에 따른 요각류 Acartia omorii이 출현량을 조사하였다. A. omorii의 출현량은 표층과 바닷가에 비해 저층에서 많았으며, 계절별로는 겨울철에 가장 많았다. 또 연구기간 동안 A. omorii의 출현량은 항상 밀물일 때보다 썰물일 때 많이 나타났다. A. omorii의 분포양상은 주야보다 조석 영향이 더 큰 것으로 나타났고, 대조 때는 강한 조류가 주야수직양상에 영향을 나타냈다. 겨울철에는 주야보다 조석주기 영향이 더 큰 것으로 나타났다. 겨울철에 A. omorii는 소조 때 주야수직이동을 하였고, 반면에 대조 때에는 역 주야수직이동을 했다. 소조 때 분포중심은 평균해수면 아래 $50\~100cm$층에 위치했으며, 대조 때는 약간 위쪽으로 분포중심 이 이동했다.

• 한국수산과학회지
• /
• 제3권1호
• /
• pp.19-26
• /
• 1970

1969년 여름 부산수산대학 양어장에서 1963년 일본으로부터 도입하여 길러온 초어와 백련을 사용 채란과 부화실험을 하였는 바, 그 결과는 좋지 못하였지만, 다음과 같은 점을 지적한다. 1. 부산지방의 못에서 양식한 초어가 백련의 성숙 채란 적기는 6월 말부터 8원 초까지의 사이에 있다고 인정된다. 2. 산란 촉진용 뇌하수체는 동종 또는 근연종의 친어로부터 그들의 산란기이 진에 적출 보관하였다가 사용하는 것이 좋다고 인정된다. 3. 백련은 체장 40cm(전장 48cm) 가량의 작은 개체도 6년생은 모두 채란 가능하였으며, 포란수는 체장 $40\~44.5cm$ 되는 것에서 $23\~26$ 만개로 추산되었다. 4. 부화 시설로서는 원추형 망부화기를 급수 파이프에 병렬하고, 각 부화기에는 수량 조절용 발브를 달아서 수중에 설치하는 것이 좋은 동작을 하였다. 5. 알의 발생 중, 분할된 할구(세포)가 배체 밖으로 방출되는 것이 생기면, 그 알은 예외없이 괴사하였다. 6. 친어의 사전 관리를 보다 철저히 하는 것이 긴요함을 느꼈으며, 좋은 먹이와 적절한 수심 및 수온을 유지시키도록 해야 할 것이다.

• 한국수산과학회지
• /
• 제16권2호
• /
• pp.111-116
• /
• 1983

1965년부터 1979년까지의 해양관측자료를 사용하여 우리나라 남해에서 일어나는 수온역전현상을 조사하였다. 그 결과를 요약하면 다음과 같다. 1) 역전현상은 여름보다 겨울에 6배정도 많이 일어난다. 2) 겨울의 경우, 남해 서부해역에서는 수온역전이 모든 수심에서 골고루 일어나는 반면, 동부해역에서는 주로 표층에서 일어난다. 3) 여름의 경우, 서부해역에서는 역전층이 주로 수온약층 아래에 형성되는 반면, 동부해역에서는 주로 표층에 형성된다. 겨울의 역전현상은 기본적으로는 표면 냉각효과에 의해서 생기는 것으로 생각된다. 다만, 서부와 동부해역에서 역전층이 형성되는 수심에 차이가 있는 것은 쓰시마난류 영향의 정도가 양해역에서 크게 다르기 때문이라고 보여진다. 여름의 경우 서부해역에서는 쓰시마난류와 황해 저층냉수가 수온약층 밑에서 혼합되는 과정에서 생기는 것으로 보이고, 동부해역에서는 보다 수온이 낮은 물이 표층을 따라 유입하기 때문에 일어나는 것으로 생각된다.

• 한국수산과학회지
• /
• 제37권4호
• /
• pp.345-353
• /
• 2004

Target strength (TS) of Japanese common squids (Todarodes pacificus) were measured using 38 and 120 kHz split beam scientific echosounders under the live condition. For the TS measurement of an individual, a total of 3 squids (mantle length (ML): 22.8, 25, and 27 cm) were used using small fishhook method, whereas for measurement of swimming angle, a total of 8 squids (ML: 21-27 cm) were used under live condition, confined with net cage with 2 m diameter At the same time, two underwater video cameras enabled continuous monitoring of squid behavior. Considering normal behavior, the mean TS at 38 and 120 kHz varied from -48.6 to -45.9 dB, and from -46.5 to -44.6 dB, respectively In both frequencies, mean TS at 120 kHz is relatively higher than that of 38 kHz, approximately 1.3-2.5 dB. From free living condition, the mean swimming angle of the squlds was $-24^{\circ}$. The results of the measurement will be provided basic information for conducting acoustic surveys of the squid.