• 생태와환경
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• 제53권4호
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• pp.445-452
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• 2020

본 연구는 낙동강지류인 밀양강에 소상한 연어를 대상으로 소상, 산란 분포를 최초로 파악하고 소상 한계선을 확인하였다. 2020년 10월 25일부터 11월 28일까지 확인된 개체들 중, 사체는 전장을 측정하고 암-수 구별을 하였다. 조사 결과 총 40개체의 연어를 발견하였으며 이 중 사체는 25마리, 살아있는 개체는 15마리였다. 대부분 산란장으로 판단되는 지점 인근 수변부에서 살아있는 개체와 사체가 발견되었다. 연어의 소상 한계선 파악의 경우 연어가 소상할 수 없는 형태의 보가 등장할 때까지 상류방향으로 이동하여 확인하였으며, 밀양강 본류의 경우 예림교 기준 상류 13 km, 지천인 단장천의 경우 밀양강 합류부에서부터 12 km까지 연어의 소상이 가능할 것으로 확인하였다. 따라서 연어가 소상하기 위한 보의 철거 및 어도설치와 같은 하천연결성 확보가 필요한 것으로 판단되며, 연어의 치어생존률을 높이기 위한 산란장 및 미소서식처 자연성 확보 방안이 필요할 것으로 판단된다.

• 한국수산과학회지
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• 제37권2호
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• pp.129-136
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• 2004

Visual line-transect surveys for the finless porpoise (Neophocaena phocaenoides) were conducted in the offshore of the west coast of Korea (WCOK) from 18 April to 17 May 2001 $(34^{\circ}18'\;to\;37^{\circ}18'N,\;123^{\circ}00'\;to\;126^{\circ}00'E),$ and in the inshore of the west coast of Korea (WCIK) from 29 July to 2 August 2003 $(35^{\circ}17'\;to\;36^{\circ}17'N,\;126^{\circ}00'\;to\;126^{\circ}25'E).$ A total of transect survey efforts were 810.27 n.m. in 2001 and 216.09 n.m. in 2003, which cover a survey areas of $23,012\;n.m^2\;and\;1,550\;n.m^2,$ respectively. There were 76 and 24 sightings for the finless porpoise during the surveys in the WCOK (2001) and the WCIK (2003), respectively. More than $80\%$ of the finless porpoise occurred near the coast within 15 n.m. from the land. Porpoise were observed mainly in a depth range from 20 to 50 m $(78\%).$ Few porpoise were observed in a depth shallower than 10 m or deeper than 60 m. The hazard-rate model, truncated at the largest $5\%$ distance, showed the best fitting from the frequency distribution of perpendicular distance of the finless porpoise sighted from the trackline in the WCOK (2001), while the uniform model showed the best fitting from in the WCIK (2003). Abundance of finless porpoises were estimated to be 58,650 individuals ($95\%$ CI=34,961-98,389) in the WCOK (2001) and 1,571 individuals ($95\%$ CI=881-2,800) in the WCIK (2003), respectively.

• 한국수산과학회지
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• 제50권5호
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• pp.561-566
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• 2017

Few studies on the finless porpoise Neophocaena asiaeorientalis have been conducted on the south coast of Korea. This region includes Gadeok Island, which is located off the Korean peninsula in an area of heavy maritime traffic. Sighting surveys of finless porpoises were conducted at seven predetermined spots around Gadeok Island in January, May, July, September, and November 2016. Finless porpoises (127 individuals in 24 schools) were sighted at all but one (spot P5) of the survey locations. Fewer porpoises were spotted in summer (Jul and Sep) than in other seasons (P<0.05). Porpoises were most abundant around the south coast of the island, where they were spotted in every season, and in significantly higher numbers than at other locations (P<0.05). Single individuals accounted for 20.8% of sightings, while 25.0% of sighted schools consisted of only two porpoises. The mean school size was 5.29 individuals (SD=6.72).

• Fisheries and Aquatic Sciences
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• 제11권3호
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• pp.166-171
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• 2008

The feasibility of photo-identification techniques for the bottlenose dolphins from Jeju Island, Korea, and the potential for dolphin watching were simultaneously evaluated in this study. During the sighting survey, a pod of bottlenose dolphins composed of approximately 30 individuals was observed in the southwestern coastal area of Jeju Island. Among 35 suitable photographs, five bottlenose dolphin individuals were identified and cataloged using unique nicks and notches on their dorsal fins. This shows that the Jeju Island dolphins can be individually identified by the nicks and notches on their dorsal fins using photo-identification techniques. Furthermore, the Jeju Island population appears to be suitable for long-term population biology studies using this technique. The potential for dolphin watching around the island would be higher if more information on the seasonal distribution, movement, and residency of this population were obtained.

• 수산해양교육연구
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• 제23권4호
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• pp.772-778
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• 2011

In order to estimate the densities and composition of floating marine debris (FMD), a sighting survey was conducted from July 1st to July 14th, 2009 in the East China Sea (ECS) using a training vessel "Kaya (1,737 ton)" of Pukyong National University. The sampled zones are divided into 5 transects by observation day during the survey days and the densities and composition in each transect were calculated using the numbers of item per $km^2$. The results of distribution of FMD are as follows: 1. During the surveys, a large variety of FMD was discovered and highest densities were found in the Central East(CE) of the East China Sea(ECS) (48.2 items/$km^2$), whereas densities in the less populated transects in Okinawa(OK1, OK2) were comparatively low(3.5 ~ 4.9 items//$km^2$). 2. Among the classified 6 items, styrofoams(Styro) were most abundant and ubiquitous(10.3 items/$km^2$, 53% of the total number), except OK2 area. Next abundant item was vinyl and plastics called V & P(4.9 items/$km^2$, 25%). Above 2 items of the major proportion of FMD accounted for 78% of the total number of FMD observed through this study. 3. The percentages of manufactured plastics(Styro and V & P) found in the Seas near Korean Peninsula were varied from 87.2% to 69.8%. It was recognized that polluted level is middle value among them.

• 한국환경과학회지
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• 제31권10호
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• pp.861-868
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• 2022

The Namdae stream in Gangneung-si is one of the rivers where salmon stock is mainly maintained by natural spawning rather than artificial seedlings. There are structures including weir, and fish distribution and movement characteristics can be different by these structures. In this study, we investigated the distribution and behavioral characteristics of salmon by sighting survey within 12 km immediately upstream of the river mouth between October 2021 and February 2022. As a result, salmon distributed within 9 km from rivermouth. There were more salmon in the lower reaches of Doosan weir than in the upper reaches of that. The main spawning ground for salmon was between 7-9 km from rivermouth and around the lower part of Doosan weir. Salmon behaved for spawning in the gravel-bed area and undercut slope of the mainstream, such as mating, digging the riverbed, and competition among males. Salmon moved more slowly in the gravel-bed area than sand-bed area. Doosan weir hinders the spawning migration of salmon by frequent flow changes and terraced fishway. This study provides primary information to understand the ecological changes of salmon by environmental changes in the Namdae stream.