• Title/Summary/Keyword: sighting

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Reappearance and Distribution Tendency of Finless Porpoises Neophocaena asiaeorientalis after their Mass Mortality in the Saemangeum Dyke (새만금호의 상괭이 대량 폐사 후 상괭이(Neophocaena asiaeorientalis) 재출현과 분포 경향)

  • Park, Kyum Joon;Lee, Seung Yong;An, Yong-Rock;Kim, Hyun Woo;An, Du Hae;Kim, Doo Nam;Kim, Yeong Hye
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.47 no.6
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    • pp.978-982
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    • 2014
  • A mass mortality of 249 finless porpoises Neophocaena asiaeorientalis occurred in the Saemangeum Dyke in February 2011. It was an extraordinary event, notable due to the death toll and the location of the occurrence, a semi-isolated lake enclosed by a man-made structure. We conducted sighting surveys that consisted of a land-based sighting survey recorded from three different platforms, and a ship-based sighting survey in the lake. The land-based survey was dedicated to clarifying the distribution of finless porpoises and whether they passed through two water gates (Shinsi and Garyek) of the dyke from 2011 to 2013. No finless porpoises were observed in the 2011 or January 2012 surveys. In April 2012, two months and one year after the mass mortality, one finless porpoise, swimming 400 m from the Shinsi water gate, was observed by a land-based survey. The number of observed individuals increased to nine in 2012 and reached 10 by May 2013 at the time of the surveys. Most of the porpoises were detected near the Garyek water gate. The density of the animals was $0.075/km^2$ in 2012 and $0.083/km^2$ in 2013. The density of porpoises was $2.063/km^2$ at the time of the mass mortality.

Occurrence and Spatial Distribution of Marine Mammals by Sighting Surveys in Korean Waters During 2011-2020 (2011-2020년간 목시조사에 의한 우리나라 연근해 해양포유류 출현 및 분포 현황)

  • Lee, Jong Hee;Kim, Eun Ho;Lee, Kyunglee;Park, Kyum Joon;An, Yong-Rock;Kim, Hyun Woo;Sohn, Hawsun;Choi, Seok-Gwan
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.55 no.6
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    • pp.938-945
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    • 2022
  • National Institute of Fisheries Science conducted a total of 39 sighting surveys for marine mammals over 624 sighting days that covered 20,771 nautical miles in Korean waters during 2011-2020. Marine mammals were detected when 83.9% of the marine environment was less than or equal to three on the Beaufort wind scale. Thirteen species of marine mammals were identified, including two species of pinniped, with a majority of cetacean species. Frequently found species were narrow-ridged finless porpoise, followed by common dolphin, minke whale, Dall's porpoise, and Pacific white-sided dolphin. Narrow-ridged finless porpoises and minke whales were located in and offshore around the Korean peninsula, common and Pacific white-sided dolphins were exclusively found in the East Sea for most seasons. The other marine mammals were spotted in some seas and for limited durations.

Estimated Abundance of the Narrow-ridged Finless Porpoise Neophocaena asiaeorientalis by Aerial and Shipboard Sighting Surveys in the Middle Region of the Western Coast of Korea (항공 및 선박 목시조사에 의한 서해 중부 연안해역의 상괭이(Neophocaena asiaeorientalis) 자원량 추정)

  • Jong Hee Lee;Kyunglee Lee;Namgyu Uh;Min Ju Kim;Yuna Cho;Hyun Woo Kim;Kyum Joon Park
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.56 no.6
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    • pp.889-898
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    • 2023
  • This study was conducted to estimate the abundance of narrow-ridged finless porpoises Neophocaena asiaeorientalis in the West Coast of Korea, where they predominantly inhabit. Sighting surveys were conducted in March and November 2021-2022 using vessels and aircraft during the same time periods and along the same survey transects. The aerial surveys yielded significantly more sightings than shipboard surveys, with 8.5-21.6 times the abundance and 6.3-16.9 times the number of observations. The detection rates were 0.000-0.047 and 0.0103 to 0.539 per km2 for shipboard and aerial surveys, respectively. The densities were estimated to be 0.003-0.061 and 0.236-1.898 individuals per km2 in the shipboard and aerial surveys, respectively. The shipboard survey conducted in March 2022 and the aerial survey conducted in November 2021 had the highest detection rates and abundance. In the coastal waters, shipboard sighting surveys face numerous challenges due to factors such as fishing gear, islands, and shallow water depths. In contrast, aerial surveys have the advantage of a shorter survey period and are less affected by weather, fisheries, coastal lines, and other variables. Thus, they are highly suitable for studying narrow-ridged finless porpoises in the coastal areas of the West Sea.

Seabird Distribution Patterns by Sighting Survey in the East Sea in Spring (목시조사(Sighting survey)에 의한 동해 봄철 해양성 조류의 분포 양상)

  • Kim, Hyun-Woo;Kim, Zang-Geun;Choi, Seok-Gwan
    • Korean Journal of Environment and Ecology
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    • v.25 no.2
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    • pp.123-131
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    • 2011
  • Seabird distribution in the East Sea was studied from April to May 2007 using line transect counts. We observed a total of 1,379 individuals of 23 species including 14 species of seabird. The overall seabird sighting rate was 2.5 birds $km^{-2}$. The Streaked shearwater(Calonectris leucomelas)(74.5%) was the numerically dominant species. Ancient murrelets(Synthliboramphus antiquus)(8.3%), red-throated divers(Gavia stellata)(5.0%), common terns(Sterna hirundo)(2.1%), Pacific divers(Gavia pacifica)(2.0%), and black-tailed gulls (Larus crassirostris)(1.1%) were also frequently observed. The sightings of seabirds was highest between $36^{\circ}N$ and $37^{\circ}N$ of the coastal area of the Korean peninsular. However, the index of species diversity(H') was higher between $35^{\circ}N$ and $36^{\circ}N$. The sighting rates of most observed species decreased with distance from the coastline. The distribution patterns of Streaked shearwater were linked to the variation in the distribution pattern of minke whales(Balaenoptera acutorostrata). Also, spatial segregation was found in the distributions of the two species of divers(Gavia spp.).

Feasibility of Aerial Surveys of Finless Porpoise Neophocaena asiaeorientalis off the West Coast of Korea (한국 서해에서 상괭이(Neophocaena asiaeorientalis)의 항공 조사 타당성)

  • Park, Kyum Joon;Sohn, Hawsun;Kim, Yeong Hye;Kim, Doo Nam;Kim, Hyun Woo;An, Du Hae;An, Yong-Rock
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.46 no.6
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    • pp.966-969
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    • 2013
  • Vessel-based sighting surveys for cetaceans have been conducted in Korean waters since 2000. The supporting data estimate the abundance of finless porpoises along the west coast of Korea; however, they are insufficient because of the coverage and frequency of the surveys. A preliminary aerial survey was conducted in 2011, and the results were assessed with respect to a sighting survey operated by a research vessel in order to compare effectiveness and potentiality. A total of 110.00 nautical miles of effective efforts were made with three sightings under Beaufort scale 4 in the aerial survey, while the vessel-operated survey covered 403.38 nautical miles over 7 days without any sightings under Beaufort scale 4. The standard deviation of the altitude in this survey was 22.7 m, which was significantly higher than that of the referenced study of 4.3 m.

A study on vertical distribution observation of giant jellyfish (Nemopilema nomurai) using acoustical and optical methods (음향 및 광학기법을 이용한 노무라입깃해파리 (Nemopilema nomurai)의 수층별 분포 관찰에 관한 연구)

  • Lee, Kyoung-Hoon;Kim, In-Ok;Yoon, Won-Duk;Shin, Jong-Keun;An, Heui-Chun
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.43 no.4
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    • pp.355-361
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    • 2007
  • A giant jellyfish (Nemopilema nomurai), which is presumed developing in the East China Sea, is recently one of major issues in the Northeast Asia region due to its fatal damage to the fishery. The biomass estimates have generally been conducted by trawl sampling and sighting survey methods. The biological research is also needed to clarify such environmental origin or diurnal migration patterns. While trawl sampling or sighting survey methods are effective to investigate its density estimates in its distributed community of near bottom or surface, they have a problem in investigation on the vertical distribution of jellyfishes. In this case, an echo sounding detection would have an advantage to survey it more extensively and effectively. This trial was conducted to observe the vertical distribution of giant jellyfish, where thermocline strongly formed, during mooring at each station of the East China Sea and southern coastal area using acoustical and optical methods. By the results, they were observed to exit and move at the water column under the thermocline using the optical camera and echo sounder system, and the information was analyzed to find out the acoustical sound scattering characteristics relatives to 120kHz frequency. These results can be utilized effectively to estimate the vertical distribution and biomass of Giant jellyfish with comparing results from trawl sampling and sighting survey methods, hereafter.

Distribution Status of Indo-Pacific Bottlenose Dolphin Tursiops aduncus in the Jeju Island Based on Social Media Data (소셜 미디어 정보를 활용한 제주도 남방큰돌고래(Tursiops aduncus)의 분포 현황 파악)

  • Kim, Hyun Woo;Lee, Dasom;Sohn, Hawsun
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.51 no.5
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    • pp.600-605
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    • 2018
  • The Indo-Pacific bottlenose dolphins Tursiops aduncus are the only cetacean species that can be observed visually on coastal areas of Jeju Island and regarded as one of valuable tour resources. We attempted to figure out location and timing information of the dolphin sightings collected from two major social media, Naver $Caf{\acute{e}}$ and Instagram. 142 of dolphin sighting information were derived from 2,501 dolphin related postings on Naver $Caf{\acute{e}}$ between 2004 to 2017. 292 informative postings also were found on Instagram through hashtag searching. The number of posts about dolphin sighting was not frequent until 2014. Since 13 posts were found in 2014, dramatic increase of the sighting numbers was accelerated as 38 in 2015, 93 in 2016 and 269 in 2017. 195 (45.7%) from coastal area of Daejeong-eup, south-western part of the Island, were posted. The number of dolphin sightings also high from Gujwa-eup(n=50, 11.7%), Hangyeong-myeon (n=49, 11.5%), Seongsan-eup (n=38, 8.9%) and Seogwipo-si (n=34, 8.0%). Our results show that social media data has a high potential to be used as a data source for study of distribution pattern of the dolphins.

Inhabitant and Appearance of Finless Porpoise (Neophocaena asiaeorientalis) in the Coastal Wido, Korea (한국 위도 주변해역 상괭이 (Neophocaena asiaeorientalis)의 출현과 서식생물)

  • Lee, Yoo-Won;Choi, Youn;Lee, Heung Heon;Hwang, Bo-Kyu
    • Journal of Fisheries and Marine Sciences Education
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    • v.26 no.3
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    • pp.578-586
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    • 2014
  • The seasonal appearance and distribution of finless porpoise (Neophocaena asiaeorientalis) was investigated with sighting survey method around Wido in West sea, Korea. Fishing survey with drag net was also conducted to investigate the species composition of inhabitants and the consignment quantity data of fisheries cooperation was collected to confirm the seasonal change of the composition and quantity of them. Finless porpoise didn't emerged around Wido in winter season, but the number of appearance in summer season amounted to 1~15 indv. for 15 observing points and the appearance frequency became lower in open sea than in inshore. There was also significant relationship between the appearances of finless porpoise (Neophocaena asiaeorientalis) and that of inhabitants. we consequently concluded that finless porpoise typically distributes from April to september, and moves to another area for wintering and food consumption from October to March.

A Review on the Status of Pinnipeds in Korea (국내 기각류 서식 현황 연구)

  • Kim, Hyun Woo;Lee, Seulhee;Sohn, Hawsun
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.54 no.2
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    • pp.231-239
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    • 2021
  • There are six species of pinnipeds in Korean waters. Because of the lack of research on pinnipeds, it has been difficult to obtain ecological information on each species. All six species have been designated as endangered species, marine protected species, or national monuments by the government, depending on historical records. In this study, the current status of pinnipeds in Korea was investigated through reviewing the literature, and sighting and bycatch records, with the intention of providing new information for the review of the six species. Spotted seals and northern fur seals are well known inhabitants of Korea. The southern part of the East Sea is thought to be the margin of the distribution of Steller sea lions. Sightings of ribbon seals and ringed seals were not confirmed in Korean waters. Sea lions have not been seen since their last sighting on Dokdo in 1951 and are thought to have become extinct after that. It is necessary to delist undistributed or extinct species in Korea from the marine protected species list.