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Oh, Y.; Sohn, H.; Lee, D.; An, Y.-R.; Kang, C.-K.; Kang, M.G., and Lee, S.H., 2018. Feeding patterns of ‘Finless porpoise (Neophocaena asiaeorientalis)’ in the yellow sea as indicated by stable carbon and nitrogen ratios. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 386–390. Coconut Creek (Florida), ISSN 0749-0208.Finless porpoise (Neophocaena asiaeorientalis) is a representative marine mammal that has the largest habitat near the Korean coastal area. However, little information on their trophic ecology has been reported in Korea to date. The stable carbon and nitrogen isotope ratios from muscle samples (n = 60) were analyzed for their trophic ecology. The muscle tissues from the stranded or by caught porpoises in the Yellow Sea were obtained in 2015 (n = 37) and 2016 (n = 23) by Cetacean Research Institute in Korea. The averages of δ13C and δ15N for all the samples were −17.74 ‰ (S.D. = ±0.74 ‰) and 12.96 ‰ (S.D. = ±0.95 ‰), respectively. The mean isotopic values of the porpoise groups obtained from different seasons were −18.13 ‰ (±0.56 ‰) and 12.43 ‰ (±0.73 ‰) and −17.06 ‰ (±0.46 ‰) and 13.87 ‰ (±0.46 ‰) for summer (n = 38) and spring (n = 22), respectively, which were significantly different among the two seasons (t-test; p < 0.01, n = 60, respectively). These increasing isotope values from summer to spring reflected a shift in major prey sources. The small increasing in δ15N values could be caused partly by different body lengths of the porpoises. However, the most plausible reason for the large shift in δ13C value relative to δ15N could be a change from pelagic to benthic prey in the different seasons since benthic diets are reported for enriched δ13C over the pelagic diets. For better understanding, further validation should be conducted.

The west coast of Korea is the largest habitat for finless porpoises, with approximately 36,000 individuals reported in 2005 (Park et al., 2007). To date, there have been no subsequent finless porpoise population estimates. However, in recent bycatches, finless porpoises accounted for the highest proportion of all cetaceans and have been reported to be most frequently caught on the west coast of Korea (Kim et al., 2013). The present study, conducted in 2011, enumerated finless porpoises inhabiting the west coast of Korea using a line transect survey in offshore and inshore regions to assess variations in their abundance. In offshore regions we found the population density of finless porpoises to be 0.122 ind./km 2 , whereas it was 0.565 ind./km 2 in 2004. In inshore regions, the population density of finless porpoises was 0.151 ind./km 2 , whereas it was 0.638 ind./km 2 in 2005. Therefore, we estimate that the population densities of finless porpoises in both offshore and inshore regions of the west coast of Korea decreased by ap proximately 70% between 2004/2005 and 2011. It is imperative to mitigate the bycatch of finless porpoises and protective action is urgently needed in the near inshore regions.

상괭이(Neophocaena asiaeorientalis)는 쇠돌고래과(Family Phocoenidae)에 속하는 소형 돌고래로 다른 돌고래류와 달리 등지느러미가 없고 둥근 머리를 가지고 있다(Jefferson et al., 2008). 분포지역은 페르시아와 일본까지 아시아에만 분포하며 최근 연구를 통해, 중국 중남부를 기준으로 아시아 서부 지역 상괭이와 동부 지역 상괭이가 종 수준으로 다르다는 것이 밝혀 졌다(Wang et al., 2008). 상괭이는 멸종위기동식물 국제거래 에 관한 협약(CITES)의 부속서 1에 등재되어 상업적인 거래가 금지된 보호 종이다(CITES, 2014). Park et al. (2007)은 한반 도 서해 연안에 약 36,000마리의 상괭이가 서식하고 있는 것으 로 추정하여 서해 연안이 상괭이의 최대서식지임이 밝혀졌다. 새만금 방조제는 이 서해안에 건설된 세계 최장 방조제(33.9 km)로 전라북도 군산에서 신시도를 거쳐 부안을 연결하였으며 두 개의 하천에 유입되는 담수를 배출하고 해수를 순환시키기 위한 두 개의 갑문을 가지고 있다. 새만금 방조제는2006년에 최종 물막이 공사가 끝났다. 물막이 공사가 끝나고 4년이 지난 2011년 2월, 새만금 방조제 호 안에서 대량 폐사한 상괭이가 발 견되면서 새만금 방조제 호 안에 상괭이가 서식한다는 사실이 처음으로 밝혀졌다 (Hankookilbo, 2011). Park et al. (2012)은 이상 저온으로 새만금호의 수면이 얼어서 호 안의 상괭이 249 새만금호의 상괭이 대량 폐사 후 상괭이(Neophocaena asiaeorientalis) 재출현과 분포 경향 박겸준*·이승용·안용락·김현우·안두해·김두남·김영혜

Finless porpoise is the one of porpoises in Korean waters that frequently observed in the coastal area. This study reported parasite infection cases of stranded finless porpoise, Neophocaena asiaeorientalis which was stranded on the Saemangeum Dyke on the west coast of Korea 21 May, 2012. The finless porpoise was male, and estimated at 8 years old. Parasites were found in abdominal cavity, skull and lung. The parasites were identified as nematode, trematoda and lungworm. Nematoda in abdominal cavity was Crassicauda sp. Trematoda found in the skull was indentified Nasitrema sp. Lungworm in lung seemed one of genus Pseudaliids. Anisakis spp. has not been found.

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 total of 116 finless porpoises, Neophocaena asiaeorientalis, were collected in the Yellow Sea off Korea. About 111 specimens were incidentally caught by stow nets on anchors from March to June 2010, and five were stranded in February 2011. Age was determined by counting dentinal growth layer groups (GLGs) in thin-sectioned teeth, and sexual maturity rating (SMR) was classified by investigating ovaries and testis macroscopically and microscopically. Immature females were ranged 1–4 years old and 92.6–141.2 cm in total body length (TBL), pubertal ones were all 5 years old and 125.4–136.0 cm, and mature ones ranged 5–19 years old and 131.6–155.2 cm. Age at attainment of sexual maturity of females was 4–5 years old. Parturition season estimated based on TBL of eight fetuses was from April to August with a peak in April to May. The first age at parturition was 5 years old. Among 62 males, immature males were 1–4 years old and 87.9–154.6 cm, pubertal ones were 3–5 years old and 121.5–134.5 cm, and mature ones...

In the late 1970s, the National Fisheries Research & Development Institute (NFRDI) started cetacean research to submit the Korean whale catch record to the International Whaling Commission. This continued until the moratorium on commercial whaling in 1986. The NFRDI resumed cetacean research with a pilot whale sighting survey in 1999. Subsequently, the NFRDI has conducted 53 cetacean sighting surveys within the Korean exclusive economic zone between 2000 and 2010. The surveys took a total of 760 days and cruising for 23,866 nautical miles. The finless porpoise Neophocaena asiaeorientalis was sighted most frequently (735 times), followed by the minke whale Balaenoptera acutorostrata (396 times), the long-beaked common dolphin Delphinus capensis (102 times), and the Pacific white-sided dolphin Lagenorhynchus obliquidens (27 times). Minke whales were distributed in the Yellow Sea and coastal area of the East Sea from spring to fall. Pacific white-sided dolphin sightings were restricted to the middle and upper coastal areas of the East Sea in summer. Common dolphins were sighted from east of the southern coast to the eastern coast of the Korean Peninsula from spring to fall. Finless porpoise occurred in all Korean coastal areas, except the middle and upper eastern coast.

Reports of the occurrence and accumulation patterns of polycyclic aromatic hydrocarbons (PAHs) and synthetic musk compounds (SMCs) in marine mammals are scarce. In this study, the concentrations and accumulation profiles of PAHs and SMCs were determined in blubber from finless porpoises in Korean coastal waters. Total concentrations of PAHs and SMCs ranged from 6.0 to 432 (mean: 160) ng/g lipid weight and from 17 to 144 (mean: 52) ng/g lipid weight, respectively. Residue levels of PAHs were lower than those reported from other studies, while residue levels of SMCs were relatively higher than those reported in other studies. Naphthalene was the most abundant PAH and HHCB was the dominant SMC observed in finless porpoises. The concentrations of PAHs and SMCs were not correlated with each other, but were significantly correlated within the same chemical groups. No correlations were found between body size and residue levels of PAHs and SMCs.

We investigated the stomach contents of finless porpoises collected in the Yellow Sea. Prey organisms in the stomachs of 109 finless porpoises were identified as 11 species of fish, 8 species of shrimp and 4 species of cephalopod. Index of Relative Importance analysis revealed that the porpoises fed mainly on the Japanese sand shrimp (Crangon affinis). The energy density of the prey was estimated to be 5.46 kJ. The daily energy requirement was estimated to be 18,051 kJ/day for a porpoise with an average weight of 32.49 kg. The estimated annual consumption by finless porpoises in the Yellow Sea was 25,454 tons. The average commercial catch in the Yellow Sea by Korean fisheries was 135,913 tons from 2005 to 2009. Assuming that the abundance of finless porpoises is stable, porpoises ate approximately 18.7% of the commercial catch. The fishery catch may be influenced by the consumption by finless porpoises, while fishery bycatch is a cause of porpoise mortality in the Yellow Sea.

To confirm the distributon of finless porpoise, Neophocaena phocaenoides, in the South Sea of Korea, data on bycatch, stranding, and drifting of finless porpoises from 1999 to 2009 were used and a sighting survey was conducted from the R/V Tamgu No. 9 and 10 in June and November, 2009 and March, 2010. The total number of bycaught, stranded, and drifting finless porpoises was 607, with position being known for 186 of these. At the center of Yeosu, there were few position data on bycaught, stranded, and drifting finless porpoises, and data could not confirm the distribution of finless porpoises. Thus, there were limits on the usefulness of bycaught, stranded, and drifting data for confirming the distribution of finless porpoises. In the three sighting surveys, the sighting rate was highest at 0.231 ind./n.m. in the western South Sea in June, 2009. Sighting rate was less than 0.1 ind./n.m. in November, 2009 and March, 2010. This is likely to be due to seasonal migration in western South Sea. All sighting rates in the eastern South Sea were over 0.13 ind./n.m.. According to the results of the sighting survey, finless porpoises are distributed around the islands and inner bay along the path of the research vessel in the South Sea. There were numerous finless porpoises in the offshore areas of Mokpo, Yeosu, Tongyeong, Dadaepo, and Gaduk-do. This study will be utilized as part of a future abundance assessment of finless porpoise in the South Sea of Korea.

Data on the concentrations and accumulation profiles of polychlorinated dibenzo- p -dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in cetaceans are scarce. In this study, concentrations and accumulation profiles of PCDD/Fs and DL-PCBs were measured in the blubber of finless porpoises ( Neophocaena phocaenoides ) collected from Korean coastal waters. Total dioxin-like toxic equivalent (TEQ) concentrations (6.5–31 pg/g lipid weight) in finless porpoises were lower than those reported for cetaceans and pinnipeds from other countries. Significant gender-specific differences were found in the concentrations and accumulation profiles of PCDD/Fs and DL-PCBs and this difference was associated with maternal and lactation transfer of contaminants from mature females to their fetus. All of the PCDD/F homologue groups were detected in all of the samples and the proportions of PCDFs were higher than those of PCDDs. The dominant congeners found in finless porpoise blubber were 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF and OCDD for PCDD/Fs and PCB 118 for DL-PCBs. The accumulation profiles of PCDD/Fs in finless porpoise in our study were different from those found for cetaceans from other countries. Total TEQ levels in finless porpoises in Korea were below the suggested threshold values for adverse health effects in marine mammals.