Food Habits of Finless Porpoises Neophocaena phocaenoides in Western Kyushu, Japan

Shirakihara, Miki; Seki, Kazuhiko; Takemura, Akira; Shirakihara, Kunio; Yoshida, Hiderou; Yamazaki, Takeshi

doi:10.1644/07-mamm-a-264.1

Cited by 34 publications

(39 citation statements)

References 13 publications

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“…This behavior is often related to an adaptation to the circadian rhythms of prey species (e.g., Baird et al, 2001;Benoit-Bird and Au, 2003;Scott and Chivers, 2009). Finless porpoises living in seawater are considered to be opportunistic feeders preying on various fish species and crustaceans (Barros et al, 2002;Park et al, 2005;Shirakihara et al, 2008). The Yangtze finless porpoise may prefer to forage on nocturnal fish or shrimp.…”

Section: Idmentioning

confidence: 99%

Variation in the production rate of biosonar signals in freshwater porpoises

Kimura

Akamatsu

Wang

et al. 2013

The Journal of the Acoustical Society of America

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The biosonar (click train) production rate of ten Yangtze finless porpoises and their behavior were examined using animal-borne data loggers. The sound production rate varied from 0 to 290 click trains per 10-min time interval. Large individual differences were observed, regardless of body size. Taken together, however, sound production did not differ significantly between daytime and nighttime. Over the 172.5 h of analyzed recordings, an average of 99.0% of the click trains were produced within intervals of less than 60 s, indicating that during a 1-min interval, the number of click trains produced by each porpoise was typically greater than one. Most of the porpoises exhibited differences in average swimming speed and depth between day and night. Swimming speed reductions and usage of short-range sonar, which relates to prey-capture attempts, were observed more often during nighttime. However, biosonar appears to be affected not only by porpoise foraging, but also by their sensory environment, i.e., the turbid Yangtze River system. These features will be useful for passive acoustic detection of the porpoises. Calculations of porpoise density or abundance should be conducted carefully because large individual differences in the sound production rate will lead to large estimation error.

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Section: Idmentioning

confidence: 99%

Variation in the production rate of biosonar signals in freshwater porpoises

Kimura

Akamatsu

Wang

et al. 2013

The Journal of the Acoustical Society of America

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“…Breeding is also likely to occur at that time, as the gestation period of the species is estimated to last 11 mo (Kasuya & Kureha 1979). During these seasons the ratio of the numbers of fishes in stomach contents of the porpoises in the Ariake Sound/Tachibana Bay population was larger than that in spring and summer seasons (M. Shirakihara et al 2008). Behaviors such as reproduction or foraging may be related to the increase in bycatch in fall and winter.…”

Section: Discussionmentioning

confidence: 81%

“…Seasonal changes in density of the genus Neophocaena have been described in various waters (Kasuya & Kureha 1979, Jefferson et al 2002, Taguchi et al 2007, Akamatsu et al 2008, Kondo et al 2010, Kimura et al 2012. The peak of the calving season in the Ariake Sound/Tachibana Bay population has been determined to occur in fall and winter (M. Shirakihara et al 2008). Breeding is also likely to occur at that time, as the gestation period of the species is estimated to last 11 mo (Kasuya & Kureha 1979).…”

Section: Discussionmentioning

confidence: 99%

“…1) were collected during a survey for the studies of life history and food habits of the porpoises in 1987 to 1992. Entangled individuals were provided by fishermen as biological specimens (M. Shirakihara et al 1993Shirakihara et al , 2008. The data included the type of gear used, net length/height, mesh size, distance from shore and depth at the location of net setting, the time of net setting and retrieving, target fish species, fish species caught, months when the net was used and months when the fishermen sighted the porpoises.…”

Section: Bycatch Data Collected In 1987 To 1992mentioning

confidence: 99%

“…1). This population, whose size in 1993/1994 was estimated at 3093 individuals (Yoshida et al 1997), suffers mortalities in bottom-set and drift gillnets (M. Shirakihara et al 1993Shirakihara et al , 2008. To clarify the magnitude of bycatch in gillnet fisheries for this population, we conducted interview-based surveys among fishermen in 2007 and 2008.…”

Section: Introductionmentioning

confidence: 99%

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Finless porpoise bycatch in Ariake Sound and Tachibana Bay, Japan

Shirakihara¹,

Shirakihara²

2013

Endang. Species. Res.

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Spatial–temporal variations in biosonar activity of Yangtze finless porpoise in the lower reaches of the Yangtze River and its correlation with underwater noise: Are quieter non‐shipping branches the remaining shelters?

Duan

et al. 2021

Aquatic Conservation

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Yangtze finless porpoise (YFP) is Critically Endangered, It relies on its biological sonar sensing system for important life activities. The rapid development of the Yangtze valley has brought busy shipping, which has resulted in increased noise. Two locations on the shipping channel and non‐shipping branch were selected. Passive acoustic monitoring was used to record the biosonar signals of porpoises and underwater noise. The number of click trains, echolocation encounters, buzzes and buzz ratios were counted and the root mean square sound pressure level of noise was calculated in five diel phases. A non‐parametric test was used to analyse the differences among different phases and between different locations. The aim of the study was to detect the spatial and temporal variations in the biosonar activity of YFPs and underwater noise between non‐shipping and shipping channels, and to provide scientific advice for YFP conservation. Significant spatial and temporal patterns were observed both in biosonar activity and noise. Average biosonar activity, including click trains, buzzes, buzz ratio and echolocation encounters, was higher in the non‐shipping channel than in the shipping channel, whereas the noise level was higher in the shipping channel than in the non‐shipping channel. In the non‐shipping channel, the buzz numbers and buzz ratios, indicators of porpoise feeding activity, were higher at night than during the day while the noise level was higher during the day than at night. These findings may be associated with the noise avoidance strategies of YFPs to adapt to the busy shipping on the Yangtze River. Maintaining the non‐shipping status of some branches of the Yangtze River can provide more shelters for the YFPs. Strengthening the measures for banning navigation at night or reducing the vessel speed at night throughout the entire year would improve the YFPs’ feeding success.

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Food Habits of Finless Porpoises Neophocaena phocaenoides in Western Kyushu, Japan

Cited by 34 publications

References 13 publications

Variation in the production rate of biosonar signals in freshwater porpoises

Variation in the production rate of biosonar signals in freshwater porpoises

Finless porpoise bycatch in Ariake Sound and Tachibana Bay, Japan

Spatial–temporal variations in biosonar activity of Yangtze finless porpoise in the lower reaches of the Yangtze River and its correlation with underwater noise: Are quieter non‐shipping branches the remaining shelters?

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