Seasonal changes in the local distribution of Yangtze finless porpoises related to fish presence

Kimura, Susumu; Akamatsu, Tomonari; Li, Songhai; Dong, Lijun; Wang, Kexiong; Wang, Ding; Arai, Nobuaki

doi:10.1111/j.1748-7692.2011.00490.x

Cited by 54 publications

(63 citation statements)

References 33 publications

(45 reference statements)

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“…In this study, porpoise biosonar behavior was significantly correlated with fish density, which supports previous findings that significantly more finless porpoises are encountered in areas with fish than in areas without fish [12]. Moreover, the higher fish densities observed in the evenings and at night in this study are consistent with more recent fixed echosounder detection findings that fish in the Yangtze River are more active (i.e., more fish are detected) and employ river bank-oriented movement at night [50].…”

Section: Discussionsupporting

confidence: 91%

The Diel Rhythms of Biosonar Behavior in the Yangtze Finless Porpoise (Neophocaena asiaeorientalis asiaeorientalis) in the Port of the Yangtze River: The Correlation between Prey Availability and Boat Traffic

et al. 2014

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Information on the habitat use of the critically endangered Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is critical for its conservation. The diel biosonar behavior of the porpoise in the port areas of the Yangtze River was examined along with simultaneous observations of fish density and boat traffic. Biosonar pulses from the porpoises were detected for 1233 min (5.77%) over a 21,380 min duration of effective observations. In total, 190 (5.63%) buzzes (an indication of prey capture attempts) were recorded among the 3372 identified click trains. Of the 168 echolocation encounters (bouts of click trains less than eight min apart), 150 (89.3%) involved single animals, indicating that solitary porpoises were frequently present and feeding in the port areas. Significant diel patterns were evident involving the biosonar behavior of the porpoises (including click trains and buzzes), fish density and boat traffic. The frequencies of the click trains and buzzes were significantly lower during the day than in the evening and at night, which suggests that porpoises in this region are primarily engaged in crepuscular and nocturnal foraging. The lack of a significant diel pattern in the echolocation encounters indicates the importance of the port in porpoise conservation. A forced feeding schedule may be associated with the lack of a significant correlation between porpoise acoustics and boat traffic. Overall, prey availability appears to be the primary factor that attracts porpoises. Additionally, porpoises tend to migrate or remain downstream in the morning and migrate or remain upstream in the evening, most likely to follow their prey. The findings of this study can be used to improve the conservation of the Yangtze finless porpoise.

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Section: Discussionsupporting

confidence: 91%

The Diel Rhythms of Biosonar Behavior in the Yangtze Finless Porpoise (Neophocaena asiaeorientalis asiaeorientalis) in the Port of the Yangtze River: The Correlation between Prey Availability and Boat Traffic

et al. 2014

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“…In this regard, the connectivity of Poyang Lake to the Yangtze River provides critical refuge for fishes adapting to the river-floodplain system. Meanwhile, the finless porpoise was observed to be more abundant in the river section up and down the mouth of Poyang Lake than in other parts of the river (Kimura et al, 2012). The availability of prey fish is suggested as a major factor influencing the distribution of the finless porpoise (Wang et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

The spatial pattern of larval fish assemblages in the lower reach of the Yangtze River: potential influences of river–lake connectivity and tidal intrusion

Ren

Song

et al. 2015

Hydrobiologia

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Landscape pattern plays an important role in structuring of larval fish assemblages in large river basins. The lower reach of the Yangtze River includes the river section from the mouth of Poyang Lake, the largest freshwater lake in China, downward to the estuary. We hypothesized that river-lake connectivity at the upstream portion and tidal intrusion at the downstream portion are significant drivers of larval fish assemblages. Larval fish were collected monthly from April 2012 through September 2013 in three locations at Anqing (AQ), Nanjing (NJ), and Jingjiang (JJ). Fifty-six taxa of larval fish were identified with 52 of them determined of species. Larval fish were highly abundant from April through August; the number of species and the abundance were much higher at AQ than at NJ and JJ; the bloom of larval fish at JJ tended to be later than at NJ and AQ. We suggest that the larger number of species and higher abundance of larval fish at AQ reflect the effects of the connectivity of Poyang Lake with the river upstream of AQ, and the delayed bloom of larval fish and the occurrence of estuarine species at JJ reflect the influences of tidal intrusion from the estuary.

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“…Few studies in cetacean foraging ecology have sampled prey availability, and of these, most have used one fishing method only to sample prey (e.g., Heithaus and Dill, 2002;Torres and Read, 2009;McCabe et al, 2010;Kimura et al, 2012;Eierman and Connor, 2014). While each fishing method has its biases and limitations, the aim of using multiple fishing methods in this study was to alleviate some of those limitations.…”

Section: Prey Sampling Using Multiple Catch Methodsmentioning

confidence: 99%

Dolphin Prey Availability and Calorific Value in an Estuarine and Coastal Environment

2016

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Prey density has long been associated with prey profitability for a predator, but prey quality has seldom been quantified. We assessed the potential prey availability and calorific value for Indo-Pacific bottlenose dolphins (Tursiops aduncus) in an estuarine and coastal environment of temperate south-western Australia. Fish were sampled using three methods (21.5 m beach seine, multi-mesh gillnet, and fish traps), across three regions (Estuary, Bay, and Ocean) in the study area. The total biomass and numbers of all species and those of potential dolphin prey were determined in austral summers and winters between 2007 and 2010. The calorific value of 19 species was determined by bomb calorimetry. The aim of the research was to evaluate the significance of prey availability in explaining the higher abundance of dolphins in the region in summer vs. winter across years. A higher abundance of prey was captured in the summer (mean of two summer seasons 12,080 ± 160) than in the winter (mean of two winter seasons = 7358 ± 343) using the same number of gear sets in each season and year. In contrast, higher biomass and higher energy rich prey were captured during winters than during summers, when fewer dolphins are present in the area. Variability was significant between season and region for the gillnet (p < 0.01), and seine (p < 0.01). The interaction of season and region was also significant for the calorific content captured by the traps (p < 0.03), and between the seasons for biomass of the trap catch (p < 0.02). The dolphin mother and calf pairs that remain in the Estuary and Bay year round may be sustained by the higher quality, and generally larger, if lesser abundant, prey in the winter months. Furthermore, factors such as predator avoidance and mating opportunities are likely to influence patterns of local dolphin abundance. This study provides insights into the complex dynamics of predator-prey interactions, and highlights the importance for a better understanding of prey abundance, distribution and calorific content in explaining the spatial ecology of large apex predators.

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Seasonal changes in the local distribution of Yangtze finless porpoises related to fish presence

Cited by 54 publications

References 33 publications

The Diel Rhythms of Biosonar Behavior in the Yangtze Finless Porpoise (Neophocaena asiaeorientalis asiaeorientalis) in the Port of the Yangtze River: The Correlation between Prey Availability and Boat Traffic

The Diel Rhythms of Biosonar Behavior in the Yangtze Finless Porpoise (Neophocaena asiaeorientalis asiaeorientalis) in the Port of the Yangtze River: The Correlation between Prey Availability and Boat Traffic

The spatial pattern of larval fish assemblages in the lower reach of the Yangtze River: potential influences of river–lake connectivity and tidal intrusion

Dolphin Prey Availability and Calorific Value in an Estuarine and Coastal Environment

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