Population Size of Indo-Pacific Humpback Dolphin (Sousa chinensis)

Themes

Abundance trends of selected taxa

PSBR model type

State (S)

Corresponding targets

Aichi Biodiversity Targets

Target 12 By 2020 the extinction of known threatened species has been prevented and their conservation status, particularly of those most in decline, has been improved and sustained.

Background

Sousa chinensis, also known as the Mazu fish, inhabits Taiwan's western coast. The current population is smaller than 100. The Forestry Bureau, Council of Agriculture, has announced that the main threats to the “Important Wildlife Habitat for Indo-Pacific Humpback Dolphin” come from reduced food sources, the disappearance of habitats, marine pollution, the underwater noise, and the accidental catch by gill net.

Definition and Calculation

In the distribution area of Indo-Pacific humpback dolphin, the environmental and human activity factors are recorded in the regular fixed-route surveys conducted based on different water depth gradients, and their spatial distribution and the dynamics of habitat utilization are tracked. In the hot-zone, temporal and spatial changes in abundance are monitored using a passive acoustic monitor, to make up for the non-visual periods (night and autumn, winter, and spring). Further, individuals are identified using photos, and numbers of individuals (including mother-child pairs) and other population parameters were calculated using methods for population estimation.

Updates

According to the monitoring report from the team led by professor Lien-Siang Chou at National Taiwan University, the number of Indo-Pacific humpback dolphins witnessed in 2018 was 51.

Trends

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Data Management Authorities

Forestry Bureau, Council of Agriculture, Ocean Conservation Administration

Data Source / URL

Chou et al. 2018, Population Ecology and Estuary Habitat Monitoring for Chinese White Dolphin (Sousa chinensis), sponsored by Forestry Bureau, Council of Agriculture.