Abstract 151 – Development of Assisted Reproduction Techniques for the Successful Restoration of the Asiatic Black Bear in Korea

Eui-beom Kyeong, Sook-jin Lee, Seung-hyo Lim, Ji-sang Yu, Ann-Na Lee, Min Kim,
Da-in Lee, Ho-nam Kang, Jeong-jin Yang, Dong-Hyuk Jeong

The Asiatic black bear (Ursus thibetanus) has been undergoing restoration in South Korea since 2004. Acquiring seed animals remains a challenge, hindering systematic project management.
Although population growth has occurred, limited genetic diversity is a concern due to
restricted male breeding participation. To address this, a combined approach of Ex-situ
breeding programs and in-situ reproduction was implemented to facilitate more strategic
population management and enhance genetic diversity. And here we describe what we have
done so far to establish artificial reproduction technology for Asiatic black bear. In females, we
analyze estrus patterns using ultrasonography, urinary hormones, and other biological
indicators. Urinary progesterone is a reliable predictor of ovulation. Indicators like external
genital size, follicular development, and vaginal cytology positively correlate with the estrus
cycle. Based on these indicators, we determine optimal timing for artificial insemination (AI)
using a ureteroscope for uterine semen injection. In males, we use ultrasound-guided urethral
catheterization to collect high-quality semen (concentration: 4,718.9 ± 1,526.1 x106/ml;
viability: 98.2 ± 2.3%). Five cubs were successfully born via AI from four females and released
into the wild. This represents a global breakthrough in Asiatic black bear artificial insemination.
Importantly, assisted reproduction technology (ART) extends beyond its scientific merits,
directly facilitating the conservation of endangered species through the release of ART-
produced offspring into their natural habitat. This study also provides one of the approaches to
address the difficulties of importing bears and increasing genetic diversity, which will aid the
restoration project and contribute to a sustainable bear population.