Kuliak, a male Steller sea lion (Eumetopias jubatus) pup was born on June 22, 2017 at the Alaska SeaLife Center to four-time mom, Eden. While obviously adorable, you may ask yourself… Why are the Steller sea lions at the ASLC breeding? For enrichment? To mimic wild conditions? To have more pups for public debut?
The answer is actually… to help us understand the reproductive biology and physiologyof this listed and declining species!
Kuliak is one of four Steller sea lion pups born of the 8yr long ASLC captive Steller sea lion breeding program. Initiated in 2009, the program was designed to investigate the reproductive physiology of adult female Steller sea lions and understand the energetic requirements of growing Steller pups.
For the adult females, we focused on developing methodologies for identifying key events in the reproductive season (i.e. estrus, implantation, and pregnancy).
1. Estrogen is a key reproductive hormone associated with a female’s sexual receptivity during the breeding season and progesterone is important to maintaining a viable pregnancy. We aimed to quantify and track the changes in estrogen and progesterone in serum and fecal samples from pregnant and non-pregnant female Steller sea lions. Understanding these fluctuations with seasons and pregnancy will aid researchers studying the population dynamics of wild Steller sea lions.
2. Similarly, we quantified and tracked cellular changes from vaginal swabs to identify estrus. If successful, this could be a tool utilized in captive facilities to time introducing females and males to optimize successful breeding events.
3. We also assessed the relationship between blood health parameters and body conditions as measured by blubber depth and D20 (a method of calculating body composition from water and lipid content) over seasons and with pregnancy.
We also can learn a lot from pups as they grow up!
4. Young sea lions are difficult to age in the wild. By tracking changes in body condition, size, cranial and dental growth in Steller sea lion offspring from the resident breeding program, we hope to develop a growth curve to estimate age in Steller sea lions < 2 years old in the wild.
Data collection on these studies has predominantly been completed and is currently being analyzed and documented to share with the public and scientific community.
Written by: Renae Sattler
All photos and research permitted under NOAA/NMFS #18534