Kon et al. (2010) sampled very old-shell female opies for GSI, ovarian color, and embryonic development. The purpose of this project was to estimate the fecundity of a population in the western Sea of Japan that has experienced a perceived increase in female average age due to artificial reefs and reserves.
Sea of Japan and Fukui Prefecture (starred) where the crabs were offloaded
With females getting older, the researchers wanted to determine if they were reproductively contributing as much as their younger sisters. Long story short: they were not.
The very old-shell females’ ovaries had dozens of nodules, which were darker tinted areas, indicating degeneration of unspawned eggs. Most of the ovarian eggs were strongly deteriorated, either through oosorption or oolysis, and none had the potential for ovulation.
red and black discolorations = nodules
The neat thing that this project discovered was how old one of their very old-shell girls was: one female was found with an 8 year 1 month old tag. She had been tagged directly after her terminal molt, which occurs at least at age 1½, so this female was more than 9½ years old!
Previous estimates in the Sea of Japan had been 8½ years old based on tagging studies, while Bering Sea females may get up to 8½ years also (6 to 7 years after their terminal molt). Atlantic female snow crabs survive 4 to 5 years after their terminal molt.
This gal was OLD! I’m glad I aged a little better, at least when I was 9½.
Nerding it up, even in 1993
(photo courtesy of my dad, Jay Fox)
Read more and check out the histology slides:
Kon, T., M. Ono, and Y. Honma. 2010. Histological studies on the spent ovaries of aged snow crabs Chionoecetes opilio caught in the Sea of Japan. Fish Sci 76: 227–233.