Not the best photomicrograph, but we were excited to see 1.4 million Native (Olympia) Oyster Ostrea lurida larvae this week. This one just released about 150 microns across.
That’s not a lot of larvae for a Pacific Oyster Crassostrea gigas which can produce well over a 100 million eggs each, but good numbers for Olympia oysters. The Ostrea genus are “brooding oysters” which means that the female oysters filter spermatophores released by the males (scientific term for a packet of sperm) out of the water and then fertilize their eggs within the mantle (shell) cavity. The females then “brood” the larvae for approximately 2 weeks. The larvae are then released midway through the larval cycle when their chances of survival are increased. The flip side of this reproductive approach is that they produce much fewer larvae, perhaps one of the reasons why Native oyster stocks have not rebounded and still remain functionally extinct throughout much of their range.
Last year with assistance from the Canadian Wildlife Foundation (CWF) and the Habitat Stewardship Program for Species at Risk (HSP) we began field work, monitoring Native oyster recruitment in the field and actively using our aquaculture skills to breed Native oysters in the lab with the intent of creating a broodstock pool on our research farm that might accelerate natural restoration in Baynes Sound. See previous post here
This year we have received CWF funding again to continue field work, but do not know yet whether the HSP funding will be renewed. Its spawning season and our little oysters have never heard of a fiscal year so we have been conditioning last years broodstock in our spare time (as it were). This week we saw our first larval releases which is great because it means that we have a big jump on the year which should really help our success. The larvae are now in our new and improved research hatchery. We are going to try some different tricks this year too; setting most as singles and then boosting them in our new SOLAR FLUPSY before adding them to the small oyster reef we are building on our farm.
Stay tuned… and if you are interested in being involved with this project please do not hesitate to contact us.
Postscript. We were starting to get worried that these weren’t going to spawn and every time we opened one to check (which we don’t like doing – they are a species of concern after all) we only found males. Oysters can change their sex in response to environmental conditions and we were starting to worry that the way they were maintained over the winter might have caused them all to become males. Glad that theory was wrong!
Update June 23d: 6.5 Million and more coming……