White Abalone Captive Breeding Program
Playing Matchmaker at BML
Introduction: Successful abalone reproduction requires that a male and female be within a few meters of each other, but the majority of wild white abalone remaining are so far apart from one another that they are unable to reproduce.
Illustration, right, by Carolina Rivera Alvarez
Breeding White Abalone
1. Conditioning abalone – Year round
Scientists control light, temperature, and diet to encourage gonad development. Greater amounts of high quality sperm and eggs generally mean more juvenile white abalone and high rates of survival through initial development. White abalone naturally reproduce only in the Spring, so scientists need to carefully prepare for and execute these annual efforts.
Kelp (Macrocystis), a brown algae, is a favorite food of the white abalone. It is often considered “sugar” for abalone, delicious but nutritionally limited.
Red algae (Dulse) has higher levels of protein compared to the aforementioned kelp. We cultivate Dulse at UCD-BML and aim to keep it in the white abalone’s tanks at all time.
2. Induce Spawning – Spring
Non-toxic chemicals convince adults to release their sperm and eggs.
We then collect these gametes and use the sperm to fertilize eggs in a controlled setting while maintaining an ideal sperm to egg ratio. After watching for and estimating fertilization rates, we let these embryos develop overnight in protected hatching trays.
3. Larval Culturing – 7 continuous days after spawning
Larvae hatch out of their eggs about 24 hours after fertilization. They then take a ride from the hatching tray down into a culturing vessel. Larval buckets come in pairs to allow for daily cleaning and constant water movement. Each day larvae travel from one larval bucket to its pair. Then a scientist cleans the vacated bucket, reattaches the bucket, and reverses water flow back into the newly cleaned bucket. This method keeps larval cultures as clean as possible by discarding any dead larvae each day. After 6 or 7 days, larvae are fully developed and ready for settlement.
4. Settlement – 1 day after larval culturing
Mature larvae are evenly distributed throughout settlement troughs, prepped with non-toxic settlement chemical cues. Induced to select this substrate and settle, larvae metamorphose to begin crawling and shed their swimming appendages. These troughs will act as abalone cribs for their first year of life as they grow and transition from feeding from their egg yolk to eating microalgae and eventually macroalgae.
5. Juvenile rearing – Year round
After successfully settling, juvenile abalone begin to eat tiny diatoms. After 3 or 4 months they switch to macrocystis and dulse like their parents. They continue growing until they’re large enough to move to a new facility, be released in the wild, or produce gametes for another generation.