Meet Our Baby Giant Sea Bass! cover

Meet Our Baby Giant Sea Bass!

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Aquarist Nicole Leier has spent years researching how to successfully breed this species. After collecting more than 1,000 eggs, she successfully hatched the Aquarium’s first healthy giant sea bass. Nicky explains the challenges she faced along the way and what this may mean for this critically endangered species.
Aquarium of the Pacific


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Meet Our Baby Giant Sea Bass!

A baby giant sea bass that hatched at the Aquarium in October is now on public view in the Redondo Canyon exhibit in the Southern California/Baja Gallery on the first floor. This small fish was the result of a spawning event this past fall and was raised in a tank behind the scenes during its early months.

Giant sea bass are difficult to breed in aquarium environments. Only one other facility has had preliminary success in breeding giant sea bass. The Aquarium was able to raise one to forty-three days in 2003, but this year’s surviving fish has now surpassed that milestone, and husbandry staff members foresee its long-term survival.

Twenty-three days old in the photo above

At its hatching, the baby fish was just 4 millimeters long. As of February, it was about two inches long and is fed on a diet of mysid shrimp.

It will take about fifteen years for this juvenile to reach its full adult size (up to 6 feet long and 500 pounds). At that age, aquarists may be able to determine its sex based on any mating behavior it displays. Until that time, it is not possible to determine its sex by sight.

The Aquarium is home to three adult giant sea bass, a well-established male-female pair that has been at the Aquarium since its opening and a younger male. All three are residents of the Honda Blue Cavern exhibit in the Great Hall. The well-established pair are the baby’s parents.

The Aquarium’s work to reproduce this species is particularly important because giant sea bass are listed as Critically Endangered on the International Union for Conservation of Nature’s Red List.

Video

Senior Aquarist Nicole Leier gathered research on breeding this species in an aquarium environment, and she and other husbandry staff members made several adjustments to the Blue Cavern exhibit to achieve success.

This is her account of this process:

When I took over caring for our Honda Blue Cavern exhibit, I had one goal in mind: I wanted to breed our giant sea bass. See, the giant sea bass is listed as a critically endangered animal, and raising a baby here at the Aquarium could help with their conservation.

Since 1998 we’ve had an adult pair in the exhibit, but have only been successful in raising the babies to forty-three days. It’s been a mystery, but I was determined to figure it out.

Since we knew the pair was capable of producing fertilized eggs, I decided to adjust various factors within the exhibit. I thought if the eggs were fertilized under different conditions, maybe it could increase their survival rate after they hatched.

I read numerous articles while doing research. Some scientists speculated that successful spawning was based on lunar cycles, while others believed that a certain water temperature yielded the best results.

For more than two years I ran tests, including manually fluctuating the water temperature to coincide with the current ocean temperatures and monitoring the natural moonlight entering the exhibit.

After hundreds of unsuccessful hatchings, a healthy fertilized egg emerged!

You can identify giant sea bass eggs by their size. Most fish will lay eggs that typically measure about 1 millimeter in size, but giant sea bass eggs are closer to 1.5 to 2 millimeters. After two days (or what felt like a lifetime for me) our first healthy giant sea bass baby was hatched!

At this point, we don’t know if the baby is male or female. In fact, we are unable to identify the sex of a giant sea bass until they begin mating at about fifteen years old.

It’s now been 130 days (on February 14, 2017), and I’m happy to report that this little fish is doing great! It recently graduated from eating smaller crustaceans like copepods to a hearty diet of mysid shrimp.

There is still a long road ahead; I hope to help breed more giant sea bass so we may one day be able to help further our understanding of the species.

In the meantime, this baby should be making his public debut in our Southern California/Baja gallery in the very near future. The next time you’re at the Aquarium, please be sure to stop by and say hello!