Ocean
Watch
Monday, April 6, 1998
Pregnant dads taking food
on ice is research dream
LAST week, I had a thrilling moment: I gazed upon my
first Hawaiian sea horses.
I've been looking for these captivating little fish for
years, poking through clumps of seaweed and parting the leaves of shallow
sea grasses. I never really knew where to look.
But when angler William Aila asked friends John
Yoshimura and Charlie Tanabe to collect a few of these little fish, they
knew exactly where to go.
At night, the two men often fish for opelu (mackerel
scad) a mile or so off Kaena Point, in about 240 feet of water. By shining
a light off the side of the boat, the anglers attract animal plankton,
which brings in opelu.
The plankton also draws sea horses, which the fishermen
easily scooped up with a net. William Aila gave the collected fish to the
Waikiki Aquarium.
When I saw the eight little sea horses there, they were
in a tank behind the scenes. Biologists there are hoping the Hawaii sea
horses will learn to eat frozen shrimp, then reproduce.
These researchers have good reason for high hopes,
because nearby, dozens of newly hatched sea horses bob and sway, the
healthy offspring of several brown sea horses living in another tank.
These handsome parents are also products of aquaculture, born and raised
at California's Scripps Aquarium.
The youngsters from one brood are a couple of inches
long and have adapted to eating frozen food. This means they're ready to
go to new homes in other public aquariums.
The other tank holds sea horses less than a half inch
long, only a couple of weeks out of their father's pouch.
Yes, it's male sea horses who become pregnant and bear
the young.
During the mating season, a male and female get
acquainted by entwining tails and performing a charming dance. When they
mate, the female deposits her eggs into the male's belly pouch.
There, the dad fertilizes and holds the eggs until they
hatch, perhaps in 10 to 20 days in warm water. When the tiny hatchlings
emerge, they are fully formed and on their own.
In the wild, sea horses eat tiny shrimp and other
drifting animals, inhaling them into tubelike snouts like little vacuum
cleaners. Such a diet might seem easy to match in captivity, but it isn't.
Sea horses can't survive on brine shrimp alone and must be taught to eat
frozen food.
This is one of the reasons the Waikiki Aquarium is
trying to learn more about raising sea horses. Director Bruce Carlson
said, "If people can buy cultured sea horses, they have a far better
chance of keeping them alive, because the fish are already trained to eat
frozen food."
The aquarium isn't selling its sea horses to the
public, but hopes others will learn rearing techniques to decrease the
taking of wild sea horses.
Another reason the aquarium is interested in sea horse
aquaculture is to restock areas depleted of natural populations. These are
dwindling worldwide because, according to traditional Chinese medicine,
sea horses are aphrodisiacs.
In December, Carlson will travel to Chicago's Shedd
Aquarium to attend a conference where researchers will exchange
information about sea horse biology, culture and conservation.
Visitors to the Waikiki Aquarium can view the success
of the facility's sea horse aquaculture program (run under biologist Karen
Brittain's guidance). All the sea horses on display were born and raised
at the aquarium.
If the new Hawaiian sea horses take to their new
surroundings, there's a good chance their offspring will some day be on
display here, too.
