2001–2002 - California Sea Grant - UC San Diego

producer of farmed caviar. The markers were also used to evaluate the
genetic diversity of the brood stock’s offspring, an important issue since
the farm replenishes its brood stock with the brood stock’s progeny. May
and Rodzen’s research has confirmed that the farm’s breeding strategy
conserves genetic diversity and that it does not need to replenish its gene
pool with wild-caught sturgeon.
The genetic markers developed in this project may provide other lasting
benefits. For example, the markers could potentially help farms eradicate
disease. It is suspected that resistance to sturgeon herpes virus, for instance,
is genetically conferred, as is susceptibility to white sturgeon
iridovirus. Both viruses are lethal in young fish and have caused massive
losses at sturgeon farms.
In a series of experiments, which focused on simpler traits, May and
Rodzen sought to identify those characteristics that are inherited and
those that are more highly influenced by environmental factors such as
diet. In particular, they looked at the degree to which body size (weight
and length) is correlated with dam and sire body size. They also examined
a variety of caviar characteristics, including weight, grade, color, firmness
and yield.
Their work has shown that adult body size, not
surprisingly, has a strong genetic link, but that most
of the coveted caviar traits are not obviously influenced
by genetics. Although caviar yield was shown
to be somewhat linked to the weight of the female,
which in turn is a function of ancestry, caviar characteristics
such as grade and color showed no bearing
on bloodlines.
Even though geneticists were unable to discern a
genetic link to caviar quality, Peter Struffenegger,
general production manager at Stolt Sea Farm
California, is convinced that such a link exists.
Perhaps, he said, a complex set of genes work
together to orchestrate caviar traits. He theorizes
that it may take studying a large number of sturgeon—only
about 100 were studied in this project—to discern the genetics
behind prized caviar.
With May and Rodzen’s markers, scientists and fish farmers can unlock
14
“There is no doubt that the
sturgeon industry would not
exist without Sea Grant as a
funding mechanism.
Sturgeon farming has been a
great collaborative work between
researchers, Sea Grant, the
California Department of Fish and
Game, and the industry.”
—PETER STRUFFENEGGER, general
production manager, Stolt Sea
Farm California, LLC
White sturgeon like the one
above can reach gargantuan
proportions, though today such
large catches are extremely
uncommon. Photo courtesy:
Oregon Historical Society
the genetic basis of superior caviar. In
the past, Struffenegger explained, if a
female produced exceptional caviar, it
was too late to breed her. (Extracting
caviar is a lethal process.) With the
genetic markers, however, it is now
possible to work backwards—to look at a
donor female’s genetic profile and ancestry, and
then through trial and error deduce which family
groups produce superior caviar.