ask a bIoLoGIst
a.
Q.
PROTEIN-PACKED BASS
by Dr. Steven Cooke
That’s a great question, and at a high level it’s true.
The same rule applies to bass as it does for
all animals: You are what you eat.
That said, there are many factors that
affect bass growth, chief among them
being metabolism. At higher water tem-
peratures bass crank through calories
more quickly to support their metabo-
lism, and a bass that is swimming
around uses up more calories than one
that is stationary under a log. This
means that how much effort (and ener-
gy) a bass spends finding, eating and
digesting a prey item is a primary driver
of its maximum growth potential.
Chasing down and digesting a spiny-
finned prey item such as a sunfish or perch is
more costly than digesting something such as a
golden shiner. So by and large softer prey fish such as
trout, shad and shiners are more energetically rewarding than
bluegills and the like.
To the bigger question though, caloric density of a prey
item is indeed an important factor, and while protein is impor-
tant to fish growth, it’s really the fat content of prey items that
tends to drive up calories and growth. Rainbow trout have
Do
California bass
get so big because
they eat trout,
which offer more
protein than other
baitfishes?
Meet Our Expert
Dr. Steven Cooke is an
associate professor and
Canada research chair of
environmental science
and biology at Carleton
University.
28
about 20 percent more calories per unit mass than yellow
perch or even fathead minnows, so it is accurate to
say that a bass feeding on the same quantity of
rainbow trout would get more calories (and
thus grow bigger) than a bass feeding on
bluegills under the same conditions.
Although prey quality and abun-
dance certainly do affect maximum
growth, any discussion on the subject
must also include genetics and climate.
We know that growth potential is dic-
tated to some degree by annual climate.
Bass that live in the North and spend
part of their year under ice – where they
eat little and live off of stored energy
reserves during winter – tend not to have the
same annual growth potential as fish that can
eat year round. That’s why you find bigger bass in
Texas and Florida than in the North.
So, those smallish reservoirs in California do tend to pro-
duce massive bass largely because of the availability of high-
quality, calorie-rich prey (rainbow trout), whereas many of
the lakes and ponds in Florida produce big fish not because
the prey quality is particularly calorie-rich, but more so
because of the climatic and genetic factors.
TJ Maglio produces the Ask a Biologist department. If you
have a question you’d like to have answered by a fisheries
expert, please email it to TJ at [email protected].
fishing tip: When targeting giant
bass, choose baits that mimic prey
fish with the highest energy-to-avail-
ability ratio. For some places this
might be trout, but in others it might
be big gizzard shad or golden shin-
ers. Paddle-tail swimbaits, glide baits
and big topwaters are ideal choices.
fLWfIshInG.com I october-noVember 2016