The first fishes I ever caught were a chub, most likely a
horneyhead chub Nocomis biguttatus,
captured on a piece of a crayfish, and a sunfish caught on small piece of worm - can’t be sure which one was first. Over the years of studying fishes, the fish
that I have encountered most frequently at the end of the line has been the
smallmouth bass Micropterus dolomieu. With Shannon Brewer I recently
wrote a short summary on the species for the upcoming Black
Bass Diversity: Multidisciplinary Science for Conservation Symposium. Although I thought I knew a lot about the
species I found that there are still new discoveries to be made and old ideas
that re-emerge. The smallmouth bass
was first described by the French naturalist Bernard Germain de Lacépède (1756-1825)
who traveled widely in the pursuit of fishes and wrote multiple volumes of Histoire
naturelle des poissons. Lacépède
named the smallmouth bass after his associate, the French mineralogist M.
Dolomieu. In a
mistake that would confuse countless novice Ichthyologists since then, the
specimen has a damaged dorsal fin, hence the genus name would forever be Micropterus,
meaning “small fin”. So I am reminded that we all make mistakes
but we hope they easier to learn from and to hide. I learned a lot from the smallmouth bass and
believe it is appropriate to pay homage to the fish.
So let’s start at the beginning. The smallmouth bass is a member of the
family Centrarchidae and the most recent common ancestral centrarchid was recently
aged at 33.59 million years ago by Thomas Near and colleagues (Evolution
59:1768-1782) using a technique that combines fossil aging and molecular
clocks. Yes, indeed there are fossil Micropterus that were aged as 12 to 16
million years old, which translates to 4
to 5 millions of generations producing changes that we can see today – nine distinct
species of Micropterus. Smallmouth bass differ from the others black
bass in having larger eggs, larger fry, and longer period of parental
care. Black bass as a group support
important recreational fisheries in North America and are easily characterized
as a mult-billion dollar group of fishes.
Smallmouth bass males select a suitable nest location, clear
it of loose material and create a depression,
before courting a nearby female.
Males are known for their aggressive defense of the nest site and the developing
brood. At the actual spawning, males
and females show sexual dimorphism in color pattern. Dark vertical bars against a pale background
are evident in the ready female smallmouth bass. The iris becomes distinctly red in the
spawning male smallmouth bass. I have seen no studies that investigate this
further. Why the more intense red
iris? How long does it last? Does it have adaptive significance? Smallmouth bass may guard the developing brood
for as long as 7 weeks. Initially the
male is able to keep the free-swimming larvae, or black fry, in a tight school
but the larvae due disperse in search for food.
However, at night the fry stay
together and settle on the bottom until sunrise. Parental care is the key factor influencing
early survival. Removal of a guarding
male may allow egg predators to swarm the nest until the male returns. The
smallmouth bass may grow as fast as 1mm/d and soon disperse from the nest and
the parental male.
Smallmouth bass have been widely introduced because of their
popularity as a recreational fish, even in areas with marginal conditions to
support these fish. Because there are an
opportunistic top carnivore they often cause shifts in fish assemblages, or
even elimination or redistribution of other fish and crayfish. They
have had a devastating effect on indigenous fishes in parts of South Africa and
Oahu (Hawaii). In their native range
they serve as intermediate hosts for a number of flatworm parasites and hosts
for native freshwater mussels, such as the wavy-rayed lampmussel Lampsilis fasciola and others These mussels have mantle flap lures that
imitate fish prey, attracting smallmouth bass, which are then infected with the
glochidea. See video of Lampsilis fasciola mantle lure by Zac Wolf. Fascinating!
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| Lampsilis fasciola mantle lure. Photo by Dick Neves |