Transcript Chapter 4 Notes - Fishing in Schools

Aquatic Entomology
& Benthic
Macroinvertebrates
With a special focus on Mayflies,
Caddisflies, and Stoneflies
Why are there so many insects around
streams, rivers, and lakes?
 Aquatic insects spend the majority of their
lives in water.
 Hatch in/under water
 Live for a large percentage of their life under
water getting bigger.
 When they are ready for adulthood they
rise/crawl to the surface to molt and begin the
adult portion of their life above the surface
 At this point their primary goal is to reproduce
Why look at invertebrates?
 An immediate indication of
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water quality can be seen
just by observing what is
living in in it.
Invertebrates are broken
down into 3 taxons:
1) Pollution sensitive
2) Somewhat- sensitive
3) Tolerant
What if you find no sensitive
organisms in a stream?
** Diversity is key!
When fishing they help you
understand what insects are
present and therefore what
the fish may feed on.
Benthic Macroinvertebrates
 Benthic- Bottom dwelling
 Macro- large
 Invertebrate- spineless
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organism
** Large bottom-dwelling
spineless organism
Most are found in the
substrate or on the bottom of
rocks. Scrapers, Shredders
Some are climbers- climb
up on plant and stems
For fishing we will look at
when they are below and
above water.
Invertebrate Classification
 Taxonomy- science of
 Kingdom
naming and classifying
organisms
 Each organism is given
a two part name
consisting of a
Genus(noun) and a
species(adjective)
 Phylum
 Class
 Order
 Family
 Genus
 Species
Insect Identification
 Insect identification begins with
the Class- Insecta
 Then is divided into more specific
orders.
 Three important examples
are:
 Mayfly = ephemeroptera
 Caddisfly = Trichoptera
 Stonefly = plecoptera
 A dichotomous key is often
used for insect identification
 This tool uses a list of identifiable
characteristics to group
organisms into related taxons
Taxa one on the S.O.S. sheet is insects and one mollusk that
are sensitive to pollution. Several orders are represented.
Adult Mayfly
 Note the Sailboat wings
Adult Caddisfly
 Note the tent wings
Adult Stonefly
 Note the size and flat wings
Insect Life Cycles
 Most insect invertebrates
found in a stream are in
some stage of
metamorphosis
 All insects undergo some
type of Metamorphosis
(series of life changes from
the egg to the adult)
 Two types- 1) complete 2)
incomplete
Complete Metamorphosis
 Four stages:
 1) egg
 2) Larva- all insects
have the post
embryonic larval stage
 3) pupal- transitional
stage, stationary
cocoon or mobile
 4) Adult- above water
 Ex. Butterfly
Incomplete Metamorphosis
 Has no Pupal stage
 Larval stage is
characterized by a
series of molts
 Periods between molts
are called instars
 Insect is sometimes
referred to as a nymph
or naiad during the
larval stage
Metamorphosis for the beginning fly
fisher (Caddis example)
 Caddis “nymph”
 Adult Caddis
Mayfly Life Cycle
How do most fly fishers refer to insect
life cycles?
 “Nymph” = Bottom dwelling version
 “Pupae” = Worm-like stage
 “Emerger” = Making it’s way to the surface
 “Adult” = Normal flying version
 “Spinner” = Laying eggs
What “life cycle stage” should I fish
with?
 It depends on quite a few things
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What are the fish feeding on
Do you like fishing a dry fly or nymph?
What is your fly selection?
Trout get 90% of their food underneath the
surface. Nymphing is more productive!
Invertebrate Sampling
 Kick net- large net used to
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sample a 3’x3’ area in a
riffle(current in a stream)
1) Place the net in a riffle,
weight down the bottom to
prevent escaping
underneath
2) pick up and rub large
rocks, place aside
3) Stir the substrate by
kicking thoroughly with your
feet
Grab net- lower right
Most fishers will turn over
rocks or run their hands
through the bushes to try to
locate bugs