Lab stuff to know Flashcards
Using beach seining, what types of fish can be collected in large numbers?
Small benthic fish
Where are backpack electroshokers used?
Streams + shallow rivers
Trawling techniques catch what types of fish?
Pelagic ones
What are the four parts of a beach seine net?
1 - Float line
2 - Webbing
3 - Lead line
4 - Poles
Minnow seines have a ____- inch mesh. A __ foot depth is sufficient for minnow seines.
1/4
4
Electrofishing more easily catches ________ fish than ______ fish.
Larger
smaller
What are the main purposes of electrofishing?
Stock assesment sampling/health surveys tagging catching spawners anaesthetising or eliminating species
What are the three pieces of gear used during electrofishing?
1 - power unit
2 - transformer
3 - electrodes
The anode is _______ and the cathode _______.
negative
positive
The choice of material and size of electrode can influence ______ _______ and the shape of these will influence the electrical field _______.
fishing efficiency
strength
What is the back of the trawling net called?
Bag
Trawling can either be done ___-____ or at the ______ of a body of water.
mid-water
bottom
Trawl mouths can range from ___ to ____ feet.
30-100
The mouth of the trawling net is held open by two large ______.
Doors
Mensual characters are ________.
Continuous
Mertistic characters are _______.
discrete
What is one issue with morphometrics? How is it remedied?
Certain absolute measures cannot distinguish juveniles and adults.
Remedied by taking proportions or percents of the fish’s SL or TL.
What is SL?
Standard length:
Tip of snout to base of caudal fin.
What is TL?
Total length:
Length from tip of snout to tip of caudal fin.
Who and what fish eat is strongly correlated with what?
Internal and external morphology
_____ and ______ of the mouth and jaw are important indicators of food items since they will _____ the type of prey that a fish can ingest.
Size
protrusibility
limit
_________ (more than one word) is correlated with the digestibility of the main food items of fish.
Length of the gut/intestine
Piscivorous fish tend to have larger _____ but smaller _______ ______ than hervivorous fish.
stomach
intestinal length
Fish with ________ mouths capture things above them and often eat small things off the surface of the water.
superior
Fish with ______ mouths eat material in the water column.
terminal
Fish with ________ mouths eat things that live in the bottom.
inferior
What is a protrusible jaw?
Premaxilla can separate from the maxilla.
Piscivorous fish tend to have _______ teeth that are either: _____, ______ or ________.
pointy
triangular, canine, villiform
Fish that have to crush hard parts with have flattened _________ teeth.
molariform
Molariform teeth can be either on the _____ or as ________ ______.
jaws
pharyngeal teeth
Some fish have no teeth. these fish strain ________ out of the water column or subsist on soft food found in the ____.
plankton
mud
What are gill rakers?
Projections of bone/cartilage that project off the gill arches.
What do rakers do?
Prevent food entering the mouth from escaping through the gills.
Piscivorous fish will have _____, ______ spaced rakers.
Species that filter small things out of the water will have _____, _____ rakers that are _______ packed together.
short, widely
long, thin, tightly
The _____ ____ is a mechanosensory system used by fish to detect ______ _____.
Lateral line
water motion
The lateral line has been described as _____ _____.
distant touch
What are the receptors in the lateral line for detecting water motion?
Neuromasts
Each neuromast has an individual ______ ____ with an attached _______.
hair cell
cupula
How is the hair cell stimulated?
Water pushes it and bends it to stimulate it
All fish have at least some free _______ neuromasts on their body surface or at the bottom of shallow pits (_______ _________)
Superficial
canal neuromasts
Schooling fish use their lateral line to _______ and predator fish used it to ________.
Detect their schoolmates
detect minute prey movements
What is rheotaxis?
Orientation to water current
What is the scientific name for a zebra fish?
Danio rerio
Growth rate and age estimates are important for what?
1 - Assessing health of the fish populations
2 - setting catch limits
3 - Identify stressors
4 - Predict future population sizes
Growth is rarely measured in the wild because?
Difficult to catch the same fish repeatedly
What are the two ways to estimate growth rate and age?
1 - Peterson method - length-frequency distribution
2 - use hard parts like scales and otoliths
What is an assumption of the Peterson method?
That fish can be placed into distinct year classes
What is a cohort?
fish born in the same year
What is a problem with scales? Why dont otoliths have this problem?
Fall off and are replaced.
Stay with the fish for life.
What are circuli?
Rings
What are annuli?
Yearly rings
What is the equation for back-calculation of growth rates?
lt = l (st/s)
lt - length at time t
l - length
st - distance from the center to the annual ring of interest
s - total distance from the center of the otolith to the edge
What plot is used to estimate growth rates and maximum fish sizes?
Walford plots
True measures of diversity can be influenced by what?
1 - number of samples
2 - method of collection
3 - timing of samples
4 - other factors
When is number of individuals relevant?
If only interested in total biomass or restrict sample to few species
Does number of individuals indicate diversity?
No
What is species richness?
number of species
