Transcript Problem 2: Worst Food in America Can you decide?

Basic Population Dynamics
Learning Objectives:
1. List factors used to determine carrying capacity for an organism.
2. Use general information to classify an example organism as r- or
k-selected and match this with survivorship curves and
correlations with success of an organism (invasive species)
3. Read age structure diagrams and differentiate between a
population that is declining or increasing and suggest the
appropriate age structure for an economic advantage (fishing)
Newfoundland Cod
Not just not-recommended, not fished anymore. Can
we use this example to explain problems with fishing?
1. Carrying Capacity
Nature of Bycatch & Habitat and Ecosystem Effects
•
•
Long-lines (Alaska) is
recommended as opposed
to bottom trawling.
54% of fishing methods
used in the U.S. involve
trawling)
Trawling: enormous net (up to the size of a football field) dragged
along the sea floor or halfway between the sea floor and the
surface.)
Bycatch: inadvertent catching of sea creatures (often discarded.)
Longlining: long (1-50 mile) fishing line laid on the sea floor and
strung with smaller lines of baited hooks (reduces problem of
inadvertently hooking sea turtles, sharks and seabirds.
1. Carrying Capacity
1. What are some things that might determine the
carrying capacity for cod? Be specific- list limiting
factors important for recovery efforts.
1. Carrying Capacity
2. Why do you think that sometimes the factors
that limit an organism are represented
pictorially like this:
2. r- and k-selected species
Status of Population
(Inherent Vulnerability)
• Cod reaches maturity at a relatively early age,
and is a fast-growing, moderately long lived
species with a maximum age of 25 years.
Intrinsic rate of increase is unknown. 50% reach
maturity at average size of 67 cm at age of 5-7
years. Aggregate over small area to spawn.
Adult female can produce 1 million eggs.3
• How can you use this information and other
population estimates to predict how a population
will fare over time, even recover?
2. r- and k-selected species
3. What are the definitions of an “r-selected”
and “k-selected” organism?
4. Would you consider cod an r- or k-selected
species?
5. List three reasons that support your
argument.
N
Time
2. r- and k-selected species
(native)
(invasive)
2. r- and k-selected species
Fill in the blank in the article title below:
?
(native)
A. r-selected
(invasive)
B. k-selected
6. Write a figure legend for these graphs:
2. r- and k-selected species
Invasive plants are
actually a big
problem in private
landscaping
practices.
7. Based on your
answer to the
previous question,
which of the following
plants would you
recommend your
environmentally
conscious friend buy
for his yard?
A
B
3. Age Structure Diagrams
8. The age structure diagrams below represent
4 cod population each in different regions.
The Canadian Government is deciding where
to open cod fishing. Which one do you think
they will open and why?
A
B
C
D
N = 350
N = 400
N = 300
N = 250
3. Age Structure Diagrams
The diagrams below characterize healthy and
overfished populations of commercially
valuable cod in the northeast US.
Healthy
overfished
9. Suggestions for recovery efforts for Newfoundland
cod include minimizing the destruction of benthic
habitat used by juvenile cod. Is this a good suggestion
for the overfished area above?
Take Home Study Questions
Wild (feral) pet populations can be problematic. Below is data for two
populations of feral cats.
1.
2.
3.
4.
5.
City population
Country population
d
35
15
b
40
30
N at reproductive age
60
60
N
100
100
How would you have assessed the total number of animals in
each population?
if R is +, -, or 0 for each? Are the populations r- or k-selected?
Draw the general age structure diagram you would expect each
population to have.
Which population would you target for control measures and
how would you propose that population be controlled?
Why might our equation (N = b – d + i – e) be important in this
case?
Ready for fish Futures Project?
The following animals all have population stresses. Taxpayer
and donated $ can help. Think about the following
questions for your flyer:
1. What kinds of measures effectively convince people to
give money or make changes in their lifestyles?
2. How would you prefer a conservation organization to
assist that species? (What would you want them to
actually do?)