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)

Basic Population Dynamics

Newfoundland Cod

Not just not-recommended, not fished anymore. Can we use this example to explain problems with fishing?

• 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

Nature of Bycatch & Habitat and Ecosystem Effects

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:

1. Carrying Capacity

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.

Time

N

2. r- and k-selected species

(native)

(invasive)

2. r- and k-selected species

Fill in the blank in the article title below:

(native)

(invasive)

?

A. r-selected

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

2. r- and k-selected species

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?

N = 400

A B C D

N = 350 N = 250N = 300

3. Age Structure Diagrams

The diagrams below characterize healthy and overfished populations of commercially valuable cod in the northeast US.

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?

Healthy overfished

3. Age Structure Diagrams

Wild (feral) pet populations can be problematic. Below is data for two populations of feral cats.

1. How would you have assessed the total number of animals in each population?

2. if R is +, -, or 0 for each? Are the populations r- or k-selected?3. Draw the general age structure diagram you would expect each

population to have.4. Which population would you target for control measures and

how would you propose that population be controlled?5. Why might our equation (N = b – d + i – e) be important in this

case?

Take Home Study Questions

City population Country population

d 35 15

b 40 30

N at reproductive age 60 60

N 100 100

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?)

Ready for fish Futures Project?