1. The Effects of a Parasitic Copepod (Achtheres) on Striped Bass Populations Presented by: Douglas Thomasey Tom Shahady and Joe Ashwell

2. Background Information Parasitic Copepod (Achtheres) Parasite becomes attached to the host Dies with the host Larva is free-swimming First outbreak occurred in 1981 in the Tellico Reservoir “Gill Maggot”

3. Mathematical Modeling Lokta-Volterra Lokta-Volterra Describes a Predator vs. Prey relationship Describes a Predator vs. Prey relationship x represents the Prey x represents the Prey y represents the Predator y represents the Predator a, b, c, d, are known as parameters a, b, c, d, are known as parameters xy is the likelihood of an encounter xy is the likelihood of an encounter

4. Smith Mountain Lake Model Assumptions Assumptions Closed system – no reproduction Closed system – no reproduction Introduce one infected fish into the population Introduce one infected fish into the population Once infected always infected Once infected always infected Loss of parasite only through the death of a fish Loss of parasite only through the death of a fish

5. Probability Fraction Is a built-in probability that an encounter with another fish would result in the transmitting of the parasite Is a built-in probability that an encounter with another fish would result in the transmitting of the parasite The chance of actually contracting the parasite is dependent on the ratio of infected fish to the entire population The chance of actually contracting the parasite is dependent on the ratio of infected fish to the entire population

6. Parameters b : Encounter rate b : Encounter rate 0.9 0.9 v : Death rate of the infected v : Death rate of the infected 0.25/12 0.25/12 d : Death rate of the susceptible d : Death rate of the susceptible 0.1/12 0.1/12

7. Sensitivity Sensitivity of parameters Sensitivity of parameters Drastic changing the values of our parameters will not influence the outcome Drastic changing the values of our parameters will not influence the outcome These values do not have to be correct to gain correct assumption about our model These values do not have to be correct to gain correct assumption about our model Keeping parameters d, v, constant, while changing the values of b, gives us an idea its sensitivity d = 0.1 d = 0.1 v = 0.25 v = 0.25 b = 1 b = 0.5 b=0.1

8. Questions be answered to If one infected fish becomes infected, how long until the entire population is infected? If one infected fish becomes infected, how long until the entire population is infected? How does the interaction rate impact transmission in this model? How does the interaction rate impact transmission in this model? How do the mortality rates and initial conditions impact the model? How do the mortality rates and initial conditions impact the model? How much to stock? How much to stock?

9. Question 1: Time it would take to infect the entire population, with certain stocking rates. Time it would take to infect the entire population, with certain stocking rates. Stocking Rates: 21 fish per acre 7 fish per acre no stock

10. Question 2: The effects of the interaction rate. Schooling fish vs. territorial fish Interaction Rate: 90% 10% 90% 10%

11. Question 3: How the initial conditions and morality rates impact the model. How the initial conditions and morality rates impact the model. Initial Population: 10 fish per acre 100 fish per acre 200 per acre

12. Question 3: (con’t) Mortality Rates: (Changing the death rate of the infected population) 0.25/12 0.5/12 0.75/12 0.25/12 0.5/12 0.75/12 How the initial conditions and morality rates impact the model. How the initial conditions and morality rates impact the model.

13. Question 4: How much to stock? How much to stock? Stocking Rates: 21 fish per acre 7 fish per acre no stock

14. Question 4: (con’t) Alternating years of stocking rates Alternating years of stocking rates Stocking Rates: (21 fish per acre for the first 2 years and the last 3 years) 7 fish per acre years 3-9 No stock years 3-9 7 fish per acre years 3-9 No stock years 3-9

15. Conclusions Spread into other states? Spread into other states?