Real Options Analysis of the Risks and Benefits of Sterile Male Sea Lamprey Transfers from Lake Ontario
Eli P. Fenichel1, Jean I. Tsao2, Michael Jones2, Graham J. Hickling3
1 School of Life Sciences, Arizona State University, PO Box 874501, Tempe, AZ 85287
2 Departments of Fisheries and Wildlife & Large Animal Clinical Sciences, Michigan State University, East Lansing, MI 48824
3 The Center for Wildlife Health, The University of Tennessee, Knoxville, TN 37996
Introduction: Introduced sea lampreys (Petromyzon marinus) are detrimental to Great Lakes fisheries. Consequently, the Great Lakes Fishery Commission (GLFC) oversees release of sterilized adult male sea lampreys into the St Mary’s River, Michigan, to reduce female lampreys’ reproductive output. Most male lampreys for release are collected nearby, but some are brought from Lake Ontario tributaries. Transfer of Lake Ontario lampreys could introduce new pathogens into Lake Huron.
· To assess whether the benefits outweigh the risks of including Lake Ontario sea lampreys in the St. Marys River sterile male release program.
· Our analysis utilized two existing simulation models of St. Marys River sea lamprey dynamics and Lake Huron food webs, and two new models of fishing behavior and the probability of pathogen transfer. These four models were integrated and Real Options Analysis (ROA) was conducted.
· We assumed that a sample of lampreys was screened for pathogens before each transfer (as per current Great Lakes Fish Health Committee procedures).
· Including 1,000 Lake Ontario sea lamprey with no disease in the annual sterile male release is predicted to reduce the parasitic sea lamprey population in Lake Huron by ~10% after 29 years, with minimal (<5%) effect on lake trout and Chinook salmon abundance and catch rates. (These are averages; the percentage changes seen in individual simulation runs were variable.)
· Given the current screening program and an assumed ‘background’ arrival rate of a new fish pathogen, once in 25 years, the use of Ontario sea lamprey increased the rate of new pathogen introduction to Lake Huron to once in 22.3 years.
· ROA indicates that even though the risk associated with these transfers is small, the benefits at the present time are not consistently large enough to outweigh them.
· We recommend delaying the use of Lake Ontario sea lamprey in the St. Mary’s River sterile male release program until local male sea lamprey become less available, or until there is greater certainty about the expected benefits of the transfers, at which time this decision should be revisited.
· Real Options Analysis provides an estimate of the appropriate measure of ‘precaution’ to be applied to risky decisions, and of the costs and benefits of delaying potentially irreversible decisions. It also helps organize information about decisions and risk is a structured way. This technique may prove useful in other fisheries management situations.