Estimation of Recruitment Forgone Resulting from Larval Fish Entrainment

Abstract

The effect of larvae entrainment on fish populations is difficult to determine because larvae abundance, mortality, and growth are difficult to estimate. The concept of production forgone (lost) was developed recently to avoid estimation of abundance, but estimates of mortality and growth rates for larvae, young-of-year, and juveniles are still necessary, and these too are difficult to estimate. For sportfish, production forgone is less important than recruitment, and recruitment forgone, or lost, as a result of larvae and egg entrainment could be useful for assessment of sportfish larvae and egg entrainment. A method is developed for estimation of recruitment forgone; it only requires estimates of population parameters for the mature population; it requires no estimates of abundance. The method is applied to assess yellow perch larvae entrainment at the Monroe Power Plant, Monroe, Michigan, located on the western basin of Lake Erie. The number of yellow perch larvae entrained was 1.28 x 10 8, which is an enormous number, but larvae mortality is high and the recruitment forgone was 8,933 fish.