9428

• UCREFRP Catalog Number: 9428
• Author: Erdahl, D. A.
• Title: Inland Salmonid Broodstock Management Handbook.
• USFW Year: no dat
• USFW - Doc Type: Bozeman.
• Copyright Material: NO

Effective Breeding Number
The effects of mating a given number of females and a given number
of males on effective population number can be estimated by using
` the following formula:
EN = 4 X (NF) X (NM)
NF + NM
Where: EN = Effective Number
NF = Number of Females
NM = Number of Males
Consider the effects of founding a broodstock using 99 females and
1 male or using 2 females and 2 males. Remember that each sex
contributes one half of the genetic material to the next
generation.
99 females and 1 male
EN = 4 x (99) x L11 = 396 = 3.96
99 + 1 100
2 females and 2 males
EN = 4 x (2L, x (2) = 16 = 4.00
2 + 2 4
The effective breeding number for 99 females and 1 male, and for 2
females and 2 males, is virtually the same. Hence, the genetic
drift and inbreeding potential of the two breeding schemes are
basically identical. In this scenario, the 4 fish breeding
population is as effective as the 100 fish population.
1-8