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]330 GOLD ET AL. TABLE I.-Summary data from 13 spawns in a study of genetic effective size in hatchery red drum populations in Texas in 2002. Tank Spawn (date) Parent Dam I Dam 2 Dam 3 Dam 4 Sires BB-I Apr 14 Sire] 0 0 0 0 Sire 2 0 0 123 123 Dams 0 0 123 123 BB-2 Apr 17 Sire I 0 77 0 48 125 Dams 0 77 0 48 125 Apr 18 Sire 1 0 47 77 0 124 Dams 0 47 77 0 124 BB-7 Apr 13 Sire I 61 1 59 121 Sire 2 I I 2 4 Dams 62 2 61 125 BB-8 Apr II Sire 1 0 0 52 52 Sire 2 0 0 64 64 Dams 0 0 116 116 Apr 13 Sire I 87 0 0 87 Sire 2 34 0 0 34 Dams 121 0 0 121 Apr J6 Sire I 72 0 0 72 Sire 2 51 0 0 51 Dams 123 0 0 123 BB-l1 Apr 21 Sire I 33 0 33 Sire 2 75 0 75 Sire 3 16 0 16 Dams 124 0 124 Apr 23 Sire 1 32 10 42 Sire 2 9 56 65 Sire 3 1 17 18 Dams 42 83 125 BB-12 Apr 20 Sire 1 105 0 0 105 Sire 2 18 0 0 18 Dams 123 0 0 J23 VB3-1 Apr24 Sire 1 0 0 101 101 Sire 2 0 0 10 10 Dams 0 0 111 111 VB3-3 Apr 19 Sire I 0 0 0 0 Sire 2 0 0 124 124 Dams 0 0 124 124 VB4-1 Apr 24 Sire [ 0 4 0 4 Sire 2 0 12 109 12J Dams 0 16 108 125 females and one male, while spawning tank BB-ll TABLE 2.-Estimates of effective size per spawn assuming contained two females and three males. (A) that all possible pairwise matings occur and that all Based on parentage analysis, 16 of the 27 dams families have an equal number of offspring; (B) the observed (59.2%) and 16 of the 18 sires (88.9%) spawned at number of pairwise matings but that all families have an equal number of offspring; and (e) the observed number of pairwise least once. On average, each of the 13 spawns involved matings and the observed size of each family. 1.46 dams and 1.85 sires. The number of spawning Scenario combinations (families) generated per brood tank varied from one (one dam X one sire) to six (three Tank (spawn) A B C dams X two sires in one tank and two dams X three BB-1 (1) 4.80 2.00 2.00 sires in a second tank). On average, more families were BB-2 (1) 3.20 2.67 2.62 generated per spawning tank if multiple spawns in the BB.2 (2) 3.20 2.67 2.62 BB-7 (1) 4.80 4.80 2.81 same tank occurred over the time interval (Table 1). BB-8 (1) 4.80 2.67 2.64 Except for tank BB-2, where there were four dams BB-8 (2) 4.80 2.67 2.66 BB-8 (3) 4.80 2.67 2.51 and one sire, the maximum expected genetic effective BB-l1 (I) 4.80 3.00 4.18 size (Ne) for each spawn, based on equation (1) and BB-ll (2) 4.80 4.80 2.75 assuming that all dams mated with all sires, was 4.8 BB-12 (1) 4.80 2.67 2.29 VB3-1 (1) 4.80 2.67 2.18 (Table 2, column A). The maximum expected Ne for VB3-3 (1) 4.80 2.00 2.00 tank BB-2 was 3.2. The average maximum expected Ne VB4-1 (1) 4.80 4.00 2.33 Average 4.55 3.02 2.59 over the 13 spawns was 4.55. Parental assignments J .I based on genotype d subset of the breed contributed to the , only the number 0 spawned, and assum pair was distributed pairs, the observed N from 2.0 to 4.8 and a~ approximately 34% I expected average N Parental assign~e variation in family si I). As an exampll combinations in tank 98% of the sampled three dams, while 97~ Similarly, in tank VB, came from one of tv contribute to the saml sampled progeny cam of these examples, tht was over 40% less th; per mating combinati( Ne derived by conside per mating pair per s 2.00 to 4.18 per spay column C). The avera! actual family size per 43% less than the average Ne of 4.55. The above results generalizations regarc offspring population ! event. First, the expect function of the numb (given a space limitati( per tank) but rather ( combinations (irrespecI spawn. As examples, ( four females and one n with most other spawni males; maximum Ne, 4. and three males), for w was the same (4.8) as (three females and two the expected family si binomial distribution, N dam X sire combinati event. Examples here i (three females X two n versus spawn 1 in tanl males = four families; 1 BB-l1 (one female X thl 3.00). Third, Ne is inver