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<br />'"
<br />
<br />). The fin~l pH of the
<br />adding 50 ilL tris-HCI
<br />
<br />lIite loci (Soc19, Soc85 ,
<br />btained via polymerase
<br />ation of genomic DNA
<br />experimental offspring.
<br />:r sequences; annealing
<br />expected heterozygosity
<br />lay be found in Saillant
<br />ir of PCR primers was
<br />fluorescent dye of set D
<br />:ity, California): 6-Fam
<br />for Soc402 and Soc428.
<br />:re performed in lO-IlL
<br />19) of genomic DNA, 1
<br />mM KC1, 100 mM tris-
<br />0), 1.5 mM MgClz, 2.0
<br />triphosphate, 5 pM of
<br />)NA polymerase (Gibco
<br />carried out as follows:
<br />. 3 min followed by 35
<br />aturation at 940C, 45-s
<br />nealing temperature, 1-
<br />inal extension of 10 min
<br />'eaction products were
<br />(Cambrex) single-pack
<br />ABI PRISM 377 DNA
<br />Biosystems). All gels
<br />Analysis 3.1.2 (Applied
<br />: performed with Geno-
<br />(Applied Biosystems).
<br />lite for each individual
<br />scored and entered into
<br />'spring to an individual
<br />genotypes at the four
<br />[lted via the program
<br />ann 1997; available at
<br />-rdanzman/software/
<br />nment was unequivocal
<br />
<br />llation size (N) of a
<br />ced in part by (1) the
<br />in a spawning tank
<br />) the variation in family
<br />< sire) combinations.
<br />:1973), the value of Ne
<br />:om the equation
<br />
<br />
<br />respectively, contributing to a spawn. The latter is
<br />based on the number of offspring (family size)
<br />produced from each dam X sire combination and
<br />accounts for unequal contributions of parents to
<br />offspring. This value of Ne was estimated from the
<br />equation
<br />
<br />Ne = .4NedNes ,
<br />Ned +Nes.
<br />
<br />where Ned and Nes are the effective numbers of dams
<br />and sires, respectively, contributing to a spawn. Values
<br />
<br />for Ned and Nes were estimated from the equations
<br />(Lacy 1989)
<br />
<br />I
<br />Ned =~
<br />
<br />I>i
<br />k=1
<br />
<br />I
<br />Nes ==,~,
<br />
<br />tqi
<br />k=1
<br />
<br />where nf and nm are the number of dams and sires,
<br />respectively, that contributed to a spawn, and q
<br />represents the proportion of progeny contributed by
<br />each dam or sire to that spawn.
<br />The genetic effective size of a released population
<br />also is influenced by variation in the number of
<br />progeny from different spawning tanks when multiple
<br />spawns contribute to a released population. To examine
<br />this, we used records at the TPWD MDC for the year
<br />2003 to generate ill empirical distribution of the
<br />mixtures of spawns (including the number of spawns
<br />mixed and the number of progeny from each spawn)
<br />that were transferred to separate prefertilized ponds for
<br />prerelease grow out. Red drum at the MDC typically
<br />spawn during the night and, on average, approximately
<br />400,000 progeny (measured by volume) from each
<br />spawning tank are collected, incubated, and transferred
<br />to prefertilized grow-out ponds. Released fish, typically
<br />about 150,000 per released population, generally come
<br />from individual grow-out ponds, meaning that released
<br />populations are derived essentially from a single
<br />night's spawn. During 2003, the number of spawns
<br />from individual spawning tanks that were mixed and
<br />transferred to individual ponds before release varied
<br />from one to seven; the number of progeny per spawn
<br />varied from about 20,000 to about 1,200,000. We used
<br />
<br />NOTE
<br />
<br />1329
<br />
<br />of each spawn was assigned randomly and varied from
<br />2.00 to 4.18, based on empirical observations (see
<br />Results). The overall genetic effective size (NeR) was
<br />estimated from the equation (Ryman and Laikre 1991)
<br />
<br />(2)
<br />
<br />I
<br />NeR=~,
<br />L:
<br />
<br />k=1 ('I
<br />
<br />(4)
<br />
<br />(3a)
<br />
<br />where Xi is the proportion of the ith spawning tank's
<br />contribution to the final population and N . is the
<br />genetic effective population size of the ith s~awning
<br />tank. We also generated via simulation estimates of the
<br />overall genetic effective size (NeR) of 10,000 released
<br />populations when (1) the number of progeny from
<br />different spawns that contributed to a released
<br />population was equalized and (2) when spawns
<br />contributing less than 10% of the progeny in a mixture
<br />were included as is and the contribution of the
<br />remaining spawns in the mixture were equalized. The
<br />latter ("pseudoequalized" mixture) represents a more
<br />realistic situation for a stock enhancement program as
<br />equalizing spawn contributions to match a low volume
<br />spawn could mean discarding large volumes of hatched
<br />progeny.
<br />
<br />(3b)
<br />
<br />Results and Discussion
<br />
<br />Genotypes at four microsatellites (Soc19, Soc85,
<br />Soc402, and So(428) were acquired for all 45 broodfish
<br />(dams and sires) and for 1,597 offspring (the genotypes
<br />of individual fish may be found at http://wfsc.tamu.
<br />edu/doc under the file name Appendix 1). Summary
<br />data for the 13 spawns are presented in Table I; data
<br />for each spawning tank include number of spawns,
<br />dams and sires contributing to a spawn, and number of
<br />offspring genotyped from each spawning tank and
<br />from each dam X sire combination. The number of
<br />spawns per spawning tank over the time interval
<br />sampled was as follows: one (six tanks), two (two
<br />tanks), and three (one tank). The number of offspring
<br />genotyped per spawn ranged from III to 125. In one
<br />spawning tank (BB-2), genotype data indicated a
<br />mismatch in the sex identification (some offspring
<br />were assigned to two breeders putatively of the same
<br />sex), while in another brood tank (BB-1I), genotype
<br />data indicated that although all six broodfish had
<br />contributed to the spawn, only two of the three fish
<br />tentatively identified as females were the same sex.
<br />
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