OK guys I have not posted much research lately. Burger how do you get me into these type questions. \:\)

I assume from this study that normal sex ratios in HSB are to be expected. If not then they would not need to sex reverse them and the normal mixed-sex yoy would not be 1 to 1 as indicated in the control groups.


Hormonal Sex Inversion in
Striped Bass and White Bass X Striped Bass Hybrids


Methods

The experiments were conducted at the Fish and

Aquaculture Research Station (Dor, Israel).

The young fish for the experiments were obtained from

kibbutz Hamaapil Fish Hatchery, where Morone

species are artificially propagated. Mixed-sex normal

progenies of striped bass and hybrid striped

bass (female white bass x male striped bass) were

used in the experiments. The androgen 17amethyltestosterone

(MT) was orally administrated

to fish with a dry prepared diet or with nauplii of

brine shrimp Artemia sp. at different periods after

hatching. Live food was used at the earlier stages

of fish ontogeny.


Experiment 1.—Three MT-treated groups and

one control group of the same origin were used in

this study. The 32-d-old white bass x striped bass

fry were collected from large production rearing

tanks (where the fish were fed rotifers) at kibbutz

Hamaapil Fish Hatchery and stocked into two

recirculating-water systems (460 fish/system) at

Dor Station. The fish in one system (group 1) were

fed with MT-enriched brine shrimp nauplii for 30

d from 34 to 64 d after hatching (d.a.h.), while the

fish stocked into the other system received intact

brine shrimp nauplii (control group; Table 1). Water

temperature was maintained at 21–228C. Later,

another batch of fish from the same hybrid progeny

was collected from the pond (where the fry were

stocked from production rearing tanks) and put

into two other recirculating-water systems (110

fish/system). The fish in one system were fed with

a dry diet containing MT for 30 d from 67 to 97

d.a.h. (experiment 1, group 2). The fish in the other

system (experiment 1, group 3) received regular

dry diet (no androgen added) up to the 97th d.a.h.

Afterwards, all fish surviving in this system (N 5

77) were transferred to the hormone-containing

diet for 30 d (from 98 to 128 d.a.h.; Table 1).Water

temperatures were 22–248C (67–97 d.a.h.) and 25–

26.58C (98–128 d.a.h.).

Experiment 2.—One MT-treatment group (group

1) and a corresponding control group taken from

another (than in experiment 1) hybrid progeny

were included. Fish were caught from a pond and

put into two recirculating-water systems (100 fish/

system). Group 1 received a diet containing MT

for 40 d (from 92 to 132 d.a.h.), while the control

group was fed a MT-free food (Table 1). Water

temperatures during the experimental period were

25–26.58C.


Fish Survival and Sex Ratio

The data on fish survival during the period of

hormonal treatment and sex distributions in experimental

and control groups are given in Table 1.

Experiment 1.—There was no significant difference

in fish survival between group 1 (29.3%) recieving

MT-enriched brine shrimp and the control

group (27.4%) fed intact nauplii during the same

period. Fish survival in experimental groups increased

with fish age and size up to 99% in group

3. The sex ratio in the control group did not differ

from 1:1 (P . 0.05). Groups 1 and 2 had similar

sex ratios (about 60% males) that did not differ

significantly from 1:1 (P . 0.05), but 12% of the

fish in group 1 had intersexual gonads. In group

3, 97.2% of fish were males (P , 0.001).

Experiment 2.—Fish survival was similar in

both groups. The sex ratio in the control group

was close to 1:1 (P . 0.05). In group 1, 95% of

the fish were males and the rest (5%) were intersex.