William A. Bray

Hybridization of Penaeus setiferus (Linnaeus, 1767) and Penaeus schmitti Burkenroad, 1936 (Decapoda)

ABSTRACT Hybrid crosses of females of Penaeus setiferus x males of Penaeus schmitti were obtained through artificial insemination. Mature females of P. setiferus (mean weight, 53 g ± 8.2 SD), collected from a wild population in the northwestern Gulf of Mexico, were inseminated with sperm of males of P. schmitti (mean weight, 27 g ± 5.3 SD) obtained from the western Caribbean Sea. Nauplii resulted from 7 of 19 artificial inseminations and were cultured to the subadult stage. Fertilization in all inseminations was less than 1% (4-4,300 nauplii per spawn), and subsequent survival of nauplii to postlarvae averaged 47%. Hybridization was confirmed by isozyme comparisons of parents and offspring using starch gel electrophoresis. Hybrids also exhibited uropod coloration typical of P. schmitti, the paternal phenotype, when sampled as subadults. Diagnostic differences between the parent species were found only by using a soluble protein stain and were not found in 11 specific enzymes tested. Sperm and ova were observed in mature hybrid offspring. These results are indicative of the phylogenetic relatedness and genomic compatibility of these species.

Reproduction of ablated and unablated Penaeus schmitti in captivity using diets consisting of fresh-frozen natural and dried formulated feeds

Abstract Reproduction of Penaeus schmitti was achieved in a recirculating seawater system using three different diets: 100% fresh-frozen,50/50% fresh-frozen/dried and 100% dried formulated feeds. Shrimp fed the50/50% fresh-frozen/dried and 100% dried diets had significantly higher ( P P. schmitti reproductive processes which were monitored during the study. One hundred percent dried formulated feed induced the best maturation, spawning and fecundity. Results using the mixed diet were slightly lower, but did not differ significantly ( P > 0.05). The mixed and 100% fresh-frozen diets induced significantly higher ( P

Electrical stimulation of spermatophore expulsion in marine shrimp, Penaeus spp

Abstract Electrical stimulation (4–6 V AC) applied near the male gonopores at the base of the fifth pereopods caused expulsion of the spermatophore in Penaeus setiferus, P. stylirostris , and P. vannamei . For healthy animals, some degree of spermatophore expulsion occurred in 80% of the attempts. Complete expulsion of one or both spermatophores occurred in only 47% (29–65%, depending on species). Shrimp with melanized terminal ampullae generally did not expel a spermatophore following electrical stimulation. The technique needs further refinement for routine use with penaeids.