Nauplii Production from Wild, Cultivated, and Mixed Populations of Blue Shrimp, Penaeus stylirostris

Abstract

ABSTRACT Due to the low nauplii production of cultivated broodstock, and to reduce the dependence on the wild stock, an experiment was carried out with 400 adult blue shrimp, Penaeus stylirostris, from wild and cultivated (F6) populations. Four treatments, each in duplicate, were applied: (1) wild females and males (W-W); (2) wild females and cultivated males (W-C); (3) cultivated females and wild males (C-W); and (4) cultivated females and males (C-C). More than 300 individual spawns were monitored to evaluate the egg and nauplii production per female. Mixed model ANOVA for factorial arrangements (4 × 3 × 23 and 3 × 23) were conducted. The factors considered besides the treatments were: rematuration (number of successive spawnings for a female), ovarian maturity, integrity of the spermatophore attached (complete spermatophore, “wings,” or “remnant”) and condition of spawning (partial or complete). The introduction of both wild females and males was a successful measure to improve the overall egg and nauplii production. Both mixed populations outperformed the cultivated broodstock, but were inferior to the wild stock (average production of eggs and nauplii: W-W-l 12,713 and 34,682, respectively; W-C-l 13,215 and 22,038, respectively; C-W-82,702 and 11,715, respectively; C-C-66,948 and 7,653, respectively). Populations with wild females produce a larger number of eggs, and wild males contribute to higher hatching rates. Other observations indicate the need to select for spawning only those females showing an advanced degree of ovarian maturity, having a complete spermatophore attached to the thelycum, and spawning completely.