Shrimp larval quality as a function of roodstock condition Ilie S. Racotta, Elena Palacios, and Ana María Iarra. Programa de Acuacultura, Centro de Investigaciones Biológicas del Noroeste, La Paz, MEXICO.
Larval quality Performance during culture (growth, survival, physiological condition) Spawn quality (eggs and nauplii) and larval quality (zoea( to PL) A priori (predictive), or a posteriori criteria (final) Higher yields and profits
Criteria of spawn and larval quality Biochemical composition Morphological (weight, size, deformities) Behavioral (positive phototropism, swimming activity) Production (fecundity, fertilization, hatching, larvae survival) Stress tests (low salinity, formalin,, low oxygen, high ammonia)
Spawn quality: iochemical composition of eggs and nauplii Lecitotrophic stages: their development depends on nutrients transferred from ovaries. Initial levels and susequent use will determine hatching and survival to further stages A final criterion for roodstock condition A possile predictive criterion of larval quality
Biochemical composition of eggs or larvae related to a performance characteristic. Biochemical component Related performance Reference Triglycerides Triglycerides, carotenoids Egg development rate Spawner condition and larval survival Wickins et al., 199 Palacios et al., 1999 (this presentation) EPA and DHA Fecundity, Hatching Xu et al., 1994 Lipids and carohydrates Successful development to PL Hernández-Herrera et al., 21 (poster) Carotenoids in diet Survival to zoea Wyan et al., 1997 RNA/DNA ratio Feeding condition of postlarvae Moss, 199
Postlarvae yield Spawn and larval quality: Production variales Fecundity, fertilization and hatching rates (a result of roodstock condition) Numer of nauplii. Larval survival through zoea, mysis and postlarval stages (a result of oth larval culture and roodstock condition)
Production variales Final criteria in studies of roodstock management or larval culture (e.g. nutrition). Could e used as a predictive criteria: e.g. survival to PL ased on early characteristics Although intuitive, few studies have addressed the suitaility of such relation
Larval quality: Stress tests Based on an arupt transfer to adverse environmental conditions (e.g. low salinity, low temperature, low oxygen, high ammonia) and survival assessment: Larvae or Postlarvae 9 8 7 6 4 3 2 1
Salinity stress test: age and condition Survival to low salinity depends on PL age (Charmantier et al., 1988; Aquacop, 1991; Samocha et al., 1998). Age Salinity Survival Condition Reference PL2 18ppt 6-9% Spawner Hernandez-Herrera, et al., 21 (poster) PL 14-2 ppt -9%* Diet* Tackaert et al., 1989, Gallardo, 199 PL1-14 ppt 18-98%* Diet* Tackaert et al., 1989; Rees et al., 1994; Wouters et al., 1997 > PL1 ppt 39-89% Spawner Palacios et al., 1999 (this presentation); Hernandez-Herrera, et al., 21 (poster) > PL1 ppt -9%* Diet* Tackaert et al., 1989; 1991; Coutteau et al., 1996 * also depends on exposure duration
Use of salinity stress test Widely used as a final criterion for experimental studies (e.g. nutrition) on larval and postlarval culture. Assumed as a predictive criterion for stocking in ponds and further growout,, although this has not een experimentally tested. In early PL stages salinity stress test could e used as a predictive criterion of further PL performance
Influence of roodstock management on larval quality Nutrition Environmental conditions Shrimp size, age and season of the year Origin of shrimp Endocrine manipulations Reproductive exhaustion Genetic variaility
Broodstock endocrine manipulations Eyestalk alation (which produce a decrease in gonad inhiiting hormone) represents y far the most commonly used procedure for most species. Controversies exists aout the consequences on spawn and larval quality. Some alternatives such as methylfarnoseate supplement in the diet, or serotonin injection have een tested on larvae production. Other alternatives (peptides, steroids) have een tested only on ovary development and sperm production.
Eyestalk alation and spawning frequency eyestalk-alated unalated spawns 1 2 3 4 to 6 7 to 1 >1
Spawn and larval quality 3 Production: quantity 1 8 Production: quality 2 x 1 1 1 % 6 4 2 Numer of eggs Numer of nauplii Unalated Alated Fertilization Hatching mg or ug /g 4 3 2 1 a Eggs iochemical composition % 1 7 Survival during larviculture Acylglycerides (mg) Carotenoids (ug) NIV ZI ZII ZIII MI MII MIII PLI
Reproductive exhaustion Decline in reproductive capacity under intensive maturation conditions. Occurs oth in males and females as a consequence either of time or consecutive rematurations. Broodstock replacement (2 to 6 months)
Time spent in maturation conditions Time in tanks Consequence Reference at 6-8 weeks fertilization, hatching, metamorphosis to zoea Simon, 1982 1 to 7 weeks sperm count, live sperm anormal sperm Leung-Trujillo and Lawrence, 1987 1 to 6 weeks hatching Bray et al., 199 to 4 days fertilization Menasveta et al., 1993 1 to 14 weeks survival to zoea Wyan et al., 1997 18 to 96 days fecundity, fertilization iochemical components Palacios et al, 1998 1 to 7 days several traits Palacios et al, 1999
Time spent in tanks and spawn quality 1 8 6 a a 3 2 a % 4 2 Fertilization Hatching 1 days 4 days 7 days x 1 1 1 Eggs/spawn a a Nauplii/spawn 2 a a a 1 2 1 mg/g in eggs 1 1 ug/g in eggs mg/g in nauplii 1 1 a c a c ug/g in nauplii Acyglycerides (Y1) Carotenoids (Y2) Acyglycerides (Y1) Carotenoids (Y2)
Time spent in tanks and larval quality 1 Survival through larviculture 8 6 % 4 2 a c NIV ZI MI PLI 1 days 4 days 7 days % survival 1 8 6 4 a a a 1 mm 1 8 6 % 4 Survival to a salinity stress test a a 2 2 PL1 to PL1 (Y1) PL1 length (Y2)
Consecutive spawns Spawn order Consequence Reference 1 to 8 gonadosomatic index = fecundity and hatching 1 to 9 hatching, = fecundity and =nauplii/spawn Lumare, 1979 Emmerson, 198 1 to = fecundity and hatching Chamerlain and Lawrence, 1981 1 to 9 = fertilization and hatching = metamorphosis to zoea Browdy and Samocha, 198 1 to 3 lipids in hepatopancreas Vázquez-Boucard, 199 1 to 6 = fecundity, hatching survival to zoea Marsden et al., 1997 1 to metamorphosis to zoea Wouters et al., 1999
Maturation capacity: ovary development Gonadosomatic index (%) 8 7 6 4 3 2 1 r =.3, p<.1 1 1 2 spawning order P V C Late Vitellogenic oocytes (% ) 2 1 1 1 1 2 spawning order 4 Mature oocytes (%) 3 3 2 1 1 1 1 2 spawning order Atresia ocurrence 2 1 1 r =.32, p<. 1 1 2 spawning order
TOTAL LIPIDS (mg/g) 6 4 3 2 1 Maturation capacity: ovary iochemical Maturation P <. 1 to 4 > composition mature ACILGLYCERIDES (mg/g) 3 2 1 1 1 to 4 > Maturation P <. inmature TOTAL PROTEINS (mg/g) 12 1 8 6 4 2 Spawns P <. Maturation P <.1 TOTAL CARBOHIDRATES (mg/g) 6 4 2 1 to 4 > 1 to 4 >
Spawn quality (%) 1 7 Fertilization rate Spawning order 1st 2nd 3rd 4 to (%) 1 7 7 to 12 Hatching rate Spawning order Acylglycerides in eggs Acylglycerides in nauplii 2 2 (mg/g) 1 1 (mg/g) 1 1 Spawning order Spawning order
Time in maturation tanks vs. consecutive spawns Total spawns/tank 4 3 3 2 1 1 1 2 3 4 spawning order 6 7 8 + 1 7 13 19 31 37 43 49 61 67 73 79 8 91 97 Time spent in tanks (days) Time spent in tanks is only partially related to consecutive spawns Evaluation must consider separately oth factors
Conclusions Eyestalk alation does not affect spawn and larval quality under our conditions Reproductive exhaustion consist of at least two factors: time spent in tanks and consecutive spawnings Time spent in tanks decreases spawn and larval quality Female maturation capacity and spawn quality was not significantly decreased y consecutive spawns
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