EFFECT OF STOCKING DENSITY OF RED HYBRID TILAPIA ( OREOCHROMIS SP.) - - PowerPoint PPT Presentation

EFFECT OF STOCKING DENSITY OF RED HYBRID TILAPIA (OREOCHROMIS SP.) ON GROWTH AND SURVIVAL OF JUVENILE TILAPIA AND SHRIMP (LITOPENAEUS VANNAMEI) IN POLYCULTURE. Alejandro Macdonald-Vera1,2 Neil J. Duncan2 Wilfrido M. Contreras-Sánchez1 Kevin Fitzsimmons3

1Universidad Juárez Autónoma de Tabasco, Tabasco, Mexico. 2CIAD A.C. Unidad Mazatlan, Mexico. 3University of Arizona, Arizona, Tucson, USA

• Shrimp Farming Industry in

Mexico.

– Industry is prospering. – Disease and pricing problems. – Inefficient farms stop

• perating.

– Over 5000 ha of shrimp ponds unused.

• Shrimp-Tilapia polyculture.

– Increased production. – Maintain or improve shrimp survival. – Remove disease carriers from system.

Alejandro Macdonald-Vera who completed the study. Shrimp ponds in Mexico.

Methods

• White shrimp – PL 16 - 0.004g

– Litopenaeus vannamei – Certified free from white spot

• Red hybrid tilapia - 4.6±0.9g

– Genetic component of Oreochromis mossambicus – All males (hormonal treatment) – Acclimatised to 35ppt sea water, 5ppt per day.

• Pond preparation.

– Salinity range - 28 to 35 ppt – Temperature range - 16.2 to 25.6°C

Mosquito mesh divisions to make experimental enclosures Pond preparation, ploughed and limed.

Methods experimental design

• 9 enclosures (7x30=210m2) in 3 blocks, A, B, C.
• All enclosures stocked with 30 shrimp/m2
• Tilapia stocked at 3 densities, 0, 0.25, 0.5 fish/m2

to give the experimental groups T0, T0.25 and T0.5

Water inlet.

• utlet

1 2 0.5 3 0.25 4 0.25 5 6 0.5 7 0.5 8 9 0.25 Block A Block B Block C

Experimental pond set up.

Methods

• Stocking

– Shrimp and tilapia were acclimatised and randomly stocked into each enclosure.

• Sampling.

– Every 2 weeks. – 20 tilapia caught and weighed. – 30 shrimp weighed.

• Harvest.

– Experiment lasted for 8 weeks. – All shrimp and tilapia were harvested, counted and a random sample weighed.

Sampling. Stocking.

Results - Statistics

• Weight data was not normal.

– Some shrimp weight distributions were highly skewed towards larger individuals. – Some tilapia weight distributions had characteristics of a bimodal distribution, 23 to 42% maturing females were found during the harvest.

• 2 way Scheirer-Ray-Hare

extension of the Kruskal-Wallis and the DUNNS test were used to compare weight distributions

• Survival distributions were

normally distributed and were compared with ANOVA.

Expected Normal VAR7 Upper Boundaries (x <= boundary) No of obs 1 2 3 4 5 6 7 15 20 25 30 35 40 45 50

Expected Normal NEWVAR13 Shapiro-Wilk W=.97111, p<.0110 Upper Boundaries (x <= boundary) No of obs 5 10 15 20 25 30 35 14 16 18 20 22 24 26 28 30 Expected Normal NEWVAR16 Shapiro-Wilk W=.97691, p<.0002 Upper Boundaries (x <= boundary) No of obs 10 20 30 40 50 60 70 80 90 100 110 120 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Tilapia distributions Shrimp distribution

Results – Tilapia Growth.

5 10 15 20 25 30 35 40 45 50 5 Dec 22 Dec 5 Jan 19 Jan 2 Feb Weight (g)

No significant differences were observed for tilapia weights among treatments T0.25 and T0.5 or blocks A, B and C.

Results – Shrimp Growth.

No significant differences were observed among treatments T0, T0.25 and T0.5

0.5 1 1.5 2 2.5 3 5 Dec 22 Dec 5 Jan 19 Jan 2 Feb Weight (g)

Results – Shrimp Growth.

Significant differences (P<0.05) were observed among blocks A, B and C.

0.0 0.5 1.0 1.5 2.0 2.5 3.0 22 Dec 5 Jan 19 Jan 2 Feb Weight (g)

Block A Block B Block C

a a a a a b a ab b a b b

Results – Survival.

There were no significant differences among tilapia survivals. There were no significant differences among shrimp survivals for treatments, T0, T0.25 and T0.5. There were significant differences (p<0.05) among shrimp survivals for blocks A, B and C.

10 20 30 40 50 60 70 80 90 100 Block A Block B Block C T0 T0.25 T0.5 Block A Block B Block C T0 T0.25 T0.5

Shrimp Tilapia Survival %

a a b a a a a a a a a

Conclusions

• Stocking densities of 0, 0.25 and 0.5 fish/m2 did

not significantly affect growth or survival of juvenile shrimp and tilapia.

• Block or position in the pond did significantly

affect (p<0.05) growth and survival of juvenile shrimp.

• These are encouraging results that suggest shrimp

tilapia poly-culture has good potential for diversifying the Mexican shrimp culture industry and rehabilitating disused shrimp ponds.

Gracias CRSP

• Gabriela Velasco
• Leonardo Ibarra
• Rafael Guzman
• Ricardo Alvarez
• Michael Achury
• Noemi Garcia
• Estela Rodriguez.

Juan Manuel Gonzalez and his family