IMPACT OF DIFFERENT STOCKING DENSITIES ON GROWTH PERFORMANCE AND WELFARE OF Penaeus vannamei IN RAS

Introduction and methodology

 Despite the  widespread farming of Pena eus vannamei , there remains a lack of recognition and assessment of welfare standards  and chronic stress markers (David et al., 2020 ; Wuertz et al., 2023).  This study adopts a holistic approach to elucidate the  effects of different stocking densities on P . vannamei.

In a RAS t hree different stocking densities were tested in replicate : low stocking density (1 kg/m2), medium (2 kg/m2 )  and high (4 kg/m2) . A stress phase of 21 days is followed by a recovery phase of 21 days  at a low density (0.8 kg/m2). After every phase growth , hemolymph parameters and morphological  status in 4 grades ( 0 = no abnormalities and 3  = severely impacted) were evaluated . Further an ethogram of stress-related behaviours including cannibalism, swimming abnormalities, loss of balance, body cramps and strong escape behaviou r was created.

 Results and Conclusions

 High stocking densities have a negative impact on survival and growth performances (Tab. 1). However, recovery and partial compensatory growth are observed in the second phase.

 Furthermore, physiological parameters in hemolymph (glucose and total proteins) do not exhibit significant variations related to the treatments in both phases (Tab. 1).

0

 Notably, antennae and uropods sustain significant damage under  higher density conditions (Fig. 2), likely due to cannibalism and abrasions caused by limited space. Rehabilitation occurs within three weeks, with no discernible differences among treatments.

 In the mixed model analysis (p-value < 0.001 ), treatments influence the frequency of stress-related behaviour occurrences, while time does not. On the contrary, the recovery phase does not show differences among treatments and trends over time . This investigation evidences the effect of stocking density on P.vannamei and its capacity to recover promptly when the stressor is removed. The results can support the optimisation of farm practice in aquaculture.

References

1.  David, P.N.F., Manipol , N.E.P.; Madamba, J.A.B.; Mariano, R.A (2020). Good Aquaculture Practices Adoption and Certification of Shrimp Aquaculture Farms in Bulacan, Philippines: Status, Issues and Prospects. J Glob Bus Trade 2020, 15, 11–26.

2.                       Weiss , M., Rebelein , A., & Slater, M. J. (2020).  Lupin kernel meal as fishmeal replacement in formulated feeds for the Whiteleg Shrimp (Litopenaeus vannamei ). Aquaculture Nutrition, 26 (3), 752-762. https://doi.org/10.1111/anu.13034.

3.                       Wuertz , S., Bierbach, D., & Bögner, M. (2023).  Welfare of Decapod Crustaceans with Special Emphasis on Stress Physiology. Aquaculture Research, 2023 .