Effect of Eyestalk Ablation on Maturation, Larval Performance, and Biochemistry of White Pacific Shrimp, Penaeus vannamei, Broodstock

ABSTRACT

Eyestalk ablation clearly increases reproductive output in Penaeid shrimp, and it is widely used to obtain larvae in commercial hatcheries. Disruptions in the overall endocrine mechanisms of spawn-ers are likely to occur, and larval quality could also be affected by uncontrolled acceleration of maturation. In the present work, during a production period in a commercial hatchery, several traits of females, ablated by cutting one eyestalk at its base, and unablated controls were analyzed. These analyses included reproductive performance, biochemical characteristics of eggs and nauplii, and larvae survival. In addition, possible long-term physiological alterations of spawners were evaluated using histological and biochemical approaches. The number of spawns a female had or the maturation stage of spawners were also considered as additional factors influencing the variables recorded. Ablated females had more frequent spawns (P < 0.01) and a higher gonadosomatic index (P < 0.05) but a lower weight gain than unablated controls (P < 0.05). Ablated females had lower levels of hemocyanin in hemolymph (P < 0.01) and of glucose in hepatopancreas (P < 0.05) but higher levels of total carotenoids in hepatopancreas (P < 0.05). The eggs of ablated females had higher levels of acylglycerides (P < 0.05). There were some differences in the biochemical levels in tissues and eggs as functions of the number of spawns between ablated and un-ablated females. No differences in the biochemical composition of nauplii or in the larval survival during culture to postlarvae 1 were found between ablated and unablated females.

Key Words:

• White shrimp
• Penaeus vannamei
• eyestalk ablation
• larval performance