Penaeus monodon (mean initial wet weight 1·19 (se 0·01) g) were fed seven diets in triplicate: a control diet (D1) without carotenoids; three diets formulated to supply 0·1 % astaxanthin alone (D2), 0·2 % astaxanthin alone (D3), and a combination of 0·1 % astaxanthin and 1 % cholesterol (D4); three diets with 0·07 % canthaxanthin alone (D5), 0·13 % canthaxanthin alone (D6), and a combination of 0·07 % canthaxanthin and 1 % cholesterol (D7). Weight gain (WG, %), specific growth rate (SGR, %/d) and survival were chosen as parameters of shrimp growth performance. Total antioxidant status (TAS), superoxide dismutase (SOD), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were chosen as indices of shrimp plasma antioxidant capacity. Meanwhile, digestibility, retention efficiency and tissue carotenoids were also investigated to determine the additive effect of cholesterol on the efficiency of astaxanthin and canthaxanthin. After 74 d rearing, WG and SGR of shrimp fed D2–D4 and D7 were higher than those of shrimp fed D1 (P < 0·05). Shrimp fed D4 had the highest survival. The apparent digestibility coefficients (ADC) of astaxanthin in D2–D4 were higher than those of canthaxanthin in D5–D7 (P < 0·05). Although ADC of astaxanthin were quite high (>98 %) in D2–D4 and no differences were found among them (P>0·05), the carotenoid retention efficiencies in the whole body, muscle and shell (D2–D3 treatments) were considerably low; however, cholesterol supplementation significantly improved the carotenoid retention efficiencies in the whole body, muscle and shell (D4 treatment). Accordingly, the addition of cholesterol also significantly enhanced the carotenoid contents of tissues. Shrimp fed supplemented carotenoid diets (D2–D7) had higher TAS and lower SOD, ALT and AST than shrimp fed D1 (P < 0·05). A low dissolved oxygen stress test was conducted for 7 d after the rearing trial and shrimp survival was also compared among the treatments. The survival of shrimp fed the diets supplemented with astaxanthin or canthaxanthin was higher than that of shrimp fed D1 during the stress test (P < 0·05). In conclusion, all data suggested that astaxanthin was better than canthaxanthin as the dietary carotenoid source in the commercial diet of P. monodon, and the supplement of cholesterol could positively enhance the efficiency of astaxanthin and canthaxanthin.

There are many environmental and socio-economic concerns about the shrimp aquaculture industry. This study, based on interviews, direct observations and literature reviews, shows that the Indian hatchery industry is heavily dependent upon the continuous support of natural resources and ecosystem services generated by marine, freshwater and terrestrial ecosystems. The mangrove ecosystem support area (‘ecological footprint’) needed to supply the hatcheries with Penaeus monodon shrimp broodstock, and the aquaculture grow-out ponds with postlarvae, exemplify the dependence on external ecosystems. Each hectare of mangrove in the Godavari River delta generated an annual fisheries catch of 0.8–1.5 P. monodon spawners (gravid females), valued at US$ 92–184. The entire Godavari mangrove delta had a partial gross economic value of US$ 3.0–6.0 million per year for the provision of shrimp spawners alone. The average hatchery, producing 75 million postlarvae annually, had an ecological footprint of 534 ha mangrove for the life-support input of shrimp spawners. The ecological footprint of intensive shrimp ponds was up to 11 times the pond area for postlarval input alone. The shrimp ponds in the State of Andhra Pradesh needed 35 000–138 000 ha of mangroves to satisfy the spawner requirement to hatcheries, and this implied a need to appropriate mangroves in other regions. Hatcheries were prepared to pay up to US$ 2000 for a single shrimp spawner, which also illustrated that the mangrove support areas regionally available were too small. Other concerns about the industry are the net loss of employment if hatcheries replace wild postlarvae collection, the extensive use of groundwater creating direct resource-use conflicts, by-catch problems in broodstock fisheries, and pollution by effluents. The risk of hatcheries introducing, amplifying and propagating disease affecting both cultured organisms and wild biota is another concern that can, and should, be addressed.

The reproductive performance of pond tiger shrimp given astaxanthin (100 mg·kg−1) and/or vitamin A (20 000 IU·kg−1) for 61 d in tanks was assessed in a 2 × 2 factorial experiment in a completely randomized design. Tissue carotenoid (total carotenoid; astaxanthin free form. AF; monoester, AM; diester, AD) was analyzed using high performance liquid chromatography. The gonad index (GI) of shrimps fed diets with astaxanthin and/or vitamin A (3.05 ± 0.11 to 3.30 ± 0.17) were significantly higher than shrimps not fed any supplement (2.24 ± 0.17). A significant interaction between astaxanthin and vitamin A for ovarian development and spawning was detected (GI, 3.18 ± 0.14). The ovarian total carotenoid (10.85 ± 1.52 μg·g−1) and astaxanthin (AF, 7.65 ± 1.43 μg·g−1; AM, 0.63 ± 0.12 μg·g−1) content of shrimps fed a diet with astaxanthin supplement were significantly higher than those without. In shrimps fed diets with and without vitamin A, no differences in ovarian total carotenoid (9.38 ± 0.58 μg·g−1) and AF (8.12 ± 1.55 μg·g−1) content were observed except for AM (0.64 pm 0.15 μg·g−1) content. In contrast, the ovarian AD level was significantly higher (1.14 ± 0.3 μg·g−1) in shrimps fed diets with both supplements compared to other diets. A significant interaction between astaxanthin and vitamin A was detected for AD storage. In the hepatopancreas of shrimps fed diets with or without astaxanthin or vitamin A, no significant differences in AF and AM content was observed. On the other hand, the AD (4.92 ± 1.3 μg·g−1) level in the hepatopancreas of shrimps fed diet with vitamin A was significantly higher than those without. These results suggest the involvement of astaxanthin in P. monodon reproduction and its need for inclusion in broodstock diets. Supplementation of vitamin A to broodstock diet of P. monodon appears to enhance its ovarian development and spawning.