Abstract
Pearl oyster (Pinctada fucata martensii) is the main species cultured for marine pearls in the world. A breeding program was carried out for desirable production traits, including high growth rate, and a fast-growing selective strain of pearl oysters was established. In the current study, we compared the growth characteristics between a selective strain and a cultured population of P. f. martensii in Beihai, Guangxi Province, China. Large size (SL) and small size (SS) individuals of the selective strain were selected, and the differences of physiological and metabolic indexes, such as feeding, respiration, excretion, and enzyme activities between SL and SS and cultured population (CL), were also compared. The results showed that at the age of 6 months, pearl oysters of the selective strain were 14.61% larger than CL, and the proportion of SL (30–40 mm) was 59%, which was two times higher than CL (28%). SL with a rapid growth rate had a high clearance rate (CR), and the CR of SL was about 1.8 times higher than that of CL and 5 times higher than that of SS. In addition, the activities of digestive enzymes (amylase, pepsin, and lipase) and growth-related carbonic anhydrase enzymes in SL were higher than those in the other two groups (p < 0.05). SS with a slow growth rate had higher oxygen consumption (OCR) and ammonia excretion (AER) rates than SL and CL (p < 0.05). Our results suggest that the rapid growth of the selective strain P. f. martensii can be attributed to increased energy intake and reduced energy consumption.
Highlights
The pearl oyster, Pinctada fucata martensii, belonging to the family Pteriidae (Pterioida, Bivalvia), is naturally distributed in countries along the west coast of the Pacific Ocean, such as China, Japan, Australia, and the Philippines (Wang et al, 2004)
We compared the growth differences between the selective strain of P. f. martensii and the control group, and results showed that the growth rate of selective strain was significantly improved (14.61%) (p < 0.05), which was consistent with the previous study on 1-year-old selective strain pearl oyster (15.31%) (Wang et al, 2011a)
We examined the difference of feeding and metabolism between the selected strain and cultured population of P. f. martensii and identified the mechanism responsible for the improved growth performance in the selective breeding of pearl oysters
Summary
The pearl oyster, Pinctada fucata martensii, belonging to the family Pteriidae (Pterioida, Bivalvia), is naturally distributed in countries along the west coast of the Pacific Ocean, such as China, Japan, Australia, and the Philippines (Wang et al, 2004). Martensii is the primary species cultured for marine pearls in China and Japan (Wang et al, 2011a). The pearl oyster industry has become one of the most important mariculture industries in several southern provinces of China, including Guangdong, Guangxi, and Hainan (Wang et al, 2004; Deng et al, 2009a, 2011; He et al, 2021; Xu et al, 2021). A rapid growth selective strain was obtained through hybrid breeding with the Indian population as the male parent and the Chinese Sanya population as the female parent (Wang et al, 2000, 2004). After seven generations of selection, remarkable genetic gains for growth rate and a high proportion of high-quality pearls were achieved in the selected strain (Wang et al, 2011b)
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