DataSheet_6_On-farm performance of genetically-improved rohu (Labeo rohita) in Bangladesh.pdf

IntroductionRohu (Labeo rohita Hamilton) is a globally significant aquaculture species for which genetically improved strains are increasingly available. In 2020, a multiplier population, comprised of highly–ranked generation-three (G3) families from the WorldFish Rohu Genetic Improvement Program, was released to hatcheries in Bangladesh for development into broodstock.
MethodsTo estimate realised genetic gain for harvest weight in the G3-multiplier population, one pond from each of 19 Bangladeshi semi-commercial farms (ten in Jashore and nine in Natore–Rajshahi districts) were stocked with equal numbers of tagged fish from each of three strains. Strains included in the study were the ‘G3-multiplier’ released to hatcheries, a ‘control’ (putatively genetically equivalent to the unimproved base population which was spawned from fish of river origin) and fish sourced from a ‘commercial’ hatchery. Once stocked, fish were managed according to each farmer’s normal practices.
ResultsThe G3-multiplier was found to be the most rapidly growing strain. Back-transformed means for harvest weight across farms for the commercial, control and G3-multiplier strains were 594 g, 659 g and 914 g, respectively, in Jashore, and 545 g, 626 g and 845 g in Natore–Rajshahi.
DiscussionThese results equate to realised genetic gains of 38.6% (Jashore) and 34.9% (Natore–Rajshahi) for the G3-multiplier over the control strain and provide evidence that a family-based (i.e. pedigree-based) approach to genetic improvement is able to generate substantial levels of genetic gain in rohu. Furthermore, the clear growth advantages exhibited by the G3-multiplier strain over the control and commercial strains in this study, should encourage more Bangladeshi hatcheries, nurseries and farmers to adopt genetically improved rohu.

引言

露斯塔野鲮（Rohu，Labeo rohita Hamilton）是全球极具重要性的水产养殖品种，目前遗传改良品系的供应日益广泛。2020年，由世界渔业中心（WorldFish）露斯塔野鲮遗传改良项目筛选出的第三代（G3）优良家系组成的扩繁种群（multiplier population），被发放至孟加拉国的各孵化场，用于培育为繁殖亲鱼。

方法

为评估G3扩繁种群收获体重的实际遗传进展，研究人员从孟加拉国19家半商业化养殖场（其中杰索尔（Jashore）地区10家，纳托尔-拉杰沙希（Natore–Rajshahi）地区9家）各选取1口池塘，每口池塘均放养来自3个品系的等量标记鱼类。本次研究涉及的3个品系分别为：发放至孵化场的‘G3扩繁品系’、‘对照组品系’（推定与未改良的基础种群遗传特性一致，该基础种群由河流野生来源的亲鱼繁育而来），以及来自‘商业化孵化场’的鱼类。放养完成后，鱼类按照各养殖场户的常规养殖模式进行管理。

结果

研究发现G3扩繁品系的生长速度最快。杰索尔地区各养殖场的商业化、对照组及G3扩繁品系的经反推计算的平均收获体重分别为594 g、659 g和914 g；纳托尔-拉杰沙希地区的对应数值分别为545 g、626 g和845 g。

讨论

上述结果表明，相较于对照组品系，G3扩繁品系的实际遗传增益在杰索尔地区为38.6%，在纳托尔-拉杰沙希地区为34.9%，这证实了以家系为基础（即系谱为基础）的遗传改良方法，能够在露斯塔野鲮养殖中实现可观的遗传进展。此外，本研究中G3扩繁品系相较于对照组与商业化品系所展现出的显著生长优势，应能推动孟加拉国更多的孵化场、育苗场及养殖户采用遗传改良的露斯塔野鲮。