DataSheet_4_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（Labeo rohita Hamilton）是全球重要的水产养殖物种，其遗传改良品系的供给正日益丰富。2020年，来自WorldFish露斯塔野鲮遗传改良项目的高排名三代（G3）家系组成的扩繁种群被投放至孟加拉国的孵化场，以培育为亲鱼群体。
【材料与方法】为评估G3扩繁种群收获体重的实际遗传增益，研究从孟加拉国19家半商业化养殖场（杰索尔区10家、诺多尔-拉杰沙希区9家）各选取1口池塘，分别放养来自3个品系的等量标记鱼类。本研究涉及的3个品系分别为：投放至孵化场的“G3扩繁品系”、“对照品系”（理论上与源自野生河流种群的未改良基础群体遗传特性一致）以及来自“商业化孵化场”的鱼类。放养后，鱼类养殖管理遵循各养殖场的常规操作。
【结果】研究发现G3扩繁品系的生长速度最快。杰索尔区各养殖场的商业化品系、对照品系和G3扩繁品系的收获体重反转换均值分别为594 g、659 g和914 g；诺多尔-拉杰沙希区则分别为545 g、626 g和845 g。
【讨论】上述结果意味着，相较于对照品系，G3扩繁品系在杰索尔区和诺多尔-拉杰沙希区的实际遗传增益分别达到38.6%和34.9%，证实了基于家系（即基于系谱）的遗传改良方法能够在露斯塔野鲮中实现可观的遗传增益。此外，本研究中G3扩繁品系相较于对照品系和商业化品系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型露斯塔野鲮。