不同动物饵料对YY超雄黄颡鱼性腺发育的影响

通过比较近10年YY超雄黄颡鱼的生产和养殖记录,发现仅近几年投喂过水蚯蚓的YY超雄黄颡鱼性腺出现问题。实验设定4组不同饵料(丰年虫、浮游动物、红虫和水蚯蚓)连续投喂YY黄颡鱼鱼苗20 d(11～30日龄),选择60日龄统计各组YY超雄黄颡鱼的存活率、体长和体质量。水蚯蚓组YY超雄黄颡鱼的体长和体质量显著高于其他3组,丰年虫组YY超雄黄颡鱼存活率显著低于其他3组。解剖观察60日龄和1年龄YY黄颡鱼的性腺结构并统计1年龄YY超雄鱼的受精率,结果显示,水蚯蚓组YY超雄黄颡鱼的性腺有75%为兼性性腺(精巢和卵巢均存在),25%为无精小叶的精巢,且1年龄的YY黄颡鱼受精率仅为36.70%±4.05%,并显著低于其他3组,而其他3组性腺发育和受精率均正常。为研究水蚯蚓引起YY黄颡鱼雌性化具体原因,实验测量4种不同动物饵料的雌二醇含量,发现雌二醇含量均较低,推测YY超雄黄颡鱼雌性化的原因可能是水蚯蚓富集的环境内分泌干扰物(EDCS)导致。研究表明,在YY超雄黄颡鱼大规格苗种培育过程中,早期应投喂浮游动物或红虫,不宜投喂水蚯蚓。

Effects of different animal baits on the gonad development of YY super-male yellow catfish (Pelteobagrus fulvidruco)

The emergence of novel variety "All-male NO.1" dramatically promoted the development of the Pelteobagrus fulvidraco industry, of which the cultivation of YY super-male was a critical step. Recently, YY super-male P. fulvidraco with intersexual gonad emerged largely, which hindered the development of P. fulvidraco industry. We only found the problem of gonad development in YY super-male breeding with Tubificidae by checking the production and breeding records for nearly 10 years. Therefore, four different baits including Artemia salina, zooplankton, Chironomus plumosus, Tubificidae were used to treat YY super-male for 20 days (11 to 30 days of age post hatching). The survival rate, body length, and body weight of each group were measured at 60 dph (day post-hatching). Tubificidae treatments significantly increased the body length and weight compared with other baits, and the survival rate of fish fed with Artemia salina was significantly lower than fish fed with the other three baits. In addition, we performed histology analysis on gonadal structure at 60 dph and 1 year old and statistics of fertilization rate at 1 year old. As a result, the fish group fed with Tubificidae displayed 75% intersexual gonad and 25% testis without seminiferous lobule, and the fertilization rate was only 36.70%±4.05%, which was significantly lower than that of the other groups. In order to study the reasons for the feminization of YY P. fulvidraco, we measured the estradiol content and found that the estradiol content was low in all four different animal baits. It is speculated that the feminization of YY super-male P. fulvidraco may be caused by the environmental endocrine disruptors (EDCS) enriched by Tubificidae. Therefore, zooplankton or Chironomus plumosus should be fed in the early stage of large-scale breeding of YY-supermale P. fulvidraco, whereas Tubificidae should not be fed.