杂交鲟(施氏鲟♀×西伯利亚鲟♂)早期生长研究

Growth of Hybrid Sturgeon Acipenser schrenckii♀×A. baeri♂ during Early Development

将体质量(0.014±0.001) g的杂交鲟(施氏鲟♀×西伯利亚鲟♂)以流水方式养殖87 d,饲养期间随时观察鱼的体征变化,自第7 d开始,每10 d取样测体质量和全长。试验结果显示,水温7~14℃时,初孵仔鱼躯体纤细透明,头部小且紧挨卵黄囊,卵黄囊椭圆形,约占整个身体的2/3。仔鱼发育至第7 d时始开口摄食,进入混合营养阶段,发育至第9 d时卵黄囊基本消失,仔鱼完全进入外源营养阶段,第37 d时,仔鱼发育已进入稚鱼期,发育至第57 d时器官发育基本完善,外部形态和体色近成鱼,进入幼鱼期。仔稚鱼全长日均增长量为1.67 mm,平均瞬时增长率为2.26%,全长(L)与日龄(t)生长关系式为L=0.1546t+1.2357(r2=0.9812)。体质量日均增长量为0.25 g,平均瞬时生长率为5.51%,体质量(m)与日龄生长关系式为m=0.3379e0.0479t(r2=0.9851)。体质量与全长生长关系式为m=0.0289L2.3444(r2=0.993),幂指数小于3,表明杂交鲟仔稚鱼的体质量生长比全长生长慢,为异速生长。

Newly hatched larvae of hybrid sturgeon Acipenser schrenckii ♀× A. baeri ♂with body weight of(0.014±0.001) g were reared in a circular glass cylinder with diameter of 2 m and water depth of 15-25 cm at a density of 1500-2000 individuals/m2and fed tubificid worm(Limnodrilus hoffmeisteri) at water temperature of 7-14 ℃ for 87 days to investigate morphological characteristics, body weight and total length of the hybrid sturgeon. The newly hatched larvae had transparent body with small head and big yolk-sac, approximately equal to two-thirds of body length. The initial feeding was observed in 7 day old larvae in transition period from endogenous to exogenous nutrient and the nearly exhausted yolk-sac was found in 9 day old postlarvae, starting the exogenous nutrient. The organogenesis was basically perfected in 57 day old, and the external morphology consistent with adulthood. The postlarvae and juveniles had average daily total length gain of 1.67 mm and body weight gain of 0.25 g, with instantaneous growth rate of 2.26% in total length and 5.51% in body weight. The total length growth was expressed as linear relation with age, and the regressive equation was described as L=0.1546t+1.2357(r2=0.9812). The body weight growth was found to be power functional relation with day age, and the weight cure expression was described as m=0.3379 e0.0479t(r2=0.9851). The relationship between total length(L) and body weight(m) of the hybrid sturgeon was expressed as m=0.0289L2.3444(r2=0.993),with exponent of less than 3, indicating that the body weight growth, as allometric growth type, is slower than that of total length growth.