根据2018年12月在日本海采集的舍氏贝乌贼(Berryteuthis magister shevtsovi)样本,对其形态特征、胴长与体质量、性腺成熟度、摄食强度与肥满度等生物学特征进行了研究。结果表明:舍氏贝乌贼的优势组胴长和体质量分别为100~120 mm和30~7...根据2018年12月在日本海采集的舍氏贝乌贼(Berryteuthis magister shevtsovi)样本,对其形态特征、胴长与体质量、性腺成熟度、摄食强度与肥满度等生物学特征进行了研究。结果表明:舍氏贝乌贼的优势组胴长和体质量分别为100~120 mm和30~70 g,鳍长与鳍宽的平均值为(58.36±5.81)mm和(90.44±6.89)mm;在体质量与胴长的关系中,条件因子a为0.0007,异速生长因子b为2.3934,胴长的增长速度快于其体质量的增加;性腺成熟度以I和II期个体为主;胴长小于110 mm时,摄食强度多以1~2级为主,胴长大于110 mm时,摄食强度为3~4级的个体占比上升;随着胴长的增加,个体肥满度呈现下降的趋势。研究结果可为后续研究其种群鉴定、生活史、资源开发和利用等提供参考。展开更多
The reproductive biology of bream Ahramis brama （L.） was studied from 546 fish collected from the lower reaches of the Irtysh River in Xinjiang, north-west China, from March to November 2013. The overall sex ratio ...The reproductive biology of bream Ahramis brama （L.） was studied from 546 fish collected from the lower reaches of the Irtysh River in Xinjiang, north-west China, from March to November 2013. The overall sex ratio （M/F） was 1.06：1, and was not significantly different from the theoretical 1：1 ratio （P〉0.5）. However, there was a dominance of males during the pre-spawning season （ 1.33 in March and 1.56 in April, P〈0.5）, while females were dominant during the peak spawning season （0.88 in June, P〈0.5）. The monthly variation in gonadosomatic index （GSI） and proportion of gonads at each macroscopic maturity stage, indicated that A. brama spawned once a year with peak spawning occurring from late May to June. The unimodal distribution of oocyte diameter each month indicated that A. brama is a single spawner, with a high degree of spawning synchronicity. The standard lengths （SLs0） and ages （As0） at first maturity for males and females, were 178 and 204 mm, and 5.6 and 6.8 years, respectively. The mean absolute fecundity （AF） was 77 311 eggs per fish, and mean relative fecundity （RF） was 162 eggs per gram of body weight （BW）. The AF ofA. brama increased linearly with increasing of gonad weight （GW）, eviscerated weight （EW） and standard length （SL）, but was not significantly correlated with age. As, A. brama in the lower reaches of the Irtysh River reaches reproductive maturity relatively late in their life span, is mature for a short period and spawns in aggregations, this fish is vulnerable to overexploitation.展开更多
基金Supported by the Special Funds for the Foundation Work of Science and Technology(No.2012FY112700)
文摘The reproductive biology of bream Ahramis brama （L.） was studied from 546 fish collected from the lower reaches of the Irtysh River in Xinjiang, north-west China, from March to November 2013. The overall sex ratio （M/F） was 1.06：1, and was not significantly different from the theoretical 1：1 ratio （P〉0.5）. However, there was a dominance of males during the pre-spawning season （ 1.33 in March and 1.56 in April, P〈0.5）, while females were dominant during the peak spawning season （0.88 in June, P〈0.5）. The monthly variation in gonadosomatic index （GSI） and proportion of gonads at each macroscopic maturity stage, indicated that A. brama spawned once a year with peak spawning occurring from late May to June. The unimodal distribution of oocyte diameter each month indicated that A. brama is a single spawner, with a high degree of spawning synchronicity. The standard lengths （SLs0） and ages （As0） at first maturity for males and females, were 178 and 204 mm, and 5.6 and 6.8 years, respectively. The mean absolute fecundity （AF） was 77 311 eggs per fish, and mean relative fecundity （RF） was 162 eggs per gram of body weight （BW）. The AF ofA. brama increased linearly with increasing of gonad weight （GW）, eviscerated weight （EW） and standard length （SL）, but was not significantly correlated with age. As, A. brama in the lower reaches of the Irtysh River reaches reproductive maturity relatively late in their life span, is mature for a short period and spawns in aggregations, this fish is vulnerable to overexploitation.
