青岛胶州湾铠平鲉年龄、生长和种群繁殖力

针对2013年和2014年采自青岛胶州湾的209尾铠平鲉(Sebastes hubbsi)样本开展了年龄、生长和种群繁殖力研究。耳石轮纹结构的年龄鉴定结果显示,铠平鲉的年龄分布范围为1~+~7~+龄,2~+~4~+龄为优势年龄组(77.5%)。体长与体重呈幂函数关系:W=8×10~(-5) L~(2.797)(R~2=0.861)。Von Bertalanffy体长生长方程为L_t=131.4×[1-e~(-0.269(t+2.697))],体重生长方程为W_t=63.6×[1-~(e-0.269(t+2.697))]~(2.797)。其生长过程可分为3个阶段:(1)1~+~3~+龄为快速生长期;(2)3~+~6~+龄为成熟稳定期;(3)6~+龄以后为高龄衰老期。所采样本的性比(2.12︰1)明显偏离1︰1(P0.05),雌性个体样本数在各体长段均高于雄性个体。性腺指数(GSI)和肝脏指数(HSI)变化趋势相反,肝脏可能为其性腺发育提供物质基础和能量来源。绝对怀卵量波动于482~6166粒,平均值为3266粒;相对体长怀卵量显著低于卵生鱼类,表明卵胎生鱼类体内胚胎发育、孵化的护卵方式可能使其以较少的怀卵量即可维持种的延续。结合拐点年龄对应的拐点体重及50%性成熟体长,建议以体长80 mm、体重20 g作为铠平鲉的开捕标准,以维护青岛胶州湾铠平鲉资源的可持续利用。

Age composition, growth, and fecundity of Sebastes hubbsi in Jiaozhou Bay, Qingdao

The age composition, growth, and fecundity ofSebastes hubbsiwas studied based on 209 samples col-lected in Jiaozhou Bay, Qingdao, in 2013 and 2014. Age was determined from the otoliths, which showed that the age ofS. hubbsi ranged from 1+ to 7+ years, with a dominant age group of 2+–4+years (77.5%). The relationship between the body length and bodyweight ofS. hubbsican be expressed by the power function,W= 8 × 10–5L2.797 (R2 = 0.861). The von Bertalanffy growth equations for the body length and bodyweight ofS. hubbsi wereLt= 131.4 × (1 – e–0.269[t+2.697]) andWt= 63.6 × (1 – e–0.269[t+ 2.697])2.797, respectively. The growth ofS. hubbsi was ini-tially rapid and then gradually stabilized. Its growth history could be divided into three stages: (1) rapid growth at 1+–3+ years old; (2) mature and stable growth at 3+–6+ years old; and (3) aged period at > 6+ years old. The sex ratio ofS. hubbsi deviated significantly from 1:1 (c2 test,P<0.05), and at every growth stage, the number of fe-males was higher than that of males. The gonadal index and hepatosomatic index displayed opposite trends, sug-gesting that the liver of S. hubbsiprovides material and energy for gonadal maturation. The absolute fecundity ofS. hubbsi individuals ranged from 482 to 6166 grains (mean 3266 grains) and the individual relative fecundity was lower than that of oviparous fish, suggesting that this kind of reproductive strategy allowsS. hubbsito maintain its population continuity with lower fecundity. Based on the age at inflection point and the body length at 50% sexual maturity, we suggest that a body length of 80 mm and a bodyweight of 20 g be set as the minimum landing stan-dards forS. hubbsi, to protect the fishery resource in Jiaozhou Bay, Qingdao.