Length-at-age and weight-at-age of larval herring (Clupea harengus) reared at three temperatures in the laboratory up to 52 days post hatch

Ten female (mean 179 g wet mass (WM) and 25.3 cm standard length (SL) and ten male (182 g WM, 24.5 cm SL) Atlantic herring (Clupea harengus L.) were obtained from Kiel Bight (54°22'N, 010°09'E) and strip-spawned. The eggs were strip-spawned onto polyethylene plates, fertilized and incubated within aerated 250-L tanks containing 16 (±0.2) psu, 10 (±0.12)°C water at a light regime of 14 h (light):10 h (dark). After hatch on April 17, 2007, larvae were reared in semi-static (30% water exchange day−1) 100-L tanks (Ø 60 cm) at 17 (±0.5) psu and either 13.2 (±0.4), 10 (±0.4) or 7.2 (±0.3)°C. Tanks were “greened” with R. baltica (50,000 cells mL−1) and larvae were fed ad libitum rations of newly-hatched A. tonsa nauplii which corresponded to 5 prey mL−1 until a larval age of 13 days post hatch (dph) and then 2 prey mL−1 of early and late naupliar and copepodite stages. During rearing, larval SL- and dry mass (DM)-at-age was monitored every 2 to 3 days.

本实验从基尔湾（54°22'N，010°09'E）采集大西洋鲱（Clupea harengus L.）共20尾，其中雌鱼10尾（平均湿重（wet mass, WM）179g，平均标准体长（standard length, SL）25.3cm），雄鱼10尾（平均湿重182g，平均标准体长24.5cm），并对其实施人工挤卵授精；将获取的卵子挤于聚乙烯板上，完成受精后置于充气的250升水箱中孵化，孵化水体盐度为16(±0.2)实用盐度单位（psu），水温10(±0.12)℃，光照周期设置为14小时光照:10小时黑暗。2007年4月17日仔鱼孵化后，将其饲养于半静态（每日换水30%）的100升圆柱水箱（直径60cm）中，养殖水体盐度为17(±0.5)psu，水温分别设置为13.2(±0.4)℃、10(±0.4)℃及7.2(±0.3)℃三个梯度；水箱中接种R. baltica（50,000 cells mL⁻¹）以培育“绿水”环境，仔鱼初始以刚孵化的汤氏纺锤水蚤（A. tonsa）无节幼体作为开口饵料，按饱食标准控制投喂密度为5个猎物/mL，直至仔鱼孵化后13日龄（days post hatch, dph）；之后调整投喂密度为2个猎物/mL，投喂早期、晚期无节幼体及桡足幼体阶段的桡足类。饲养期间，每2至3天监测一次仔鱼的标准体长及干重（dry mass, DM）随日龄的变化情况。