江黄颡鱼的仔稚鱼发育及行为生态学

江黄颡鱼从出膜仔鱼至夏花历时26d。仔、稚鱼发育分为仔鱼前阶段、仔鱼阶段、稚鱼前阶段和稚鱼阶段;每个阶段义分为3个时期,共12个时期。其中仔鱼前期分为附着期、平游期和开口期。在仔鱼附着时期要提供合适的附着物;仔鱼开口时期的饵料是小型枝角类。仔鱼阶段仍为混合营养阶段,除消耗卵黄外。其主要摄食枝角类。进入傩龟阶段后,其食性先后经2次转食：第1次由浮游动物转为底栖动物;第2次转食由底栖动物转为以动物性饵料为手的杂食性,并开始摄食人工精饲料。根据江黄颡鱼仔、稚鱼的发育特性,提出了一整套提高江黄颡鱼出苗率和成活率的科学方法。     

Effect of different sources and levels of dietary phospholipids on performances and fatty acid composition of pikeperch (Sander lucioperca) larvae

The aim of this study was to evaluate the effects of dietary phospholipids (PL) sources (fish gonad G‐PL and soybean lecithin S‐PL) and levels (50 and 90 g kg^?1 dry matter) on the performances and fatty acid (FA) composition of pikeperch larvae. From day 10 to day 34 posthatching (p.h.), larvae were fed with three isoproteic and isolipidic microdiets. The best results of growth and skeletal development were related to a high phospholipid level regardless of their origin and FA profile. Jaw deformities seemed associated with high dietary highly unsaturated FA (HUFA) level. The optimal level of eicosapentaenoic acid and docosahexaenoic acid (EPA + DHA) for pikeperch larvae appeared to be around 12 g kg^?1 (dry matter) associated with a PL level around 90 g kg^?1. FA composition of diets and larvae revealed a better incorporation of arachidonic acid, EPA and DHA into PL fraction especially in larvae fed with soybean PL. Moreover, 34‐day‐old pikeperch larvae may have capability of converting 18 carbon n‐3 FA into the n‐3 HUFA. Hence, for pikeperch larvae, PL from plant origin were as efficient as those from marine fish origin.     

Reproductive performance of indoor‐reared pikeperch (Sander lucioperca) females after wintering in outdoor earthen ponds

Photo‐thermal induction of gonadal maturation in completely controlled conditions is still not well explored in pikeperch. Thus, wintering intensively reared breeders in outdoor pond conditions might be rather suitable alternative to use these fish for larvae production. In this study, we compared the propagation success of indoor‐reared [recirculating aquaculture systems (RAS)‐reared fish, RRF] and wild (WCF) pikeperch females wintering them in outside earthen ponds. Each group was composed of six females and four males which were artificially propagated following hormonal induction with human chorionic gonadotropin. Beside the main parameters of reproductive success, fatty acid composition of dry eggs and mortality during early larviculture were assessed. The only statistically significant difference among reproductive parameters was found in latency time, which was significantly lower in RRF. Fatty acid profiles of dry eggs were rather similar between the groups; however, significant difference was noticed in phospholipid fraction in EPA/AA (eicosapentaenoic acid; C20:5n‐3/arachidonic acid; C20:4n‐6) ratio which was, on average, five times higher in the RRF (5.1 ± 3.8) than in WCF (0.9 ± 0.3). Significantly lower mortality was seen in the larvae originating from wild breeders (13.4 ± 1.7% and 27.0 ± 4.9% for WCF and RRF respectively). Wintering indoor‐reared females in outdoor pond conditions led to appropriate gonadal maturation, and ovulation occurred in all examined females. The lower quality of larvae was likely caused by suboptimal broodstock nutrition, which should be studied further, with special consideration given to the EPA/AA ratio and the phospholipid content and composition of the diet.     

菲律宾蛤仔稚贝期不同培育密度对生长、成活率的影响

2001年～2002年在大连普兰店市进行了菲律宾蛤仔稚贝期在大水体培育条件下,培育密度为260万～400万枚/m2对稚贝的日生长速度、成活率的影响试验,2001年试验中总平均日生长速度为44 7μm,出苗量为12 168亿枚,成活率为85 4%;2002年试验中总平均日生长速度为39 2μm,出苗量为15 47亿枚,成活率为90 7%。试验表明,菲律宾哈仔稚贝培育密度为260万～400万枚/m2在实际生产中是可行的,对稚贝的日生长速度、成活率影响不显著。     

Stable carbon (δ13C) and nitrogen (δ15N) isotopes as natural indicators of live and dry food in Piaractus mesopotamicus (Holmberg, 1887) larval tissue

This study proposed the use of the stable isotope technique to track the type of food utilized by pacu Piaractus mesopotamicus larvae during their development, and to identify the moment when the larvae start using nutrients from the dry diet by retaining its carbon and nitrogen atoms in their body tissues. Five‐day‐old pacu larvae at the onset of exogenous feeding were fed Artemia nauplii or formulated diet exclusively; nauplii+formulated diet during the entire period; or were weaned from nauplii to a dry diet after 3, 6 or 12 days after the first feeding. δ¹³C and δ¹⁵N values for Artemia nauplii were ?15.1‰ and 4.7‰, respectively, and ?25.0‰ and 7.4‰ for the dry diet. The initial isotopic composition of the larval tissue was ?20.2‰ and 9.5‰ for δ¹³C and δ¹⁵N respectively. Later, at the end of a 42‐day feeding period, larvae fed Artemia nauplii alone reached values of ?12.7‰ and 7.0‰ for δ¹³C and δ¹⁵N respectively. Larvae that received the formulated diet alone showed values of ?22.7‰ for δ¹³C and 9.6‰ for δ¹⁵N. The stable isotope technique was precise, and the time at which the larvae utilized Artemia nauplii, and later dry diet as a food source could be clearly defined.     

黑龙江鳜仔稚鱼的生长及主要生长性状的通径分析

本研究通过逐日测量7~24日龄鳜Siniperca chuatsi仔、稚鱼的全长和体高,及100尾24日龄鳜稚鱼的全长、体长、头长、吻长、体高,及体质量,运用相关分析和通径分析研究这5个形态性状对体质量的影响。结果显示:经过18d的养殖,鳜稚鱼全长增长189.55%,体高增长152.23%;全长、体高与日龄的回归关系分别为TL=0.019D~2+0.181D+4.674,BH=-3.227E-5D~3+0.005D~2+0.077D+1.364。相关分析结果表明:各形态性状与体质量间相关系数均达到极显著水平(P0.01)。多元回归分析发现,仅全长对体质量的影响达到显著性水平,其相关系数P_1=0.965,是影响鳜稚鱼体质量的主要性状。     

Providing harpacticoid copepods via floating sieve improves herring (Clupea harengus L.) larval feeding incidence

Harpacticoid copepods are being considered as alternative candidates for live feed in aquaculture, but their benthic affinity may pose problems for pelagic fish larvae. We compared the swimming behaviour and feeding incidence of herring larvae (Clupea harengus) in the presence of harpacticoid copepods (Tachidius discipes) and rotifers (Brachionus plicatilis). Additionally, we provided T. discipes via a floating sieve to improve the prey availability. The comparison was performed at 5 and 10 days post hatch (dph) via 2D‐video observations. Quantitative analyses of larval trajectories allowed the estimation of feeding behaviour through a series of indicators: swimming speed, straightness of trajectories, turning angles and swimming activities (break, sink, slow, normal, fast). The outcomes highlighted that the prey type had no significant effect on swimming speed or straightness of the swimming path. However, at 10 dph directly copepod‐fed larvae spent less time in slow but more time in the normal swimming‐state than rotifer‐fed larvae and larvae fed with Tachidius via sieve. This suggests higher energy expenditure of directly copepod‐fed larvae. Moreover, the feeding incidence was higher in larvae fed with Tachidius via sieve than directly Tachidius‐fed larvae. Thus, providing harpacticoid copepods via a floating sieve can improve the rearing of marine fish larvae.     

僧帽牡蛎幼体附着和变态的诱导

采用外加人工化学物质检验对僧帽牡蛎眼点幼体的附着和变态诱导活性,结果表明去甲肾上腺素、野上腺素和L-多巴可有效诱导幼体不固着变态.在药物持续作用下,肾上腺素的最佳诱导浓度为10-5mol@L-1(变态率67.4%),去甲肾上腺素的最佳诱导浓度为5×10-5mol@L-1(变态率52.2%),L-多巴的最佳诱导浓度为10-5mol@L-1(变态率43.0%),而对照组变态率为0.幼体大多在药物作用12～24h之间完成变态.三种药物诱导的变态个体中有85%以上是不固着变态.比较多种附着基和EPI的变态诱导活性,显示同种贝壳的活性较肾上腺素还高.去甲肾上腺素诱导幼体变态效应对低盐海水有较强耐受能力,而对高盐海水适应性差.     

大菱鲆早期变态发育和体表黑色素细胞形态学观察

对大菱鲆早期变态发育及体表黑色素细胞的形成过程进行了研究。绘制了1－60日龄大菱鲆鱼苗形态发育图，同时观察拍摄不同发育时期体表黑色素细胞的形态变化。14－17℃水温时，大菱鲆早期变态发育约需60d。1－14日龄主要为器官发育；14－40日龄主要为形态变化，25日龄左右开始变态；40－60日龄变态基本完成。变态前，鱼苗体表的幼体黑色素细胞对称分布，以素细胞密度先增加后减少。变态开始后，鱼体两侧体色出现不对称。有眼侧体表幼体黑色素细胞减少，逐渐由成体黑色素细胞替代，体色变深；无眼侧幼体黑色素细胞逐渐消褪，未出现成体黑色素细胞，体色逐渐变为白色。若有眼侧体表成体黑色素细胞的出现受阻，则形成白化。