黄(鮟)(鱇)繁殖生物学研究

以2008年9月至2009年7月在黄海南部捕获的644尾黄(鮟)(鱇)(Lophius litulon)为对象,对该种鱼的繁殖生物学进行了研究.结果表明,所采样本性比接近于1:1(x~2=2.61,P>0.05);但全长在251～400 mm范围时,雄性个体数量远超过雌性(P<0.01);全长在450～550 mm范围时,雌性个体数量多于雄性(P<0.01);全长大于550 mm范围时,个体均为雌性;冬季,雄性个体数量占绝对优势(P<0.01).利用逻辑斯蒂拟合方程估算的黄(鮟)(鱇)50%个体初次性成熟全长L50,雄性为332 mm,雌性为483 mm.通过对性腺指数的月变化和不同卵巢发育阶段雌性个体所占比例的分析,初步推测黄(鮟)(鱇)产卵时期为2-6月份,繁殖盛期为3-4月份;其绝对繁殖力为(614 820±253 800)粒,相对繁殖力为(244±43)9lg.黄(鮟)(鱇)不同性腺发育阶段的肝脏指数存在显著变化,雌性,F=9.97,P<0.01;雄性,F=4.48,P<0.01,肝脏在该鱼种卵巢发育过程中可能起到了能量供给作用.(鮟)(鱇)类资源对捕捞的承受压力极其脆弱,50%个体初次性成熟全长可作为其资源管理的基础生物学指标.本研究旨在为黄(鮟)(鱇)的种群数量变动研究和渔业管理提供基础资料.     

鲢鱼骨胶原多肽螯合钙的制备研究

文章探讨了以鲢（Hypophthalmichthysmolitrix）鱼骨为原料,采用风味蛋白酶酶解制备骨胶原多肽水解液,剩余骨渣经乳酸提取制备骨粉酸解液（钙液）,研究其通过螯合制备鲢鱼骨胶原多肽螯合钙的工艺条件。分析了酶解时间对鲢鱼骨蛋白酶解产物产品品质和功能特性（溶解性和热稳定性）的影响以及采用乳酸提取鲢鱼骨中钙时提取温度对钙溶出率的影响,并以螯合率为指标,考察pH、时间、温度和多肽液与钙液体积比对螯合反应的影响。结果表明,在温度50℃,按原料鱼排质量0．09％加入风味蛋白酶酶解30min制备出的鲢鱼骨胶原多肽具有良好的产品品质和功能特性;乳酸提钙时提取温度对钙溶出率没有显著性影响（P〉0．05）;在pH8、温度25℃条件下,多肽液与钙液体积比1：1反应40min得到的鲢鱼骨胶原蛋白螯合钙螯合率最高（85．24％）。     

黄海典型断面渔业资源结构的季节变化

为了解黄海渔业资源结构的动态变化,实验基于2006年9月(秋季)和12月(冬季)、2007年3月和5月(春季)对黄海南部三个典型断面(S1断面位于南黄海南部北部水域,S2断面位于黄海和东海交界处,S3断面位于黄海南部中部水域)的渔业底拖网调查数据,对黄海断面的渔业种类更替、生物量变动、多样性季节变化及其与环境因子的关系进行了初步分析.结果显示,各季节调查共捕获渔业生物156种,其中鱼类109种,底层鱼类占89.0％.各季节前10位渔业种类的渔获量均占总渔获量的60％以上,且主要渔业种类组成变化不大,以小黄鱼、黄(鮟)(鱇)、细纹狮子鱼、鳀和脊腹褐虾等为主.各季节S2断面的主要渔业种类组成有显著变化,而S1和S3断面的主要渔业种类组成变化不大,但各种类渔获量在总渔获量中的比例变化很大;各断面渔业生物个体体质量一般都小于40 g.黄海南部海域从南向北各断面渔业种类多样性递减;各季节的渔业种类数与群落丰富度指数呈正相关.研究表明,黄海各断面渔业资源结构从北向南存在明显的季节变化,并且与底层温度和盐度的关系密切.     

鳕鱼骨钙片的制备及其生物利用

为有效利用鳕鱼加工中产生的鱼骨下脚料,研究采用碱醇法制备了鳕鱼骨钙粉,探讨了鳕鱼骨钙片制备方法,同时以Wistar大鼠为模型研究鳕鱼骨钙片的生物学功效。结果表明,采用NaOH和乙醇浸泡制取鳕鱼骨钙粉的最佳工艺参数为1mol/L NaOH溶液,浸泡时间30h,乙醇浓度60%,浸泡时间15h,制取的鳕鱼骨粉钙含量为27.8%,磷含量12.2%,蛋白质含量3.67%,脂肪含量0.44%。骨粉色泽洁白,无任何异味;粘合剂选用浓度为4%的聚乙烯吡咯烷酮乙醇溶液,填充剂与奶粉的配比为1∶2;崩解时间实验显示鳕鱼骨钙片崩解时间小于12min,无须添加崩解剂。动物实验表明,鳕鱼骨钙片2g/(kg.d)和鳕鱼骨钙片5g/(kg.d)可显著提高大鼠血钙、血磷和骨钙含量,具有促进骨生长、提高骨密度和防止骨质疏松的功效。     

黑龙江唇(鱼骨)的生物学特性及苗种培育技术

唇(鱼骨)(Hemibarbu labeo)地方名为重重或重唇,(鱼骨)属于硬骨鱼纲、鲤形目、鲤科、鮈亚科、属的一种.唇(鱼骨)主要分布在黑龙江及其支流、镜泊湖、五大连池等,是黑龙江名优土著鱼类[1].唇(鱼骨)营养价值较高,具有很高的经济价值[2].在20世纪60年代至70年代,唇(鱼骨)在黑龙江流域的渔获量中占有一定的比例,但随着近些年环境的破坏及过渡捕捞等,资源量锐减[3].目前随着人们对唇(鱼骨)的喜爱增加,市场价格也随之逐年升高.     

饲料中浒苔添加量以及处理方法对幼刺参生长、消化率、消化酶和非特异性免疫酶的影响

采用单因素实验设计,先配制6种浒苔含量(0、5％、10％、15％、20％和25％)饲料饲养初始体质量(1.44±0.01)g幼刺参49 d,然后根据浒苔含量实验结果配制20％含量、3种方法处理的浒苔[干燥粉碎(DC)、纤维素酶酶解后干燥粉碎(DCC)和蛋白酶酶解后干燥粉碎(DCP)]饲料饲养初始体质量(4.58 ±0.23)g幼刺参60 d,以研究饲料中浒苔添加量以及处理方式对幼刺参生长、消化率、消化酶和非特异性免疫酶的影响.实验每组饲料设3个重复,每个重复饲喂35头刺参.结果显示:(1)浒苔对提高刺参特定生长率(SGR)、肠道淀粉酶(AMS)活性和超氧化物歧化酶(SOD)和降低饲料系数(FCR)有显著作用(P＜0.05),其中20％浒苔含量最好,浒苔能显著降低饲料干物质表观消化率(ADCd)和粗蛋白质表观消化率(ADCp)(P＜0.05),对刺参摄食率(FI)、成活率(SR)、肠道胃蛋白酶(PP)活性和酸性磷酸酶(ACP)无显著性影响(P＞0.05).(2)3种方法处理的浒苔中,DCC和DCP浒苔对提高刺参SGR、ADCd、ADCp、肠道AMS、PP、SOD和ACP活性和降低FCR有显著作用(P＜0.05),其中DCC浒苔最好,3种方法处理的浒苔对刺参FI和SR亦无显著性影响(P＞0.05).在本实验条件下,幼刺参饲料中浒苔适宜含量为20％;纤维素酶酶解后干燥粉碎浒苔是一个理想的浒苔处理方法.     

酶解磷虾粉替代鱼粉对珍珠龙胆石斑鱼幼鱼生长性能、体组成及血清生化的影响

以酶解磷虾粉分别替代基础饲料中0(T0)、10％(T10)、20％(T20)、30％(T30)、40％(T40)、50％(T50)的鱼粉,配制6种等氮等能的饲料,研究饲料中酶解磷虾粉替代鱼粉对珍珠龙胆石斑鱼幼鱼生长性能、体组成、血液生化指标、抗氧化性能及氟残留的影响.选取初始均重为(57.80±0.28)g的珍珠龙胆石斑幼鱼360尾,随机分为6组,每组3个重复,试验周期为56 d.结果显示,(1) T30组的增重率、特定生长率和摄食率均显著高于T0组(P＜0.05);在替代量大于20％时,饲料干物质表观消化率显著高于T0组()＜0.05);各替代组的饲料系数、肥满度、肝体比、蛋白质效率、蛋白质消化率与T0组无显著差异(P＞0.05).(2)各替代组全鱼和肌肉水分、粗脂肪、粗灰分含量与T0组无显著差异(P＞0.05);T30组肌肉粗蛋白质含量显著高于T0组(P＜0.05).(3)各组间血清谷丙转氨酶、谷草转氨酶、总蛋白、白蛋白、碱性磷酸酶、甘油三酯和高密度脂蛋白含量无显著差异(p0.05);T30组尿素氮含量显著低于T0组(P＜0.05);各替代组低密度脂蛋白含量显著高于T0组(P＜0.05).(4)酶解磷虾粉替代鱼粉显著升高了珍珠龙胆石斑鱼幼鱼血清和肝脏中谷胱甘肽过氧化物酶及血清超氧化物歧化酶的活力(P＜0.05),同时,显著降低了血清和肝脏中丙二醛含量(P＜0.05).(5)各组肌肉氟含量均在可检测范围以下,各组间骨骼氟含量随着替代比例的升高而升高,各组差异显著(P＜0.05).研究表明,综合考虑生长性能、体成分、生化指标及抗氧化性能,酶解磷虾粉可替代珍珠龙胆石斑鱼饲料中40％以下的鱼粉,替代量为30％时效果最佳.     

斑点叉尾(鱼回)鱼骨制取胶原蛋白和骨粉的试验研究

鱼骨中蛋白质的存在会影响骨钙的吸收,将鱼骨中的蛋白提取出来加以利用,钙质保留在骨中,既充分利用了鱼骨中的蛋白质成分,又使高钙成分利于吸收,可以实现资源利用的"零废弃".试验在4℃条件下,斑点叉尾NFDAA(长吻NFDAA,Ictalurus punctatus)鱼骨先用0.1 mol · L-1的NaOH浸泡6 h,再用2.5%NaCl浸泡6 h去除杂蛋白,用10%的异丙醇溶液去除脂肪,0.1 mol · L-1的柠檬酸浸提3 d能较好的提取胶原蛋白,无色无味,提取率可达11.87%.粗提液再经盐析、透析可得到纯度较高的胶原蛋白制品.鱼骨胶原蛋白溶液的粘度随着蛋白浓度的增大而增大,其变性温度为33.9℃.SDS-PAGE试验结果表明,提取的NFDAA鱼骨胶原具有较高的纯度,含有2条α链,β链含量较高.提取胶原后的NFDAA鱼骨粉钙含量可达60%,作为钙添加剂加到饼干中,不会对饼干的口感和味道造成显著性差异,是良好的钙添加剂,可用于食品再加工.     

花(鱼骨)养殖技术之二池塘养殖花(鱼骨)不同模式对比试验

为了发掘花(鱼骨)的池塘养殖潜力,提高花(鱼骨)池塘养殖效益,近年来,江苏省涟水县水产工作站成功进行了池塘主养花(鱼骨)(下称模式一)、池塘主养花(鱼骨)混养蟹虾(下称模式二)和池塘主养蟹虾混养花(鱼骨)(下称模式三)等3种养殖模式的对比试验,现将试验结果报告如下.     

唇(鱼骨)(♀)×花(鱼骨)(♂)杂交育种初步研究

研究分析了唇(鱼骨)(♀)×花(鱼骨)(♂)杂交育种的特点和可行性.结果表明:2008-2011年,共计获得约164万粒受精卵,杂交F1鱼苗111.7万尾.在水温18～26℃条件下,唇(鱼骨)(♀)×花(鱼骨)(♂)的催产率、受精率和孵化率可达到85.5％～89.2％、80.6％～81.2％和80％～85.6％.在水温(20±1)℃条件下,杂交F1受精卵在受精后94 h 10 min,仔鱼开始出膜.初孵仔鱼全长5.75 ～ 6.83 mm.杂交F1成鱼的体色和体型与母本比较相近.唇(鱼骨)(♀)×花(鱼骨)(♂)的杂交育种是可行的.     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

美人鱼发光杆菌对凡纳滨对虾非特异性 免疫功能及抗病力的影响

在基础饲料中分别添加0.1%和1%美人鱼发光杆菌灭活菌、0.1%美人鱼发光杆菌活菌配制成3种免疫实验饲料,以基础饲料为空白对照组饲料,每组设3个平行样。对个体质量为(4.83±0.36)g的凡纳滨对虾进行为期20 d的饲养实验,分别在0、5、10、15和20d进行取样,以血清中的酚氧化酶(PO)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)和溶菌酶(UL)活性为免疫指标,探讨了美人鱼发光杆菌作为免疫制剂对凡纳滨对虾非特异性免疫效应的影响;在投喂免疫饲料后的第22天,按0.004 2 kg/kg体重的剂量,直接投喂对虾白斑综合征病毒(WSSV)病料,并记录累积死亡率。结果表明,美人鱼发光杆菌免疫实验组对凡纳滨对虾血清中PO、ACP、AKP、UL和SOD活性影响明显高于对照组,并且在饲料中添加美人鱼发光杆菌后,明显提高了对虾抵御WSSV感染的能力。其中0.1%美人鱼发光杆菌活菌实验组的抗病毒感染能力最强,WSSV感染14d内累计死亡率为63.3%±5.8%;而对照组为96.7%±3.3%。研究表明,美人鱼发光杆菌添加在对虾饲料中能提高凡纳滨对虾非特异性免疫水平,增强抵抗疾病的能力,将其作为对虾免疫增强剂具有良好的应用前景。     

Effects of Spirulina platensis as a feed additive on growth and coloration of blue dolphin cichlids (Cyrtocara moorii Boulunger, 1902)

This study was carried out to investigate the effects of replacing fish meal with dietary Spirulina as a feed supplement on the growth performance and coloration of blue dolphin cichlids (Cyrtocara moorii). Five isonitrogenous (47% crude protein) and isocaloric (17.36 kJ/g digestible energy) diets were for formulated to replace FM with 0, 5, 10, 15 and 20% Spirulina (designated as Control, SP5, SP10, SP15 and SP20 respectively) and fed to the fish (initial body weight, 3.15 ± 0.01 g). Fish were randomly distributed into fifteen 120 L aquariums (26.5 ± 1.00°C), 15 fish per aquarium. The diets were tested in triplicate for 12 weeks. Experimental groups were fed twice daily (09:00 and 17:00) by hand to satiation. At the end of the feeding trial, significantly (p < 0.05) higher weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and lower feed conversion ratio (FCR) were observed in fish fed the SP10 diet when compared to the SP20 diet. There was no significant difference in these parameters between the other groups. The skin coloration of blue dolphin cichlid fed a diet containing Spirulina meal was enhanced. The best coloration was observed in the SP15 group. These impressions were objectively validated by chemical determinations of carotenoids extracted from fish skins and passed statistical tests of significance. The study findings show that Spirulina meal does not diminish growth rates except at very high levels.     

Dietary thiamin and pyridoxine requirements of fingerling Indian major carp,Cirrhinus mrigala (Hamilton)

Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg^?1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg^?1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg^?1 diet. Broken‐line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg^?1 diet (0.096–0.179 μg thiamin kJ^?1 gross energy). In experiment II, six casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg^?1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg^?1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg^?1 dietary pyridoxine. Broken‐line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg^?1 diet. Data generated during this study would be useful in formulating thiamin‐ and pyridoxine‐balanced feeds for the intensive culture of this fish.     

Sea bream culture in Egypt; status, constraints and potential

Marine fish farming in Egypt began in 1976 with the culture of gilthead sea bream, (Sparus aurata) as this fish was notably adaptable to brackish and marine pond conditions. Today, marine fish and shrimp farms amount to about 19,000 ha, out of which 42% is already in production while the rest, i.e., 58% is still under construction. In 1997, cultured gilthead sea bream production of 2,250 tons made up 3% of the 75,000 tons total aquaculture catch. In polyculture, usually with the grey mullet and sea bass, gilthead sea bream contributed 440 kg ha^–1 to the total yield of 1,700 kg ha^–1 (26%) over a period of 16 months. For the same period, the yield of monoculture ponds averaged 100 kg ha^–1, while in marine cages, yields ranged from 4–10 kg m³. In 1996–1997, fry of 0.25–1 g and fingerlings 1–10 g with a total of 3 million, were collected from the wild and 1 million fry were produced in the three marine hatcheries out of the four existing ones. The development of sea bream culture in Egypt is now severely inhibited by the shortage of seeds and adequate feeds. Exports of both sea bream and sea bass, during 1994–1996 averaged 1,300 tons per year.     

A Minchinia mercenariae‐like parasite infects cockles Cerastoderma edule in Galicia (NW Spain)

The cockle Cerastoderma edule fishery has traditionally been the most important shellfish species in terms of biomass in Galicia (NW Spain). In the course of a survey of the histopathological conditions affecting this species in the Ria of Arousa, a haplosporidan parasite that had not been observed in Galicia was detected in one of the most productive cockle beds of Galicia. Uni‐ and binucleate cells and multinucleate plasmodia were observed in the connective tissue mainly in the digestive area, gills and gonad. The parasite showed low prevalence, and it was not associated with abnormal cockle mortality. Molecular identification showed that this parasite was closely related to the haplosporidan Minchinia mercenariae that had been reported infecting hard clams Mercenaria mercenaria from the Atlantic coast of the United States. The molecular characterization of its SSU rDNA region allowed obtaining a fragment of 1,796 bp showing 98% homology with M. mercenariae parasite. Phylogenetic analysis supported this identification as this parasite was clustered in the same clade as M. mercenariae from the United States and other M. mercenariae‐like sequences from the UK, with bootstrap value of 99%. The occurrence of M. mercenariae‐like parasites infecting molluscs outside the United States is confirmed.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.