第 42 卷 第 6 期 水 生 生 物 学 报 Vol. 42, No. 6
2018 年 11 月 ACTA HYDROBIOLOGICA SINICA Nov., 2018 doi: 10.7541/2018.144
EVALUATION OF FECUNDITY OF ERIOCHEIR SINENSIS PARENT CRABS RELEASED INTO THE YANGTZE RIVER ESTUARY
FENG Guang-Peng1, 2, ZHANG Hang-Li1, 2, WANG Hai-Hua2, 3, XU Jing-Jing1, 2, JI Hui1, 2 and ZHUANG Ping1, 2 (1. East China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai 200090, China; 2. College of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China; 3. Jiangxi Institute for Fisheries Sciences, Poyang Lake Fisheries Research Centre of Jiangxi Province, Nanchang 330039, China)
Abstract: During the reproductive migration of Chinese mitten crab in the Yangtze River estuary, the rela- tionship between fecundity and carapace width of released and wild Chinese mitten crab populations was ana- lyzed, and then the differences between the wild and released populations were compared. The results showed that, with the increase of carapace width (CW), the fecundity (F) of released and wild population crabs in- creased significantly (P<0.05). In the same range of carapace width, there was no significant differences of the fecundity between the wild and released populations (P>0.05). Regression analysis showed that the rela- tionship between the F and CW of the released population belongs to exponential function, which is F=3.979CW6.208 (R2=0.822). In addition, the relationship between F and CW of the wild population is F=1.696CW6.636 (R2=0.673). Covariance analysis showed that the curves of the wild and released crab popula- tions fit well in significant 0.05. It could be concluded that the fecundity of the wild and released populations was at the same level. There was no significant difference between the wild and released crab population on the relationship of F and CW. The released population could reproduce well in the natural water of the Yangtze River estuary.
Key words: Yangtze River estuary; Eriocheir sinensis; Wild population crab; Released population crab; Fecundity CLC number: S932.5 Document code: A Article ID: 1000-3207(2018)06-1180-06
Eriocheir sinensis, commonly known as river has been performed since 2004 in the Yangtze River crab, is an important crustacean based on its delicious estuary. and fresh taste and high economic value. It is distri- Crab reproduction biology research can assess buted in China's Bohai Sea, Yellow Sea, and the east crab resources and the outcome of breeding and re- coast of several provinces. High-quality germplasm leased. Fecundity (F) is the inherent ability of crabs resources of E. sinensis have been found in the that is determined by various traits associated with its Yangtze River estuary, where the largest spawning reproduction, including carapace length (CL), cara- grounds are located[1, 2]. Due to excessive fishing and pace width (CW), body weight (W), and F[5]. There- the construction of hydraulic projects in the Yangtze fore, the accurate evaluation of its reproductive capa- River estuary, the yield of E. sinensis has significantly city requires comprehensive evaluation of multiple in- decreased[3]. To protect and restore the stock of E. si- dicators of F, instead of a single indicator[6,7]. Stu- nensis, breeding and released activities have been dies on crab breeding biology have mainly focused on sporadically conducted since the 1970s by relevant F. Foreign scholars have performed some studies on departments[4]. Large-scale parent crab stock released crab spawning, including the F of Paraalithodes
Received date: 2017-10-09; Accepted date: 2018-03-15 Foundation item: Supported by the Special Scientific Research Funds for Central Non-profit Institutes, East China Sea Fisheries Research Insti- tute, Chinese Academy of Fishery Sciences (2016M05); Special Fund for Agro-scientific Research in the Public Interest (201203065) Corresponding author: Feng Guang-Peng, E-mail: [email protected]; Zhuang Ping, Professor, E-mail: [email protected] 6 期 冯广朋等: 长江口中华绒螯蟹放流亲蟹的繁殖力评估 1181 camtschaticus in Alaska[8, 9] and the effects of food on study, only the number of eggs produced at the first the number, quality, and size of eggs[10]. Research on spawning was analyzed. Analyzing all the data of the crab F in China have mainly focused on Scylla ser- number of eggs per brood of berried crabs helps to rata Forskal, including the effects of temperature and identify of the two populations, as well as to compare salinity[11], as well as the effects of different sources F of the released and the wild group of the E. sinen- of lipids on F of E. sinensis[12]. While the compara- sis in the Yangtze River estuary. The berried crabs of tive study on the F of the released population and the E. sinensis were divided into four groups according to wild population of E. sinensis in the Yangtze River the CW: 4.6—5.5 cm, 5.6—6.0 cm, 6.1—6.5 cm, and estuary was not be studied. This paper studied the F 6.6—7.3 cm. of two populations in the Yangtze River estuary in or- 1.4 Statistical analysis der to evaluate the reproductive ability of the re- The results were expressed as the mean±stan- leased parent crabs and to provide basis for evaluat- dard deviation (mean±SD). Significance analysis was ing breeding and released efficiencies. performed with Excel (Ver. 2007) and SPSS (Ver. 1 Materials and Methods 17.0). The significance test of the mean value was performed using the one-way ANOVA, and the signi- 1.1 Source of the experimental crab ficant difference is set as 0.05. Covariance analysis Berried crabs were obtained from monitoring was used to test the regression equation of fecundity ships and divided into the released and wild groups. and CW of the released and the wild populations[14]. The released group was labeled with chelate cuffs, which can be distinguished from the wild populations. 2 Results In addition significant morphological differences 2.1 The fecundity of the released and wild popula- were observed between the released and wild popula- tion tions. All released berried crabs obtained from the dif- For the released population, the average CW and ferent sections of the Yangtze River estuary from 29 W were (5.59±0.57) cm and (80.96±25.32) g, respec- December, 2011 to 22 May, 2012. And they were re- tively, and the average absolute F was (206508±10616) leased on 10 December, 2011 at Shanghai Bao Yang pcs (Tab. 1). The CW and CL of the smallest berried Port (31°26.450′ N, 121°28.870′ E). The wild berried crab were 4.6 cm and 4.0 cm, respectively, with the crabs were obtained near the Xinmin Port (31°14.124′ N, corresponding W of 41.9 g and number of eggs per 121°59.766′ E) of Hengsha Island from 25 November, brood of 78900 pcs. In addition, the CW and CL for 2011 to 7 March, 2012. the largest berried crabs were 6.5 cm and 5.7 cm, re- 1.2 Determination of the fecundity parameters of spectively, with the corresponding W of 113.9 g and berried crabs number of eggs per brood of 489100 pcs. For the wild The experimental berried crabs were transported population, CW and W were (5.85±0.56) cm and to the laboratory and their CL, CW, and W were mea- (91.60±31.89) g, respectively, with an absolute F of sured. The number of eggs per brood was measured [13] (263995±23677) pcs. The CW and CL of the mini- based on weight as described by Hamasaki using an electronic balance with an accuracy of 0.0001 g. mum berried crab were 4.9 cm and 4.2 cm, respec- Measurements were performed in triplicate for each tively, with the corresponding W of 44.9 g and num- crab, and the mean value was adopted in the analysis. ber of eggs per brood of 41800 pcs. The CW and CL 1.3 Calculation of fecundity of maximum berried crabs were 7.3 cm and 6.6 cm, Fecundity includes absolute F which is the num- respectively, with the corresponding W of 178.5 g and ber of eggs per brood of an individual, and the rela- number of eggs per brood of 1037200 pcs. A signific- tive F, which is the ratio of absolute F to body weight ant difference in absolute F was observed between the (F/W). Research previously indicated that there is no released and the wild populations (P<0.05). However, significant difference in the number of eggs per brood for relative F, no significant difference was observed between crabs from various seasons[13]. In the present between the two populations (P>0.05).
Tab. 1 Morphological parameters and fecundity of Chinese mitten crab (Eriocheir sinensis) Population Sample size Carapace width (cm) Body weight (g) Absolute F Relative F b a Released population 47 5.59±0.57 80.96±25.32 206507.73±10615.75 2344.59±953.57 a a Wild population 85 5.85±0.56 91.60±31.89 263994.56±23676.71 2665.66±1422.24 Note: Different lowercase English letters at the top right of the data in the same column suggested that significant difference existed between groups (P<0.05) 1182 水 生 生 物 学 报 42 卷
2.2 The relationship between F and biological indica- 6 y=3.979 CW 6.208 tors of the released populations 5 R2=0.822 The F of berried crabs increased with the CW for 4 released populations (Fig. 1). Due to the limited popu- lation size of the released crabs, no significant advan- 3 tage in CW was observed for different size groups. 2
The number of eggs ranged from 50000 pcs to Fecundity (×100000) 1 500000 pcs for released crabs. The relationship 0 between the F and the CW of the released population 4.0 4.5 5.0 5.5 6.0 6.5 7.0 of E. sinensis in the Yangtze River estuary can be Carapace width (cm) presented using the exponential function: F=3.979 CW 6.208 (R2=0.822). Fig. 1 The relationship between carapace width and fecundity of 2.3 The relationship between F and biological indica- the released population of Eriocheir sinensis tors of the wild populations 12 y=1.696 CW 6.636 The statistical data of F and CW of the wild popu- 2 10 R =0.673 lation are shown in Fig. 2. The F of berried crabs in- creased with CW. The advantageous CW of the ber- 8 ried crabs was 5.0—6.0 cm, and F ranged from 6 100000 pcs to 400000 pcs. The relationship between F and CW of the wild population of E. sinensis in the 4 Yangtze River estuary can be presented as an expo- Fecundity (×100000) 2 nential function: F=1.696 CW 6.636 (R2=0.673). 0 2.4 Comparison of F between the released and wild 4.5 5.0 5.5 6.0 6.5 7.0 7.5 populations Carapace width (cm) The absolute F of the wild population of E. sinen- sis in the Yangtze River estuary was significantly Fig. 2 The relationship between carapace width and fecundity of higher than that of the released population (P<0.05), the wild population of Eriocheir sinensis whereas no significant difference was observed for the difference was not statistically significant (P> the relative F (P>0.05) (Tab. 1). 0.05). The F of both the released and the wild popula- The logarithm of the F-CW curves of the re- tions of E. sinensis in the Yangtze River estuary in- leased and the wild populations can be expressed as creased with CW (Tab. 2). A significant difference in follows: ln F=a+blnCW. The two curves are analyzed F was observed among crabs of different sizes from by fitting with goodness variance analysis and regres- the released population (P<0.05). The F of the wild sion significance test (Tab. 3): F1
Tab. 2 The comparison of fecundity between released and wild populations of Eriocheir sinensis
Range of carapace Carapace width (cm) Absolute F (number of eggs per brood) width (cm) Released population Wild population Released population Wild population a a aA aA 4.6—5.5 5.04±0.27 5.20±0.20 88603±33890 113335±83829 b b bA aA 5.6—6.0 5.77±0.14 5.72±0.20 201574±71189 200277±86058 c c cA bA 6.1—6.5 6.32±0.16 6.30±0.15 371930±72868 386381±131587 d d dA cA 6.6—7.3 6.75±0.53 6.88±0.32 598245±321347 605542±330162 Note: Different lowercase English letters at the top right of the data in the same column shows a significant difference between the two populations (P<0.05). Similar capital letters indicate no significant difference between the wild and released populations within the same range (P>0.05) 6 期 冯广朋等: 长江口中华绒螯蟹放流亲蟹的繁殖力评估 1183 population of berried E. sinensis still possesses ma- thereby balancing egg size and yield. Increase in egg ture ovaries. Berried crabs are likely to undergo a yield with decrease in egg size was observed. Tem- second ovigerous stage after hatching. Therefore, the perature is often closely related to this result: egg size F of E. sinensis is generally greater than what can be decreases with increasing temperature but increases measured at the first spawning[15]. For a given year, with lowering temperature[13]. Therefore, the results of the F of E. sinensis depends on the eggs produced this study could explain the fluctuations in the amount during both the first and second spawning. and size of crustacean eggs due to change in seasons A positive correlation between F and CW was and regions. Size of eggs of E. japonica also changes [28] observed in E. sinensis, which is similar to that in with breeding season . Sampling studies should also Portunidae crabs, including Ovalipes punctatus[16,17] be conducted in different breeding seasons to study and Arenaeus cribrarius[18]. Furthermore, the indi- whether similar results can be achieved with E. sinen- vidual F was lower when compared with O. punctatus sis. Due to the long sampling period (from December of the corresponding CW[17], whereas it was higher 2011 to May 2012), the observed size of the eggs may than E. hepuensis, which has the closest relationship be affected by seasonal factors considering that crab with E. sinensis [19]. Because the size of Scylla ser- eggs generated in the spring tend to be smaller in size rata was significantly larger than E. sinensis, the lat- when the temperature is relatively high. ter species has significantly lower F than the for- 3.2 Comparison of F of the released and wild popu- mer[20]. The F of both wild and released populations lation in the Yangtze River estuary increased with CW (Tab. 2). However, within a cer- The F of the released and wild population of E. tain rage of CW, a relatively significant increase in F sinensis in the Yangtze River estuary both increased of up to 40000 eggs (50%) was observed in the wild with CW (P<0.05) (Tab. 2). For crabs with CW with- population (CW=6.5 cm, Fig. 2). Tuset[21] reported in the range of 4.6—5.5 cm and 6.1—6.5 cm, F of the that the fluctuation in F in the American deep-sea red wild population was higher than the released popula- crab (Chaceon affinis) was within the range of tion, but without significant difference (P>0.05). 45%—65%. This difference is due to the loss of eggs Upon reaching brackish water, part of the energy of during spawning. Egg loss during crab incubation crabs is consumed for osmotic pressure regulation. may be due to disease, fungal infection, or natural Therefore, in addition to being transferred to the loss during egg development[22]. The relatively long ovary, the energy generated by the hepatopancreas is spawning period of female parent crabs may also be utilized for other purposes, thereby resulting in a another reason[23]. The spawning period of E. sinensis lower F in the released E. sinensis population com- may last for 5 to 6 months[24], during which large pared to the wild population. The observed F values amount of eggs may be lost. Kuris[16] indicated that of the released and wild populations were compa- the egg loss rate in crustaceans is within the range of rable to crabs with CW within the range of 5.6—6.0 cm, 11%—71%, which may be due to egg retention, prey and this may be explained by inter-individual diffe- of other crabs, parasitic diseases, and spawning fai- rences among the collected crabs. The absolute F of lure, which may all contribute to fluctuations in F. the released population was lower than that of the The female E. sinensis buries itself in the sediment of wild population, and the relative F (F/W) of the re- a river after laying its eggs. Therefore, sediment qua- leased population was also lower than that of the wild lity also affects the F of E. sinensis. Soft sediment, in population. This indicated that the wild population of which crabs can easily bury their eggs, contributes to E. sinensis has higher overall quality than the re- higher spawning. On the contrary, crabs in harder leased population. However, covariance analysis beds often move forward and backward with the wa- showed that (Tab. 3) with significance level set at ter, thereby making it difficult for the eggs to attach to 0.05, the F-CW curves of the released and wild popu- the bristle and thus are easily shed off[25]. The Yangtze lations can be relatively satisfactory fitted. This result River estuary is composed of alluvial sediments, with suggested that there was no significant difference the bottom mostly covered with soil and sand, which between the regression F-CW equations. The released limits the effect of sediments on fluctuations in F. Tab. 3 Estimated parameters with 95% confidence intervals Crabs of smaller sizes may also present with between parentheses for the linear regression model, lnF= high absolute F (Tab. 2). The size of the egg is de- lna+blnCW, between carapace width of females (CW) and fecun- dity of Eriocheir sinensis termined by its inherent energy. Hines[26] and Nakao- ka[27] previously reported that the hepatopancreas Goodness of fit test F1=0.0290 F0.05=161* F0.01=4052** provide a certain amount of energy to female crabs, Regression significance test F2=60.938 F0.05=18.51* F0.01=98.49 1184 水 生 生 物 学 报 42 卷 population experienced similar spawning conditions lysis in the study of Acipenser sinensis cray fecundity [J]. after adjusting osmotic pressure regulation. Journal of Xinyang Agricultural College, 2000, 10(1): The F of crabs is evaluated by multiple factors 46—49 (in Chinese) such as individual size, species, and external factors, [7] Jiang X Q, Yu C G, Chen Q Z. 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长江口中华绒螯蟹放流亲蟹的繁殖力评估
冯广朋1, 2 张航利1, 2 王海华2, 3 徐静静1, 2 姬 慧1, 2 庄 平1, 2 (1. 中国水产科学研究院东海水产研究所, 上海 200090; 2. 上海海洋大学水产与生命学院, 上海 201306; 3. 江西省水产科学研究所, 南昌 330039)
摘要: 在长江口中华绒螯蟹亲蟹生殖洄游期间, 通过研究中华绒螯蟹放流群体和自然群体繁殖力随壳宽的变 化规律, 比较放流群体和自然群体繁殖力的差异, 从而评估人工增殖放流亲蟹的繁殖力。结果显示, 随着壳宽 的增大, 中华绒螯蟹放流群体和自然群体的繁殖力都显著增加(P<0.05)。在相同壳宽范围内, 放流群体和自然 群体的繁殖力之间没有显著差异(P>0.05)。回归分析显示, 放流群体繁殖力(F)与壳宽(CW)呈幂函数关系: F=3.979CW6.208(R2=0.822)；自然群体F与CW呈幂函数关系: F=1.696CW6.636(R2=0.673)。协方差分析显示, 放流 群体与自然群体F与CW的两条曲线在显著性为0.05时拟合较好。研究结果表明, 放流群体与自然群体的繁殖 力与壳宽之间无显著性差异, 推断放流亲蟹能够适应长江口天然水域环境, 并与自然群体的繁殖力水平相当。
关键词: 长江口; 中华绒螯蟹; 自然群体; 放流群体; 繁殖力