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1.
This work investigated the biology of Paromola cuvieri in the Atlantic Ocean, including reproductive patterns, sex structure, depth distribution and egg development. Females were more abundant than males, mainly at depths greater than 600 m. Males were dominant in size classes larger than 110 mm carapace width (CW), especially over 120 mm, for which only males were observed. The mean length of both sexes decreased with depth. P. cuvieri appears to have continuous reproduction throughout the year. Large females tend to spawn mainly between summer and winter, but smaller females spawn during the summer. Four maturity categories were identified based on the ovary colour, and these categories were histologically validated. Three categories of testes were identified according to their colour and morphology. Sexual maturity was estimated at sizes between 71.6 and 74.0 mm CW for females and at 91.0 mm CW for males. The relative growth showed changes along the ontogeny, at 73.6 mm CW (females) and 91.3–92.2 mm CW (males). Egg development appears to not be completely synchronous, and two colour patterns can be observed simultaneously. Four stages of egg development were found: eggs undivided and fully filled with yolk in orange egg masses; eggs with a free region of yolk visible in orange or red egg masses; embryos with slightly pigmented, crescent-shaped eyes in brown egg masses; and embryos with visible pigmented structures, enlarged eyes, segmented appendages and abdomen in brown egg masses. The mean number of external eggs carried by females in stage I was estimated to be 315,753±19,267. Three species of barnacle were observed on the exoskeleton: Poecilasma aurantia, Poecilasma crassa and Heteralepas microstoma (Cirripedia, Thoracica).  相似文献   

2.
Green (spiny) lobsters Panulirus regius were obtained by diving at Cape Verde, West Africa, during three sampling periods: May–November 2001, April–December 2002 and April–June 2003. Totals of 429 male lobsters and 423 females (852 in all) were caught. Half the females were ovigerous throughout the sampling periods. Female estimated size-at-50% maturity was 87.9mm carapace length (CL). Brood size and egg developmental stage were examined in 68 ovigerous females. The relationship between brood size (BS, thousands of eggs) and CL (mm) was BS = 1.59CL2.77. Females in the size-class 100–105mm and 115–120mm CL produced half the eggs in the population. Based on these results, an increase in the minimum landing size is proposed. The potential implementation of a maximum landing size is discussed.  相似文献   

3.
大治河河口无齿螳臂相手蟹生长和成熟的研究   总被引：1，自引：0，他引：1  
无齿螳臂相手蟹是长江口潮间带和潮上带的优势种之一,具有重要的生态功能。为探求无齿螳臂相手蟹不同阶段的异速生长和成熟状况,于2009年10月至2010年9月期间采集样本,通过聚类和分段线性回归等分析方法对雌雄蟹头胸甲、螯、腹部等形态数据进行分析,建立区别不同生长阶段的判别函数并用逻辑斯蒂回归估计其50%形态成熟点。结果如下:雌雄蟹50%形态成熟点分别为头胸甲宽18.22mm和16.36mm。雄蟹的螯宽和雌蟹的腹宽均表现出明显的异速生长;根据相对生长率的不同,雄蟹异速生长可分为三个阶段,雌蟹分为2个阶段;不成熟的雄蟹异速生长拐点发生在壳宽11.78mm,不成熟和成熟雌蟹腹部在壳宽13.04～18.64mm范围内重叠。同时研究了50%的生理成熟大小,雌雄成熟大小分别为17.50mm,17.20mm。雄性形态成熟大小小于生理成熟大小,而雌性则相反。  相似文献   

4.
无齿螳臂相手蟹是长江口潮间带和潮上带的优势种之一,具有重要的生态功能。为探求无齿螳臂相手蟹不同阶段的异速生长和成熟状况,于2009年10月至2010年9月期间采集样本,通过聚类和分段线性回归等分析方法对雌雄蟹头胸甲、螯、腹部等形态数据进行分析,建立区别不同生长阶段的判别函数并用逻辑斯蒂回归估计其50%形态成熟点。结果如下:雌雄蟹50%形态成熟点分别为头胸甲宽18.22mm和16.36mm。雄蟹的螯宽和雌蟹的腹宽均表现出明显的异速生长;根据相对生长率的不同,雄蟹异速生长可分为三个阶段,雌蟹分为两个阶段;不成熟的雄蟹异速生长拐点发生在壳宽11.78mm,不成熟和成熟雌蟹腹部在壳宽13.04～18.64mm范围内重叠。同时研究了50%的生理成熟大小,雌雄成熟大小分别为17.50mm,17.20mm。雄性形态成熟大小小于生理成熟大小,而雌性则相反。  相似文献   

5.
Fecundity in the New Zealand spiny lobster Jasus edwardsii (Hutton) has been investigated by a detailed examination of 14 selected females “in berry” (i.e. carrying external eggs), ranging in carapace lengths from 9.5 cm to 17.0 cm. The following data were obtained for each specimen: (a) the total weight of eggs carried, (b) the average number of eggs per 1 g sample, and (c) the total number of eggs carried.

A positive correlation was noted between the total weight of eggs carried and increase in carapace length. The total weight of eggs carried ranged from 26.9 g in a small specimen of 9.5 cm C.L., to 123.9 g in a large female of 16.0 cm C.L. No relation was found between the average number of eggs per 1 g sample and increase in carapace length. A low count of 3,541 eggs per 1 g sample was recorded, and a high count of 5,005 eggs. A direct relation was noted between the total number of eggs carried by J edwardsii and increase in carapace length. The number of eggs carried ranged from a low figure of about 124,278 in a small specimen of 9.5 cm C.L., to a high figure of about 538,242 in a large female of 17.0 cm C.L. The rate of increase in fecundity was found to be greater in smaller than in larger females of J. edwardsii  相似文献   

6.
Breeding in the freshwater crayfish paranephrops planifrons white   总被引：2，自引：2，他引：0  
The breeding cycle of female Paranephrops planifrons is described. The incubation of eggs and young takes place between April and December and covers about 25–26 weeks. The winter population contains some apparently adult females which do not breed. The number of eggs laid increases with the size of the parent, and in the population studied varied from some 20 to 30 eggs at 17 mm carapace length to 150 eggs at 30 mm carapace length. After hatching the young pass through two moults while still attached to the parent.  相似文献   

7.
The life history of Plesionika edwardsi (Brandt, 1851) around the Canary Islands in the Eastern Central Atlantic was investigated, based on a total of 11 434 shrimps ranging in length between 8 and 40 mm carapace length (CL). The species carries out seasonal migrations; they concentrate in deep water during winter, move shallower in summer and return to deep water again in autumn. Ovigerous females occur throughout the year, but a spawning peak was determined between April and September. The size at maturity for females was approximately 26 mm CL. Shrimp size generally increased with increasing water depth. The growth parameters for males were L ∞ = 25.75 mm CL and K = 0.55 year?1, and L ∞ = 28.28 mm CL and K = 0.66·year?1 for females. The species displays the typical reproductive pattern of tropical pandalids and is dioecious.  相似文献   

8.
Growth and reproduction of the Japanese mantis shrimp, Oratosquilla oratoria, were investigated in the Tongyeong, Korea from July 2014 to August 2015. A total of 2,621 samples (1,380 females and 1,241 males) were collected during the study period. Females were observed more frequently than males. The mean body length (BL) was 128.5 ± 0.38 mm in females and 126.9 ± 0.42 mm in males. The mean body weight (BW) was 31.2 ± 0.28 g in females and 31.1 ± 0.32 g in males. There was a significant difference in the length-frequency distribution between females and males. The relationship between BL and BW was lnBW = 2.85 × lnBL - 10.43 for females and lnBW = 2.87 × lnBL -10.52 for males. The gonadosomatic index (GSI) varied on a monthly basis. The GSI reached a maximum in May and a minimum in November. The highest values of the GSI coincided with the spawning period of O. oratoria. Larger individuals of O. oratoria have their spawning season earlier than smaller ones. The size at sexual maturity of females was estimated as 96.5 mm. The Von Bertalanffy growth function parameters were BL∞ = 184.5 mm, K = 0.72 year?1, C = 0.36 and WP = 0.45 for females and BL∞ = 183.75 mm, K = 0.82 year?1, C = 0.38 and WP = 0.22 for males. The growth of males was slightly faster than females. The present study will help with the fisheries management of O. oratoria based on ecological parameters.  相似文献   

9.
Fecundity in Jasus verreauxi (H. Milne Edwards, 1851) has been studied by a detailed investigation of (a) the total weight of eggs carried by female specimens, (b) the average number of eggs per 1 g sample, and (c) the total number of eggs carried by females. In mid October 1966, 217 females “in berry” (that is, carrying external eggs) were examined and measured at Spirits Bay, New Zealand. The fecundity study is based on the results obtained from 21 selected specimens, with carapace lengths from 15.5 cm to 23.5 cm.

A direct relation was found between the total weight of eggs carried and increase in carapace length. The total weight of eggs carried varied from about 51 g to 238 g for carapace lengths of 15.5 cm to 23.5 cm. No correlation was shown between the average number of eggs per 1 g sample and increase in carapace length. Considerable variation was noted in the number of eggs per 1 g sample, which ranged from a low count of 6,453 eggs to a high count of 8,341 eggs. The total number of eggs carried by female J. verreauxi was found to be related to an increase in carapace length. Furthermore, increase in fecundity per relative carapace length increase was noted to be greater in smaller specimens than in larger specimens. The total number of eggs carried ranged from about 385,000 for a carapace length of 15.5 cm to 1,940,000 for a carapace length of 23.5 cm.

Fecundity, as measured by the total weight of eggs carried and the total number of eggs produced, was found to be much higher in J. verreauxi than in several Jasus species previously studied by other workers.  相似文献   

10.
Abstract. The population dynamics and life history characteristics of Callinectes similis and C. sapidus in the Mobile Bay-Mississippi Sound estuarine system of the northern Gulf of Mexico were studied. We report that C. similis is numerically dominant in open-bays, while C. sapidus is more abundant in shallow salt marshes. Juvenile C. similis recruit into both open-bays and salt marshes, but juvenile C. sapidus primarily recruit into shallow salt marshes. Sex ratios of C. similis and C. sapidus were generally skewed towards higher proportions of males than females. Callinectes similis appears to have a life cycle similar to that of C. sapidus. Egg-carrying C. similis migrate to higher salinity waters and presumably release larvae to nearshore shelf waters; following development, the larvae re-invade estuaries as megalopae. Juvenile C. similis grow more slowly than C. sapidus. This may be attributable to reduced feeding rates. Marked differences in fecundity and reproductive effort were found between these species. Callinectes similis and C. sapidus , respectively, produced 2.4–5.5 times 105 and 2.1–3.2 times 106 eggs and invested 24–49 and 171–372 kJ per brood. Rhizocephalan barnacle infestation by Loxothylacus texanus was encountered in C. sapidus , while sympatric C. similis were free of this rhizocephalan parasite.  相似文献   

11.
Abstract. Pinnotherid crabs are typically found associated with many benthic invertebrates. On sandy beaches of southern Brazil, Pinnixa patagoniensis R athbun , 1918 inhabits burrows of the ghost shrimp Sergio mirim R odrigues , 1971. The population dynamics of this crab were studied from monthly samples taken between March 1989 and November 1991 near the Patos Lagoon outlet, southern Brazil ca. 32°13'S; 52°15'W. There was no correlation between the number and size of the crabs and the size of their respective hosts. Mean densities and incidence reached 3.1 indiv. opening-1 range: 0 to 29 and 83.9%. respectively. Sex-ratios were not significantly different from 1:1 for the different size classes and sampling dates. Ovigerous females were found between October and March, showing an average fecundity of 1529 eggs per female. The annual recruitment pattern was bimodal, with a minor peak in summer and a fall peak that accounted for almost 70% of the population maintenance. Males and females both reached a maximum carapace width of 11.5 mm and had a life span of nearly two years as estimated from fitted von B ertalanffy growth curve parameters.  相似文献   

12.
Observations on growth increments at moult in a population of freshwater crayfish, Paranephrops planifrons, were made from periodic recaptures of marked animals. The growth increment increased with increasing size of crayfish up to about 20 mm carapace length (65 mm total length) after which a slight decrease was evident. By analysis of the size distributions in samples taken at different times of year it was found that four to five year classes were normally present. Growth of these age components could be followed through consecutive samples. Mean size at leaving the parent in December was 3.5 mm, after one year 11.4–11.8 mm, after two years 18.2–19.3 mm, after three years 22.1–23.8 mm, and after four years 26.7–29.6 mm, all sizes quoted as carapace lengths. After sexual maturity growth in the females was less than in the males. The number of moults completed by each year class was found by relating data on growth increment per moult to growth shown in consecutive quantitative samples. In the first year of life nine moults were completed, in the second year three moults, in the third year two moults, and in the fourth one moult. Independent data on moult frequency recorded from marked crayfish agreed well with these figures.  相似文献   

13.
采用多元分析方法定量研究了日本沼虾池养越冬抱卵亲虾体重(BW)、净重(NW)、体长(BL)、头胸甲长(CL)、胸宽(CW)、胸高(CH)、腹节长(AL)、额剑长(RL)、尾节长(TL)等11项表型性状对其个体繁殖力的影响效应。结果表明:(1)实验对象所测各表型性状间均呈极显著相关(P<0.01),它们在对个体繁殖力各评价指标的影响上具较好的区分度;(2)影响个体绝对繁殖力(FJ)、体重相对繁殖力(FW)和体长相对繁殖力(FL)的关键表型性状及其直接作用强弱排序分别为BW>BL>CH>RL>AL>NW,BW>CL>RL>CH>TL>NW和BW>CL>CH>RL>NW,相关指数依次为0.810、0.621和0.798,其中BW-NW组合和CH-RL组合分别为决定个体繁殖力的核心变量和公共从属变量;(3)适用于估算个体繁殖力的回归方程分别为:FJ=5087.802BW-6599.877NW+200.927CH+114.774RL+211.878BL-154.965AL-6266.840,FW=1140.538BW-2018.663NW+85.217CH+70.852RL+78.694CL+74.623TL-1152.576,FL=105.453BW-134.613NW+4.307CH+2.709RL+3.623CL-61.737;(4)W(♀)=0.029BL+0.065CL+0.121CW+0.105CH-2.448可精确估算其净重值。  相似文献   

14.
Population biology of the amphipod Ischyrocerus commensalis Chevreux, 1900, a facultative commensal of the red king crab Paralithodes camtschaticus (Tilesius, 1815), is here described on samples collected during summers 2005–2009 in Dalnezelenetskaya Bay (Southern Barents Sea, Russia). The studied features included infestation indices, size composition, morphometric, and reproductive parameters of the summer generation. During the studied period, prevalence and mean number of I. commensalis per host were 34.4% and 54.4 ± 3.3 individuals, respectively. The majority of amphipods were found on the host mouth parts, limbs, and gills. The amphipod sex‐ratio was significantly biased towards females (F:M = 1.36:1). The size frequency distributions observed in July and August were similar but in July the proportion of the smallest amphipods (<2.1 mm body length) was two times higher than that in August. All the amphipods with body length >5.1 mm were males or females. Length–weight relationships in female and male amphipods differed significantly, suggesting that females were heavier than the same‐sized males. The females carrying eggs in their brood pouches were the most abundant groups (54.8% in July 2009 and 51.6% in August 2005–2008). The minimal body length of a female which had released juveniles was 7.0 mm in July and 6.2 mm in August. The size at 50% maturity of I. commensalis females was estimated to be 6.58 mm. The number of eggs laid is positively linearly correlated with the size of a female. The proportion of the females with eggs in the latest developmental stage in July was 10 times higher than in August. The differences of biological features in symbiotic amphipods between the July and August may be explained by more intensive reproduction effort in the earlier month.  相似文献   

15.
对雌雄异体受精的东方扁虾的性腺发育，交配，排卵，抑卵孵育及孵化等繁殖习性进行了初步调研，同时也对闽南海区东方扁虾若干繁殖生物学参数进行了研究，结果表明：东方扁虾抱卵季节为3月初至10月中旬，高峰期是3月中锂至4月中锂，东方扁虾头甲长与体长之间的关系显示了雌雄二态现象，这一现象明显地与产卵特征相关联，抑卵雌虾的抑卵量（N）与体长呈曲线相关：N＝12.039(体长）^1.4813(r^2=0.7742)，东方扁虾在一年内可多次排卵，抱卵，卵径平均范围为0.96-1.29mm,卵重平均范围为0.575-1.000mg,卵径和个卵重都随胚胎发育的进展而增大。  相似文献   

16.
选取日本沼虾5月龄同生群雌、雄虾各90尾,分别测量其体重、体长、头胸甲长、胸宽、胸高、腹节长、腹节宽、腹节高、尾节长、尾节宽、尾节高、眼窝距、额剑长等13个表型性状,并采用相关分析、通径分析和偏回归分析等方法定量研究了雌、雄个体形态性状对体重的影响效应。结果表明：（11雌、雄测定群体各形态性状测量值间均存在显著的性别差...  相似文献   

17.
Protandrism was confirmed in Crepidula fecunda Gallardo 1979 by histological analysis of the gonad. Individuals were classified as immature (12 mm or less in shell length), male (13–26 mm), intersex (25–28 mm), and female (over 26 mm). There was an evident loss of mobility with growth— large females became completely sessile. The presence of epithelial glands in mobile individuals was associated with the need for lubrication during crawling, whereas the proliferation of subepithelial glands in sessile females was associated with adhesion. Mobility of immature and male individuals was related to grazing activities on biofilms, and in males was also associated with copulation. Grazing activity of motile individuals was carried out so that the radula teeth did not come into direct contact with the substratum, but rather harvested the biofilm surface. Sessile females used the radula to rasp the area under their shells, thus cleaning the substratum in preparation for oviposition. Since this process required that the radula enter into direct contact with the substratum, it suffered abrasion of radular teeth and loss of radular denticles, producing important alterations in its appearance in mature females. A complex interaction was observed between size, mobility, histological changes in the foot, activity, and tooth‐wear of the radula, which have been related to the sessile habit, sex change, and the oviposition process in this species.  相似文献   

18.
This study measured aspects of the physiology of juvenile [(<35mm carapace width (CW)] and adult (>60mm CW) Carcinus maenas to test the hypothesis that these different life-history stages exhibit different sensitivities to environmental contamination. Newly-collected juveniles had significantly (P<0.05) lower immunocompetence (phagocytosis and cellular integrity), lower metabolic energy (haemolymph glucose) and increased scope for growth compared with adults. Seven day exposure to a sub-lethal concentration (200microgL(-1)) of pyrene significantly (P<0.01) reduced immunocompetence, elevated basal heart rate and decreased respiration (at rest) for juveniles but had no overall impact on adult crab physiology. Results confirm that physiological differences exist between juvenile and adult shore crabs, and cause juveniles to be more susceptible to the effects of pyrene exposure than adults. Such differences in sensitivity to contamination between life-cycle stages of the same species have to be taken into account during the risk assessment process.  相似文献   

19.
The catchability of western rock lobsters (Panulirus cygnus) during the spawning season (October and November) may be affected by their reproductive state. In this study, movement and food consumption of males and females of different reproductive states held in laboratory tanks were measured as proxies for catchability. Density of lobsters was found to influence both movement and food consumption. Solitary animals and, to a lesser extent, two lobsters per tank, were more sedentary and consumed significantly less food than animals at a density of three or four specimens per tank. Tests using three animals per tank confirmed that mature, unmated, and ovigerous females carrying early stage eggs moved more frequently away from their shelters than males or females carrying late stage eggs (P < 0.0001, d.f. = 3). Further, unmated females and females with early stage eggs recorded significantly higher food consumption (P < 0.0061, d.f. = 3) compared with males or females carrying late stage eggs. The greater time spent away from shelter and also food consumption make unmated females and females with early stage eggs likely to be more catchable than males or females with late stage eggs. As catchability is commonly used to obtain population estimates from survey data, these results have implications for surveys which use catch rates of breeding animals as indicators of egg production.  相似文献   

20.
The deep-water trawl fishery along the KwaZulu-Natal coast of South Africa targets several crustacean species, with the knife (or pink) prawn Haliporoides triarthrus contributing most of the catch. Logbook data of fishing effort and catch between 1988 and 2010 were used to assess the distribution and abundance of H. triarthrus on fishing grounds. Generalised linear models were used to quantify the effects of year, month and depth on catch rates. Standardised trends indicated a general decline in abundance between 1990 and 1998, followed by an increase between 2001 and 2008. Catch rates peaked in March, and they were highest between 200 and 499 m depth. Biological samples collected during commercial fishing were used to assess size and sex composition, growth rates and reproductive activity of H. triarthrus. Females became larger than males and mean carapace length (CL) varied by month. The youngest female cohort appeared in November (modal CL of 25 mm), and dissipated after two years (39 mm). Sex ratios were equal for all data combined, but fluctuated by month and CL. Few reproductively active females were recorded. Length-based methods and the standard von Bertalanffy growth function were used to estimate growth parameters (L∞ and K) of females (40.6 mm CL and 1.06 y–1) and males (35.2 mm and 1.27 y–1) respectively. Our findings were compared with information on H. triarthrus from Mozambican waters.  相似文献   

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