Captive breeding of climbing perch Anabas testudineus (Bloch, 1792) with Wova-FH for conservation and aquaculture

Induced breeding of climbing perch, Anabas testudineus was conducted by synthetic hormone Wova‐FH in the intensity level of 0.1, 0.2 and 0.3 mL kg^?1 of body weight respectively. The brooders were injected one time and left to spawn in the spawning hapa in the sex ratio between male and female as 2:1. It was found that at all the intensity level hormone Wova‐FH could enhance the fishes to breed and lay eggs whereas no breeding was observed in control set. The spawning time, quantity of the brooder spawn, fertilization rate, hatching rate and survival rate were quantified in each set of experiment. The egg output/female was significantly higher in 0.3 mL in comparison with 0.1 and 0.2 mL kg^?1 of body weight. The statistical analysis showed significant (P≤0.05) effect between hormone dose on fertilization rate, egg output and hatching rate. The present experiment suggests that Wova‐FH at the dose of 0.3 mL kg^?1 body weight of fish is more effective which might be considered for raising captive population.     

Geographic variation in host fish use and larval metamorphosis for the endangered dwarf wedgemussel

相似文献   

Studies on the captive breeding of the Knysna seahorse, Hippocampus capensis

Seahorse populations throughout the world are vulnerable toexploitation for use in traditional Chinese medicines. Variouscaptive breeding ventures have been established in attempts tomeet the demand and to reduce the pressure on the naturalpopulations. Many of these programmes have relied on the captureof wild pregnant males which then give birth under captiveconditions. This would however limit production during the non-breeding season. In this study Knysna seahorses, Hippocampuscapensis, were bred in captivity during the non-breeding season(winter) using photothermal manipulation. Three constantphotoperiods (20L:4D, 16L:8D & 12L:12D) were tested incombination with three temperatures (22 °C, 25 °C& 28 °C). All combinations tested were successful inextending the breeding season of H. capensis. The frequency ofpregnancies as well as the number of young produced/pregnancy wasnot affected by the different photoperiod/temperaturecombinations. Each male gave birth to 39.38 ± 20.81juveniles every 34.03 ± 17.25 days during a four monthperiod. The mean juvenile weight and length was influenced by thephotoperiod and/or temperature regimes. Juvenile length decreasedwith increasing temperature (p 0.0001), while an increasein the light phase of the photoperiod regime at 20L:4D resultedin a significant increase (p 0.0006) in length whencompared to the 16L:8D and 12L:12D photoperiods. Juvenile weightdecreased with increasing temperature, while the combination ofphotoperiod 16L:8D and the lowest water temperature (22 °C)yielded the highest mean weights. Further studies are necessaryto determine whether mean juvenile weight or length influencesjuvenile survival     

Feed management and stocking density of the endangered wild zebra pleco: Implications for captive breeding

Due to the economic potential of Hypancistrus zebra in the ornamental fish market and its current classification as an endangered species in its natural occurrence sites, the present study sought to determine a suitable feed management strategy and stocking density to allow for an adequate captivity maintenance of this fish species. Three experiments were conducted as follows: (1) feed preference (artemia Artemia sp., shrimp Litopenaeus vannamei, fish Cynoscion spp. or mussel Perna perna); (2) determination of feeding rate (5% and 10% live weight day^?1) and frequency (1, 2 or 3 meals. Day^?1); and (3) evaluation of stocking density (0.25, 0.50, 1.00 and 2.00 g/L). Zebra pleco did not present the characteristic buccal scraping behaviour on the feed, commonly seen in other Loricariids. Artemia was the preferred diet followed by fish, shrimp and mussels. The frequency of two daily meals and the feeding rate of 10% live weight day^?1 allowed for an improved zootechnical performance. Zebra pleco showed enhanced specific growth rate at the density of 2 g/L. Our results suggest that, to improve the zebra pleco rearing conditions, it should be maintained at a density of 2 g/L, fed two daily meals at a feeding rate of 10% live weight day^?1. These findings correspond to useful information for an adequate management of this species and could assist in the supply of healthy specimens to the ornamental fish market as well for the restocking of declining wild populations.     

Preliminary assessment of the environmental and selective effects of a captive breeding and rearing programme for endangered Atlantic salmon,Salmo salar

The selective and environmental effects of captivity on several fitness‐correlated traits were assessed in smolts of endangered Atlantic salmon, Salmo salar L., from the inner Bay of Fundy, produced via artificial spawning and released into the wild as juveniles. Smolts were sampled as they migrated downstream and identified through microsatellite‐based parentage analysis as offspring of either wild‐spawning adults or adults that were spawned in captivity. Overall, captive‐origin smolts exhibited a significantly later run timing and smaller body size than wild smolts. Significant differences in run timing and body size were also found between captive‐origin smolts that had experienced rearing environments that differed in duration of captivity and thermal regime. Significant differences in run timing, fork length and weight were found between first and second generation captive‐origin smolts, although the expression of these differences depended on the rearing environment experienced, suggesting a possible genotype by environment effect. The ratio of effective‐to‐census number of breeders that produced the captive‐origin smolts was higher than that of the wild‐origin smolts due to successful captive breeding management practices. These results have direct implications for captive breeding and rearing programmes for salmonids and wider implications for understanding the rates of evolutionary and environmentally induced change that can occur in captivity.     

Life history traits and conservation actions for the Maugean skate (Zearaja maugeana), an endangered species occupying an anthropogenically impacted estuary

1. The Maugean skate, Zearaja maugeana, is endemic to two isolated western Tasmanian (Australia) estuaries. The species' persistence in one of these estuaries (Bathurst Harbour) is uncertain, while the other estuary (Macquarie Harbour), potentially the remaining stronghold for the species, is an anthropogenically impacted system.
2. Key life-history parameters were studied to inform conservation actions for this species. Reproductive information was obtained using non-lethal methodologies, circulating concentrations of sex steroids and ultrasonography. Growth and age parameters were estimated based on vertebral sections from a small sample of individuals.
3. Females and males reached 870 and 760 mm total length, respectively. The species reached a maximum age of at least 10 years. Females and males attained 50% sexual maturity at 665 and 633 mm total length, respectively, probably maturing somewhere between four and six years of age. Females displayed an asynchronous, discontinuous reproductive cycle, being able to reproduce throughout the year, with a probable decline in reproductive activity during summer. No egg cases were observed in-utero. Males produce sperm all year round, with a peak in testosterone production during spring–autumn.
4. Conservation strategies for Z. maugeana will need to focus on reducing anthropogenic impacts on the environmental health, the primary impacts being altered river flows associated with the production of hydroelectricity and increased nutrient load associated with salmonid aquaculture. There is a need to better understand how reproductive success, egg survival and recruitment are affected by these environmental challenges if the future well-being of this species is to be secured.

     

On the breeding behaviour and reproduction of the freshwater prawn,Macrobrachium rosenbergii (de Man 1879) (Decapoda‐Crustacea) under laboratory conditions

The giant freshwater prawn, Macrobrachium rosenbergii is one of the most common decapod species, and now getting more attention from the aquaculturists world wide due to its high market demand. It is commercially important because of its size as well as its eating flesh qualities. The breeding behaviour, reproduction and hatching of this species were observed for about 8 months during 2009. Juveniles (0.55 ± 0.177 g total weight and 2.7 ± 0.12 cm, total length) were reared in rounded fibre glass tanks (1.3 m, diameter). Pre‐mating moult occurs in prawns once the ovaries ripen in their carapace cavity so as to transform the prawn into berried stage. Recorded incubation period ranged from 18 to 24 days. The number of eggs ranged from 2050 to 150 500 and the fecundity ranged from 435.2 to 3849.1 eggs. Number of hatched larvae ranged from 1825 to 123 410 larvae for females of 4.71 to 39.1 g respectively. The number of eggs carried by female prawn was directly proportional to its body weight (no. of eggs = 3441.3 wt. of female – 32 292, r² = 0.819). (fecundity = 82.066 wt. of female ? 235.04, r² = 0.7779; fecundity = 317.86 length of female ? 2651, r² = 0.833). Hatching rate ranged from 65% to 91%, and there was a correlation between number of hatched larvae and size of female parent (no. of larvae = 10 369 length of female – 102 965, r² = 0.8159; no. of larvae = 2792.9 wt. of female – 26 268, r² = 0.829). This study can greatly help in the management strategies of prawn hatcheries and improve its hatching technology.     

Potential ship strikes and density of humpback whales in the Abrolhos Bank breeding ground,Brazil

相似文献   

Community‐based management of the environment: lessons from the past and options for the future

1. Traditional community‐based systems of managing coastal fisheries were (or in some cases are) successful in managing resources at sustainable levels. These systems are used as models in the present study. 2. They were (or are) under‐pinned by a sense of ownership and intimate knowledge of the environment in local people. 3. Such features have been largely lost, as subsistence economies have been replaced by capitalist ones, and environmental management responsibilities have shifted from local communities to national or international government. 4. There are, nevertheless, some examples of community‐based management systems that still operate successfully and we believe that modern management practices, in general, would benefit from increased community involvement. This will require renewed emphases on feelings of ownership and increased knowledge of the environment in the general public. 5. Environmental education will have a fundamental role to play in achieving this goal. However, its impact in schools and universities has been disappointingly ineffective so far in promoting a population that is sufficiently knowledgeable and well‐motivated to partake meaningfully in environmental management processes. 6. It is argued that educational initiatives, which involve all ages and sections of society, are required. Five promising possibilities are: (i) the participation of community groups in scientific projects; (ii) increased emphasis on life‐long learning; (iii) educational campaigns; (iv) citizens' juries; and (v) the involvement of community groups in environmental planning and management processes. 7. Wide‐scale adoption of innovations of these kinds will require funding and this will be achieved only by national re‐assessments of educational needs and priorities. Copyright © 2001 John Wiley & Sons, Ltd.     

金沙江下游中华沙鳅的资源现状、繁殖特性及人工繁育的初步研究

2011年5～12月,对金沙江屏山以下江段中华沙鳅(Botia superciliaris)的资源现状、繁殖特性进行了调查,并在实验室对该鱼的人工繁育进行了探索。所获中华沙鳅雄鱼(n=251)平均体长81.3 mm,平均体重8.7 g;雌鱼(n=486)平均体长109.7 mm,平均体重15.9 g。屏山调查点中华沙鳅占总渔获物(尾数)的2.68%,日均单船产量平均为0.12 kg;安边调查点中华沙鳅占总渔获物(尾数)的0.17%,日均单船产量平均为0.06 kg。雌雄性比为1.31∶1;雌、雄最小性成熟年龄均为2+龄。雌鱼的绝对怀卵量最大值为5 948粒,平均为4 455粒。中华沙鳅属一次性产卵类型,在流水中产漂流性卵;繁殖高峰期在5～6月。人工繁育时,受精卵在水温25～26℃孵化29 h仔鱼出膜,孵化率约70%,刚出膜仔鱼全长4.9～5.1 mm。半年后幼鱼的成活率为11.13%,全长约30 mm。     

Current knowledge and new assumptions on the evolutionary history of the African lungfish,Protopterus, based on a review of its fossil record

Lungfish have a large fossil record that started over 400 Ma ago and a relict modern diversity within Australia, Africa and South America. Their study mostly concentrates on their sister‐group relationship with the tetrapod vertebrates, on their early evolution and on the physiology of their air breathing and of the ability of certain species to aestivate. Conversely, little is known about the evolutionary history of modern taxa. In this study, the focus is on the single polytypic extant genus, Protopterus. Four species and seven subspecies are currently present in African freshwater. As fossils, Protopterus are recognized by their heavy tooth plates. Indeed, the review of the diagnostical characters shows that so far we are not able to confidently distinguish fossil species. The fossil record is thus explored through the analysis of the distribution of the genus. A comprehensive scenario for their evolutionary history is built by including also knowledge of the ecology, distribution and phylogeny of modern Protopterus, in the context of the environmental changes that affected Africa over the last 100 Ma. The genus has been present in Africa for at least 100 Ma when the continent separated from South America. Northern Africa might be the cradle for the African lineage, but other regions of Africa cannot be ruled out. During the Paleogene, lungfish disappeared from northern Africa, whereas modern Protopterus arose in a peri‐equatorial area with dispersal from this area late in the Pliocene. This correlates with great environmental change that occured during the last 25 Ma in eastern Africa.     

Joint effect of temperature,salinity and pH on the percentage fertilization and hatching of Nile tilapia ( Oreochromis niloticus)

Rested upon Box‐Behnken experimental design and response surface method, the joint effect of temperature, salinity and pH on the fertilization and hatching in Nile tilapia was studied under laboratory conditions. Results showed that the linear and quadratic effects of temperature, salinity and pH on fertilization and hatching were all statistically significant (P < 0.01). Interactions between temperature and salinity, and between temperature and pH on fertilization and hatching statistically differed from zero (P < 0.05). Interaction between salinity and pH on hatching was significant (P < 0.05), but nonsignificant on fertilization (P > 0.05). Regressions of fertilization and hatching towards temperature, salinity and pH were established, with the determination coefficient being 99.17% for fertilization and 99.79% for hatching, and could be used for prediction. By utilizing statistical optimization technique, the optimal temperature/salinity/pH combinations were attained: 27.6°C/9.3 ppt/7.5 for fertilization, at which the maximum fertilization was 87.7%, with the desirability being 92.11%; and 27.1°C/9.2 ppt/7.4 for hatching, at which the maximum hatching rate reached 81.2%, with the desirability as high as 96.74%. It could be said that the fertilization and hatching concurrently culminated at the 27.3°C/9.2 ppt/7.4 combination. It can be envisioned that the application of these results derived would give an impetus to the tilapia seed production efficiency and in turn to the development of tilapia husbandry.     

Nest site selection and aspects of the reproductive biology of the pygmy sculpin (Cottus paulus) in Coldwater Spring, Calhoun County, Alabama

Abstract – Imperiled pygmy sculpins are known from only one locality in Alabama, USA. One conservation strategy for the species is the creation of another population by introducing the species into a suitable habitat. Before such action is considered, however, an understanding of the life history, including reproductive biology and habitat use, of the species must be obtained. In this study, nesting of pygmy sculpins was found to peak in July, although the species has an extended reproductive period. Preferred nesting sites had higher flow and shallower water depth than the surrounding habitat. Pygmy sculpins readily used artificial nest substrates that were introduced into the spring run, where natural nest substrate was uncommon. ^Note     

Decimation of a population of the endangered species Scutellastra mexicana (Broderip and Sowerby, 1829) (Mollusca,Gastropoda) in the Marías Island (Eastern Ocean Pacific) Biosphere Reserve

1. Scutellastra mexicana is the largest known patellid limpet species and probably is one of the most endangered marine invertebrates.
2. The species was once distributed along the American Pacific coast from Mexico to Peru, but their large size (up to 35 cm long) and easy accessibility (shallow sublittoral), made it very vulnerable to human collection and now is extinct on most of the mainland Mexican coast.
3. In August 2017, a large population of this species was found on María Cleofas island, off the coast of west‐central Mexico (Marías Archipelago, Pacific Ocean). This constitutes the only report of a population of this species since 1988.
4. A total of 808 adult individuals of up to 26 cm in length and 20 cm in width were estimated, together with the presence of juveniles, suggesting that it is a self‐sustaining population. The population was monitored in August 2017 and August 2018.
5. Although the species is under the category ‘Special Protection’ in the General Mexican Wild Law, and that María Cleofas island is a Biosphere Reserve, fishermen that operate with impunity in the area decimated the limpet population within a year of its discovery. Abundance in the shallowest area decreased significantly from 120 individuals per transect (65 m long and 2.75 m wide) in August 2017 to 48 individuals in August 2018, and the estimated adult population decreased from 808 to 304 limpets.
6. Neither passive national conservation policies nor local practices have reduced current threats to biodiversity and resource depletion in Marías Archipelago. Protected areas like this are ‘paper parks’—parks in name only—because there is no active conservation strategy or protection of marine species.

     

宽壳全海笋人工繁育技术

2003-2005年,进行了宽壳全海笋繁殖的初步观察和人工育苗技术研究.通过观察,揭示了宽壳全海笋繁殖和胚胎发育的整个过程.利用实验生态学的方法,筛选出了受精卵孵化、幼虫生长和采苗的适宜环境条件.在浙南沿海,宽壳全海笋的自然繁殖时间是每年的4-6月份,水温为18～22 ℃.壳长6 cm以上的雌性成熟个体1次产卵可超过2 000万颗,成熟卵的卵径约50 μm.受精卵发育最适宜的温度是22～26 ℃,盐度21～26,在适宜条件下经过18 h左右发育至D形幼虫.幼虫生长发育的最适宜的温度范围是22～26 ℃,而盐度范围为16～26;幼虫前期培育的最适宜饵料为球等鞭金藻;经26～50 d培育幼虫进入变态附着期.幼虫变态附着最适宜的基质为泥底质.2005年度,在面积120 m2水池中,培育出宽壳全海笋稚贝数量6 100万颗,单位面积出苗量5.08×105 grain/m2,平均壳长1.43 mm.     

Optimal temperature and photoperiod for the spawning of blue crab,Callinectes sapidus,in captivity

Like all poikilotherms, the growth and reproduction of blue crab, Callinectes sapidus depends on temperature and season. Warmer water temperatures in the Chesapeake Bay allow for ovarian development and spawning, while colder water temperatures slow their metabolism and reproduction. The current study aimed to identify optimal environmental conditions for inducing reproduction in animals held in long‐term captivity for year round production in aquaculture through environmental manipulations. Temperature and photoperiod were the main environmental factors tested for 25 weeks: 11°C and 21°C, with the following photoperiods: 0L:24D, 8L:16D, 16L:8D and 24L:0D. At 21°C, the females increased spawning frequency, which was arrested at 11°C. Shorter light exposure at 21°C increased spawning frequency, while constant light inhibited and did not produce spawning. Constant dark (0L:24D) at 21°C produced the most (86%) spawns, but yielded poor larval quality. At 21°C with all photoperiod conditions except constant light, the first spawning took 94.8 ± 32.4 days to occur (n = 17). With females producing multiple spawns, the intervals between the first and second spawns and the second and third spawns were 37.7 ± 8.7 days (n = 6) and 31.0 ± 7.1 days (n = 2) respectively. Analysis of our data using response surface methodology (RSM) predicts the following conditions: at 15–19°C and 0–10 hr darkness for maximal survival and at 19–22°C and 0–8 hr darkness for spawning. The number of larvae produced was positively correlated with size (weight) of the female C. sapidus, suggesting the importance of female size in reproduction.     

Variation in rates of food consumption and evidence for compensatory responses in the three-spined stickleback, Gasterosteus aculeatus L. in relation to growth and reproduction

Abstract – Evidence that rates of food consumption differ between individuals in a population is noted. Preliminary estimates of individual variation in a population of three-spined sticklebacks ( Gasterosteus aculeatus L.) are provided and compared with similar estimates for a population of Phoxinus . Experimental studies are reviewed to demonstrate the capacity of sticklebacks to compensate for variations in food availability by compensatory changes in food consumption. These changes allowed sticklebacks on fluctuating rations to maintain growth and reproductive performances comparable to sticklebacks receiving constant, daily rations. Such studies start to define the scope for compensation that buffers the effect of environmental variability in food supply. ^NOTE     

Spawning aggregation behaviour in the Creole perch,Percichthys trucha (Percichthyidae): A target species for conservation

1. Habitat fragmentation and loss threaten freshwater biodiversity worldwide. Habitats that are essential as fish spawning and nursery sites are critical, and must be identified for conservation purposes. Littoral zones within Patagonian lakes, especially shallow vegetated areas, represent important areas for the Creole perch, Percichthys trucha.
2. Spawning behaviour has been little studied, so it is not known whether these movements are performed in groups. A particular area of a deep lake in northern Patagonia was studied to identify the environmental conditions under which spawning occurs, and to analyse spawning aggregation behaviour in relation to the lunar cycle.
3. To identify spawning sites, spawning occurrence time, and the environmental parameters that determine it, fish capture data were analysed. Underwater cameras were also set up at three depth strata in the shallow zone to detect spawning aggregation behaviour. Aggregation was scored as the greatest number of individuals present in a single frame, and the number present per depth stratum. The relationship between the lunar cycle and Creole perch abundance by depth was then determined.
4. This is the first visual record of a spawning bed and the spawning aggregation behaviour of Creole perch in Patagonian lakes. The abundance of mature Creole perch in the shallow strata during the austral spring suggests that vegetated areas constitute spawning sites. Spawning aggregation takes place at a shallow depth 2 days before the full moon.
5. As the reproductive behaviours of Creole perch are important phenomena in the life history of the species, the results of this study have important implications for conservation and management.

     

Reproduction, condition and mortality of the Pacific oyster Crassostrea gigas (Thunberg) in Sonora, México

Starting in 1997, mortality outbreaks in cultured oysters Crassostrea gigas have been reported in northwestern México. Previous studies have shown that massive die‐offs result from multi‐factor processes related to reproduction of the species. We studied the reproductive cycle and the condition index of cultured oysters in the coastal lagoon of El Soldado, Sonora, as well as the relationship of the life cycle with environmental parameters. We used oocyte diameter to determine reproductive stages and the condition index to describe the physiological state of oysters. Additionally, the temperature, salinity, seston and chlorophyll a were recorded at the study site. The results showed that C. gigas began accelerated reproductive activity in March under the influence of high temperature and increased concentrations of food. No spawning events were recorded and gametes were reabsorbed within the gonad in September and October. The results showed a period of nutrient storage during autumn–winter and another period of gamete production in spring–summer. A mortality event occurred at the end of winter, tied to significant increases in temperature and availability of food and in accelerated reproductive activity and high condition index. These conditions were very similar to those reported in other countries during summer die‐offs of C. gigas.     

The case for the African catfish, Clarias gariepinus Burchell, 1822, Clariidae: a comparison of the relative merits of Tilapiine fishes, especially Oreochromis niloticus (L.) and C. gariepinus Burchell, for African aquaculture

Abstract. The relative merits of tilapiine fishes, especially Oreochromis niloticus (L.) and Clarias gariepinus Burchell, are compared with respect to their suitability for aquaculture in Africa. Reproductive, nutritional and production data are drawn where possible from work carried out under African conditions.
In view of the fact that African aquaculture is insignificant in terms of worldwide production and in terms of local fish consumption it is suggested that a broader view of species choice might be adopted in relation to aquaculture projects.
The African catfish, by virtue of its suitable reproductive strategy, its nutritional efficiency and its ability to breath atmospheric oxygen, clearly represents an excellent candidate for aquaculture in Africa.