Reconstructing the history of the sand tiger shark (Carcharias taurus) in the Mediterranean Sea

1. Sharks are globally exposed to several anthropogenic threats, which, in many cases, have severely reduced their distribution and have impacted populations. In the Mediterranean Sea, because of its long history of exploitation and the relatively short span of scientific monitoring, reconstructing shark baselines is challenging. Many vulnerable species declined in population abundance and geographic distribution before it was possible to adequately track these changes. Consequently, for many of these species, current conservation assessments are now suffering from a severe case of shifting baseline syndrome, whereby their historical occurrence in the area is questioned.
2. The sand tiger shark (Carcharias taurus) is one of these cases. Characterized by high philopatry, restricted home range, and low interchange between populations, its Mediterranean population may have been severely impacted by the high historical fishing pressure in the region before scientific monitoring began.
3. In this study, the history of the abundance and distribution of C. taurus in the Mediterranean Sea was reconstructed through a comprehensive search of occurrence records in the literature and in museum collections. Between 1810 and 2008, 31 occurrence records and 54 publications provided information on the presence of the species in the area. These records were sparse but systematic over time and indicated occurrence hot spots in the south‐western Mediterranean Sea and in the eastern Adriatic Sea.
4. The presence of ten sightings of juveniles from a total of 18 sightings with length information suggested local parturition. Habitat and extinction models indicate that the area has suitable oceanographic conditions for the occurrence of the species and that the species cannot be considered extinct in the Mediterranean Sea. Our study suggests that there is still hope for the recovery of the species and underlines the crucial role of historical investigations to reconstruct the history of large elasmobranchs in the Mediterranean Sea.

     

Liver lipids of female Carcharias taurus (spotted raggedtooth) sharks: a comparison between seasons

Female raggedtooth sharks (Carcharias taurus) migrate from the waters off the eastern Cape past KwaZulu-Natal and up to southern Mozambique and then back on an annual basis. They mate off the KwaZulu-Natal coast, gestate the pups off Mozambique, then deliver same off the eastern Cape. Prior to mating, they hypertrophise their livers and store large amounts of lipid, then towards the end of gestation subsist on this stored lipid as well as using it to feed their pups in utero. Raggedtooth sharks are aplacental, and hepatic lipids provide nutrients to the pups via continued ovulation throughout pregnancy. The fact of the liver hypertrophy was well documented, but whether the nature of the stored lipid or the amount of lipid per Kg of liver changed with season was unknown. Samples from raggedtooth females caught throughout the year were analysed for their lipid and fatty acid contents and significant differences noted between lipid, but not fatty acid, concentration with certain seasons. Liver mass decreased from spring to winter (16.3–9.9 kg) as did lipid concentration (572–326 mg/g). Within the fatty acids, 22:6n3 was ±17%, 20:5n3 ±7%, total n3 ±30% and total n6 ±7%. Also, both total polyunsaturates (±36%) and total monounsaturates (±33%) were greater than the total saturates (±28%).     

The use of the Auto-Microbic-System (AMS) for mastitis diagnosis in cattle

In the period of January 1987 to March 1988 15,800 quarter milk samples of dairy cows from problem herds in Lower Austria were collected and 744 streptococci strains isolated. For the classification of those 744 isolates a comparative evaluation was carried out by means of the Auto-Microbic-System (AMS), API 20 STREP and CAMP-Test. With the AMS, 360 (= 48.4%) of the 744 isolates examined could be identified as streptococci and classified as follows: 16 Sc. agalactiae; 205 Enterococci (101 Sc. faecalis, 92 Sc. faecium, 12 Sc. avium); 74 Sc. uberis; 61 Sc. of the viridans streptococci and 4 Sc. pneumoniae. The test systems showed a correlation of 91.6%. AMS and API 20 STREP could classify 4 CAMP-negative streptococci strains to Sc. agalactiae. Based on these examinations the AMS can be recommended for the identification and classification of mastitis streptococci. It can be concluded that AMS is simple to use due to the automatic cycle, and is time saving because results can be obtained between 5 to 6 hours. On the other hand, AMS requires expensive equipment.     

The biology and conservation status of the grey nurse shark (Carcharias taurus Rafinesque 1810) in New South Wales,Australia

1. This paper summarizes aspects of the biology and conservation of the grey nurse shark (Carcharias taurus) in south-eastern Australian waters. This species has been a totally protected species in the State of New South Wales since 1984 and, as far as is known, was the first protected shark in the world. 2. Aspects discussed include systematics and taxonomy, distribution and biogeography, morphology and behaviour, reproduction and migrations, feeding habits, fisheries value and claims of attacks on humans, and impacts of protective beach meshing, spearfishing and SCUBA diving. The background to, and history of, moves to protect and conserve the species in New South Wales waters are also covered. 3. Results of surveys of the abundance of this species at Seal Rocks, an area off the mid-north coast of New South Wales where grey nurse sharks are known to aggregate, are reported. Also, a summary of the results of a telephone survey of commercial dive shop operators regarding the occurrence of grey nurse sharks along the New South Wales coastline is presented. 4. Finally, recommendations are made concerning the need for further research on, and management of, this species in Australian waters.     

Scuba diving with the grey nurse shark (Carcharias taurus): an application of the theory of planned behaviour to identify divers beliefs

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Accumulated occurrence of lipomatosis in a cattle herd in Assiut (Egypt)

A total number of 30 native breed cows were used in this investigation. Ten animals were clinically healthy and kept as control, while 20 diseased cows were selected according to rectal findings. At the beginning of the disease, the cows appeared obese with marked deposition of fat in the subcutaneous tissue at the lumbosacral area, later on they became emaciated. Additional signs were digestive disturbance in form of diarrhea or constipation and tympany. Rectal examination revealed hard irregular masses of various size which were palpated in the pelvis, the perirenal area around the colon and the rectum. More information about the nature and character of the lesions were taken from slaughtered cows. Biochemical analysis, including total lipids, cholesterol triglycerides and creatine kinase, were carried out in both healthy and diseased cows. In advanced cases of bovine lipomatosis hyperlipemia and hypercholesterolemia as well as increased creatine kinase values were constant findings. The aetiology of this disease is still unknown.     

叶尔羌高原鳅胚胎发育与胚后发育观察

采用形态学和生态学方法,对叶尔羌高原鳅[Triplophysa(Hedinichthys)yarkandensis(Day)]胚胎发育和胚后发育阶段全过程进行观察、拍照并测量。结果显示:叶尔羌高原鳅,卵微黏性,略有沉性,受精卵呈卵圆形,卵径为(0.60±0.052)mm,在水温(20.0±1.0)℃下,历时65 h 34 min完成整个胚胎发育分为7个生理阶段过程;胚后发育主要根据卵黄囊、体色、鼓鳔和须的变化分为仔鱼期、稚鱼期、幼鱼期。初孵卵黄囊仔鱼全长(2.0±0.65)mm,出膜后7 d,卵黄囊吸收完毕,完全消失;初孵仔鱼继续培育至16日龄,仔鱼鳃盖后缘鼓鳔明显长出,须清晰可辨,体色加深,心脏红色素明显,体色与成体相似,标志后期仔鱼发育完全进入稚鱼期,此时鱼苗全长(8.0±0.45)mm;培育至30日龄,仔鱼鼓鳔完全,鳃盖张合明显,身体透明特征消失,稚鱼阶段完成发育进入幼鱼期,此时全长达(13.0±0.55)mm,其外部形态和生态习性均与成鱼相似。试验中,卵黄囊长度(LY)和出膜天数(D)的关系式:LY=0.0286D2–0.0636D+3.1196(R2=0.9050);用直线方程拟合卵黄囊长度(LY)和卵黄囊仔鱼全长(LT)的关系式:LY=–1.315LT+5.368(R2=0.8199);拟合卵黄囊仔鱼全长(LT)和出膜后仔稚鱼天数(D)的关系式:LT=–0.0263D2+0.5113D+1.6169(R2=0.9890)。本研究旨在通过了解叶尔羌高原鳅的早期发育特征为该物种的保护和增殖对策提供科学依据,并对其苗种生产提供理论指导。     

时间-温度指示器(TTI)的发展现状

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倒刺鲃的胚胎发育及水温对胚胎发育的影响

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我国水产养殖工程学科发展报告（2007—2008）

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Early development of the shortfin silverside Chirostoma humboldtianum (Valenciennes, 1835) (Atheriniformes: Atherinopsidae)

The shortfin silverside Chirostoma humboldtianum has been considered for culture in Mexico, but success has been limited by a poor knowledge of its early development. First synthesis of the early development of the shortfin silverside is presented to determine conditions suitable for rearing. Brooder maturation was induced through photothermal cycles. C. humboldtianum ova were fertilized in vitro. The eggs were incubated in reconstituted water (160-180 mg/L CaCO₃) at 18 °C and 5 gm of NaCl per litre. During the hatching day, 300 shortfin silversides were stocked and followed up until metamorphosis in order to establish the timing of exogenous feeding, changes in food type, growth and development during critical periods for survival, according to the theory of saltatory ontogeny. Free embryos hatched 12 days after fertilization at 18 °C. First critical point for survival is the beginning of exogenous feeding. Free embryos started mixed feeding on day four of post-hatching (dph), point of no-return was presented towards the end of mixed feeding on 6 dph, larval period began at six (dph) when the anus is opened, and metamorphosis to juvenile was presented at 65 dph with a SL of 19.34 ± 2.28 mm, when scales and fins were well developed. Differences in growth between periods were detected: free embryos growth slower than larvae but mouth size depicted a larger growth rate in the former. Cephalic length and mouth size were negatively related to standard length in embryos and larvae. Mouth size was positively related to cephalic length in free embryos but negative in larvae. Results suggest that during the free embryo phase, growth priorities are directed to the development of apparatuses and systems; whereas, during the larval period, energy is directed to growth in length, mouth size and development of fins, which allows them to increase their swimming velocity, grants them a greater capacity to obtain exogenous food and, in consequence, increases fitness for survival.     

Ontogeny and development of the gastrointestinal system in Indian walking catfish (Clarias magur) during its early development

Fish Physiology and Biochemistry - Ontogeny of the digestive tract and its accessory organs and their further development in the Indian walking catfish (Clarias magur) were examined in larvae,...     

Digestive enzyme activity during larval development of the Senegal sole (Solea senegalensis)

The activities of the main digestive enzymes (proteases, amylase, lipase) as well as those of acid and alkaline phosphatases were assessed during the larval development of the Senegal sole, Solea senegalensis. Important variations in specific activities of all the enzymes were observed during the period of study and were mostly related to the beginning or the end of metamorphosis. Both acid and alkaline protease activities were identified at early stages of development. Acid proteases accounted for only 10% of total protease activity in a 9 days-old larva, but exceeded 75% in a 33 days-old individual. Maximum lipase activity was related to the development of exocrine pancreas (days 6 to 10) and to metamorphosis. It is suggested this can be related to the metabolism of lipid reserves taking place during this morphological change. Activity of alkaline phosphatase decreased from day 5 to day 20 but therafter revealed a sharp increase, possibly linked to the development of enterocytes. The pattern of development of the main digestive enzymes found in S. senegalensis is similar to that described in other flatfish species.     

Egg development and lifecycle timing in the noble crayfish (Astacus astacus)

Egg development time in Astacus astacus was strongly influenced by temperature. Five batches of eggs were subjected to different temperature regimes after approximately 600 degree days and, by increasing the temperature, the total number of degree days to hatching was reduced from 1900 to 1300. There were no systematic differences in hatching success or juvenile survival due to different temperature treatments. Females molted and rematured (50–100%) 4–8 weeks after hatching.     

Embryonic development of Ganga river prawn Macrobrachium gangeticum (Bate)

Macrobrachium gangeticum (Bate) are commercially valuable prawns that are broadly distributed in the Ganga river that flows from northern to eastern India. We studied embryonic development from cleavage (blastomeres), segmentation, formation of optic vesicle, eye pigment development to larva formation, as these data are largely unknown in this species. We conducted this study using mature M. gangeticum broodstock placed in freshwater tanks. Just after spawning, females were kept in separate aerated tanks, where fecundity was estimated from the total number of eggs. Thereafter, egg samples from berried females were used to study their embryonic stages. The correlation coefficient between size and prawn weight, egg weight, egg number, body weight and egg mass of different sizes of prawns was analysed. Our results show that an increase in prawn size led to an increase in egg weight and egg number while decreases in body weight:egg mass ratio was noticed. Further results indicate that an increase in prawn weight had a positive impact on egg weight and egg number. The embryo development stages were used in this study as a tool to evaluate the development process of the prawn in a hatchery environment.     

Early development of Lamprey Lampetra japonica (Martens, 1868)

Studies of lamprey early development have produced major insights into primitive developmental patterns and the evolution of vertebrates. In this study, the effectiveness of the morphological and histological characteristics of Lampetra japonica during embryological, yolk‐sac larval and ammocoete stages were examined. Based on the external and histological morphology, the embryological phase was divided into eight stages, including the zygote, cleavage, blastula, gastrula, neural plate and groove, head protrusion, prehatching and hatching stages. A set of key morphological and histological transformations occurred through the yolk‐sac larval stage, reflecting the larva‐ammocoete transition. In the ammocoete stage, all organ systems were differentiated. Except for the melanophores, the lamprey did not develop any further morphological complexity beyond the ammocoete stage. The total length and body weight of larva and ammocoete generally increased over time. We hope that this study might form the basis for future studies of the phylogenetic development of this interesting group of animals.     

池养大鲵生长发育的初步研究

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赤潮异弯藻对鳀鱼早期发育的影响

就赤潮异弯藻(Heterosigma akashiwo)藻液及各组分对鳀鱼(Engraulis ja ponicus)早期发育阶段的影响进行了研究。并就鳃鱼早期发育过程中对赤潮异弯藻的敏感性时期作了探讨。实验结果表明,原肠期前的发育卵和初孵仔鱼对赤潮异弯藻较其他发育阶段更为敏感。在同等条件下藻细胞内容物对鳃鱼早期发育各阶段的毒性最大,其次是藻细胞碎片和藻液,去藻过滤液的毒性最小。暴露在高浓度90000c／ml藻细胞内容物中,96h后仔鱼的存活率为4％;而在同浓度的去藻过滤液中,96h后仔鱼的存活率为75％。藻细胞内容物和藻细胞碎片对鳃鱼仔鱼96hI。C∞分别为2818、6760c／mL．