温水鱼对钙、磷的需要

钙和磷是构成骨组织的必需元素,在陆生脊椎动物身体内大约99％的钙和86％的磷都集中在骨骼和牙齿中,它们在其中起骨架作用。鱼类的骨骼中也含有大量的钙而且鱼鳞中也沉积着大量的钙有报道指出在鳟鱼的皮肤内含有大约40％的钙在罗非鱼的鳞里也含有大量的钙占干重的19～24％。罗非鱼、金鱼、鲤鱼及鲜鱼在产卵和食物缺乏时鳞内的钙含量减少,但鳞对矿物质有重吸收的功能。鲤鱼、狗鱼、罗非鱼、鳊鱼及鲑鳟鱼骨骼和鳞中的Ca/P是1.5～2.1。对大多数温水鱼来说,在整个鱼体中Ca/P是0.7～1.6,磷占整个鱼体体重的0.4～0.5％。钙不仅在鱼的身体和鳞中起骨架作用,

鸿雁池渔场渔业资源及鱼病调查

鸿雁池渔场位于乌鲁木齐市郊。是全疆最大的大型温水鱼养殖基地。为了了解鸿雁池水库的渔业资源和鱼病发生情况,于2001年9月对该场进行了调查,现将结果报告如下。

Embryonic development of Pelteobagrus fulvidraco(Richardson,1846)

For production enhancement and procedure upgrade, the developmental phases of labora-tory-reared eggs of catfish Pelteobagrus fulvidraco were investigated. Twenty mature females and 10 males were collected from Dadongmen wholesale fisheries market in Wuhan City on May 8, 2003. Zy-gotes were stripped from mature fish after hormone-induced ovulation, fertilized, and incubated through whole embryonic development. The fertilized eggs were stocked in density of 100 eggs/L in white square tanks of 10 L. Incubation water was dechlorinated tap water with continuous aeration. The tanks were lit directly with 60 W fluorescent bulbs with a 12 light:12 dark photoperiod. Water temperature, dissolved oxygen and pH were 29.0±0.5℃, 6.7±0.4 mg/L and 7.4±0.2, respectively. The results showed that the eggs of P. fulvidraco were yellow, sticky and contained much yolk. The mean diameter of fertilized eggs was 2.03 mm. At the water temperature of 29.0±0.5℃, the ontogenesis spent about 33 h after fertilization. From fertilization to hatching, the embryonic development can be divided into 30–40 phases, which var-ies in the emphasis and direction of development. The detailed embryonic movement was also described.

Physiological responses of Chinese longsnout catfish to water temperature

We evaluated the effect of water temperature on the growth and physiology of the Chinese longsnout catfish （Leiocassis longirostris Günther）. The fish were reared at four temperatures （20, 25, 30, and 35℃） and sampled on days 7, 20, and 30. We measured plasma levels of insulin, free thyroxine （FT4）, free 3,5,3＇-triiodothyronine （FT3）, lysozyme and leukocyte phagocytic activity. The optimum water temperature for growth was 27.7℃. The plasma levels of insulin and FT4 declined significantly （P〈0.05） on day 30 at temperatures above 20℃. Lysozyme activity was significantly （P〈0.05） lower at 25℃ than at other temperatures. We conclude that final weight, insulin, FT4, and lysozyme were significantly affected by water temperature.

Variation in the distribution of wintering anchovy Engraulis japonicus and its relationship with water temperature in the central and southern Yellow Sea

In the present study,we investigated a shift in the spatial distribution of wintering anchovy(Engraulis japonicus)and its relationship with water temperature,using data collected by bottom trawl surveys and remote sensing in the central and southern Yellow Sea,during 2000–2015.Our results indicate that the latitudinal distribution of wintering anchovy varied between years,but there was no consistent pattern in the direction of change(north or south).Wintering anchovy did not move northward with increasing water temperature.However,the latitudinal distribution of wintering anchovy correlated well with 10°C and 11°C isotherms.The results of both a one-step and a two-step generalized additive model indicated that water temperature was associated with both presence and biomass of wintering anchovy.This paper is the fi rst to systematically examine the relationship between anchovy distribution and water temperature using a variety of techniques.All the fi ndings confi rm the impact of water temperature on wintering anchovy distribution,which has important implications for the continued management of the anchovy resource and the enhancement of marine fi shery resources in the Yellow Sea,especially as the climate changes.However water temperature only partly explains the species distribution of anchovy,and stock characteristics also aff ect fi shery distribution.Therefore,other factors should be considered in future research.

Differences in sensitivity of native and exotic fish species to changes in river temperature

This paper describes the effects that temperature changes in the Rhine river distributaries have on native and exotic fish diversity. Site-specific potentially affected fractions （PAFs） of the regional fish species pool were derived using species sensitivity distributions （SSDs） for water temperature. The number of fish species in the river distributaries has changed remarkably over the last century. The number of native rheophilous species declined up until 1980 due to anthropogenic disturbances such as commercial fishing, fiver regulation, migration barriers, habitat deterioration and water pollution. In spite of progress in river re- habilitation, the native rheophilous fish fauna has only partially recovered thus far. The total number of species has strongly in- creased due to the appearance of more exotic species. After the opening of the Rhine-Main-Danube waterway in 1992, many fish species originating from the Ponto-Caspian area colonized the Rhine basin. The yearly minimum and maximum river tempera- tures at Lobith have increased by circa 4 ~C over the period 1908-2010. Exotic species show lower PAFs than native species at both ends of the temperature range. The interspecific variation in the temperature tolerance of exotic fish species was found to be large. Using temporal trends in river temperature allowed past predictions of PAFs to demonstrate that the increase in maximum river temperature negatively affected a higher percentage of native fish species than exotic species. Our results support the hy- pothesis that alterations of the river Rhine＇s temperature regime caused by thermal pollution and global wanning limit the full recovery of native fish fauna and facilitate the establishment of exotic species which thereby increases competition between native and exotic species. Thermal refuges are important for the survival of native fish species under extreme summer or winter temperature conditions

Effects of temperature and diet on length-weight relationship and condition factor of the juvenile Malabar blood snapper(Lutjanus malabaricus Bloch & Schneider, 1801)

In this study we aimed to analyze the effects of water temperature and diet on the length-weight rela- tionship and condition of juvenile Malabar blood snapper Lutjanus malabaricus over a 30-d experimental period. The experiment was conducted in the laboratory using a flow-through-sea-water system. The fish were subjected to four different temperatures （22, 26, 30, and 34 ℃） and two diets （commercial pellet and natural shrimp）. Fish were fed twice daily. L. malabancus exhibited negative allometric growth （b〈3） at the beginning of the experiment （Day 0） at all temperatures and both diets except for 22 ℃ fed with shrimp, which showed isometric growth （b=3）. Conversely, at the end of the experiment （Day 30） fish showed isometric growth （b=3） at 30 ℃ fed with the pellet diet, indicating that the shape of the fish did not change with increasing weight and length, and a positive allometric growth （b〉3） at 30 ℃ fed with shrimp diet, which indicated that fish weight increases faster than their length. The rest of the temperatures represented negative allometric growth （b〈3） on both diet, meaning that fish became lighter with increasing size. The condition factors in the initial and final measurements were greater than 1, indicating the state of health of the fish, except for those fed on a pellet diet at 34 ℃. However, the best condition was obtained at 30 ℃ on both diets. Nev- ertheless, diets did not have a significant effect on growth and condition of juvenile L. malabaricus. The data obtained from this study suggested culturing L. malabaricus at 30 ℃ and feeding on the pellet or shrimp diet, which will optimize the overall production and condition of this commercially important fish species.

Boldness is related to the development of the cephalic crest in the male of the river blenny Salariafluviatilis （Asso, 1801）

Boldness is defined as the tendency of an individual to take risks when exposed to novel objects or situations. The main aim of this work was to dilucidate if boldness was related to the development of the secondary sexual traits （SSTs） in the male of the fiver blenny Salariafluviatilis, a freshwater fish which takes care of eggs. As a second objective SSTs effect on pa rental status adoption was also be explored. Wild young fish were caught in the Segre River （Ebro basin） in November 2010. Fish were kept in five aquaria in groups of eight males and eight females with artificial nests. Boldness （boldness score and hesitancy） of males （initially with little SSTs development） was tested as the time required to exit a refuge when exposed to a new environ ment. Fish were mantained in the same aquaria for several months, and males＇ SSTs development and reproductive behaviour were monitored. Boldness score was negatively associated to cephalic crest development. Hesitancy was negatively related to male length and was also influenced by the interaction between male length and cephalic crest. Parental status acquisition was positively related to the male＇s length, marginally related to anal gland development, and nonrelated to cephalic crest. These re sults suggest an intrasexual role of the crest as an informative trait of boldness （honest signal） which might not necessarily be chosen by the females. It is also discussed that correlational selection could be responsible for linking boldness and growth rate in this species. Sexual selection, in addition to having directed the evolution of secondary sexual traits, might have favored certain personality traits （e.g. boldness） associated with the achievement of a larger body length .