An investigation into the growth of 0‐group roach, (Rutilus rutilus L.) with special reference to temperature

Juvenile (12–152 g) shortfinned eels Anguilla australis and longfinned eels A. dieffenbachia caught in New Zealand streams were fed squid mantle Nototodarus spp. 4 days per week in laboratory experiments. A linear multiple regression equation showed the amount of food eaten (0–2·7% w day−1) explained 77·7% of the variation in specific growth rates (–0·60 to +1·07% w day−1) among individual eels, while previous growth rates, water temperature (10·0–20·6°C), and eel weight (12–152 g) explained a further 5·6, 1·4 and 0·8%, respectively. Growth in length ranged from –0·3 to +0·9 mm day−1. Eels which were starved and then given high rations grew substantially faster than expected. Once growth rates were adjusted for differences in ration and other factors, there were no significant differences in growth rates between species or individual fish. Growth of shortfinned eels fed maximum rations of commercial eel food depended on fish size and water temperatures and ceased below 9·0°C. Growth rates in the wild were substantially less than the maximum possible, after seasonal changes in water temperatures were taken into account, indicating that food supplies and not low water temperatures were controlling growth rates in the wild.

Juvenile (12–152 g) shortfinned eelsAnguilla australisand longfinned eelsA. dieffenbachiacaught in New Zealand streams were fed squid mantleNototodarusspp. 4 days per week in laboratory experiments. A linear multiple regression equation showed the amount of food eaten (0–2·7% w day−1) explained 77·7% of the variation in specific growth rates (–0·60 to +1·07% w day−1) among individual eels, while previous growth rates, water temperature (10·0–20·6°C), and eel weight (12–152 g) explained a further 5·6, 1·4 and 0·8%, respectively. Growth in length ranged from –0·3 to +0·9 mm day−1. Eels which were starved and then given high rations grew substantially faster than expected. Once growth rates were adjusted for differences in ration and other factors, there were no significant differences in growth rates between species or individual fish. Growth of shortfinned eels fed maximum rations of commercial eel food depended on fish size and water temperatures and ceased below 9·0°C. Growth rates in the wild were substantially less than the maximum possible, after seasonal changes in water temperatures were taken into account, indicating that food supplies and not low water temperatures were controlling growth rates in the wild.

Experiments were conducted to study the effect of temperature, fish size, and somatic growth rate on mean daily otolith growth rate in Arctic char (Salvelinus alpinus) fry fed maximum rations. Long-term experiments at two different temperatures (8 and 13 °C) showed exponential relationships between otolith weight and fish wet weight, with the exponent of wet weight for the higher temperature being significantly higher than for the lower temperature. Increasing exponents at each sampling date indicated a difference in growth rates of the char and its otoliths. Short-term experiments showed that specific growth rate of the fry at six different temperatures was that of an optimum curve whereas the otolith growth rate continued to increase with increasing temperatures. A clear uncoupling between otolith growth rate and fish growth rate was demonstrated whereas temperature and fish wet weight modeled otolith growth rate reasonably well. It was found that otolith growth rate expressed as daily increase in weight gave a model with better fit and higher generality than growth rate along various radii. Several examples of uncoupling between fish growth rate and otolith growth rate in the literature were reexamined, and an explanation of otolith growth rate in terms of a metabolic expression was suggested.

Larvae of Luciobarbus xanthopterus and Ctenopharyngdon idella were cultured in ponds with treated wastewater in marine science center by adding 20 larvae to each pond in a replicate to each species as well as the control ponds to the two species. Experiment was expend to six weeks depending on the natural food available in the pond. While standard artificial diet was add to the control ponds. Some biological measurements were done including length and weight rates, weight increase and daily weight increase, relative and specific growth rates and survival rates. Results showed a clear excellence of treated wastewater ponds in all biological measurements from the control ponds at the tow species. Larvae of L. xanthopterus showed a length and weight rates, weight increase and daily weight increase and survival rates higher than C. Idella which were (4.41 ± 0.04) cm, (0.35 ± 0.06) gm, (0.322 ± 0.005) gm, (0.008 ± 0.0002) gm/day and (91.67 ± 2.89) % respectively, while C. Idella showed relative and specific growth rates higher than L. xanthopterus larvae which were (3790.40 ± 877.88) % and (8.85 ± 0.56) %gm/day respectively. The study showed that the use of treated wastewater in L. xanthopterus and C. Idella larvae culture was excellent and rise the growth and survival rates of these larvae.

Decrease of concentration and colloidal fraction of organic carbon and trace elements in response to the anomalously hot summer 2010 in a humic boreal lake

<p><em>The research was to know the influence of the supplementation lemuru fish oil and L-carnitine on the local male ducks’ performance. The cattle used were 96 local male ducks aged 10 days. Research materials were corn, bran, concentrate 144, lemuru fish oil, and L-carnitine. The research design used was Complete Random Design with 3 treatments and 8 repetitions; each repetition contained 4 local male ducks. The treatment consisted of ration control P0 = corn, barn, concentrate and mineral; P1 = corn, barn, mineral and 4% lemuru fish oil; P2 = corn, barn, concentrate, mineral, 4% lemuru fish oil and 30 ppm L-carnitine. The investigated modifiers were feed consumption, feed conversion, daily weight increase and Income Over Feed Cost value. Data feed consumption, daily weight increase, feed conversion was analyzed using variance analysis. If there were a concrete influence, further analysis should be conducted using orthogonal contrast. Results showed that the supplementation of lemuru fish oil and L-carnitine had a very significant influence (P<0.01) on feed consumption, daily weight increase and feed conversion. Further test results orthogonal contrast showed that the supplementation of lemuru fish oil and L-carnitine could decrease feed consumption, feed conversion and increase daily weight rate (P<0.01) if compared control. Result Income Over Feed Cost showed that treatment with add lemuru fish oil and L-carnitine produced Income Over Feed Cost value higher if compared control. Based on the results of the research, it could be concluded that the supplementation of 4% lemuru fish oil and 30 ppm L-carnitine in ration could decrease feed consumption and feed conversion, increase daily weight rate, and the IOFC of local male ducks.</em></p>

Natural reproduction of pallid sturgeon Scaphirhynchus albus has been limited for decades and a recruitment bottleneck is hypothesized to occur during the larval stage of development. In this study, we evaluated the effects of water velocity and temperature on the swimming activity, energy use, settling behaviour and mortality of endogenously feeding larvae. The swimming activity of drifting sturgeon larvae (i.e., fish exhibiting negative rheotaxis) increased at low water velocity. In subsequent experiments, we observed greater energy depletion and resultant mortality of larvae in no-flow environments (0 cm s-1 ) compared to tanks with water velocity ranging from 3.5 to 8.3 cm s-1 . The growth rate of drifting larvae was positively related to water temperature (18.7-23.3°C), but reduced growth rate at low water temperature (18.7°C) resulted in protracted development that extended average drift duration by ~4 days compared to larvae reared at 23.3°C. This study provides evidence that cooler summer water temperatures, characteristic of present-day conditions in the upper Missouri River, can reduce larval development and extend both the drift duration and distance requirements of S. albus. Moreover, if dispersed into low velocity environments, such as in reservoir headwaters, larvae may experience increased mortality owing to a mismatch between early life stage drift requirements and habitat conditions in the river. Manipulation of water releases to increase seasonal water temperature below dams may aid survival of S. albus larvae by shortening the time and distance spent drifting.

La creciente demanda de proteína acuícola sugiere buscar alternativas biotecnológicas que mejoren el cultivo de especies de interés comercial. En este estudio se evaluó Bacillus firmus C101 como promotor del crecimiento y potencial probiótico, el cual fue caracterizado y posteriormente administrado (106 UFC mL-1 * día) en poslarvas de camarón blanco (Litopenaeus vannamei) y en rotíferos (Brachionus plicatilis sensu stricto). Se observó que B. firmus C101 tiene tolerancia a sales biliares, fuerte actividad fosfatasa y actividad antimicrobiana frente a patógenos como Vibrio alginolyticus y Aeromonas hydrophila, entre otros. Por otro lado, tras su administración por tres semanas a poslarvas de camarón causó un aumento significativo (p < 0,05) en la tasa específica de crecimiento (TEC = 3,8 ± 0,7 % día-1), el incremento de peso diario (ADG = 1,5 ± 0,1 mg día-1) y en la tasa de conversión alimenticia (TCA = 1,5 ± 0,1 %) en comparación con los controles sin adición de esta bacteria (PBS estéril). Así mismo, la administración de B. firmus C101 (106 UFC mL-1 * día) a rotíferos causó un aumento en la tasa de crecimiento poblacional (TC = 20,2 ± 1,5 % día-1), fecundidad (F = 0,4 ± 0,03 huevos individuos-1) y productividad (R = 16,0 ± 0,7 individuos mL-1 * día), después de 48 h de cultivo. Con base en lo anterior y en comparación con otros estudios, se sugiere a B. firmus C101 como potencial probiótico y promotor del crecimiento en poslarvas de camarón, y como primer reporte del efecto de su administración en rotíferos. No obstante, se precisan estudios sobre los posibles mecanismos de acción, y pruebas a escala piloto y comercial para validar estos resultados y su posible transferencia al sector productivo.

Identifying and examining traits that influence the distribution of species is crucial to the understanding of community structure. Theory predicts that traits should differ between species that live in temporary and permanent waters because of differing major environmental variables; viz drying out and predator presence, respectively. Species, however, will also be influenced by their evolutionary history, i.e. by the traits of their common ancestors. We studied differences in life history and behaviour traits in a series of laboratory experiments using pairs of dragonfly species out of three genera of Namibian Libellulidae (Odonata) with one species from each type of habitat. As predicted, growth rates were significantly higher in the temporary water species compared to the permanent water species. Activity and foraging, in contrast, differed between the genera, but did not differ between the habitat types. Hence, our study implies that the behavioural traits are influenced by phylogenetic inertia rather than by the habitat variables, while growth rate is adapted to the habitat. We argue that in all three genera one species has diverged recently from a sister species that lives in the original habitat of the genus, which may be temporary waters inCrocothemisBrauer and inOrthetrumNewman, and permanent waters inTrithemisBrauer. The behavioural traits may therefore be less well adapted. Rapid growth may be the more relevant trait because it is crucial to survival in temporary waters.

The effect of time-restricted demand feeding on feeding activity growth and feed conversion in rainbow trout ( Oncorhynchus mykiss)

Invasive apple snail, Pomacea canaliculata is one of the major mollusc pests affecting rice production in Malaysia. This pest not only gives fatal effects to rice but also decreases the water quality in the ecosystem due to the use of pesticides to control it. With the unpredictable changes on global climatic in Malaysia, it is important to have knowledge on the effect of water temperature on growth and survival rate of P. canaliculata in water bodies, in order to avoid loss in paddy field and its adverse effects on aquatic ecosystems. Water temperature is one of the most important environmental factors influencing the survival, growth rate, reproduction and behaviour of freshwater snails. The aim of this study is to evaluate the growth and survival rate of juvenile P. canaliculata at different temperature regimes. Growth and survival of juvenile P. canaliculata were evaluated at different constant water temperatures (15, 20, 25, 30 and 35°C). Our findings show, at 30° C the growth rate of P. canaliculata is higher compared with the other temperatures, however had low survival rate. Meanwhile, at room temperature (21 - 24°C), a higher survival rate (100%) was recorded. The results showed that different water temperatures affect the growth and survival rate of P. canaliculata and it is an important indicator for predicting and understanding the changes of water temperature when controlling this pest.

Este experimento tuvo como objetivo evaluar el crecimiento y la supervivencia de juveniles de tiburoncito Ariopsis seemanni, una especie ictica del Pacifico Colombiano, alimentándola de cinco dietas comerciales, con la finalidad de conocer el desempeño zootécnico para poderlo incorporar en la acuicultura marina del país. Previo al experimento, hubo un periodo de adaptación a condiciones de laboratorio y al consumo de una dieta comercial, de 30 días. El diseño utilizado fue completamente al azar, con cinco tratamientos y tres repeticiones. Se utilizaron tanques plásticos con volumen útil de 40 L de agua a una salinidad de 10%, en donde se ubicaron 20 juveniles por unidad experimental. Los peces con peso inicial de 3,25 ± 0,26 g, fueron alimentados tres veces al día a razón del 6 % de la biomasa por día, por un periodo de 58 días. Se determinaron los índices de supervivencia, incremento en peso, tasa especifica de crecimiento e índice hepatosomatico. El análisis bromatológico arrojó que las dietas comerciales presentaron un nivel proteico real de 28, 37, 45, 50 y 53%. Con las dietas de 45, 50 y 53% no se observaron diferencias significativas (P > 0,05) en los índices de desempeño productivo. La supervivencia fue superior al 75%. El incremento diario máximo en peso fue de 0,06 g/día con la dieta de 53%, y el mínimo fue de 0,03 g/día con la dieta de 28%; lo que representa una diferencia de 50% a favor de la dieta de 53% en relación a la de 28% de proteína. En los peces alimentados con la dieta de 53% de proteína se observó un crecimiento óptimo y una supervivencia cercana al 75%. En la dieta con 45% de proteína se observó un menor incremento en peso, compensado con una supervivencia cercana al 95%, que significó un aumento en el lucro por el mayor número de unidades vivas para comercializar.

Theory, experiments and field studies indicate that the somatic growth rate of freshwater consumers is shaped by the individual, additive and multiplicative effects of multiple factors, including consumer size and condition, temperature, prey resources and biotic interactions. While our understanding of how these factors affect wild populations of freshwater consumers is improving, the topic remains poorly studied, especially with respect to mobile species. Here, we report on an 8‐year, seven‐stream (n = 49 stream‐year combinations) observational study examining the individual and interactive effects of invertebrate prey concentration (F, mg/m3), mean daily water temperature (T, °C) and juvenile Chinook salmon (Oncorhynchus tshawytscha) density (D, fish/100 m2) on summer daily growth rates (%/d) of mobile, anadromous, juvenile Chinook salmon (age‐0+, n = 382) and sub‐yearling (age‐0+, n = 61) and yearling (age‐1+) steelhead trout (O. mykiss, n = 70) rearing in cold (mean daily summer: 12.1°C, range: 4.2°C–16.7°C) mountain tributaries of the Salmon River basin in central Idaho (USA). AICc model selection indicated that daily juvenile salmonid growth positively correlated with water temperature, prey biomass concentration, local juvenile Chinook density and the interaction between water temperature and food but with species and age‐specific differences. Water temperature was a covariate in all top‐ranked models, with daily growth (%/day) rate increasing (0.05%–0.23%/d) linearly with mean daily summer water temperature. In addition to a direct positive relationship with daily growth rate, there was evidence that prey concentration positively interacted with water temperature to accelerate daily growth (F × T). The positive relationship between juvenile salmonid daily growth rate and juvenile Chinook density is difficult to explain and could result from confounding factors. The individual success observed in these streams may contribute to population‐level benefits for the focal consumers, as prey‐rich, warm summers may result in larger individuals with higher energy reserves at the end of the summer/autumn growing season, contributing to improved overwinter survival. Our results, taken in combination with evidence from models, experiments and observational studies, have climate change implications. Current and predicted increases in water temperature will necessitate higher rates of prey consumption by aquatic ectothermic consumers to offset accelerated metabolic demands. Thus, to improve the resilience of mobile freshwater consumers in a warming climate, we suggest that natural resource managers not only consider physical and chemical habitat conditions but also biotic conditions, including the spatiotemporal quantity and quality of prey resources.

For establishing the technology of pisciculture, it is necessary to be able to forecast the growth of the cultured fish. With this purpose in mind we have analyzed reliable field data concerning the average growth of the O-year-old yellow tail (Hamachi in Japanese) cultured in fish farms located on the Seto Inland Sea coast. If the food supply is sufficient in quantity and adequate in quality when under the normal influence of all other possible factors, the average growth rate of the cultured fishes may be given as a function of water temperature (the most potent environmental factor) and average fish size (the most fundamental biotic factor) by the following empirical relationship. d (W/W∞)/dt=λ(1-W∞) {In (1-W/W∞ )-1}γ where W is the average body weight at time t, W∞ the theoretical maximum body weight ( ?? 15.8Kg), dW/dt the growth rate, γ a constant characteristic of the species and λ depends upon the water temperature and perhaps upon the species. In case of the 0-year-old cultured yellow tail, the value of γ was determined to be 0.167 (Fig. 1) and then the dependence of λ upon the water temperature was accounted for as shown graphically in Fig. 2. It may be thought that the amount of fish produced in any fish farm presents the “results” brought about by the combined action of natural and artificial factors on the growth of the fishes cultured there. Accordingly, the empirical relationship above shown will also serve as a standard of comparison with which to examine the actual growth of the cultured fish and to clarify the time when or the degree in which the adverse influence of some factors exercising on the growth shows itself. pplied to the growth rate curve of fishes cultured in some fish farms different in shape, structure, rate of water exchange and degree of crowding of fishes, these procedures reached considerable success in diagnosing the environmental conditions existing during the course of culture and in obtaining correlations from which to predict the effect of some factors on the growth (Fig. 4).

Ice problems in channels for water transfer in cold regions seriously affect the capacity and efficiency of water conveyance. Sometimes, ice problems such as ice jams in water transfer channels create risk during winter periods. Recently, water temperature and environmental factors at various cross-sections along the main channel of the middle route of the South-to-North Water Transfer Project in China have been measured. Based on these temperature data, the heat balance state of this water transfer channel has been investigated. A principal component analysis (PCA) method has been used to analyze the complex factors influencing the observed variations of the water temperature, by reducing eigenvector dimension and then extracting the principal component as the input feature. Based on the support vector machine (SVM) theory, a new approach for judging the heat loss or heat gain of flowing water in a channel during winter periods has been developed. The Gaussian radial basis is used as the kernel function in this new approach. Then, parameters have been optimized by means of various methods. Through the supervised machine learning process toward the observed water temperature data, it is found that the air–water temperature difference and thermal conditions are the key factors affecting the heat loss or heat absorption of water body. Results using the proposed method agree well with those of measurements. The changes of water temperature are well predicted using the proposed method together with the state of water heat balance.