Laboratory studies on food intake, growth and food conversion of young herring, Clupea harengus (L.)

Food intake, growth and food conversion of young, O-group herring were studied at two temperatures and feeding regimes over a period of 19 weeks. The food intake of fish fed to satiation twice daily showed considerable variation. Food intake per fish at 14.5° C was about three times that at 6.5° C, and was generally much higher than in most other species of fish studied. The mean increase in wet weight over the 19-week period was 0.581 g/week at 14.5° C and 0.236 g/week at 6.5° C in fish fed to satiation and 0.094 g/week at 6.2° C and a ration of 1.3% of the body weight. Growth depensation was found to occur even in fish fed to satiation. The changes in specific growth rate, that is the percentage increase in weight/day, showed similar trends at different temperatures and food regimes. The mean conversion efficiency of fish on a ration of 1.3% at 6.2° C was higher than that of fish fed until satiation, at 14.5 and 6.5° C. The conversion efficiency of fish fed to satiation at 14.5° C showed a distinct decrease with increasing weight while at 6.5° C such a clear trend was not observed. In general, the conversion efficiency of young herring were found to be much lower than that of most other species studied. The weight exponent of the quantitative relationship between food intake and body weight at 14.5° C was 0.744. The total metabolic expenditure at 14.5° C, calculated using Winberg's (1956) 'utilization coefficient, gave a weight exponent of 0.773.     

Maximum daily ration of juvenile fish fed on living natural zooplankton

Juveniles of five species of cyprinids of body length 15–90 mm as well as juvenile perch, Perca fluviatilis L., were fed on living natural zooplankton over periods of 2 or 3 days. For all species the correlation of the daily ration (% body weight) with body weight showed a maximum curve. The maximum was reached at a body weight (wet weight) of 0.6 g for Leuciscus leuciscus (L.) and 0.1 g for a group consisting of varying numbers of Rutilus rutilus (L.), Abramis brama (L.) and Alburnus alburnus (L.). For L. leuciscus , the maximum was 220% body weight (wet weight), corresponding to 40% on a dry weight basis. For the mixed species group the maximum was about 500% (wet weight) and about 140% on a dry weight basis. The highest daily ration coincided with the occurrence of the spring bloom of zooplankton.     

Do random fluctuations in daily ration affect the growth rate of juvenile three-spined sticklebacks?

The effect of random fluctuations in daily ration on the growth performance of individual juvenile three-spined sticklebacks Gasterosteus aculeatus was studied in experiments lasting 21 days at 14°C and a photoperiod of 10L:14D. Two mean ration levels were used: a maintenance ration of 2%, and a high ration of 6% of initial body weight per day. For experimental fish, the daily ration varied randomly about the required mean value with a coefficient of variation of 33%. The controls received a constant daily ration. The experiment was replicated in winter (Dec.-Jan.) and spring (Mar.-Apr.). At a given ration, there was no significant difference between the specific growth rates of fish receiving constant or varying ration. Neither the final dry weight, final body water content nor final lipid content (% dry weight) differed significantly. As expected, ration had a significant effect on growth rate, final dry weight and body lipid and water content. There was a significant difference in mean growth rate between the winter and spring replicates. The growth rates observed in these experiments were compared with those predicted from a previously described empirical growth model developed for sticklebacks fed constant rations. The model underestimated mean growth rates.     

Aspects of energetics of adult walleye pollock, Theragra chalcogramma (Pallas), from Alaska

Body energy partitioning was examined for field-caught, adult walleye pollock; additional laboratory studies were conducted on fish held under controlled temperature conditions at Seward, Alaska.
Average consumption for pollock feeding daily was 0.5% of body weight (3100 cal) at 5°C, resulting in an average growth of 0.12% body weight day⁻¹. These results suggest that large pollock grow at similar rates and have similar food conversion efficiencies to those of Atlantic cod held at similar temperatures.
Resting metabolic rates measured on adult fish were combined with similar data from juveniles to calculate a regression of specific metabolic rate against wet weight: y = 173x⁻⁰²⁶. Maintenance rations amounted to 4.8 cal g⁻¹ day⁻¹ at 5°C, very close to the 0.28% value for juveniles. Estimation of metabolic rate using maintenance ration data resulted in values that were 55% higher than those obtained from oxygen consumption data for unfed fish. Weight loss during starvation was 0.18% of body weight day⁻¹ at 5°C, corresponding roughly to a starvation metabolic rate 50% lower than the resting metabolic rate we report.
We estimate that an adult pollock will lose about 37% of its prespawning body weight and about 46% of its body energy during spawning. These losses result, primarily, from changes in the weight of gonad, liver and somatic tissues as opposed to changes in specific energy content of those tissues.     

小鳞鱼箴的维持日粮与转换效率

1998年 8月在一个养虾场蓄水池利用网箱进行了小鳞鱼箴维持日粮与转换效率的研究 .小鳞鱼箴生长率(GR)与日粮 (DR)的关系可表示为GR =14 0 .37DR -2 4.0 3 ;食物转换效率和能量转换效率分别为 13 .96 %和16 .12 % .从生长率和特定生长率计算的小鳞鱼箴维持日粮分别为体重的 17.12 %和 2 0 .39% ,表明从生长率和特定生长率计算维持日粮可能会导致不同的结果 .当日粮水平低于 3 .30 %时 ,小鳞鱼箴生长表现异常 ,意味着它可能利用了网采浮游动物以外的其它食物源 .     

小鳞Jian的维持日粮与转换效率

1998年8月在一个养虾场蓄水池利用网箱进行了小鳞Jian维持日粮与转换效率的研究,小鳞jian生长率（GR）与日粮（DR）的关系可表示为GR＝140．37DR－24．03;食物转换效率和能量转换效率分别为13．96％和16．12％,从生长率和特定生长率计算的小鳞Jian维持日粮分别为体重的17．12％,和20．39％,表明从生长率和特定生长率计算维持日粮可能会导致不同的结果,当日粮水平低于3．30％时,小鳞Jian生长表现异常,意味着它可能利用了网采浮游动物以外的其它食物源。     

Bioenergetics of growth of a cyprinid, Phoxinus phoxinus (L.): the effect of ration and temperature on growth rate and efficiency

Growth of minnows, Phoxinus phoxinus , weighing 1-5.5 g was studied experimentally at five ration levels from starvation to ad libitum and four temperatures ranging from 5 to 15°C. The relationship between specific growth rate (SGR) and ration was a decelerating curve. SGR at maximum rations increased with increased temperature, but at restricted rations it decreased with increased temperature. Predictive models for the specific growth rates were developed using multiple regression. Maintenance rations and optimum rations both increased with increased temperature. Maintenance rations were less sensitive to temperature than optimum rations and mostly lay between 1 and 2% of body weight per day. Conversion efficiencies increased with increased ration from zero value at the maintenance ration to a peak at the optimum ration, then decreased with further increases in ration. At a given restricted ration level, conversion efficiencies generally decreased with increased temperature. At maximum rations, conversion efficiencies were relatively insensitive to temperature. Growth in wet weight, dry weight and energy content showed similar responses to ration, temperature and body weight.     

Recovery growth following periods of restricted rations and starvation in rainbow trout Salmo gairdneri Richardson

Fingerling rainbow trout (6.9 to 11.6 cm fork length) maintained at 12° C were either: fed restricted rations (3% of dry body weight/day) for 16 weeks, or starved for 3 weeks (14.5% weight loss), or for 13 weeks (32.5% weight loss). Whole body wet weights and dry weights (as % of wet weight), and wet and dry weights of tissues (heart, spleen, liver, skin, gonad, gut, visceral fat, and 'carcase') resulting from these treatments were compared to corresponding weights of an 'initial sample'. Visceral fat was completely utilized during both short and long-term starvation and gut was significantly reduced in the extended starvation group.
During subsequent recovery growth on full rations, following food deprivation, fish grew at approximately the same rate as fully-fed controls, which had not suffered food deprivation, as regards body wet weight and condition ( K ), but tended to surpass controls in % dry weight.
Heart, liver, gonad, gut and visceral fat also increased during recovery growth in a manner suggestive of overcompensation in response to former food deprivation. Gut, skin and carcase dry weights were less in the control, and in the 14.5% weight loss groups following recovery growth than in those in 3% rations and in the severely starved group, indicating that the effects of slow growth resulting from limited rations resemble those of severe starvation more than those of limited starvation.     

Effect of salinity and temperature on the growth of yearling Arctic cisco (Coregonus autumnalis) of the Alaskan Beaufort Sea

The growth of 1-year-old Arctic cisco ( Coregonus autumnalis ) was monitored under laboratory conditions for fish acclimated to one of two temperatures (5 and 10° C) and one of five salinities (6, 12, 18,24, 30‰). Fish were maintained for 43 days at rations of 3% wet body weight per day at 5° C and 5% wet body weight per day at 10° C, with rations adjusted for weight gain every 7–12 days. Fish increased 9–11% in length and 55–71% in weight at 5° C, and 23–27% in length and 141–161% in weight at 10° C. Length and weight increased linearly over 43 days. There was a statistically significant effect of temperature on growth but no statistically significant effect of salinity. Higher growth rates at 10° C were partially attributable to significantly greater gross conversion efficiency at the higher temperature. Over the course of the experiment, the condition (weight per unit length) of all fish increased by 3·2 to 63·6% at 5° C and by 5·6 to 46·0% at 10° C. There was no discernible effect of salinity on condition at either temperature. These results demonstrate that, with salinity acclimation and high food ration, 1-year-old Arctic cisco can grow at equivalent rates across salinities ranging from 6 to 30‰. The ecological implications of the results are discussed.     

Protein, lipid and caloric contents of bluntnose minnow, Pimephales notatus Rafinesque, during growth at different temperatures

Changes in the relative proportions of protein, lipid, water and caloric contents of bluntnose minnow growing at various temperatures (15, 25, 30° C) were investigated by application of the allometry equation, y=ax^b . Fish grew significantly faster at 25° C (closest to optimum), more slowly at 30° C and most slowly at 15° C. Protein, as a percentage of body wet weight, tended to increase with fish size at all temperatures ( b > 1.000), whereas in juveniles (<0.7 g) it decreased ( b < 1.000). However, with the exception of the 15° C group, protein as a percentage of body dry weight, decreased in all groups ( b < 1.000). Temperature appeared to modify the body composition of bluntnose minnows, e.g. decreasing temperature led to significantly enhanced protein content during growth. Lipid (%) and caloric content (cal g⁻¹) increased with increasing fish weight ( b > 1). The slower growing fish (15°, 30° C) deposited significantly more lipid (and had higher caloric contents) than those growing most rapidly (at 25° C). Water content (%) decreased with increasing body weight in all groups. Despite intergroup growth rate differences, all groups showed evidence of a tendency to follow similar trends in b values for body constituents and caloric content (except for protein v. body dry weight for the 15° C group). This suggests a general conservativeness of body composition in bluntnose minnow. The correlations between body constituents, caloric content and body weight were high ( r ²>0.9) so that estimates of body composition can be obtained from body weight for all temperature groups.     

Growth, daily ration, and gastric evacuation rates of milkfish (Chanos chanos) fed supplemental diet and natural food

Growth, daily ration, and gastric evacuation rates of milkfish ( Chanos chanos ) that fed on natural food and supplement diet were evaluated. Milkfish fingerlings (5.5g) were stocked at 1.5 fish/m² in ten 12 m² concrete tanks layered with 15-cm thick earthen bottoms. All tanks were regularly fertilized (16–20–0 and chicken manure) to maintain natural food production; 4 of the tanks additionally received a supplemental diet containing 34.3% protein and 4290 kcal/kg gross energy. Estimates or daily ration (based on dry weight of stomach contents) were calculated using the E lliot and P erson (1978) and E ggers 1977) models. Gastric evacuation rate was lower in fish that fed on natural food (1.57) compared to fish fed a supplemental diet (1.79). Consequently, the lower rate resulted in lower food intake and slower fish growth. When fish were provided a high quality supplemental diet, daily rations for fingerlings (35 g) to marketable size (116 g) ranged approximately from 0.60 to 19.68 kcal/fish/day. The deviation in daily ration (kcal/fish/day) from the above estimates may indicate the insufficient quantity of dietary energy taken by fish from natural food alone, which could be provided by supplemental diet.     

Laboratory growth of larval lampreys (Lampetra (Entosphenus) tridentata Richardson) at different food concentrations and animal densities

Lampreys are important research animals. This study investigates some of the Parameters important for culturing the Suspension feeding larvae: food concentration, temperature and crowding. Large larvae ( Lampetra ( Entosphenus ) tridentata Richardson) were used, weigh-ing from l·5 to 3·0 g (wet). Two food types were employed: suspended yeast cells ( Saccharo-myces cerevisiae , 0–20 mg1 – (dry), or, in a few tests, a fine particulate fish food, Liquifry® (Interpet LTD, 0–13 mg l^-1). At both 14 and 4°C, yeast could sustain weight increases comparable to those in nature: >6% month^-1 for up to 6 months, the duration of the study. In a single lest, a vitamin Supplement failed to improve growth on yeast. Growth-was fastest at 14°C (+41% month^-1, max. weight increase), although also substantial at 4°C (+11% month^-1, max). Growth could not be sustained at 20°C, due perhaps to difficulty in removing products of food decay from the aquaria. Food level being constant, growth rate varied inversely with animal density. It is suggested that larval lampreys release a growth-inhibiting substance into the sand which they inhabit. Overall, the best growth was obtained at 14° C, with <0·05g of animal (wet weight) – aquarium water and average daily yeast concentrations between 4 and 13 mg –. Liquifry was associated with lowered growth rates when present continually above 4 mg (dry weight) – (14° C), although growth did occur at lower concentrations.     

Effects of Body Size and Food Ration on Over-winter Survival and Growth of Age-0 Atlantic cod, Gadus morhua

This study examined the effects of body size and food ration on over-winter survival of age-0 Atlantic cod. Cod were divided into two groups based on standard length (large=76.95±1.10 mm SL; small=57.65±1.02 mm SL; mean±1 SE) and wet weight (large=4.02± 0.21 g; small=1.52±0.09 g). Replicate tanks (n=2) of 10 large and 10 small cod were exposed to one of two food rations (0.25% and 1.0% body weight day^-1) for the entire experiment (December to June). Tanks were examined daily for mortalities and feeding was adjusted accordingly. The experiment was run under ambient light and seawater conditions. All but large age-0 cod exposed to the low food ration grew over the course of the experiment. The specific growth rate (SGR) of small cod was significantly higher (0.2425% wet weight day^-1) than that of the large fish (0.0443% wet weight day^-1). Food ration had no significant influence on SGR or over-winter survival. Significantly more of the large age-0 cod survived the winter (58.5% of those originally introduced) compared to the smaller fish (14%). Our results are consistent with those from studies of several other fish species, and are discussed in relation to the ecology of age-0 cod, and their potential use in aquaculture in Newfoundland.     

Influence of body size and food ration on the energy budget of rainbow trout Salmo gairdneri Richardson

Three size classes (3 g, 200 g, 1–3 kg) of rainbow trout, Salmo gairdneri Richardson, were each fed five rations ranging from zero to a 'maximum' ration and the relationships among body size, food ration, metabolism and growth examined. Water temperature was constant at 11–4°C. The gross growth efficiency in wet weight, K , increased asymptotically with increasing ration but decreased with increasing body size. Changes in fat and moisture content of the body, however, were such that Kin terms of energy utilization was independent of body size when the fish were feeding at the same level. This result was not apparent when wet weight values only were considered and use of a constant to convert wet weight offish to calorific values can lead to errors in interpretation of results. Assimilation efficiency averaged 71 -7 % over all feeding groups and was independent of body size and food ration. Total metabolic expenditure, however, increased with increasing body size and feeding level, but at any given feeding level a similar proportion of the energy of the assimilated ration was used for metabolism. At a single feeding level, therefore, the percentage utilization of energy in each category of the energy budget remained similar over all body sizes. Such a result can only be expected under laboratory conditions but it provides a base-line for comparison with the performance of other more complicated systems.     

Energy and ration requirements of juvenile Pacific halibut (Hippoglossus stenolepis) based on energy consumption and growth rates

Growth of captive juvenile Pacific halibut was linearly related to energy consumption (J g⁻¹ day⁻¹) at 4°C by the following equation: growth (% body weight (b.w.) day⁻¹)=0–007 (consumption J g⁻¹ day⁻¹)– 0.192; r² =0.81. Weight gain was independent of size for fish between 9 and 7000 g when growth was expressed as a function of consumption in J g⁻¹ day⁻¹. Maintenance ration determined in feeding–growth experiments averaged 27.4 J g⁻¹ day⁻¹ at 4–0°C. Small halibut ate significantly more food than large fish. Single meals following 2 day fasts averaged 4.1% b.w. for halibut under 100 g, 1.72% b.w. for 1.2 kg fish and 1.1% B.W. for 6.8 kg fish. Both large and small size categories of halibut tended to evacuate their meal in about 3 days even though small fish ate relatively larger meals. Minimum estimates for daily ration to achieve growth rates observed in the Gulf of Alaska were approximately 0.5 to 2.4% b.w. day⁻¹ depending on fish size and whether northern shrimp or yellowfin sole were their prey.     

Feeding dynamics of sturgeon fingerlings (Acipenseridae) depending on food concentration and stocking density

Sturgeon fingerlings of 20.0 g at a water temperature of 18.20° C, fed for 130 min and consumed 6.5% of their body weight when the food concentration was 2 g m⁻². At 38 g m⁻² the fingerlings stopped feeding after 45 min but consumed 9.0% of their body weight. As satiation approached the intervals between successive food intakes increased and feeding rate decreased. The rate of feeding was inversely proportional to the amount of food already consumed, and an equation describing this relationship is given. During the first minutes of feeding the ration size was directly proportional to food concentration but with further feeding the relationship changed. The equations of Ivlev and Rashevsky were close approximations to the relationship between ration size and food concentration. At a density of 12 individuals/m² the feeding duration and ration size was low in comparison to single fingerlings and to fish fed at higher densitites.     

Effects of ration, temperature and body size on the body composition, energy content and condition of the minnow, Phoxinus phoxinus (L.)

The effects of ration and temperature on the body composition, energy content and indices of condition of the minnow. Phoxinus phoxinus (L.) (Cyprinidae). were studied experimentally. Five ration levels over the range starvation to ad libitum and five temperatures over the range 5–15°C were used. The fish weighed 1-5-4 g. At each temperature, the relative dry matter content, lipid content and energy content increased with increased ration. The response of the protein content to ration was temperature-dependent. Temperature had a significant effect on body composition and energy content, but this effect was irregular. The Fulton condition factor was less sensitive to ration than the wet or dry liver-somatic index. Temperature had a significant effect on the condition factor and liver indices. Significant, positive correlations were found between growth rate, lipid content and the indices of condition. The liver indices were better predictors of growth rate than the condition factor or lipid content and may provide useful information on the physiological condition offish in field studies.     

Correlation between digestion rate and feeding frequency in the stomachless teleost, Blennius pholis L.

Foregut emptying in Blennius pholis at 16–18°C is exponential ( S_t = S_o e^-Rt; R=0.006 when t is in min and s in mg dry weight). In consequence, the time for the foregut to empty completely varies in proportion to ln (meal size) in a chosen size of fish or to ln (body weight) in different sized fish fed to the same relative amount (% body weight). Appetite returns rapidly in comparison with other species (4–15 h for fish of 0.5−30 g) and, because of the tidal constraints imposed on this littoral fish, voluntarily ingested meals are large (14–9% body weight depending on fish size). Studies on digestion in small, stomachless fish are not adequately made using X-radiography and must be supported by sequential gut samples after a meal.     

食物水平和初始体重对杂交罗非鱼生长和个体生长分化的影响

将72尾杂交罗非鱼分别养在12个水槽内,每个水槽内养6尾大小不同的鱼(A、B、C、D、E、F),其中鱼A的初始体重为62．69±1．46g,B为56．48±1．30g,C为50．75±1．19g,D为35．56±1．18g,E为31．05±0．88g,F为27。35±0．95g(平均值±标准误)．在4周实验中,实验鱼分别被停食或每天按体重1．5％、3．0％和饱食水平投喂．鱼的特定生长率(SGR)和食物效率(FE)先随食物水平增加而增加,当食物水平超过鱼体重的3．0％后,继续增加投喂量,SGR不再升高而FE明显下降．按体重1．5％投喂的鱼SGR和终体重个体间变异较大．对鱼A而言,食物水平超过体重1．5％后对其SGR无显著影响,但对鱼F而言,食物水平对SGR影响较大．结果表明,杂交罗非鱼的生长和个体生长分化与食物条件和初始体重有关,当食物水平超过体重的3．0％后,鱼的SGR较高,个体生长分化相对较轻．     

Nahrungsaufnahme,Stoffumsatz und Energiehaushalt des marinen HydroidpolypenClava multicornis

Clava multicornis Forskål (Cnidaria, Hydrozoa) from the North Sea was cultured under a variety of environmental conditions, and quantitative aspects of the following processes examined: food intake, growth, oxygen consumption, losses of material, and food conversion. The experiments were conducted in sea water (salinity 32 ‰) at different constant temperature levels (6°, 11° and 16° C) and different daily food rations. The polyps were fed living larvae of the brine shrimpArtemia salina. Daily rations ranged from 2.3 % (6° C) to 19.0 % (16° C) of the dry weight of the polyp colonies. The food ration essential for minimum growth increased with the test temperature. The calorific value of theArtemia larvae was 5854 cal per g organic dry substance. The calorific values of the colonies ofClava multicornis increased at all 3 test temperatures with ascending daily food rations; they ranged from 5367 to 6003 cal per g organic dry substance. Colony growth was determined in 3 different ways: by measuring the increase in polyp number, the length increase of all polyps of a given colony, and the increase of the dry weight of the organic substance of a given colony. Growth was exponential in all 3 cases. The lowest test temperature, or small daily rations, caused slow growth; the highest temperature, or large daily rations, resulted in rapid growth. Oxygen consumption of individual colonies was measured at 16° C and 3 different daily rations; the colonies showed the same intensity of respiration at all 3 daily rations. A colony of 1.5 mg organic dry substance respired 0.107 ml oxygen per 24 hours, a colony of 5.0 mg, 0.269 ml oxygen. At 11° and 16° C gonophores developed well and were counted; at 6° C no gonophores were observed. The amount of the excrement discharged byC. multicornis at 16° C increased from 26.0 % of the food eaten (minimum daily ration) to 39.3% (maximum daily ration). Gross efficiency increased with falling temperature and rising daily ration. At 16° C, net efficiency increased with rising daily ration. On the basis of the data obtained for gross efficiency, oxygen consumption and excrementation, an energy budget was made up.