Showing papers in "Journal of Fish Biology in 1978"
TL;DR: Rainbow trout consumed food in direct proportion to their body weight although the ration increased with temperature as mentioned in this paper and satiation time varied as 0.031 weight + 0.868 temperature + 29.145 min.
Abstract: Rainbow trout consumed food in direct proportion to their body weight although the ration increased with temperature. Satiation time varied as 0.031 weight+0.868 temperature+29.145 min. Appetite after deprivation returned in close conjunction with gastric emptying, as judged from serial slaughter studies. Trout trained to operate demand feeders ate less but exhibited feeding rhythms even under conditions of constant illumination. Radiography showed that these rhythms closely paralleled gastric emptying. When offered food diluted with kaolin, the fish compensated by eating more food. This was achieved by increasing feeding frequency caused by a more rapid rate of gastric emptying.
304 citations
TL;DR: The hearing of the salmon, Salmo salar L., was studied by means of a cardiac conditioning technique and it is concluded that salmon are unlikely to detect sounds originating in air, but that they are sensitive to substrate borne sounds.
Abstract: The hearing of the salmon, Salmo salar L., was studied by means of a cardiac conditioning technique. Fish were trained to show a slowing of the heart, on hearing a sound, in anticipation of a mild electric shock applied later. The minimum sound level to which the fish would respond was determined for a range of pure tones, both in the sea, and in the laboratory. The fish responded only to low frequency tones (below 380 Hz), and particle motion, rather than sound pressure, proved to be the relevant stimulus. The sensitivity of the fish to sound was not affected by the level of sea noise under natural conditions but hearing is likely to be masked by ambient noise in a turbulent river. Sound measurements made in the River Dee, near Aberdeen, lead to the conclusion that salmon are unlikely to detect sounds originating in air, but that they are sensitive to substrate borne sounds. Compared with the carp and cod the hearing of the salmon is poor, and more like that of the perch and plaice.
193 citations
TL;DR: It was found that the lower ovaries were invariably heavier than the upper ovaries at all times, and a similar relationship was found in testes prior to and during the spawning season.
Abstract: Measurements have been made of the annual cyclical changes in gonosomatic index (GSI), hepatosomatic index (HSI) and condition factor (K) in male and female dab Limanda limanda (L.). There is a direct correlation between HSI and K, and an inverse correlation of these factors to GSI but with a three month lag. It was also found that the lower (‘ventral’) ovaries were invariably heavier than the upper (‘dorsal’) ovaries at all times, and a similar relationship was found in testes prior to and during the spawning season.
183 citations
TL;DR: When food energy is restricted, haddock appear to achieve a balance between somatic growth and reproduction, and egg production and feeding level were correlated positively.
Abstract: Individual haddock, Melanogrammus aeglefinus (L.) were maintained at different feeding levels in an aquarium from November until the completion of spawning. The mean duration of spawning was 33.2 days (range 19–59) during which an average of 16.6 (range 10–25) batches of eggs were produced. The size and dry weight of the eggs declined during the spawning period. Egg production and feeding level were correlated positively. There was some suggestion that when female haddock received low rations ( 13 kcal day -1). The relation between daily growth in wet weight, g, and daily surplus energy intake, kcal, was: G=(0.295E)— 0.328. When food energy is restricted, haddock appear to achieve a balance between somatic growth and reproduction.
180 citations
TL;DR: Exposure to acutely lethal un-ionised ammonia concentrations resulted in a 3.3-fold increase in oxygen consumption and was associated with increases in ventilation volume, respiratory frequency and amplitude, while ‘Cough’ frequency was not significantly affected.
Abstract: Exposure to acutely lethal un-ionised ammonia concentrations resulted in a 3.3-fold increase in oxygen consumption. This was associated with increases in ventilation volume, respiratory frequency and amplitude. ‘Cough’ frequency was not significantly affected. Heart rate and dorsal aortic blood pressure were increased and cardiac output was estimated to have more than doubled. Dorsal aortic blood Po2 decreased but no significant changes in erythrocyte number, haematocrit, haemoglobin concentration, blood pH or P50 were observed. Possible toxic actions of ammonia were discussed and it was speculated that, as in mammals, ammonia may act by impairing cerebral energy metabolism.
157 citations
TL;DR: It is shown that the predominantly nocturnal emigration pattern is evident on occasions in alevin, fry and parr stages also, and the diel periodicity probably represents a seasonal locomotor rhythm which, under changed behavioural and physiological circumstances, results in downstream displacement.
Abstract: Behavioural and physiological mechanisms postulated for the control of downstream migration of Atlantic salmon smolts are reviewed briefly, and some new evidence is presented for their refusal to undergo sustained swimming. Although these mechanisms imply passive displacement as the primary means of emigration, it is likely that active components must also exist as the rates of travel of smolts through loch systems are only slightly slower than those recorded for river systems. The timing of these movements within 24 h periods is reviewed and it is shown that the predominantly nocturnal emigration pattern is evident on occasions in alevin, fry and parr stages also. Thus at migration the diel periodicity probably represents a seasonal locomotor rhythm which, under changed behavioural and physiological circumstances, results in downstream displacement.
147 citations
TL;DR: Rainbow trout trained to operate a demand feeder showed a marked preference for a diet flavoured with a synthetic mixture of chemicals over the unfavoured diet, while the individual components of the mixtures were inactive or repellent.
Abstract: Rainbow trout trained to operate a demand feeder showed a marked preference for a diet flavoured with a synthetic mixture of chemicals over the unfavoured diet. The gustatory feeding stimulant activity resided in the amino acid fraction and was stereospeciflc for the L-forms. Certain mixtures of L-amino acids were stimulatory, while the individual components of the mixtures were inactive or repellent.
129 citations
TL;DR: The annual reproductive cycle in female dab may be divided into four morphologically and histologically distinct periods: prespawning, spawning, postspawning, resting and resting period.
Abstract: Oogenesis in the dab is described in six easily identifiable stages: oogonium (Stage I), primary oocyte (II), primary vitellogenesis (III), secondary vitellogenesis (IV), tertiary vitellogenesis (V) and hyaline oocyte (VI). The annual reproductive cycle in female dab may be divided into four morphologically and histologically distinct periods: prespawning (October–January), spawning (February–April), postspawning (May–June) and resting (July–September) period.
124 citations
TL;DR: There was a correlation between increased enzyme activities and a decrease in plasma hormone levels and a significant increase in the activities of all the enzymes measured except 1-leucyl-β-naphthylamide splitting enzyme.
Abstract: Aroclor 1254 was administered intraperitoneally (25 mg kg body wt−1 in 1 ml of arachis oil) at weekly intervals for 4 weeks to trout and carp; arachis oil was used as the control. Activities of the following hepatic microsomal enzymes, aminopyrine demethylase, p-nitroreductase, UDP-glucuronyl-transferase and 1-leucyl-β-naphthylamide splitting enzyme were measured in both species; cytochrome P450 and microsomal protein contents were also determined.
The changes in the levels of androgens, oestrogens and corticoid hormones were measured in the circulating blood of control and treated groups at weekly intervals. The blood was obtained by cardiac puncture.
Results indicated (a) a significant increase in the activities of all the enzymes measured except 1-leucyl-β-naphthylamide splitting enzyme, (b) cytochrome P450 and microsomal protein contents were increased in trout, but not in carp, (c) a significant reduction in the plasma levels of androgens, oestrogens and corticoids in the treated groups, particularly at the end of the fourth week and (d) there was a correlation between increased enzyme activities and a decrease in plasma hormone levels.
120 citations
TL;DR: Observations indicate that the ovaries are to some extent insulated from fluctuations in resource availability and supports experimental studies which indicate that egg production in the female stickleback can be subsidised by depletion from the carcase and liver when necessary.
Abstract: The annual cycles in female Three-spined sticklebacks from an upland (275 m) and a lowland (25 m) population were compared. The average length and weight of the lowland females were greater, but in both populations growth was checked in winter and again in the breeding season. Both populations also showed a winter decline in condition followed by a sharp increase in spring associated with the maturation of the ovaries. The hepato-somatic index of the females also increased during the spring, but the dry matter content of the liver declined during the spring and early summer. Lowland females had larger livers than the upland fish. In both populations average gonadosomatic index increased steadily throughout the winter, then abruptly in spring. The lowland population bred from May to early August, but the upland population bred only in May.
The energy content of the carcases of females was lowest in winter and again during the breeding season whereas the ash content showed maxima at these two periods. Lipid and glycogen analyses of the carcase, liver and ovaries also suggested that winter and the breeding season were periods of depletion from the carcase and liver, but not from the ovaries.
The observations indicate that the ovaries are to some extent insulated from fluctuations in resource availability. This supports experimental studies which indicate that egg production in the female stickleback can be subsidised by depletion from the carcase and liver when necessary.
119 citations
TL;DR: Tissue water levels were not significantly different between stunts and normal seawater smolts, suggesting that the stunting phenomenon may not be caused primarily by osmoregulatory failure but may be due to shifts in metabolic patterns.
Abstract: Serum protein, glucose and fat levels were determined for Coho salmon parrs, freshwater smolts, seawater smolts, seawater stunts and freshwater desmolts. Liver and muscle glycogen, fat, protein and water concentrations were also calculated. Serum protein, glucose and fat levels were significantly lower in the freshwater smolts than in the parrs. Furthermore, both liver and muscle total fat levels were markedly decreased in the smolts, suggesting that smoltification is associated with increased catabolism. Smolts that failed to reach seawater by late summer reverted to a parr-like appearance and also regained the biochemical characteristics of parrs (high body fat and glycogen). Premature transfer of Coho presmolts into seawater caused impaired growth (stunting). Stunted Coho had higher muscle protein levels than normal smolts and parrs. Tissue water levels were not significantly different between stunts and normal seawater smolts, suggesting that the stunting phenomenon may not be caused primarily by osmoregulatory failure but may be due to shifts in metabolic patterns. In contrast to the pronounced changes seen in Coho salmon, transfer of King salmon to sea water did not result in increased catabolism of body reserves or in the production of stunts.
TL;DR: A reliable method for gynogenetic mass-production has been developed in carp and by means of gynogenesis, the crossover frequency and map distance of the transferrin locus have been determined.
Abstract: A reliable method for gynogenetic mass-production has been developed in carp (Cyprinus carpio L.). The effect of different cold shock treatments applied after fertilization were examined. The yield of viable diploid gynogenetic animals could be significantly increased when the cold shock was applied 5 min or 15 min after fertilization. A negative correlation has been found between the effectiveness of these two treatments, so both were used on separate batches of eggs. By means of gynogenesis, the crossover frequency and map distance of the transferrin locus have been determined. Successful pilot experiments were made on grass carp (Ctenopharyngodon idella Val.) and sheatfish (Silurus glanis L.) with respect to gynogenetic mass production.
TL;DR: Investigations of species in Jamaican waters have covered relative and absolute growth rates, spawning seasons, fecundity, size at maturity and at sex change, and size compositions, mortality rates, and relative abundances of exploited and unexploited populations.
Abstract: Hinds and groupers (Teleostei, Serranidae) form a valuable component of catches of reef fishes in the Caribbean Sea and adjacent regions. Investigations of species in Jamaican waters have covered relative and absolute growth rates, spawning seasons, fecundity, size at maturity and at sex change, and size compositions, mortality rates, and relative abundances of exploited and unexploited populations.
TL;DR: The highly significant correlation between the composition of prey fish species in the lake and prey fishspecies in the diet of piscivorous fishes, indicates that piscvores are feeding in a density dependent manner.
Abstract: The food and feeding ecology of piscivorous fish in Lake St Lucia was monitored for two years. Piscivorous fishes feed predominantly on the planktivorous Gilchristella aestuarius and Thryssa vitrirostris but a wide range of prey species was recorded. Numbers of the predominant piscivores, Argyrosomus hololepidotus and Elops machnata, in an area appear to be related to the densities of their major prey, T. vitrirostris and G. aestuarius. Large piscivorous fishes are restricted to the deeper portions of the lake, whereas small piscivores such as Johnius belengerii and Terapon jarbua feed predominantly on small fishes in the littoral zone. The highly significant correlation between the composition of prey fish species in the lake and prey fish species in the diet of piscivorous fishes, indicates that piscivores are feeding in a density dependent manner. However, factors such as habitat, fish size and swimming speed of prey species are shown to be important in prey selection. Juvenile fish of species such as Sarotherodon mossambicus, Liza macrolepis and Acanthopagrus berda remain in shallow marginal areas, thus avoiding large piscivorous fishes. However by frequenting shallow areas these species become vulnerable to bird predators, especially egrets and herons.
TL;DR: Among hatchery bred Sparus aurata, 5.4% of the offspring of a single parent pair showed severe skeletal deformations coupled with marked growth retardation and pathological changes in the swimbladder, which resulted from extreme proliferation, then hypertrophy, of the cuboidal epithelial cells of the gas gland.
Abstract: Among hatchery bred Sparus aurata, 5.4% of the offspring of a single parent pair showed severe skeletal deformations coupled with marked growth retardation and pathological changes in the swimbladder. This resulted from extreme proliferation, then hypertrophy, of the cuboidal epithelial cells of the gas gland and proliferation of the rete mirabile. This caused almost complete congestion of the swimbladder air space. The nature of the pathological changes in the swimbladder and the possibility of hereditary origin for both the skeletal and swimbladder deformations are discussed.
TL;DR: It was concluded that cystacanths were likely to evert in any species of fish, and it was suggested that the Irish parasites may constitute a different strain of P. laevis, since they use a different species of intermediate host and are better able to survive in brown trout.
Abstract: The status of brown and rainbow trout as hosts ofPomphorhynchus laevis was studied in the field and by means of laboratory investigations. Field data indicated that rainbow trout might belong to the group of preferred hosts of P. laevis, whereas brown trout belonged to the group in which the parasite achieved less than optimal growth and maturation. This was confirmed by laboratory infections. In rainbow trout P. laevis attained up to three times the growth rate in brown trout and maturation occurred whereas in brown trout establishment was lower, growth slower and no parasites matured. Changes in the behaviour of infected Gammarus pulex induced by the presence of P. laevis cystacanths were such as to render the shrimps more vulnerable to predation by trout and other surface and mid-water feeding fish, and selective predation upon infeged G. pulex by fish was demonstrated. nvestigations into the stimuli necessary for eversion of cystacanths of P. laevis revealed that the most important factor was a non-specific component of bile, and it was concluded that cystacanths were likely to evert in any species of fish. Recognition of the different status of brown and rainbow trout as hosts of P. laevis still fails to explain some peculiarities in the distribution of the parasite in the British Isles, where in Britain it occurs in trout in only one river but in Ireland in all rivers throughout the country. It is suggested that the Irish parasites may constitute a different strain of P. laevis, since they use a different species of intermediate host and are better able to survive in brown trout.
TL;DR: Alevins hatching from eggs which had been exposed to Cadmium survived longer in cadmium than alevins not exposed as eggs, suggesting that the pretreatment of eggs with cadmiam serves some protective function.
Abstract: The uptake of cadmium by eggs and alevins of rainbow trout from water concentrations of between 0.01 and 50.0 mg Cd 1−1 was investigated. The cadmium content of eggs and alevins increased with time and with exposure concentration. Lower cadmium levels were detected in alevins than in eggs. Most of the cadmium (98%) in the eggs was found to be associated with the egg membrane or chorion. This explains the considerable reduction in cadmium concentration observed in alevins after hatching. Alevins hatching from eggs which had been exposed to cadmium survived longer in cadmium than alevins not exposed as eggs. This suggests that the pretreatment of eggs with cadmium serves some protective function. Behavioural and pathological signs of cadmium poisoning such as erratic swimming and blood clotting in alevins were observed.
TL;DR: The hypothesis that photoperiod is the major factor in the environmental control of reproductive activity in the rainbow trout is strongly supported.
Abstract: The sequential changes in serum oestradiol 17β (measured by specific radioimmunoassay), vitellogenin (measured by phosphoprotein phosphorus content) and total calcium (measured by fluorimetry) in male and female rainbow trout under a simulated natural photoperiod cycle were investigated. Resting levels of 130 pg/ml serum oestradiol in both male and female fish were found in April and May. In the female, levels reached a peak of 4800 pg/ml in October, and almost returned to resting levels just prior to spawning in mid-January. No significant change from resting levels was seen in the male fish.
In both male and female fish levels of 25 μg/ml serum phosphoprotein phosphorus and 10–14 mg % total serum calcium were found from April to July. Coincident with the rise in oestradiol 17β, in the females serum levels of phospho-protein phosphorus and total calcium increased to 400 uβg/ml and 58 mg% respectively just prior to spawning. In the males no significant change in either of these values was observed throughout the cycle. These results strongly support the hypothesis that photoperiod is the major factor in the environmental control of reproductive activity in the rainbow trout.
TL;DR: It is suggested that natural swimming speeds are close to 1Ls−l and the trout mosaic fibres are better adapted for use at this speed in comparison with coalfish white muscle fibres.
Abstract: Rainbow trout were trained for 3–4 weeks in a flume at swimming speeds of 1, 2 and 3 l s−1. For each experiment growth rates were estimated and by measuring the hypertrophy of red and mosaic skeletal muscle fibres their function was described at particular swimming speeds and compared with earlier experiments on coalfish using the same technique.
Maximum growth, compared with controls in still water, occurred at swimming speeds of 1 l s−1. At this speed the trout mosaic muscle fibres hypertrophied by 40% but the red muscle fibres showed only a 25% hypertrophy. It is suggested that natural swimming speeds are close to 1Ls−l and the trout mosaic fibres are better adapted for use at this speed in comparison with coalfish white muscle fibres.
TL;DR: Tissue reaction to invasion by two Henneguya species was studied in gills of three species of fish, finding evidence that inflammatory responses are of regular occurrence in the final stages of most myxosporidian infections.
Abstract: Tissue reaction to invasion by two Henneguya species was studied in gills of three species of fish. Henneguya psorospermica and Henneguya creplini develop in secondary lamellar arterioles in perch (perca fluviatilis) and ruff (Acerina cernua). In pike (Esox lucius), H. psorospermica develops in the artery. During the growth of the vegetative stage, the gill tissue may undergo local atrophy or hyperplasia of the epithelium and displacement and disfiguration of the lamellae. After the myxosporidian cyst, surrounded by a host tissue capsule has reached maturity and contains fully-formed spores, an inflammatory reaction may set in which reduces the cyst to granulomatous tissue. This inflammatory process is essentially of the same type as that observed in mammals. There is evidence that inflammatory responses are of regular occurrence in the final stages of most myxosporidian infections. Transfer from low to room temperature provokes a rapid elimination of the cysts by granulomatous inflammation.
TL;DR: Hormone levels showed a seasonal variation, maximal levels of both hormones occurring in winter and minimal concentrations in mid summer, and the presence of a diurnal rhythm in serum T4 levels of trout sampled in September and in April.
Abstract: The concentrations of thyroxine (T4) and triiodothyronine (T3) in the blood plasma of rainbow trout (Salmo gairdneri Richardson) at intervals throughout the year have been measured by a chemically specific gas-liquid chromatographic (GLC) method Mean hormone levels showed a seasonal variation, maximal levels of both hormones occurring in winter and minimal concentrations in mid summer An apparent secondary maximum in mean T4 and T3 concentrations was observed in spring (T4)/(T3) ratios have been found to be highest in winter and lowest in summer A radioimmunoassay procedure, validated by GLC analyses, revealed the presence of a diurnal rhythm in serum T4 levels of trout sampled in September and in April
TL;DR: Seasonal, diel and tidal rhythmic activity of hatchery-reared Atlantic salmon (Salmo salar) smolts migrating through a large estuary was studied by ultrasonic tracking of 46 individuals during two seasons.
Abstract: Seasonal, diel and tidal rhythmic activity of hatchery-reared Atlantic salmon (Salmo salar) smolts migrating through a large estuary was studied by ultrasonic tracking of 46 individuals during two seasons. Prior to 10 May each year most smolts were inactive and remained near shore in shallow water. After 10 May nearly all smolts moved away from the release point into swift water and made rapid seaward progress. Initiation of migration each year occurred when river and hatchery water temperatures rose above 9°C. Migration in the estuary was largely passive drift, and as a result there were distinct tidal rhythms of ground (‘swimming’) speed and net seaward travel. There were no diel rhythms in ground speed or net seaward travel; smolts drifted seaward on the tides during both day and night. Smolts may be slightly deeper during day than night.
TL;DR: Ultrasonic telemetry was used to follow the movements of two groups of smolts in the estuaries of two small Scottish rivers, finding that wild Smolts released into a typical wedge flow, partially mixed estuary had movements which were dominated by the influence of tide on the direction of water flow.
Abstract: Ultrasonic telemetry was used to follow the movements of two groups of smolts in the estuaries of two small Scottish rivers. Hatchery reared smolts released into a typical wedge flow, partially mixed estuary had movements which were dominated by the influence of tide on the direction of water flow. The net movements of wild native smolts in a two layer flow estuary, in which freshwater flow dominated, was downstream but were intermittent consisting of short steps and numerous long pauses. The hatchery reared smolts escaped from the estuary within a tidal cycle, moving out on an ebb tide. The wild smolts remained in the estuary for periods up to 108 h, none escaping within one tidal cycle.
TL;DR: Grey mullet appear to have a different digestive strategy to tilapia and may rely upon the establishment of a ‘colloid mill’ in the stomach.
Abstract: Tilapia guineensis, which feeds on leafy material, and Sarotherodon melanothron, which utilizes blue-green algae, were both capable of producing a pH 2 or less in the stomach which could contribute to the lysis and digestion of blue-green algae and bacteria. Of the grey mullets investigated, Liza falcipinnis had a gastric pH 3.3–4.5, which may not be low enough to cause cell lysis, whilst Liza dumerili, Mugil cephalus and Mugil curema all had stomach, caecal and intestinal pH's of 7–8.5. Grey mullet appear to have a different digestive strategy to tilapia and may rely upon the establishment of a ‘colloid mill’ in the stomach.
TL;DR: There is evidence that none of these ecto-parasitic species can develop within the range of 7-20‰ salinity, and high temperature increases the effects of adverse salinities on parasites.
Abstract: In brackish water the variety of marine and freshwater parasite species is considerably reduced. The distribution in brackish water of most marine endoparasites is restricted by the salinity tolerance of their hosts, most of the parasite species are more tolerant than their hosts. The influence of salinity and temperature on nine species has been examined; first stage larvae of Contracaecum aduncum develop in 0-32‰ salinity; Cryptocotyle lingua proved to be infective at salinities down to 4‰. The greatest resistance was found in Anisakis larvae from herring Clupea harengus, which survived for more than half a year. Parasites in the fish intestines appear to be unaffected by changing water salinities, as the osmolarity in the intestines stays nearly constant. Marine ectoparasites (Acanthochondria depressa, Lepeophtheirus pectoralis) survive about three times longer than freshwater species (Piscicola geometra, Argulus foliaceus) when salinity is 16‰. High temperature increases the effects of adverse salinities on parasites. There is evidence that none of these ecto-parasitic species can develop within the range of 7-20‰ salinity.
TL;DR: The parasites of brown trout have been, and still are, capable of rapid and widespread dissemination throughout mainland Britain, and their occurrence in any lake is a result of the combination of a number of local factors.
Abstract: The composition of the parasite fauna of brown trout Salmo trutta in nine British lakes from varying geographical locations has been analysed with regard to several selected physico-chemical parameters of the lakes. Significant correlations existed between the size of the lake and the number of parasite species harboured by trout and between the altitude of the lake and the number of parasite species present. No significant relationships were found between the number of parasite species and the geographical position, age, degree of isolation or CaCO, levels of the lakes. Similarly no relationships existed between the proportions of the parasites with different life cycles and the parameters examined, or between the presence or absence of a particular species of parasite and the lake's limno-logical features. It is concluded that the parasites of brown trout have been, and still are, capable of rapid and widespread dissemination throughout mainland Britain, and their occurrence in any lake is a result of the combination of a number of local factors. The predictive value of the conclusions is tested and discussed with special reference to the parasite fauna of trout in reservoirs.
TL;DR: Variation between families in smolting rate and mortality rate is influenced by both parents, but more by the male than the female, and variation in mean length is influenced almost entirely by the female parent.
Abstract: The proportion of potential 1-year smolts, their mean length, the mean length of potential 2-year smolts, and the mortality rate in four half-sib families of Atlantic salmon, reared under four contrasted conditions of overhead cover, is shown to be inffuenced primarily by genetic factors (89.9%, 86.1 %, 82.7% and 80.2% of total variance respectively). Variation between families in smolting rate and mortality rate is influenced by both parents, but more by the male than the female. Variation in mean length is influenced almost entirely by the female parent. These results are discussed in relation to previous findings on bimodality of size distribution and inheritance of growth and mortality characteristics in Atlantic salmon.
TL;DR: A reappraisal of oxygen uptake by Sarotherodon mossambicus was undertaken using a continuous flow respirometer and the routine metabolic energy expenditure was described by the equation E=0.0086 t2 0783M0 652.
Abstract: A reappraisal of oxygen uptake by Sarotherodon mossambicus was undertaken using a continuous flow respirometer. Measurements were obtained over the temperature range 16°C–37°C for fish weighing between 10 g and 150 g. Oxygen uptake was converted to energy equivalents (Qox) using the value 13.68 J mg O2–1and the routine metabolic energy expenditure can be described by the equation E=0.0086 t2 0783M0 652 where E is the energy requirement for routine metabolism expressed in J h-1, t the temperature in °C and M the mass in g.
TL;DR: The biology of a Scottish population of the burrowing goby Lesueurigobius friesii was studied and marked differences in year-class strength were found, although the amount of food in the stomachs was lowest in the early hours of the morning.
Abstract: The biology of a Scottish population of the burrowing goby Lesueurigobius friesii was studied from February 1975 until October 1976. The fish lives at depths of 10–130 m on muddy grounds and attains a length of at least 94 mm and an age of 11 years, females generally living longer than males. Most growth takes place in the first three years of life after which it proceeds very slowly. Marked differences in year-class strength were found. Both sexes mature in their third year and the breeding season lasts from late May until August. Each female can spawn at least twice during this period and the eggs are laid on the roof and sides of the U-shaped burrows which the fish dig in the mud. Fecundity is length dependent and varies between approximately 3–11 000. The fish feeds predominantly on polychaetes, although small Crustacea and molluscs also feature commonly in its diet. No marked diurnal variation in the feeding pattern was noticed, although the amount of food in the stomachs was lowest in the early hours of the morning.