Showing papers in "Journal of Fish Biology in 1979"
TL;DR: It is concluded that juvenile salmon feed predominantly on drifting material and that their daytime distribution reflects the current velocity related abundance of drift.
Abstract: The distribution, social behaviour, and feeding behaviour of juvenile Atlantic salmon were studied in a selection of stream and river habitats in northern Scotland using Scuba diving techniques. The results are discussed with respect to food acquisition and choice of feeding site. It is concluded that juvenile salmon feed predominantly on drifting material and that their daytime distribution reflects the current velocity related abundance of drift.
205 citations
TL;DR: The effect of particle size of a commercial pelleted feed on the growth of Atlantic salmon from first feeding alevins to first and second year smolts was investigated using 20-day feeding experiments and growth rate was found to be closely related to feed size.
Abstract: The effect of particle size of a commercial pelleted feed on the growth of Atlantic salmon from first feeding alevins to first and second year smolts was investigated using 20-day feeding experiments. Ten experiments were performed over a two year period, each comprising six groups of fish separately selected from stock populations. Each group was presented with one of six sizes of food particle ranging from larger than the respective mean mouth breadth (100% feed size), through 50%, 25%, 12·5%, 6·25% to 3·125%. Experiments were performed in six radial flow/circumferential drain tanks under ambient photoperiod and water temperature. Growth rate was found to be closely related to feed size. Maximum growth in each case was shown only on one size of particle; larger and smaller sizes resulted in reduced growth. The particle size for maximum growth increased in direct proportion to fish length. Fish from 4·2 to 20·3 cm in length showed maximum growth on particle diameters 0·022 to 0·026 × fish fork length (PFR). First feeding alevins were found to show comparable growth rate on particle diameters 0·0115 to 0·090 PFR. Some seasonal variation in growth response was indicated. The results are discussed in relation to developmental and seasonal effects. Possible factors affecting the energetics of prey size related differential growth are discussed.
167 citations
TL;DR: The distinctive morphological features of the different stages of development of the gonads are characterized in Tilapia nilotica and there is evidence that females breed more than once a season.
Abstract: Tilapia nilotica reaches maturity in the first year of life; females mature shortly before males (11·4 and 14·3 cm in length). The distinctive morphological features of the different stages of development of the gonads are characterized. The sex ratio varied in populations of different age (size)-groups: a ratio of 2·81:1 and 0·47:1 (females:males) was obtained in populations of young and old fish. In medium-sized populations the sexes were equally abundant. There is evidence that females breed more than once a season. Fecundity varied more with body length (r=0·860) and weight (r=0·806) than with age (r=0·604). These variations were of the order of 2·02; 0·83 and 0·83 exponentials of length, weight and age, respectively.
134 citations
TL;DR: Interspecies haematological differences to MS 222 and neutralized MS 222 anaesthesia were investigated in Sarotherodon mossambicus, Cyprinus carpio and Salmo gairdneri acclimated under identical laboratory conditions.
Abstract: Interspecies haematological differences to MS 222 and neutralized MS 222 anaesthesia were investigated in Sarotherodon mossambicus, Cyprinus carpio and Salmo gairdneri acclimated under identical laboratory conditions. Anaesthesia with MS 222 resulted in a ‘chemical stress’ in all fish, as was evident from changes in the haematological profiles of the animals. Such species specific variations in the haematology persisted throughout the whole experiment protocol which employed different concentrations of the anaesthetic. The use of neutralized MS 222, whereby aquarium water quality remained unchanged, improved the haematological profile. Possible reasons for the interspecies differences observed are discussed.
122 citations
TL;DR: Experimental meals diluted with kaolin were evacuated in significantly less time than a control diet, suggesting that turbot may adjust feeding rates when food quality varies, and in agreement with a recently proposed model relating G.E.T. and G.R. to meal size.
Abstract: The gastric emptying time (G.E.T.) in turbot was investigated using X-radiography and was found to decrease with temperature. Small fish processed a given ration, expressed as percent body weight, faster than large fish (G.E.T. was found to be proportional to (fish weight)0.364). Large meals in a given fish were processed at a faster rate than small meals. Gastric emptying rate (G.E.R.) was found to be proportional to (meal size g)0.613 at 8° C and (meal size g)0.788 at 19° C. These exponents are in agreement with a recently proposed model relating G.E.T. and G.E.R. to meal size (Fange & Grove, 1978). Large fish emptied a meal of given absolute size from the stomach at a faster rate (g h−1) than small fish. Experimental meals diluted with kaolin were evacuated in significantly less time than a control diet, suggesting that turbot may adjust feeding rates when food quality varies.
106 citations
TL;DR: The biology of filter feeding teleosts in St Lucia, was studied for two years from 1976 to 1978 and there was a close correlation between the zooplankton cycles, both diel and annual, and the feeding, reproduction and recruitment of the three common filter feeders.
Abstract: The biology of filter feeding teleosts in St Lucia, was studied for two years from 1976 to 1978. The three common species, Gilchristella aestuarius, Hilsa kelee and Thryssa vitrirostris were studied with the composition and cyclical nature of the zooplankton which formed their food. Stolephorus commersonii and Hepsetia breviceps which were rare were only briefly examined. The zooplankton was dominated by the calanoid Pseudodiaptomus stuhlmanni which formed > 70 % of the calorific value of the zooplankton for 70 % of the study period. The mysid Mesopodopsis africana was second in importance in terms of calorific contribution while the amphipod Grandidierella lignorum was relatively abundant. Larval forms, particularly post-veligers of Assiminea bifasciata were also important. There was a close correlation between the zooplankton cycles, both diel and annual, and the feeding, reproduction and recruitment of the three common filter feeding teleosts. G. aestuarius spent its whole life-cycle in the system and spawned in early summer when the resulting juveniles could feed on the summer zooplankton peaks. They grew at 0.5 cm month−1 and attained maximum size in one year. They were non-selective taking mainly P. stuhlmanni and post-veligers. H. kelee spawned in the sea and juveniles were common in St Lucia during 1978 when they fed non-selectively, chiefly on P. stuhlmanning the summer before disappearing over the winter. The resulting offspring went through a sequence of dietary changes which were closely related to zooplankton cycles. The importance of P. stuhlmanni in the pelagic food web of St Lucia is illustrated. The species supports not only the filter feeding teleosts but indirectly the predatory fish Argyrosomus hololepidotus and Elops machnata which feed on G. aestuarius and T. vitrirostris.
105 citations
TL;DR: No significant differences in amylase activity between fish feeding on animals and those feeding on plants are revealed, although in both species the enzymatic activity was lowest when Chara served as food.
Abstract: Seasonal changes of the amylolytic activity in the gut content of roach and rudd in four Tyrolean lakes and the adaptation of the amylase to four acclimation temperatures and to different natural foods were studied. In roach amylolytic activity varied with the environmental temperature. Between September and October, however, enzyme activity shifted to a higher level where it remained for the entire cold season. In rudd, which has almost the same seasonal pattern of amylolytic activity as the roach, the activity of the enzyme is independent of environmental temperature. This suggests an endogenous rhythm of enzyme activity. Under natural conditions the roach, but not the rudd, has a higher amylolytic activity when feeding on animals and a lower activity when feeding on detritus. The laboratory experiments revealed no significant differences in amylase activity between fish feeding on animals and those feeding on plants, although in both species the enzymatic activity was lowest when Chara served as food.
101 citations
TL;DR: The energy utilized by anabolic and catabolic processes associated with the ingestion of a standard diet was identified as biochemical SDA, which rose exponentially with increase in ingested energy, reflective of the cost for growth and catabolism.
Abstract: Apparent SDA was defined as the energy expenditure associated with the ingestion of a meal. In the present study apparent SDA was equated to an increase in oxygen consumption above the postabsorptive level subsequent to the ingestion of a meal. The energy cost for physically processing a meal, mechanical SDA, was equated to the oxygen uptake associated with the ingestion of non-digestible cellulose. The energy utilized by anabolic and catabolic processes associated with the ingestion of a standard diet was identified as biochemical SDA. Apparent, mechanical and biochemical SDA were each positively related to the energy intake of the standard diet. Apparent SDA expressed relatively to energy ingested equalled 10·5% and was independent of the caloric content of the meal. Mechanical SDA increased asymptotically with ingested meal size and energy content. Relative to apparent SDA, mechanical SDA decreased with meal size, suggestive of an enhancement in efficiency. Biochemical SDA rose exponentially with increase in ingested energy, reflective of the cost for growth and catabolism.
94 citations
TL;DR: The finding that ovulation occurs at approximately the same time of day at temperatures from 12° to 26° C suggests the time of the endogenous preovulatory gonadotropin surge may change with the temperature.
Abstract: Spontaneous ovulation in goldfish is synchronized with photoperiod and influenced by water temperature and aquatic vegetation. As the latency to ovulation from injection of HCG is highly temperature dependent, the finding that ovulation occurs at approximately the same time of day at temperatures from 12° to 26° C suggests the time of the endogenous preovulatory gonadotropin surge may change with the temperature. The time of spontaneous ovulation adjusts to a reversed light:dark cycle within 2 weeks; some 4–6 h shifts in a single light:dark cycle modify the time of ovulation.
Few sexually mature females kept under long photoperiod (16L:8D) and transferred from cold (13 ± 1°C) to warm (21 ± 1°C) water ovulated spontaneously. Exposure to artificial aquatic vegetation for as little as one light phase significantly increases the proportion offish ovulating in warm water. Fish kept in cold water without vegetation do not ovulate; the addition of vegetation induces ovulation, although the response latency is longer than in warm water. Aquatic vegetation may be an effective stimulus for ovulation in other teleosts which spawn on this substrate.
87 citations
TL;DR: It is concluded that the female dogfish has a very extended breeding season, though the peak frequency of egg-laying occurs in the winter and spring.
Abstract: Various aspects of the reproductive physiology of the female lesser spotted dogfish, Scyliorhinus canicula L., demonstrate marked annual cycles. Pituitary ventral lobe gonadotrophin content and plasma oestradiol and testosterone levels rise through the autumn as the ovary recrudesces and the percentage of fish bearing eggs in the oviducts increases. The pituitary gonadotrophin and plasma sex steroid levels remain elevated throughout the winter but decrease during the spring, two months prior to a fall in both the gonadosomatic index (GSI) and the percentage of fish with eggs in their oviducts. The lowest gonadotrophin and sex steroid levels are found in early summer, again preceding the minimum GSI and rate of egg-laying by two or three months. Some of these cycles are pronounced, the pituitary gonadotrophin levels varying by more than 100-fold, and the oestradiol levels by more than 10-fold, throughout the year. It is concluded that the female dogfish has a very extended breeding season, though the peak frequency of egg-laying occurs in the winter and spring.
77 citations
TL;DR: An anatomical study of the digestive tract of the channel catfish revealed that the oesophageal mucosa was longitudinally folded and that secondary folds were occasionally located on the primary longitudinal folds.
Abstract: An anatomical study of the digestive tract of the channel catfish revealed that the oesophageal mucosa was longitudinally folded and that secondary folds were occasionally located on the primary longitudinal folds. The infoldings were more numerous near the stomach. The stratified squamous epithelium covering the folds was made up of a basal layer, large mucous cells and simple squamous cells on the surface. The epithelium on the side of the folds consisted primarily of mucous secreting cells. Taste buds were observed between mucous cells on the apical portion of the oesophageal folds and were more prevalent in the cranial part of the oesophagus. The remaining layers of the oesophagus were: a lamina propria-submucosa, tunica muscularis and adventitia or serosa.
The J-shaped stomach had two regions: a large sac-shaped region containing gastric glands and a smaller, nonglandular pyloric region. The large rugae of the stomach became gradually smaller near the pylorus. There was a well developed pyloric sphincter. The mucosa included a simple columnar epithelium, a lamina propria and adventitia or serosa.
The intestine could be differentiated into a thick ascending segment, a descending segment, a thin convoluted segment and a thicker terminal segment, the rectum. Many mucosal folds containing branched villi characterized the ascending segment of the intestine. The descending and convoluted segments contained fewer folds with shorter and less-branching villi and were smaller in diameter and thinner walled. Descending and convoluted segments were also mildly convoluted and accounted for 80% of the total length of the intestine. An intestinal valve with a sphincter marked the beginning of the rectum. There was an approximately four-fold increase in the thickness of the tunica muscularis of the terminal segment of the intestine.
TL;DR: For fish acclimated for 1 day to a concentration of ammonia close to the 24-h median for un-acclimated fish, the median is increased between 38 and 79%, depending on test conditions.
Abstract: The survival of Atlantic salmon smolts on exposure to constant concentrations of ammonia has been measured under laboratory conditions. At concentrations of dissolved oxygen close to the air-saturation value, the 24-h LC50 of un-ionised ammonia is 0.15 mg NH31−1 in fresh water (hardness 264 mg 1−1 as CaCO3) and 0.3 mg NH31−1 in 30% sea water; at concentrations of dissolved oxygen of 3.5 mg 1−1 in fresh water and 3.1 mg 1−1 in 30% sea water, the 24-h LC50 is 0.09 mg NH3 1−1 and 0.12 mg NH3 1−1 respectively; for fish acclimated for 1 day to a concentration of ammonia close to the 24-h median for un-acclimated fish, the median is increased between 38 and 79%, depending on test conditions.
TL;DR: There was considerable yearly variation in the numbers of eggs which hatched, but there were no marked differences between the three species in the tolerances of the eggs to acid water; pH 3·5 was lethal within 10 days to all the eggs, but at pH 4·5 and higher pH levels there was no obvious difference in hatching attributable to acidity.
Abstract: The survival of salmon Salmo salar, sea trout and brown trout Salmo trutta eggs in acid water in the range pH 3·5±7·0 was investigated over a period of three winters. The effects of fertilising the eggs in acid water at pH 4·0, 4·5 and 5·0, and dilution of the test media were also studied. There was considerable yearly variation in the numbers of eggs which hatched, but there were no marked differences between the three species in the tolerances of the eggs to acid water; pH 3·5 was lethal within 10 days to all the eggs, but at pH 4·5 and higher pH levels there was no obvious difference in hatching attributable to acidity.
TL;DR: Experiments to determine the growth rate of eels (Anguilla anguilla L.) at different temperatures are described and show the optimum temperature for growth to be 22–23° C and the ultimate upper lethal temperature was found to be 38° C.
Abstract: Experiments to determine the growth rate of eels (Anguilla anguilla L.) at different temperatures are described and show the optimum temperature for growth to be 22–23° C. The ultimate upper lethal temperature was found to be 38° C and the critical thermal maximum varied from 33 to 39° C for fish acclimated at 14 to 29° C. An attempt was also made to determine lower lethal temperatures. Eels enter a state of torpor at temperatures varying from 3° C for fish acclimated at 29° C to less than 1° C for fish acclimated at 23° C or below. The results have been used to estimate the growth rates expected from eels cultured in power station cooling water using different types of temperature control.
TL;DR: Differences in the reproductive biology of the fish were found following the alleviation of stunting; the gonads of both sexes achieved a greater relative weight, and correspondingly the fecundity of the females was higher, although this latter effect became progressively less marked with increasing size.
Abstract: Two sudden and pronounced changes in the growth rate of roach, Rutilus rutilus (L.), in Slapton Ley, Devon, have been observed between 1972 and 1976. At first the growth rate declined to the point at which the population became stunted, then subsequently it improved again. These changes were correlated with population density; the numbers of roach were increasing during the late 1960's/early 1970's, and this increase was substantially reinforced by very strong year classes in 1972, and, to a lesser extent, in 1973. The increase in population density resulting from the strong 1972 year class was apparently adequate to accelerate the onset of the stunting observed. The improvement in growth rate in 1976 followed immediately after extensive mortalities amongst the roach during 1975, caused by an epidemic of the parasite Ligula intestinal is (L.). Some improvement in the growth of O group roach had been evident during 1975, but this was not observed in the population. Ford-Walford plots showed a decline in the value of L after the onset of stunting in 1972.
Differences in the reproductive biology of the fish were found following the alleviation of stunting; the gonads of both sexes achieved a greater relative weight, and correspondingly the fecundity of the females was higher, although this latter effect became progressively less marked with increasing size. It was not apparent amongst the largest individuals. There was also some evidence of a decline in the proportion of fish maturing at minimum size. The changes in the reproductive biology were associated with the improvement in conditions for individual fish following the decline in population density.
TL;DR: The median period of survival for fish pretreated at 0·01 mg Cd 1−1 was found to be increased at test concentrations up to 10mg Cd1−1 compared with alevins pretreated with dilution water, however, at concentrations above 10mgCd 2−1 pretreatment at 0 ·01 mgCd 1·1 reduced the medianperiod of survival.
Abstract: A toxicity test with cadmium concentrations ranging from 0·1 to 100·0 mg Cd 1−1 was used to assess the effect of cadmium pretreatment on rainbow trout (Salmo gairdneri Richardson) alevins. The median period of survival for fish pretreated at 0·01 mg Cd 1−1 was found to be increased at test concentrations up to 10mg Cd 1−1 compared with alevins pretreated with dilution water. However, at concentrations above 10mg Cd 1−1 pretreatment at 0·01 mg Cd 1−1 reduced the median period of survival.
TL;DR: Fecundity and fertility were significantly higher among females of one and two gestation periods from the lowest than from the highest density and a significant relationship was found between gonad volume and total body length and between Gonad weight and body length at the same population level.
Abstract: Experiments were performed to examine the influence of population density on the fecundity and fertility in the guppy, Poecilia reticulata. The frequency of females with only ova or with different combinations of reproductive units and developmental stages in the ovary was significantly different between different densities but not between females with one and two gestations from the same population density. The ovarian width of females with one gestation from the lowest density was significantly larger than in the highest population density. Gonad length and height and ovarian volume of females with two gestation periods were larger in the lowest compared with the highest density. After one gestation, females at the lowest population level had greater ovarian length, height, gonad weight, width and volume compared with those from the higher density. Ovarian length, height and volume and gonad weight were also significantly greater among females of two gestation periods in the lowest than in the second lowest density. The average gonadosomatic ratio was highest in the lowest population density. A significant correlation was found between gonad volume and total body weight and between gonad volume and ovarian weight of females at every population level. This was also the case when ovarian weight vs. total body weight was examined in each population density. Only at the lowest population level was there a significant correlation between fecundity and total body length and between fertility and body length. A significant relationship was also found between gonad volume and total body length and between gonad weight and body length at the same population level. No significant difference of fecundity and ovum size was found between females of one and two gestation periods from the same density. Fecundity and fertility were significantly higher among females of one and two gestation periods from the lowest than from the highest density.
TL;DR: The digestive efficiency of Tilapia zillii fed Najas guadalupensis was studied in the laboratory and an estimate was made of the amount of Najas necessary to satisfy the caloric expenditure of the fish.
Abstract: The digestive efficiency of Tilapia zillii fed Najas guadalupensis was studied in the laboratory. Digestion was dependent on the ability of the fish to triturate the plant tissues. Based on a dietary reference, cellulose, the total digestibility of Najas was 29.3%. Digestive efficiency of the fish for non-cellulose organic matter, protein and fat was 55.7%, 75.1% and 75.9%, respectively. Of the total caloric content of the plant, 45.4% was assimilated. An estimate was made of the amount of Najas necessary to satisfy the caloric expenditure of the fish.
TL;DR: Between 1974–1977 the gonads of a number of commercial reef fishes were examined during a study of gear improvement and stock assessment along the East African Coastal waters.
Abstract: Between 1974–1977 the gonads of a number of commercial reef fishes were examined during a study of gear improvement and stock assessment along the East African Coastal waters. Different methods of fishing ranging from modern methods of trawling to local methods of traps were used. Twenty-one families with a total of 73 species were examined. The spawning of these species occurred throughout the year with two peaks in January to March and September to November. The highest peak of breeding was in October, corresponding to the time of the South East Monsoons, and to the highest water temperature.
TL;DR: Results indicate that stunted coho salmon have a decreased ability to bind GH which may be reflected in perturbations in GH-mediated processes.
Abstract: The premature transfer of juvenile Coho salmon into seawater results in high mortality and a reduction of growth (stunting) of a significant portion of the population while the remainder of the salmon continue to grow normally. Binding studies were conducted with I25I-labelled tilapia (Sarotherodon mossambicus) growth hormone (tGH) to determine if differences in specific binding of tGH existed in membrane preparations of tissues of stunted and normal coho salmon. Membrane preparations of both liver and gill of stunted salmon obtained from stocks in California, Washington and British Columbia and kidney membrane preparations obtained from stunted salmon in California exhibited deficiencies in 125I-labelled tGH-binding sites compared to corresponding membrane preparations of normal smolts. These results indicate that stunted coho salmon have a decreased ability to bind GH which may be reflected in perturbations in GH-mediated processes.
TL;DR: Rainbow trout of the Kamploops variety were sampled at intervals from October to the end of March a decline was noted in red cell count, haematocrit,Haemoglobin concentration and plasma osmotic concentration, but increases were seen, however, in mean cellular volume, mean corpuscular haemoglobin,mean corpuscular Haemoglobin Concentration and the water content of liver and dorsal muscle.
Abstract: Rainbow trout of the Kamploops variety were sampled at intervals from October to the end of March. During this period a decline was noted in red cell count, haematocrit, haemoglobin concentration and plasma osmotic concentration. Increases were seen, however, in mean cellular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration and the water content of liver and dorsal muscle. Sexual differences were found in all values with the exception of mean corpuscular haemoglobin concentration and the water content of both tissues. Males always had higher values in those parameters in which sexual differences were noted. All trends, with the exception of male haemoglobin and mean cellular volume and female mean cellular volume and osmotic concentration, were significantly linear.
None of the findings in this study could be correlated with temperature or photoperiod. Neither could the declining plasma osmotic concentration be correlated with the rising mean cellular volume or tissue water content. However, correlations were noted between haemoglobin and haematocrit, red cell count and haematocrit and between osmotic concentration and haematocrit. A negative correlation was seen between mean corpuscular haemoglobin concentration and mean cellular volume.
TL;DR: It is concluded that insufficient glucose was moved through the circulation to account for the rate of glycogen formation observed in the recovering exhausted muscle.
Abstract: The conclusion from two in vivo experiments is that a significant proportion of the lactic acid, normally formed by glycolysis from glycogen and held in the muscle cells following exhausting exercise of the anaerobic swimming muscle of the teleost fish Pleuronectes platessa L, is converted by gluconeogenesis to form glycogen in the recovering muscle.
In the first experiment a technique for measurement of [3H]glucose turnover in the plaice was developed and applied to measure turnover in resting and exhausted fish. It is concluded that insufficient glucose was moved through the circulation to account for the rate of glycogen formation observed in the recovering exhausted muscle.
In the second experiment, an intramuscular injection of [14C]lactate to exhausted fish revealed a direct uptake of [14C]lactate by the recovering muscle cells, and the incorporation of substantial proportions of lactate into the restored glycogen. Simultaneous use of [3H]-mannitol allowed measurement of the isotope distribution between extra- and intracellular spaces.
TL;DR: To evaluate physiological stress resulting from environmental influences, a haematological study of a natural population of largemouth bass was undertaken to establish a ‘normal’ blood profile.
Abstract: To evaluate physiological stress resulting from environmental influences, a haematological study of a natural population of largemouth bass, Micropterus salmoides, was undertaken to establish a ‘normal’ blood profile. Several parameters including haemoglobin concentration, haematocrit, erythrocyte count, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, plasma protein concentration and glucose levels were investigated. Haematocrit, haemoglobin, and total plasma protein were positively correlated with fish length. Haemoglobin and haematocrit were positively correlated with fish age while mean corpuscular haemoglobin, concentration was negatively correlated with fish age. Both haemoglobin and haematocrit values were related to erythrocyte counts.
TL;DR: Inbreeding depression was observed in Half and Full sib matings of Zebra Danios and no effect of inbreeding on either number of eggs per spawn or hatchability were found.
Abstract: Inbreeding depression was observed in Half and Full sib matings (Inbreeding Coefficient 0.125 and 0.25) of Zebra Danios (Brachydanio rerio). Inbreeding at these levels reduced fertility, survival to 30 days, and length at 30 days. There was an increase in the incidence of crippled fry. No effect of inbreeding on either number of eggs per spawn or hatchability were found.
TL;DR: The temporal pattern of hormonally induced spawning in Sparus aurata females reared in captivity is reported, where a low dose of human chorionic gonadotropin induced a daily cycle of maturation, ovulation and spawning of fertilizable eggs.
Abstract: This paper reports the temporal pattern of hormonally induced spawning in Sparus aurata females reared in captivity. A low dose of human chorionic gonadotropin (100–400 i.u. kg−1 body weight), administered to females with oocytes in the last stages of vitello genesis, induced a daily cycle of maturation, ovulation and spawning of fertilizable eggs. This cyclic pattern lasted for a period of 4–100 days. In fish injected with saline and most of the untreated fish, all vitellogenetic eggs underwent rapid atresia.
TL;DR: Neither dose nor route had any significant effect on the primary response, however, in the secondary response the intramuscular route resulted in significantly increased immunoglobulin production.
Abstract: Immunoglobulin production in the primary and secondary immune response of brown trout to keyhole limpet haemocyanin has been investigated including the effect of dose size, route and number of injections, and the use of adjuvant. Antibody activity was found in the first fraction from Sephadex G200 and in the second from Sepharose 6B. Trout immunoglobulin had β2—Γ1 electrophoretic mobility, and Sapp of 16·7 and an approximate molecular weight of 670 000 daltons. It was sensitive to dithiothreitol and stable at 56°C for 30 min. Immunoglobulin concentrations were measured by single radial immunodiffusion with a specific rabbit antiserum. Sera from non-injected trout had a mean immunoglobulin level of 7·3 ± 0·3 mg ml−1 which accounted for 10% of the total serum protein. Phosphate buffered saline-injected controls contained 6·7 ± 0·2. In fish given a single injection the mean concentration ranged from 7·5 to 12·9 and in those given more than one injection from 12·6 to 16·8. The use of adjuvant resulted in higher immunoglobulin concentrations. Neither dose nor route had any significant effect on the primary response. However, in the secondary response the intramuscular route resulted in significantly increased immunoglobulin production.
TL;DR: A histological study on scale structure in the common goby, Pomatoschistus microps (Kroyer) has established a similarity to other teleost scales, but yielded two new findings that may reflect a rhythm in scale growth.
Abstract: A histological study on scale structure in the common goby, Pomatoschistus microps (Kroyer) has established a similarity to other teleost scales, but yielded two new findings. First, the osseous layer of the scale was formed of successive and parallel calcified bands that may reflect a rhythm in scale growth. Second, extracellular matrix vesicles (100–200 nm) were identified by electron microscopy, at the calcifying area in the anterior growing edge of the scale; distribution of these vesicles corresponded closely to the pattern of scale calcification. A proposal on the mechanism of growth and calcification of scale has been made. The surface topography of the scale has also been examined by scanning electron microscopy. The raised edge of the circulus is formed of minute knobs, which may be used as criterion in fish taxonomy.
TL;DR: In terms of biomass, the three dominant fish species in the Huizache-Caimanero lagoon system during 1975-76 were the mullet Mugil curema, the anchovy, Anchoa panamensis and the catfish, Galeichthys caerulescens as discussed by the authors.
Abstract: In terms of biomass, the three dominant fish species in the Huizache-Caimanero lagoon system during 1975–76 were the mullet Mugil curema, the anchovy, Anchoa panamensis and the catfish, Galeichthys caerulescens. Peaks in the abundance of the secondary predators occurred at the end of the wet season (September-October), while pelagic forms and members of the centropomid-gerreid association (Warburton 1968a) were most common during November-February and December-February respectively. Twelve species, including the ten having the highest overall mean biomass, were selected for growth and production studies. Lagoon-specific differences in the patterns of growth and recruitment of several species were observed. The total estimated annual fish production in Caimanero lagoon was 34·48 g m−2 y−1, with M. curema contributing 9·36 g m−2, A. panamensis 9·24 g m−2 and G. caerulescens 6·15 g m−2 (maximum estimate). Mean turnover ratios (annual production: mean biomass) were 3·25 (demersal species), 8·44 (pelagic species) and 4·48 (all species). Implications for possible fishery and aquacultural expansion are discussed.
TL;DR: Biochemical investigations showed a significant decrease in blood and kidney ascorbic acid levels within a month of feeding the deficient diet, and a prolonged deficiency beyond 150 days resulted in a rapid rise in the cholesterol content of the liver.
Abstract: The results of a series of experiments on Channa punctatus previously conditioned to a complete synthetic diet and later fed vitamin C deficient diet for 210 days followed by 30 days of recovery with fortified vitamin C ration are reported. The survival, growth, morphological abnormalities and biochemical changes in tissue ascorbic acid and cholesterol levels were studied.
Deficiency of vitamin C resulted in a mortality of up to 25% and retarded growth accompanied by anorexia and loss of weight. Marked skeletal abnormalities, viz., lordosis, scoliosis and degenerative changes in the thoracic vertebrae were revealed by X-ray studies. Biochemical investigations showed a significant decrease in blood and kidney ascorbic acid levels within a month of feeding the deficient diet. A prolonged deficiency beyond 150 days resulted in a rapid rise in the cholesterol content of the liver. These biochemical changes were reversed when vitamin C was added to the ration.
TL;DR: Electromyography was used to determine the functional roles of the axial musculature in striped bass and bluefish at imposed swimming velocities and found the lateral red muscle powers propulsive movements at all sustainable swimming speeds in both species.
Abstract: Electromyography was used to determine the functional roles of the axial musculature in striped bass and bluefish at imposed swimming velocities. The lateral red muscle powers propulsive movements at all sustainable swimming speeds in both species. The amplitude and frequency of EMG's from the red muscle grade with increasing swimming velocity. The white muscle, forming the main mass of the myotome, is reserved for high-speed burst swimming above maximum sustainable speeds. The proportion of the myotome occupied by the red muscle at the level of the caudal peduncle is 10.9% and 18.6% for the striped bass and the bluefish respectively.