bluuebunny/crossref_metadata_2025 huggingface dataset:
Temperature acclimation in crucian carp, Carassius carassius L., morphometric analyses of muscle fibre ultrastructure
Authors: Johnston I. A. , Maitland B.
Published: January 2006

Carp show a partial compensation in metabolic rate and activity following temperature acclimation. In the present study crucian carp, Carassius carassius, were acclimated for eight weeks to either 2deg; C or 28deg; C. The effects of temperature acclimation on muscle fibre ultrastructure has been investigated. The fractional volume (%) of each fibre type occupied by mitochondria and myofibrils was determined using a point counting morphometric method. Mitochondrial density was found to be higher in the muscles of cold (red fibres 25%; pink fibres 20% and white fibres 4%) than in those of warm acclimated fish (red fibres 14%, pink fibres 11%, white fibres 1%). The proportion of subsarcolemmal to intra‐myofibrillar mitochondria was significantly lower in the red fibres of cold acclimated fish. Metabolic compensation to low temperatures are therefore associated with an increase in the number of mitochondria per cell. In contrast, the fractional volume occupied by myofibrils actually decreased following cold acclimation. Evidence is reviewed that temperature compensation of contractile activity results from qualitative rather than quantitative changes in myofibrillar proteins.
Comparison of the parasitic fauna of Aplocheilus panchax and A. melastigma
Authors: Madhavi R.
Published: January 2006

The metazoan parasite fauna of two species of freshwater fishes Aplocheilus panchax and A. melastigma collected from a stream at Waltair is compared; 17 parasite species were found. Aplocheilus panchax served as a host to 13 parasite species and A. melastigma to 10 parasite species. Of the 17 parasites collected, 12 were larval helminths to which the fishes act as intermediate and paratenic hosts. This has been attributed to the interaction between terrestrial birds, mammals and fishes in determining the parasite fauna in the biocoenosis. The parasite fauna of these fishes is divided into typical and less typical according to their frequencies. Among less typical there are peripheral division parasites which are abundant in other fishes in the stream. Only six parasite species occurred in both A. panchax and A. melastigma and both fish shared most of their parasite fauna with other fishes. Differences in the parasite fauna of these fishes are attributed to the morphological, behavioural or ecological features of these fishes.
The swelling egg of the long rough dab, Hippoglossoides platessoides limandoides (Bloch)
Authors: Lønning S. , Davenport J.
Published: January 2006

The egg of Hippoglossoides platessoides limandoides swells when released into sea water. The swelling takes place entirely outside the ovoplasm and creates a large perivitelline space which can make up 85% of the total egg volume. Swelling occurs in both unfertilized and fertilized eggs although a small proportion of unfertilized eggs, believed not to have been activated, do not swell. Swelling is dependent upon the breakdown of cortical alveoli, together with an unusually soft and elastic chorion. The cortical alveoli, present in greater numbers than is usual in teleost eggs, release colloidal material when they break down on egg activation; adsorption of water by this material is responsible for the egg volume increase.
Seasonal variations in plasma concentrations of 11‐ketotestosterone and testosterone in male rainbow trout, Salmo gairdnerii Richardson
Authors: Scott A. P. , Bye V. J. , Baynes S. M. , Springate J. R. C.
Published: January 2006

Measurements were made of plasma 11‐ketotestosterone and testosterone in control and sex‐reversed male rainbow trout, before and during their first spawning season (winter 1978/1979). Plasma concentrations of both androgens (in both groups) were 2–3 ng ml‐1 in January 1978 (apart from some precocious spawners), rose slowly to 9–11 ng ml‐1 in April and July and then increased rapidly to 100–150 ng ml‐1 in November. From this time, testosterone levels declined but those of 11‐ketotestosterone continued to rise to a peak of 260 ng ml‐1 in February 1979. No significant differences in hormone levels were found between control male and masculinized female fish.
A new species of the deep‐sea fish genus Coelorinchus Giorna (Macrouridae) from the eastern North Atlantic, with notes on its ecology
Authors: Merrett N. R.
Published: January 2006

A new species of macrourid, Coelorinchus abditilux, is described from 51°N, 11°W in the Porcupine Sea‐Bight, eastern North Atlantic. It is distinguished by its minute ventral light organ which lacks an external naked fossa, short snout, naked underside of head, body scales lacking prominent median keels and low gill raker count (8–9) in inner series of first arch. The uniqueness of this species is such that it may represent a new sub‐genus of Coelorinchus. It is relatively deep‐living (770–1042 m) with a very restricted known distribution in a coralline area.
Population changes after two years of salmon (Salmo salar L.) stocking in upland trout (Salmo tmtta L.) streams
Authors: Kennedy G. J. A. , Strange C. D.
Published: January 2006

The survival of salmon stocked in upland trout streams in the presence of salmon parr was found to be only about half the value recorded when trout alone made up the resident stock. Changes in the trout population were also recorded following the two years of salmon stocking, and these suggested that the presence of salmon parr may also influence trout fry survival. The findings are discussed in the context of habitat competition and total stream holding capacity.
Food consumption, growth and survival of grass carp Ctenopharyngodon idella Val at four salinities
Authors: Kilambi Raj V.
Published: January 2006

Grass carp were raised in 227‐1 indoor tanks at 3,5,7 and 9%osalinities and 18·5 and 29·5°C temperatures at a density of five fish per tank. Growth rate did not differ under these conditions. Food consumption was similar between temperatures at a given salinity but differed among the salinities with most food intake at the 5%o salinity. An average of 40% of grass carp survived for 180 or more days.
An autoradioraphic and cytochemical study of erythropoiesis in a fresh water fish, Channa punctatus Bloch
Authors: Mahajan C. L. , Dheer J. M. S.
Published: January 2006

Using spleen and head kidney imprints, studies on erythropoiesis in Channa punctalus have been made describing each developmental stage with regard to its morphology, morpho‐metry and cytochemistry. This has been undertaken using the new techniques available for haematopoietic studies of fishes. These include autoradiography for information on DNA synthesis and Graham‐Knoll's benzidine method with Giemsa used as a counterstain for the differential staining of haemoglobin. Thus, a more definitive picture of the haematopoietic phenomenon in Channa punctatus has been evolved.
Induced triploidy in carp, Cyprinus carpio L.
Authors: Gervai J. , Páter S. , Nagy A. , Horváth L. , Csényi V.
Published: January 2006

A method for mass production of triploid carp was developed by the cold treatment of eggs after fertilization. Triploidy was demonstrated by cytophotometry and chromosome preparation techniques. Of the haploid embryos, 100% showed morphological abnormalities and died soon after hatching. Haploid embryos of maternal and paternal origin occurring in the course of cold treatment were distinguished by using a genetic marker. Among morphologically normal larvae, the frequency of triploidy was 100%, and the viability of the triploid embryos, larvae and the juvenile fish did not differ from the diploid control. Sex differentiation started in the triploid fish, but was greatly retarded. Gonad size and the small number of growing oocytes suggest that most of the triploid individuals will be sterile. Triploid carp grew at the same rate as diploid controls in the laboratory test.
A review of the biology, handling and storage of salmonid spermatozoa
Authors: Scott A. P. , Baynes S. M.
Published: January 2006

Several aspects of salmonid sperm have been critically reviewed: structure, density, volume, chemical composition, metabolism, fertilisation techniques, motility, dilution, activation, storage at temperatures above and below 0deg; C and cryopreservation.
Seasonal relationships of ovary weight, liver weight and fat stores with body weight in the goldfish, Carassius auratus (L.)
Authors: Delahunty G. , de Vlaming V. L.
Published: January 2006

The relationships of ovary weight, liver weight and visceral lipid stores to body weight in the goldfish were examined at different times of the year. Both arithmetic and logarithmic relationships were examined. Ovary weight significantly increased relative to increasing body weight in goldfish and the exact nature of this relationship changed from month to month. However, larger fish were found to have proportionately larger ovaries than small fish at specific times of the year. Regression lines for liver weight versus body weight were also determined. Monthly differences were found in the liver weight‐body weight relationship. Visceral lipid stores expressed per gram of protein were found to be independent of body weight. Lipid stores expressed in this manner peaked in February while ovary weight peaked in April. The consequences of compensating for body size when expressing organ (liver, ovary) sizes, such as hepatosomatic index and gonosomatic index, are discussed.
Correlation between digestion rate and feeding frequency in the stomachless teleost, Blennius pholis L.
Authors: Grove D. J. , Crawford C.
Published: January 2006

Foregut emptying in Blennius pholis at 16–18°C is exponential (St=Soe‐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.
Oxygen uptake in developing eggs and larvae of the cod, Gadus morhua L.
Authors: Davenport J. , Lönning S.
Published: January 2006

Unfertilised cod eggs showed a mean oxygen uptake rate at 5°C of 0.089 μl O2, dry wt.−1 h−1; this gradually rose to 0.768 μl O2 mg dry wt.−1 h−1 in eggs about to hatch. From hatching to complete yolk absorption larvae respired at 1.6 μl O2, mg dry wt.−1 h−1. During starvation following yolk absorption, uptake fell significantly to 1.1 μl O2, mg dry −1 h−1. Much of this decrease in oxygen consumption was shown to be caused by reduction in activity. Loss of weight during the embryo and larval phases could not easily be reconciled with total oxygen consumption; it is suggested that cod embryos and larvae may not rely solely upon endogenous energy reserves during development.
Studies on the relationship between osmotic or ionic regulation and thyroid gland activity in two salmonid fishes, Salmo gairdneri Richardson and Oncorhynchus kisutch Walbaum
Authors: Milne R. S. , Leatherland J. F.
Published: January 2006

In freshwater‐acclimated rainbow trout a single intraperitoneal injection of ovine TSH significantly elevated plasma thyroxine (T4) levels within 1 h after the injection. In seawater adapted trout the increase in T4 after TSH‐treatment was not evident until 6 h after the injection. TSH caused a transient fall in plasma Na+ and Cl‐ between 3 h and 9 h after the injection in seawater‐adapted fish and plasma Na+ was lowered in freshwater‐adapted trout 24 h after the injection. Although there were clear histological changes in the thyroid gland of freshwater‐adapted trout after TSH‐injection, no such changes were evident in seawater‐adapted fish.

Plasma thyroid hormone levels and thyroid histology in freshwater‐adapted rainbow trout and coho salmon transferred to sea water, and seawater‐adapted trout transferred to fresh water showed no consistent changes compared with controls.

The data are interpreted to indicate that although ambient salinity may have indirect effects on thyroid activity there is no direct involvement in ionic or osmotic regulation in the two species.
A stomach sampler for use on live fish
Authors: Giles N.
Published: January 2006

A stomach sampler for live fish is described and its construction outlined; 50 adult perch were sampled, subsequently killed and dissected to assess the efficiency of the device. Survival of previously sampled fish was followed using individually recognisable dorsal fin tags.
The eye lens weight and age in the common carp, Cyprinus carpio L.
Authors: Crivelli A.
Published: January 2006

The validity of the use of the weight of dried eye lenses as an indicator of age in the common carp, Cyprinus carpio L., is tested. There is a significant difference between males and females for fish of two and three years old. Otherwise no significant difference is noted between sexes. The linear relationship between the dry weight of eye lenses and age + 1 are: In Y+ 1= 0.5202 + 16.4928X (r= 0.93) for female and ln Y+ 1=0.4276 + 16.7364X (r= 0.94) for male.

The method for determining age is valuable for fish until three years old. However for older fish, in spite of a correlation coefficient between lens weight and age and even with a significant difference between annual groups, the age determination may be misleading due to the overlap in lens weights. In conclusion therefore this method may not be useful for back calculation of growth, for production estimates or studies in which accurate estimates of age are needed.
Population biology of the nematode Camallanus lacustris in perch, Perca fluviatilis L., from an oligotrophic lake in Norway
Authors: Skorping A.
Published: January 2006

Samples of perch, Perca fluviatilis, were examined for the contents of their gastrointestinal tract and for the intestinal nematode Camallanus lacustris (Zoega). The seasonal dynamics, dispersal pattern and site preference of the nematode were studied. Both larvae and adult worms were present in the perch throughout the year. The abundance of C. lacustris was non‐seasonal, but seasonal cycles were found in the numbers of larvae and of gravid females. C. lacustris showed a tendency to an increase in mean intensity with the size of perch. The frequency distribution of the nematode followed the negative binomial at different times of the year and in different length groups of perch. C. lacustris showed a seasonal site preference in the perch gut.
Changes in experimental gillnet catches from the Kafue Floodplain, Zambia, since construction of the Kafue Gorge Dam
Authors: Dudley R. G. , Scully R. J.
Published: January 2006

The Kafue Floodplain fishery produces an annual fish yield of about 5000 tonnes. The 1971 closure of the Kafue Gorge Dam downstream from the floodplain modified flooding patterns. Pre‐impoundment studies predicted this modification would increase fish stocks. Experimental gillnets set in 1975 and 1976 caught 18 species on a regular basis, nine of which were abundant enough for comparison with catches in similar gillnet samples taken prior to completion of the Kafue Gorge Dam. Of these nine species, experimental gillnet catches of three predator species were smaller in 1975–76 than in 1969–70. Catches of only one species increased significantly. Whether this change is due to the modified flooding pattern is unclear; unusually dry flood conditions in 1973 and increased fishing effort may have contributed.
Observations on the food and diel feeding behaviour of pelagic O‐group gadoids in the northern North Sea
Authors: Robb A. P.
Published: January 2006

The diets and diel feeding behaviour of six O‐group gadoid species are described, the cod Gadus morhua (L.), the haddock Melanogramus aeglefinus (L.), whiting Merlangius merlangus (L.), saithe Pollachius virens (L.), Norway pout Trisopterus esmarkii (L.) and the blue whiting Micromesistius poutassou (R.). There were differences, in the main food groups selected by each species with respect to the type, size and number. The main prey consumed did not vary with depth. Cod, saithe and Norway pout had only one period of feeding activity whereas haddock and whiting apparently had two. The diets of haddock and whiting varied in association with these two periods. It is suggested that the differences between the diets were the result of each species having a different feeding behaviour which reflects that adopted in adult life.
Peculiarities of sperm production by anadromous and parr Atlantic salmon (Salmo salar L.) and fish cultural characteristics of such sperm
Authors: Kazakov R. V.
Published: January 2006

This study describes peculiarities of sperm production by anadromous and precocious parr Atlantic salmon. It was possible to obtain 15 sperm samples with total volume of 130 cm3 from anadromous males at the peak of the spawning run. Changes in the sperm characteristics with the increase of the sea‐life age and weight of anadromous males are shown. Such changes are also shown throughout the spawning period. The properties of parr spermatazoa were investigated and it is suggested that these spermatozoa are suitable for insemination.
The effects of various cations on the survival of brown trout, Salmo trutta at low pHs
Authors: Brown D. J. A.
Published: January 2006

The survival times of hatchery reared year‐old brown trout (Salmo trutta) were tested in solutions containing various ions at pHs between 3.5 and 4.0. The effect of calcium in prolonging the survival time compared with that in deionized water at all pHs tested, was more marked than that of sodium which was only effective at pH 4.0. Potassium and magnesium had no effect individually, but aluminium prolonged the survival time in sodium solutions. Fish from a naturally acid river (Tovdal‐Norway) survived significantly longer than hatchery reared fish, indicating the importance of the previous history of the fish to their sensitivity to low pH.
Density related growth of grass carp, Ctenopharyngodon idella (Val.) in managed small impoundments in Alabama
Authors: Shelton W. L. , Smitherman R. O. , Jensen G. L.
Published: January 2006

Growth data for grass carp, Ctenopharyngodon idella, in managed small impoundments were examined for density related effects. Ponds ranged in area from 0.02 to 5.0 ha; various species stocking combinations were used. Growth during the first year of life was strongly affected by density. Total standing stock increased and average size decreased with increasing density. This growth–density relationship was more variable among fish in the second year of life, primarily because of differences in availability of preferred food in different ponds. Survival tended to vary during the first year of life depending on the size at stocking but was uniformly high in the second year.
The ultrastructure of the atrial myocardial cell in three teleostean species
Authors: Leknes I. L.
Published: January 2006

The atrial myocardial cell in three teleostean species Gadiculus thori J. Smith, Melanogrammus aeglefinus (L.) and Onos cimbrius L. is described. The contractile material is located in the periphery of the cell, whereas the nucleus and mitochondria occupy the central part. The tubules of the sarcoplasmic reticulum are of larger diameter at the Z‐band levels than elsewhere in the sarcomere. The transverse part of the intercalated disc is composed of alternating desmosomes and intermediate junctions. In the longitudinal part of the disc desmosomes occur, situated in close proximity to Z‐bands. Short nexuses were found in the longitudinal part of the disc, usually near the transverse part. In G. thori numerous atrial specific granules were seen. A high number of mitochondrial granules and glycogen granules seems to occur in O. cimbrius. In the atrial myocardial cell of two or six day‐old larvae of M. aeglefinus. the contractile material is organized into thin myofibrils, and numerous ribosomes are located in the sarcoplasm.

The results of the present work are compared to those previously described in the teleostean atrium and ventricle. The differences in the heart structure within the gadoid family are discussed from a functional and an evolutionary point of view.
Seasonal variations in RNA–DNA ratios and in indicators of feeding, reproduction, energy storage, and condition in a population of bluegill, Lepomis macrochirus Rafinesque
Authors: Bulow F. J. , Zeman M. E. , Winningham J. R. , Hudson W. F.
Published: January 2006

Liver and epaxial muscle RNA concentrations and RNA‐DNA ratios (RNA/DNA) of bluegill Lepomis macrochirus from a central Tennessee lake were maximum in the spring, low during the summer, high again in the fall, and low during the winter. Liver‐somatic indexes and DNA concentrations indicated that liver cell volume and energy storage varied seasonally and were lowest during late spring and summer. Seasonal variations in gonosomatic indexes were typical of this species, and RNA/DNA decreased as gonads matured during the spring. RNA/DNA and energy storage in the liver decreased during the major spawning season. Seasonal variations in food consumption may have effected seasonal growth and energy storage. However, a summer depression in RNA/DNA may have been more closely associated with the effects of thermal stratification and dissolved oxygen stress.
Determination of age, growth and sexual maturity of Barbus grypus in the Dukan reservoir of Iraq
Authors: Al‐Hakim A. W. H. , Al‐Mehdi M. I. A. , Al‐Salman† A. H. J.
Published: January 2006

A total of 317 carp Barbus grypus were collected during one year (1977–1978) from the Dukan reservoir of Iraq to study age, grwoth and sexual maturity. The length‐weight relationship was found be: log: W=–4.2298 + 2.6832 log L. and the condition (K) was 0.88. Back calculation was determined by using a correction factor (45.727) in Lee's equation. Predicted standard length and weight were found to be less than the actual values. The maximum increase in length was noted in the first year group, while the maximum increase in weight occurred at the time of sexual maturity. Males were found to attain maturity earlier than the females. Spawning took place during May and June.
A holding box system for physiological experiments on rainbow trout (Salmo gairdneri Richardson) requiring rapid blood sampling
Authors: Swift D. J.
Published: January 2006

The construction and use of a holding box system for rainbow trout is described. The equipment was designed to take fish of up to 25 cm in length with ten fish in each independent tray unit. Fish can be exposed to experimental changes in water quality and individuals removed at random during an experiment without disturbance to the other fish. A mean total time of 2 min 17 s (± 1.8 s standard error; 200 fish) to remove, anaesthetize, weigh, measure and obtain a blood sample from a fish was achieved.
Seasonal dynamics in abundance, development and pattern of infection of Bunodera luciopercae (Müller) in perch, Perca fluviatilis L. from an oligotrophic lake in Norway
Authors: Skorping A.
Published: January 2006

Samples of perch, Perca fluviatilis L., were examined monthly for the presence of the intestinal trematode Bunodera luciopercae (Müller). Marked seasonal cycles in incidence and intensity of infection were found, with a minimum level in July, when all the fish examined were free of the fluke, and a maximum level in February. Five developmental stages of the fluke were recognized and the seasonal changes in the percentage distribution of these stages were studied. Infective larvae were found in the period August–March, with a peak in January. Gravid worms were mainly found in the period May‐June. The frequency distribution of parasite counts were over‐dispersed and followed the negative binomial distribution within fish samples from different periods of the year.
Biology of the sand‐smelt (Atherina presbyter Valenciennes) around Fawley power station
Authors: Turnpenny A. W. H. , Bamber R. N. , Henderson P. A.
Published: January 2006

Past studies of fish impingement at Fawley power station have shown that sand‐smelts, Atherina presbyter Valenciennes, are susceptible to impingement and may be a useful species for examining effects of impingement mortalities on population size and structure. A 21 month study of populations in the vicinity of Fawley power station was carried out to obtain data on the biology of the species for future population dynamics modelling studies. Aspects included in the study were growth, sex ratio, reproduction, survival and mortality rates and diet. Differences in apparent and true rates of growth indicated some size‐selective mortality towards younger age groups, possibly caused by the power station. A seasonallyoscillating von Bertalanffy growth equation is given to predict mean length‐at‐age. Most female sand‐smelts (73%) matured at the end of their first year of life, fecundities ranging on average from 1394 eggs per female for 1+ group fish to 6872 for III+ fish. The sex ratio was even (1 : 1). An annual survival rate of 10–8% was estimated for mature fish, and the consequent age structure of the population indicates that the bulk of egg production lies with the smaller (1+ group) fish. Since smaller fish are generally more vulnerable to impingement this factor may render populations sensitive to impingement mortalities. Gut content analysis indicated that sand‐smelts probably actively select zooplankters from the general plankton when young and, once larger than 104 mm in length, increasingly feed upon natant macrofaunal species.
Changes in swimbladder retial morphology in Anguilla rostrata during premigration metamorphosis
Authors: Kleckner R. C. , Krueger W. H.
Published: January 2006

During metamorphosis from the yellow to the silver phase in Anguilla rostrata, the length of the swimbladder retial capillaries increases by a factor of 2.5, the mean retial capillary lumen diameter and total retial cros‐sectional area increase by 1.5 and the calculated counter current exchange efficiency increases by 3.4. Metamorphosis of the retia begins before changes in integument pigmentation become apparent. These changes in retial morphology are part of a complex of transformations that permit. The maintenance to swimbladder function at greater depths during the spawning migration.
Lethal temperature of marine fishes of the Gulf of Thailand
Authors: Menasveta P.
Published: January 2006

Twenty four marine fish species of the Gulf of Thailand were studied. The results suggested that increased acclimation temperature resulted in increased mean avoidance temperature (AT), critical thermal maximum (CTM) and upper incipient lethal temperature (UILT). At the acclimation temperature, which is normally the ambient seawater temperature of the Gulf of Thailand (28° C), the upper incipient lethal temperature ranged from 34° C to 37–5° C. Monocanthus chinensis and Cynoglosus puncticeps had the lowest thermal resistance. Mugil dussumerii, Therapon theraps and Scatophagus argus the highest and the rest in the middle range.
Furunculosis in cultured American eel Anguilla rostrata (Le Sueur)
Authors: Hayasaka S. S. , Sullivan J.
Published: January 2006

Diseased American eels, Anguilla rostrata, were collected from an eel culture facility in South Carolina and examined. The disease was characterized by skin lesions located on the body. A bacterium identified as Aeromonas salmonicida was isolated from the lesions and shown to be the causative agent. The bacterium was also isolated from the kidney during later stages of the disease.
Superficial neuromasts of the flatfish Peltorhamphus novaezeelandiae (Günther)
Authors: Roper D. S.
Published: January 2006

Examination using light and transmission electron microscopy showed that each superficial neuromast of the New Zealand sole, Peltorhamphus novaezeelandiae, consists of a typical sensory epithelium lying between two epidermal lappets. The neuromasts occur both singly and in rows over the head and along and above the lateral‐line on the body. As well as variation in the shape of the lappets and the size of the organs from different areas of the fish, there is a marked difference between their distribution on the left and right sides. It is suggested that the lapperts may improve the directional sensitivity of the neuromasts, or alternatively, that their function may be purely protective. The possibility is discussed that variation in the size and form of the organs reflects functional differences.
Effects of bovine growth hormone on plasma FFA concentrations and liver, muscle and carcass lipid content in rainbow trout, Salmo gairdneri Richardson
Authors: Leatherland J. F. , Nuti R. N.
Published: January 2006

Bovine growth hormone (GH) given daily to rainbow trout, Sulmo gairdneri for 4 or 7 days at either 10.00 or 14.00 hours, significantly increased plasma free fatty acid (FFA) levels but had not effect on plasma cholesterol levels. Liver lipid content of the GH‐injected trout after seven injections was significantly lower than comparable controls in groups injected at both 10.00 and 14.00 hours. There were no apparent effects of GH on carcass or muscle lipid content although in fish injected and sampled at 14.00 hours there was a significant correlation between the number of injections and carcass lipid content.

Changes in hepatosomatic index (HSI), liver, muscle and carcass lipid content, plasma FFA and cholesterol concentrations and somatotrop activity during food‐deprivation for up to 60 days are described. Despite significant decreases in liver and muscle lipid content and increases in plasma FFA levels in food‐deprived fish, there was no concomitant change in apparent somatotrop activity.

The data are interpreted to indicate that although exogenous GH, in the doses used here, appears to stimulate mobilization of lipid reserves, particularly from the liver, there is no evidence that enforced changes in lipid reserves elicits a response of the endogenous somatotrop cells.
Population regulation in lake whitefish, Coregonus clupeaformis (Mitchill)
Authors: Jensen A. L.
Published: January 2006

Mechanisms that might compensate for changes in mortality are well known but documentation of their operation and determination of their relative capacities is difficult. In this study the potential of lake whitefish to compensate for fishing mortality is quantified using a conventional fishery stock assessment model. The mechanisms examined are proportion of females, fecundity, survival of eggs and larvae, decrease in age at maturity and growth. The change in each of these parameters necessary to maintain constant recruitment with increasing fishing pressure is determined. Decrease in age of maturity and increased survival of larvae and eggs have the greatest potential for compensation. The total capacity for compensation appears large even when the mechanisms are considered alone. A review of several lake whitefish population studies indicates a large variation in the vital statistics. There is a close relation between total mortality and growth. There is also a close relation between growth and age at maturity. The analyses indicate that increased fishing results in increased growth which then results in a lower age at maturity. This feedback mechanism enables lake whitefish to respond to changes in environmental conditions and on average to maintain a birth rate in balance with mortality.
A note on the growth‐rate and year‐class strength of bream, Abramis brama (L.), in three eutrophic lakes, England
Authors: Goldspink C. R.
Published: January 2006

In this study some comparative observations on the growth‐rate and year‐class strength of bream, Abramis brama, in three Shropshire‐Cheshire meres are given. All populations are exposed to variable recruitment. The occurrence of four strong year‐classes (1959, 1966, 1969,1973) suggests that climate is an important factor influencing spawning success. Water temperatures ≥16°C in July and August may be particularly important. All other intervening year‐classes are absent. The growth‐rate of bream in Tatton Mere and Ellesmere Mere is good (L∞= 541–561 mm) but comparatively poor (L∞= 448 mm) in Cole Mere. The significance of population density, food supply and parasitic infestation by Ligula intestinalis is discussed.
The biology of the Norway goby, Pomatoschistus norvegicus (Collett), on the west coast of Scotland
Authors: Gibson R. N. , Ezzi I. A.
Published: January 2006

The biology of the small offshore goby, Pomatoschistus norvegicus (Collett), was studied on the west coast of Scotland over a period of 19 months. Catches were highest in April‐June and lowest in August‐September. Virtually all growth takes place in the first two summers, very little in those fish surviving to a third summer. The fish mature after their first winter and the breeding season lasts from March‐July. Fecundity is linearly related to standard length and varies from approximately 1000–4000 eggs. Approximately 75% of fish survive their first breeding season but all die after their second. Males live slightly longer than females. The diet consists mainly of amphipods and small caridean decapods. The life history ofthe species is compared with other members ofthe genus.
Dietary digestibility and the influence of food components on gastric evacuation in plaice, Pleuronectes platessa L.
Authors: Jobling M.
Published: January 2006

Digestibility values are reported for a variety of diets fed to plaice. It was found that animal proteins were digested better than those from plant sources and the inclusion of indigestible carbohydrate (starch) led to a decrease in the efficiency of digestion and absorption of protein. The results of the digestibility trials were used to investigate the influence of various dietary parameters on gastric emptying and it was found that the gross energy content of the diet was the most important determinant of evacuation. The findings are examined in relation to published data on food intake by fishes and the implications discussed.
The effect of exercise on plasma cortisol and blood sugar levels in the rainbow trout, Salmo gairdnerii Richardson
Authors: Zelnik P. R. , Goldspink G.
Published: January 2006

Preliminary experiments were performed to determine the diurnal variation in cortisol, using trout which had been cannulated three days previously. These results indicated that cortisol levels were reasonably stable between 10.00 and 18.00 hours, thus permitting experimentation during this period without diurnal fluctuations masking the cortisol response. Uncannulated fish were exercised in a flume for 2 h at 1, 2.6 and 5 bl s‐1 and plasma samples taken from groups of five animals at 15, 30, 60 and 120 min after the start of exercise and at 1½, 12 and 24 h after the exercise ceased. The cortisol levels in all cases were elevated after 15 min, but the magnitude of the elevation increased with swimming speed. At 1 bl s‐1 the cortisol levels increased from 76.4 (± 20.4) to 129.2 (± 20.4) ng ml‐1 [mean (±s.d.)]. At 2.6 bl s‐1 the increase was from 72.4 (± 17.1) to 254.4 (± 34.4) ng ml‐1 and at 5 bl s‐1 the increase was from 69.5 (± 27.5) to 326.4 (± 39.0) ng ml‐1. The cortisol levels were stable over the exercise period and all groups recovered to baseline levels after 24 h, though the sample taken 12 h after the termination of exercise was elevated due to regular nocturnal increases in cortisol levels. There were no dramatic changes in blood sugar levels during and after exercise at 1 and 3.2 bl s‐1.
The physiological responses of blood during thermal adaptation in three freshwater fish species
Authors: Smit G. L. , Hattingh J. , Ferreira J. T.
Published: January 2006

Sarotherodon mossambicus, Cyprinus carpio and Salmo gairdneri were acclimatized at temperatures of 15, 20 and 25° C in order to study physiological responses of blood to temperature fluctuations in the laboratory. Cyprinus carpio exhibited the greater ability to survive at these temperatures. Sarotherodon mossambicus experienced osmoregulatory collapse at 15° C which also occurred in trout at 25° C. This was associated with acid‐base malfunction in the trout.
The effect of sodium and calcium concentrations on the hatching of eggs and the survival of the yolk sac fry of brown trout, Salmo trutta L. at low pH
Authors: Brown D. J. A. , Lynam S.
Published: January 2006

The effect of various external concentrations of sodium and calcium on the survival and hatching of brown trout, Salmo trutta, eggs at pH 4.5 was tested. A calcium concentration of approximately 10 ppm (500 μE l−1) enables freshly fertilized eggs to survive whereas eyed ova are tolerant of deionized water acidified by sulphuric acid with no other ions added. Concentrations of sodium and calcium of 1 ppm (44 and 50 μE l−1, respectively) are sufficient to ensure the successful hatching of eyed ova and subsequent survival of the alevins. At pH 4.5 hatching is prolonged by the alevins passing through a temporary encapsulated stage.
Long term studies on the population biology of two specie of eyefluke, Diplostomum gasterostei and Tylodelphys clavata (Digenea: Diplostomatidae), concurrently infecting the eyes of perch, Perca fluviatilis
Authors: Kennedy C. R.
Published: January 2006

Changes in the size of the infrapopulations of metacercariae of Diplostomum gasterostei and Tylodelphys clavata were studied in a small lake for a period of seven years in perch Perca fluviatilis. Tylodelphys clavata appeared in the lake at the commencement of the study and its subsequent population increase and changes were typical of those of a species recently established in a new habitat. Population size increased slowly at first, then rapidly, then declined again as population density approached equilibrium level. By contrast, the population size of D. gasterostei declined throughout the study. Two processes were responsible for the decline: a decrease in the proportion of fish carrying heavy infections which was continuous throughout the seven years and a dramatic decline in recruitment rate in young fish during the last two years. In earlier years recruitment rate had changed annually and changes in overall infrapopulation size had largely reflected the recruitment rate two years previously. It was concluded that these two processes were independent of each other and related to changes in the population density of other species of eyeflukes. The decline in the proportion of heavily infected fish was significantly negatively correlated with the increase in population density of T. clavata and the decline in recruitment rate in young fish was coincident with the appearance and infrapopulation increase of T. podicipina metacercariae in the eyes of young perch. It is suggested that these two species interact negatively with D. gasterostei and are currently partitioning the perch habitat between themselves.
Development of photobehavioural responses in young rainbow trout, Salmo gairdneri Richardson
Authors: Carey W. E. , Noakes D. L. G.
Published: January 2006

The photobehaviour of young rainbow trout was studied from the time of hatching to completed emergence using an artificial turf substrate incubation system. At all light energies tested, free‐embryos initiated a substantial downward movement and rates of fish descent did not appear to reflect the order of light energy levels. A nocturnal activity rhythm was established early in the downward phase. The occurrence of a rapid photoresponse shift 21 days after hatching coincided with the synchronous onset of emergence in all fish groups and the depletion of 85% (by volume) of the yolk reserve. Concurrent morphological observations indicated that the photoresponse change occurred when fish were about 25 mm long, and when paired and median fins were fully developed.
The humoral immune response of Salmo trutta L. and Cyprinus carpio L. exposed to heavy metals
Authors: O'Neill J. G.
Published: January 2006

Salmo trutta L. and Cyprinus carpio L. were exposed to low levels of waterborne heavy metals, 0.75 mg Ni dm‐3, 1.06mg Zn dm‐3, 0.29 mg Cu dm‐3 and 1.01 mg Cr dm‐3, at pH 7.83, water hardness 206.9 mg CaCO, dm‐3, and water temperature 15.5° C. During a 38 week exposure period, the humoral antibody response to MS2 bacteriophage was followed using a 50% viral neutralization assay (SD50) method. A suppression of the immune response was observed in fish exposed to the four heavy metals. Total suppression of the humoral antibody response was found only in C. carpio exposed to Cu or Cr, and these fish exhibited symptoms of acute toxicosis. The time for the primary blood clearance of live bacteriophage was increased in S. trutta exposed to the heavy metals, with the exception of Zn‐exposed fish, and in C. carpio exposed to Cu. Following the suppressed primary responses, the Ni‐exposed S. trutta and Zn‐exposed C. carpio exhibited an adjuvant‐like response to the second bacteriophage challenge.
Comparison of bottom trawl stock densities in the inner Kavirondo Gulf of Lake Victoria
Authors: Muller R. G. , Benda R. S.
Published: January 2006

A comparison of mean bottom trawl stock densities (kg ha‐1) from 19 UNDP 1969/70 tows, 69 EAFFRO 1975 tows and 167 fourth quarter FFRI 1977 tows in the inner Kavirondo Gulf of Lake Victoria showed the following changes from 1969/70 to 1977.

A reduction in mean stock densities for Bagrus docmac, Clarias mossambicus, Haplochromis spp., Protopterus aethiopicus, Schilbe mystus and Synodontis spp.

An increase in mean stock densities for Lates niloticus, Tilapia nilotica and T. variabilis.

No change in mean stock density for Labeo victorianus.

No T. esculenta or Mormyrus kannume collected in 1977.
Age determination and growth of luderick, Girella tricuspidata (Quoy and Gaimard), taken from Moreton Bay, Australia
Authors: Pollock B. R.
Published: January 2006

Age and growth patterns of luderick, Girella tricuspidata (Quoy and Gaimard), taken in the Moreton Bay net fishery are described. Scales have prominent annuli which are formed during the period May‐July. The mean body length is similar for males and females, except for age class III where female fish are significantly larger. This probably results from the early movement of faster growing females onto the fishing ground. The scale method and length‐frequency analysis both indicate that the variation in body lengths in each age class is large. The length‐weight relationship was obtained and relative condition factor was found to be highest in July which corresponded with the peak in gonosomatic index.
Some age related changes of adult rainbow trout, Salmo gairdneri Rich., peripheral erythrocytes separated by velocity sedimentation at unit gravity
Authors: Lane H. C. , Weaver J. W. , Benson J. A. , Nichols H. A.
Published: January 2006

Velocity sedimentation at unit gravity separated peripheral erythrocytes of adult rainbow trout according to age and size. The cells located at the top of the gradient contained numerous polyribosomes, few mitochondria and an essentially electronlucent nucleus. The cells at the bottom of the gradient no longer contained these cytoplasmic organelles and had an essentially electron‐dense nucleus. The middle of the gradient contained cells with either very few polyribosomes or cells devoid of this organelle.

The length, width and mean corpuscular volume (MCV) of the average cell increased and the width to length ratio decreased progressively from the top of the gradient to the bottom.

No Statistical significance could be determined in the changes of the mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) although they appeared to follow theoretical projections.

The use of haematocrit, red cell count, haemoglobin concentration, MCV, MCH and MCHC in assessing erythropoietic activity and the size and haemoglobin content of the maturing cell is discussed.
Cadmium toxicity to rainbow trout, Salmo gairdneri Richardson: a study of eggs and alevins
Authors: Woodworth J. , Pascoe D.
Published: January 2006

Cadmium toxicity to rainbow trout was evaluated at two cadmium concentrations (0.01, 0.10 mg1−1) and in water without added cadmium using eggs reared through the larval (alevin) phase to swim‐up fry. Exposure to 0.1 mg Cd 1−1 promoted premature hatching, retarded growth, increased rates of mortality and the occurrence of developmental abnormalities such as spinal curvature and blood clots. Three methods of holding the eggs and alevins during the toxicity test were compared. Hatching time and success, alevin mortality, growth and development were not influenced by the method of containment but of the three methods, a subdivided perforated box system proved particularly useful for monitoring the responses of specific animals throughout the toxicity test.
Body deformation in hatchery reared European sea bass Dicentrarchus labrax (L). Types, prevalence and effect on fish survival
Authors: Barahona‐Fernandes M. H.
Published: January 2006

The main types of body deformation found in sea bass, Dicentrarchus labrax (L), reared at the Centre Océanologique de Bretagne, from hatching to 100 days, are described and classified. Frequency of occurrence of each type of abnormality was followed in different batches of reared fishes. Results suggest that the majority of the abnormalities which appear in larval fish are lethal (from 0 to 40 days), while those which become apparent only in the post‐larval fish (after 40 days) do not interfere with survival.
Feeding activity and food habits of the shad, Ethmalosa fimbriata (Bowdich), in the coastal waters of Cape Coast, Ghana
Authors: Blay J. , Eyeson K. N.
Published: January 2006

The monthly feeding activity and food habits of populations of Ethmalosa fimbriata occurring in the sea and an estuary in Cape Coast, Ghana district were investigated during a 14‐month period. The juvenile fish, whose total length (T.L.) ranged from 5.3 to 14.7 cm, occur in the estuary and appeared to be more active feeders than the marine samples which measured 15.0–30.4 cm. The peak feeding activity in the marine population coincided with the onset of‘upwelling’ in the sea, which period is characterized by high salinities, decreasing temperatures and high zooplankton production. The species is primarily a plankton feeder. The stomachs of the marine samples contained mainly protozoa, crustacea, molluscan larvae and a considerable amount of detritus while the stomachs of the estuarine fish contained mainly phytoplankton, protozoa, sand grains and organic detritus. These observations have been discussed in relation to other reports on populations occurring along the West African coast.
Observations on the pancreas of the marine lizard fish Saurida tumbil (Bloch)
Authors: Shyamasundari K. , Kumari V. J. V. Raja , Rao K. Hanumantha
Published: January 2006

The pancreas in the marine lizard fish Saurida tumbil (Bloch) encircles the pyloric region of the gastro‐intestinal canal. The islets of Langerhans are ovoidal usually with a central cluster of β cells and the α cells in the periphery. In contrast to the β cells, the α cells have larger nuclei. Saurida tumbil is heavily parasitized by cestodes, nematodes and trematodes which infect the pancreas displacing or replacing much of the tissue.