bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects on a pike (Esox lucius L.) population of intensive fishing in a South Swedish lake
Authors: Otto C.
Published: January 2006

During seven years of intensive fishing, the average individual size of pike caught declined progressively until the last year of the study. The size structure of the population markedly changed. Three phases could be identified. 1. a high proportion of large fish, 2. a high proportion of small fish, and 3. equal numbers of large and small fish. The growth of the different year classes in their first year of life showed an increase from 180 to 220 mm.
The population density, growth rate and production of roach Rutilus mtilus (L.) in Tjeukemeer, The Netherlands
Authors: Goldspink C. R.
Published: January 2006

A method of estimating the population density of roach in Tjeukemeer (21.3 km2) using 20 529 introduced fin‐clipped fish is described. Fyke nets proved to be an effective method of sampling the population for marked fish during the spawning season. A total of 20 277 roach were processed during the recapturing period. The population density of roach (? 14 cm) was estimated to be 1 246 458. The growth rate of roach in the lake although relatively poor (von Bertalanffy's L ∞ for males and females, 22 and 26 cm respectively) for the species was similar to that recorded in three other Friesian lakes. The mortality rate of males was higher than that of females. Logarithmic length‐weight regression analyses showed that the value of the coefficient varied both within and between the sexes, that of females being higher (range 3.03–3.375) than that of males (range 2.76–3.254). Seasonal changes in the size of the coefficient were due to a disproportionate loss of gonad weight in larger fish. The fecundity of the population was comparatively high for the species.

The total production of the population was estimated to be 95 hg ha−1 of which 39 kg ha−1 was contributed by fry. In older (? IV) fish the production of females (12 kg ha−1) exceeded that (2 kg ha−1) of males, due to differences in their growth and mortality rates. The relatively poor performance of roach in Tjeukemeer, in terms of biomass and production was due to a scarcity of zoobenthos and competition from other species offish. There is no evidence either from this study or the literature that the productive potential of roach in lakes is high, even though macrophytes and detritus can be consumed in significant amounts.
Sub‐lethal effects of the organophosphate blackfly larvicide, Abate (temephos) on Sarotherodon mossambicus (Peters)
Authors: Adeney R. J. , Matthiessen P.
Published: January 2006

Sarotherodon mossambicus was exposed for up to 10 weeks to concentrations of Abate larvicide in excess of those produced during blackfly control in African rivers. Despite this treatment, several indicators of sub‐lethal poisoning, e.g. growth, plasma glucose, acetyl‐cholinesterase activity remained almost unchanged. A possible explanation for the low toxicity of Abate is given.
Metazoan parasites of whitefish Coregonus clupeaformis (Mitchill) and cisco C. artedii Lesueur from Southern Indian Lake, Manitoba
Authors: Watson R. A. , Dick T. A.
Published: January 2006

Metazoan parasites of whitefish Coregonus clupeaformis and cisco C. artedii from Southern Indian Lake, Manitoba were studied to reveal: species composition, differences with host age, sex, and location and season of capture. Whitefish hosted 19 species, 18 of which were also in cisco with generally lower intensity levels. Parasites exhibited definite patterns of abundance with host age and season, the primary causes being dietary and behavioural. No differences in parasite abundance existed between host sexes. Ranking of cisco parasites was significantly different between two sampling sites while whitefish parasites did not differ. Whitefish and cisco from sites 40 miles (64 km) apart had significantly different abundances of Tetracotyle intermedia but not Triaenophorus crassus. An increase in the abundance of copepod‐vectored cestodes with a concomitant decrease in abundance of amphipod‐vectored parasites is predicted after flooding and diversion.
Ventilation frequency compensation responses of three eurythermal estuarine fish exposed to moderate temperature increases
Authors: Burton D. T.
Published: January 2006

Ventilation frequency patterns of Trinectes maculatus, Morone americana and Leiostomus xanthurus were used to evaluate potential thermal stress after exposure to moderate temperature increases. Fish acclimated to 5°, 15° and 25° C were exposed to a 5°C T; fish acclimated to 30° C were exposed to a 2.5° C A T. Ventilation frequencies were measured at each acclimation temperature before the fishes were exposed over a 15‐min period to the increased temperatures. Ventilation rates were then measured at the elevated temperatures for the next 24 h. Significant increases in rate frequency occurred after the temperature increases in T. maculatus and M. Americana acclimated to 5°, 15° and 25° C and in L. xanthurus acclimated to 15°, 25° and 30°C. In general, rate frequencies increased as the temperature increased. Ventilation rates stabilized quickly at the higher temperatures and remained relatively constant throughout the remaining exposure period. Acclimated rate‐temperatures curves (R‐ T curves), acute R‐ T curves and Q10 temperature coefficients used to assess the significance of the changes in rate frequency and to compare the species in an ecologically meaningful way, showed that several adaptive types occurred among and between species. The Q,10's of the acute R‐ T curves, in most cases, were found to approximate those values derived for the acclimated R‐T curve. This suggests that the temperature increases had a negligible effect, that is, little or no thermal stress occurred.
A dense cell in the epithelium of the gill lamellae of the brook trout, Salvelinus fontinalis (Mitchill)
Authors: Morrison C. M.
Published: January 2006

A cell was found in freshwater brook trout which was similar to a chloride cell as it was mitochondria‐rich with an extensive tubular network, but differed in having a dark cytoplasm, large round vesicles in the apical cytoplasm, and large membrane‐bound bodies near the nucleus. The base of the cell was separated from the basement membrane by cytoplasm from another epithelial cell. The cell was more rarely found in trout adapted to brackish water and salt water.
Egg, fry and smolt production from salmon, Salmo salar L. and sea trout Salmo trutta L. reared entirely in fresh water
Authors: Jarrams Peter
Published: January 2006

For five years hatchery reared salmon and sea trout which had spent their entire lives in hatchery tanks were stripped each Autumn to investigate the survival of the resulting offspring.
Vitamin C deficiency in Channa punctatus Bloch
Authors: Mahajan C. L. , Agrawal N. K.
Published: January 2006

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.
Haematological assessment of the effects of the anaesthetic MS 222 in natural and neutralized form in three fresh water fish species: haemoglobin electrophoresis, ATP levels and corpuscular fragility curves
Authors: Smit G. L. , Hattingh J. , Burger A. P.
Published: January 2006

The effects of MS 222 and neutralized MS 222 anaesthesia on haemoglobin electrophoresis, erythrocyte adenosine triphosphate (ATP) levels and corpuscular fragility curves were studied in Cyprinus carpio, Sarotherodon mossambicus and Salmo gairdneri. Haemoglobin electrophoresis showed no significant intra‐species differences in the percentage composition of the various fractions for any concentration of MS 222 and neutralized MS 222 used. Significant interspecies differences were, however, still observed. ATP levels showed intra and interspecies differences ascribed to the response of the fish species to MS 222‐induced stress and not to actual changes in erythrocyte ATP concentrations. Differences were also observed in corpuscular fragility curves for all three species when using MS 222 or neutralized MS 222 compared to curves obtained without the use of the anaesthetic, but the mechanisms involved are not clear.
The annual reproductive cycle of the female lesser spotted dogfish, Scyliorhinus canicula L., and its endocrine control
Authors: Sumpter J. P. , Dodd J. M.
Published: January 2006

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.
Metechinorhynchus salmonis infection and diet in the river‐spawning whitefish of the Bothnian Bay
Authors: Valtonen E. T.
Published: January 2006

A total of 206 river‐spawning whitefish Coregonus lavaretus (L.) from the Bothnian Bay was investigated for food objects and acanthocephalans in the years 1975–78. The only acanthocephalan species found was Metechinorhynchus salmonis (Müller 1780), the total number of which was 1295.

The whitefish is shown to be highly susceptible to infection by M. salmonis, with as many as 88·9% of specimens infected in a sample in June 1978, although the mean intensity was only 8·9 parasites per host. The river‐spawning whitefish does not favour the intermediate host, Pontoporeia affinis, in its summer diet in the Bothnian Bay preferring to feed on eggs and molluscs, so that the incidence of M. salmonis infection decreases to 33·3% by the middle of summer. This is further reduced in the late summer by the fast associated with the migration to their upriver spawning grounds. The fact that the other acanthocephalan inhabiting the river‐spawning whitefish in the southern Gulf of Bothnia, Echinorhynchus gadi Müller, 1776 is not to be found in the Bothnian Bay population suggests that the fish captured in spring have remained in the Bothnian Bay throughout the winter.
Contribution to the biology of the redbanded perch, Ellerkeldia huntii (Hector), with a discussion on hermaphroditism
Authors: Jones G. P.
Published: January 2006

The presence of oocytes in the testes of several males indicates that the redbanded perch Ellerkeldia huntii exhibits protogynous hermaphroditism. All males appear to be secondary in origin; however the structure of the testes differ from most other protogynous serranids. In samples collected from the Poor Knights Is., New Zealand, males outnumbered females 2.7: 1 (n= 52). The numbers in each sex were equal until a length of 100–110 mm, after which the male proportion increased to 100%. The oldest female was aged 2+ years, whereas males were found as old as 5+ years. There were no colour differences associated with sex. The mean testes weight was only 7% of the mean ovary weight. Both sexes grew at the same rate. Observations during December indicated that although many individuals were solitary, some were paired. The larger individuals of pairs were males, the smaller females. Individuals foraged in the algal canopy on gammarid amphipods and mysid shrimps. The average range of movements was only 2·2 m2.
The population dynamics of Nemipterus marginatus (Cuvier & Val.) off Western Kalimantan, South China Sea
Authors: Pauly D. , Martosubroto P.
Published: January 2006

The following parameter values are derived for a West Kalimantan (West Borneo) stock of the threadfin bream, Nemipterus marginatus:

L
∞= 24·5 cm(L.T.), W∞= 210g, K = 0·42, t= ‐0·41 andM= 1·73.

Yield‐per‐recruit curves for N. marginatus are presented. Catch per hour of N. marginatus is very low, even in the area of highest density (=3·5 kg/h at 45 m depth). Single‐species exploitation of a stock of the type represented by N. marginatus appears unfeasible and the conclusion is reached that the traditional single‐species approach in fish population dynamics—such as exemplified in this paper—does not help in formulating rational exploitation schemes.
Haematological assessment of generally used freshwater fish blood anticoagulants
Authors: Smit G. L. , Hattingh J.
Published: January 2006

Heparin injection B.P., containing 0·5% phenol as preservative, disodium ethylenediamine tetra‐acetate (EDTA), trisodium citrate (TSC) and ammonium potassium oxalate (APO) were compared as anticoagulants for routine haematological investigations in Cyprinus carpio and Sarotherodon mossambicus. The acidic nature and haemolytic effects of EDTA and APO render them unsuitable for use with fish blood. TSC was required in higher concentrations (than heparin) for effective anticoagulation and this was undesirable for the determination of blood pH and pCO2 and certain other parameters. Several important interspecies differences in the reactions towards the anticoagulants are also reported. In general, heparin proved to be the anticoagulant of choice, although unsuitable for some assays.
An energy budget for juvenile thick‐lipped mullet, Crenimugil labrosus (Risso)
Authors: Flowerdew M. W. , Grove D. J.
Published: January 2006

A series of experiments were carried out to construct an energy budget for juvenile thick lipped mullet, Crenimugil labrosus Risso. A partial factorial experimental design was used to examine the effects of temperature, fish size and meal size on growth. The maximum ration that the fish were able to ingest completely per day was found to be 0·8, 1·4 and 2·3% wet body weight (b.w.) at 13,18 and 23°C, respectively. Ingested maintenance requirements (M.R.) were estimated to be 137, 205 and 288 cal fish‐1 day‐1 at 13, 18 and 23°C, respectively. At 18deg; C, M.R. varied as 25 W1.04 cal day‐1, where W= fish weight (g). Growth rate increased with increasing temperature. Maximal conversion efficiency was 21–24% and was achieved closer to the maximum ingested ration with increasing temperature.

The relationship between respiration rate and W at 18deg; C for 3‐20 g fish is described by: respiration rate (ml O2 h‐1) = 0·128 W0.976

The energy cost of apparent specific dynamic action at 18deg; C was found to vary between 5·1% and 23·6% of the calorific value of the ingested meal (1% wet b.w.), mean (± S.E.)=10·2 ± 2·0%.

Post mortem analyses of groups of fish fed 0·2, 0·8 and 1·5% wet b.w. meals showed a significant increase in total lipid and a significant decrease in water content with increasing ratio size. A negative correlation was found between body water content and total lipid (and calories).

The mean assimilation efficiency (±s.e.) for 5–10 g mullet at 18deg; C was 73·9 ± 3·6%.

The observations reported in this study were brought together to construct an energy budget for juvenile C. labrosus which was found to give a reliable prediction (within 10%) of energy demand and growth under the prevailing experimental conditions. Both gross (K1) and net (K2) growth efficiencies, based on energy values, increased with increasing ratio size up to satiation and were independent of temperature. The maximum values of K1 and K2 observed were 0·33 and 0·46, respectively. The third order efficiency (K3) appeared to be independent of temperature and ration size; mean values ranged between 0·66 and 0·84.
Effects of malachite green on leucocyte abundance in rainbow trout, Salmo gairdneri (Richardson)
Authors: Hlavek R. R. , Bulkley R. V.
Published: January 2006

Blood counts from more than 1000 young‐of‐the‐year rainbow trout, Salmo gairdneri (Richardson), were examined to determine if static exposure to malachite green at 1·35,13·5, or 21·0 mg/1 for 25–30 min or 42·0 or 72·0 mg/1 for 5 min caused chronic leucopaenia. The major changes in fish exposed for 25–30 min came during the first 24 h. After an initial lag of 3·4 h, total leucocyte‐thrombocyte counts in both treated and control fish rapidly declined. Recovery was essentially complete 1·4 days after exposure, and no leucopaenia was noted after 14 or 28 days. Thrombocytosis developed during the first 24 h in fish exposed to the higher concentrations. Lymphopaenia and neutrophilia also developed, but abated after the 4th post‐treatment day. Leucocyte numbers in control and exposed groups were virtually the same by the 14th day. The total leucocyte‐thrombocyte counts in fish exposed for 5 min declined after 24 h, but counts were not as depressed as those in fish exposed for 30 min.

Because leucocyte changes similar to those in exposed fish were evident in the controls in both experiments, we believe that the leucocyte changes in rainbow trout exposed to malachite green were a result of a nonspecific vertebrate stress syndrome, rather than of specific leucocytotoxic effect of this chemical.
Automated chemical analysis in fish health assessment*
Authors: Smith A. C. , Ramos F.
Published: January 2006

Before and after application of severe, debilitating stress, automated chemical analysis was applied to the skin mucus and the serum of four subsistence fish species: Chanos chanos, Mugil cephalus, Sarotherodon macrochir and S. mossambicus. Certain tests were found to reflect the stress effects. Future use of these tests may be on an individual, less expensive basis. Greater use of mucus for analysis is suggested because it is more accessible and less traumatically obtained than blood.
Identification of peripheral blood leucocytes of the dogfish (Scyliorhinus canicula L.) by electron microscopy
Authors: Morrow W. J. W. , Pulsford A.
Published: January 2006

Dogfish peripheral blood leucocytes were examined by electron microscopy after the injection of colloidal carbon. The cells were classified as lymphocytes, plasma cells, monocytes, thrombocytes and granulocytes. The granulocytes were further classified into four types according to the structure of their granules. Monocytes, thrombocytes and two types of the granulocytic cells were phagocytic.
Histological, histochemical and ultrastructural studies on the interrenal and chromaffin cells of the fathead minnow, Pimephales promelas Rafmesque
Authors: Yoakim E. G. , Grizzle J. M.
Published: January 2006

Light and electron microscopic examination of fathead minnow head kidneys revealed that the interrenal and chromaffin cells were intermingled and always closely associated with the cardinal veins and their tributaries. Histochemical tests for lipids in the interrenal cells were positive, and two types of chromaffin cells were indicated by chromaffin reactions. Interrenal cells contained abundant smooth endoplasmic reticulum and mitochondria with tubulo‐vesicular cristae, characteristic of steroid‐producing cells. Only one interrenal cell type was found. Two types of chromaffin cells were present with differences in cytoplasmic density and in types of granules. In light cells, adrenaline granules were most common, and in dark cells noradrenaline granules predominated.
Histopathological survey of male gonads offish from petroleum production and control sites in the Gulf of Mexico
Authors: Stott G. G. , Mcarthur N. H. , Tarpley R. , Sis R. F. , Jacobs V.
Published: January 2006

Testes, collected from 11 species of demersal and platform associated pelagic fishes, were examined microscopically for petroleum induced lesions. The fish were taken from 19 oil and gas production platforms and four control sites from the north‐central Gulf of Mexico, during two periods, spring and late summer. The status of the spermatogenic cycle at the time specimens were collected correlated well with the known spawning times for the respective species of fish with one exception. Histopathological evaluation revealed acidophilic granular cells, chromatophores, degeneration and focal leucocytic aggregations as the most prominent and abundant conditions in testes, with encapsulated cysts, protozoa and helminths being observed only rarely. No evidence of adverse effects on gonadal morphology was found.
The relationship between mosaic muscle fibres and size in rainbow trout (Salmo gairdneri)
Authors: Weatherley A. H. , Gill H. S. , Rogers S. C.
Published: January 2006

The dynamics of increase of the mosaic muscle in hatchery reared rainbow trout (2·3 to 61·3 cm fork length) are investigated. In trout <5 cm, all fibres are <40 μm in diameter; from 5 to 20 cm the diameter mode remains in the 0–39·9 μm class and there is some extension in range of diameter, thereby suggesting that mosaic muscle increase up to 20 cm is mainly by recruitment of new (small) fibres. When trout exceed 20 cm, mode of fibre diameter shifts to the 40–79·9 um class and fibres of larger diameter (> 100 μrn) appear but the subsequent overall fibre diameter frequency distribution changes little until 50 cm. Increase in muscle during the phase 20–50 cm seems partly attributable to increase in fibre diameter, but remains largely the result of recruitment of small fibres, although the mechanism of the latter process appears less clear than in fish of <20 cm. The recruitment of new fibres stops at 55 cm and further increase in mosaic muscle evidently depends upon the ability of existing fibres to increase in diameter. Possible means by which increasing muscle fibre diameter may limit the ultimate size which trout may achieve are discussed. A phenomenon of apparent reduction in fibre diameter in winter among fish 20–39·9 cm long is noted and its significance is considered.
A cytochemical, light and electron microscopic study of the eosinophilic granule cells in the gut of the rainbow trout, Salmo gairdneri Richardson
Authors: Ezeasor D. N. , Stokoe W. M.
Published: January 2006

The distribution, morphology and cytochemistry of the eosinophilic granule cells in the gut of the rainbow trout, Salmo gairdneri, were studied using light and electron microscopes. Granule cells were associated generally with the propria of the gut wall, the majority being arranged in a definitive layer, as a stratum granulosum. The cytoplasm of the eosinophilic granule cells contained numerous spherical, membrane‐bound, homogeneous electron‐dense granules, ranging from 0·1–1·3 urn in diameter. A portion of the cytoplasm located towards one pole of the cell was usually devoid of organelles other than ribosomes. Whatever their location, the eosinophilic granule cells were always associated with fixed connective tissue cells, referred to here as ‘ensheathing’ cells. Phospholipid, acid mucopoly‐saccharide and the activities of alkaline phosphatase, acid phosphatase, arylsulphatase and 5‐nucleotidase were demonstrated in the granules. It is hypothesized that the ‘ensheathing’ cells and eosinophilic granule cells constitute a part of the body defence mechanism.
Food habits of the mudskipper, Pseudapocryptes dentatus (Val.)
Authors: Sarker A. L. , Al‐Daham N. K. , Bhatti M. N.
Published: January 2006

The food habits of the mudskipper, Pseudapocryptes dentatus (Val.) ranging from 43 to 205 mm in total length collected from the mudflats at Fao estuary, Iraq were studied. A combination of numerical, frequency occurrence and gravimetric methods was used to analyse the stomach contents, both qualitatively and quantitatively. The fish was found to be a strict herbivore and a frequent feeder. It fed solely on phytoplankton dominated by benthic forms. Diatoms were the most important food item in respect of both numerical and frequency occurrence methods comprising about 84% of the total number of phytoplankton organisms. The types of phytoplankton that contributed significantly to the diet were, in decreasing order of importance, Pleurosigma, Navicula, Nitzschia, Synedra, Closteriopsis and Oscillatoria. Larger fish had consumed lesser amount of food, and there was usually a gradual decrease in consumption with increase in size. The mudskipper consumed food ranging from 1·3 to 10·5% of its body weight.
An analysis of the spawning behaviour of the Arctic grayling Thymallus arcticus (Pallas) with observations on mating success
Authors: Kratt L. F. , Smith R. J. F.
Published: January 2006

In the Fond du Lac River, adult male Arctic grayling defend territories on the spawning ground for up to 7 days. Females do not defend territories and do not exhibit agonistic behaviour during the breeding season.

The behaviour patterns exhibited by Arctic grayling during spawning are virtually identical to those exhibited by European grayling. The characteristic large dorsal fin of the grayling is of major importance during the spawning act.

Less than 50% of all spawning attempts proceed to completion. Interference by other fish or the improper orientation of one fish may result in one member of the spawning pair moving away. Most often however, incomplete acts are the result of the female moving away for no apparent reason. Females may initially ‘test’ males or may simply not be ready to spawn when approached by males. Homosexual spawning attempts were rarely observed.
The effect of methallibure and cyproterone acetate on the gonadotrophic cells, plasma androgen levels and testes of precocious 1+ male Atlantic salmon parr Salmo salar L.
Authors: Murphy T. M.
Published: January 2006

Developing 1+ male Atlantic salmon parr were treated with methallibure and cyproterone acetate. Both these drugs failed to prevent gonad maturation but they did decrease the gonadotrophic cell size and lower plasma androgen levels. These results are discussed in relation to previous studies. It is concluded that gonadotrophic cells control gonadal androgen production, that cyproterone acetate is a central inhibitor of gonadotrophin production and that these two chemical agents could be effective as chemosterilants if administered early in gonad maturation cycle.
Effect of body weight and temperature on the maximum daily food consumption of Gasterosteus aculeatus L. and Phoxinus phoxinus (L.): selecting an appropriate model
Authors: Wootton R. J. , Allen J. R. M. , Cole S. J.
Published: January 2006

The relationships between the maximum, daily food consumption, body weight and water temperature for the stickleback, Gasterosteus aculeatus L., and the minnow, Phoxinus phoxinus (L.), were studied. The two species occupy the same lakes in mid‐Wales, but differ in that G. aculeatus has a true stomach whereas P. phoxinus lacks a true stomach.

For both species, the relationship between food consumption (F) and body weight (W) could be described by the model: logeF=a + b logeW. The effect of temperature (T) could be incorporated in the form: logef=a+ b, loge W+b2logeT. These models were selected because they accounted for a high proportion of the variance in the dependent variable, and because an analysis of the residuals obtained after fitting a model showed no trends which would have signalled the inadequacy of the model.
Formation of lethal blood clots in fishes
Authors: Smith A. C.
Published: January 2006

Evidence is presented of lethal blood clot formation in fishes. A variety of factors commonly encountered under aquacultural conditions may generate such clots.
Response of the tench (Tinca tinca L.) to potassium nitrate enriched water
Authors: Demaël A. , Garin D. , Peres G.
Published: January 2006

When the tench (Tinca tinca L.) was exposed to a slight increase, 8.5 mg/l, in the potassium content of the water, metabolic and hormonal changes occurred which lasted more than four weeks. An initial phase of lipolysis was followed by a partial consumption of glycogen reserves, which in turn was followed by a phase of gluconeogenesis. Hyperglycaemia persisted throughout the experiment. The ion distribution in erythrocytes and liver changed relatively early; there was no observable change in water content. These changes are similar to those observed during the osmoregulation of fish.
Ecological changes in a lake fishery and their effects on a stunted roach Rutilus rutilus population
Authors: Linfield R. S. J.
Published: January 2006

Data for two sampling years (1969/70 and 1970/71) is presented to illustrate the changing composition, density and biomass of the macroinvertebrate fauna in a South Lancashire lake. Six faunal groupings are recognised for a non‐parametric analysis of the data and significance levels are given for the between‐station and between‐year differences recorded. The mean density of macroinvertebrates (1.2 mm mesh sieve) estimated for the lake as a whole increased by 28.5% in the second year (2519 m−2‐3237 m−2) whereas the estimated mean biomass in g m−2 increased by 86% wet weight (8.61−16.01) and 196% dry weight (1.74−5.15). Molluscs contributed substantially to the increased standing crop which was accompanied by increased development of macrophytes.

A comparative study of the diets of roach in two size groups in winter and summer is described. The variety of food items consumed was found to be greater than in a preliminary study in May 1969 and, for the roach sampled, the average quantity of food consumed per fish increased after the 1969/70 winter. The possible relationships between invertebrate standing crop, roach diet and previously reported changes in the growth of the roach are discussed and an explanation is offered concerning the sequence of biological changes observed in the lake.
The immune response of the brown trout Salmo trutta to lipopolysaccharide
Authors: Ingram G. A. , Alexander J. B.
Published: January 2006

Brown trout produced high molecular weight, thermostable, dithiothreitol sensitive, non‐precipitating, complement‐fixing antibodies and agglutinins to lipopolysaccharides after intramuscular injection with adjuvant. Antibodies were first detected on Day 14 and reached maximum titres after 56 to 63 days when a single injection was given. When either a second or a third injection was administered maximum titres occurred 34 to 40 days after the injection. After each injection the titres increased significantly, and the protein concentration of the sera was significantly decreased. In cellulose acetate electrophoresis experiments those bands which migrated in the β‐ to γ‐globulin regions were increased.

Antibody‐secreting and antigen‐binding cells were detected on Days 8 and 4 respectively and maxima were reached between Day 16 and Day 18. The number of cells per 106 lymphoid cells was higher in the spleen than in the kidney.
Migration and capture of pink salmon, Oncorhynchus gorbuscha Walbaum in Finnmark, North Norway
Authors: Bjerknes V. , Vaag A. B.
Published: January 2006

Pink salmon transplanted to the north Atlantic coast from the Soviet Union reached a peak in 1973, both in the Soviet Union and in Finnmark. Pink salmon catch statistics were compiled in 1977 for the inshore coastal and fjord areas of Finnmark from the atlantic salmon fisheries conducted locally and outside the coastal limits of Finnmark. The survey indicated a total sea catch of 12 800 specimens or 18 450 kg in Finnmark in 1977. The pink salmon reached the coast in the western regions of Finnmark during the first half of July, after which the main migration continued eastwards along the coast. The migrations into the western fjords were few, with half the total inshore catch captured in the most eastern fjord, Varangerfjord.
A scanning electron microscope study of the pseudobranchs of two marine teleosts
Authors: Mattey D. L. , Morgan M. , Wright D. E.
Published: January 2006

The pseudobranchs of bass, Dicentrarchus labrax L., and grey mullet, Liza ramada (Risso) (Mugil capito), were examined in the scanning electron microscope (S.E.M.). Both pseudobranchs appeared gill‐like in situ but the S.E.M. revealed their gross morphology to be different. The bass pseudobranch was a‘free’ pseudobranch, having separate lamellae along the filaments, with areas of fusion on the leading edges of some lamellae, whilst the mullet pseudobranch was ‘semi‐free’ since the secondary lamellae were fused over a large area and only free along their trailing (opercular) edge where the chloride cells were situated. The surface of the epithelial cells presented different patterns of microridges and microvilli depending on their position in the pseudobranch. Three types of cell opening were found at the cell surface, belonging to chloride cells, mucous cells, and possibly rodlet cells. The S.E.M. observations were correlated with those of transmission electron microscope (T.E.M.) studies.
Myxosoma microspora n. sp. (Myxosporidia: Protozoa) parasitic in the gills of Mugil cephalus L.
Authors: Narasimhamurti C. , Kalavati C. , Saratchandra B.
Published: January 2006

A new histozoic species of myxosporidian, Myxosoma microspora n.sp., infecting the gill filaments of Mugil cephalus is described. Cysts measuring 0.5–1.0 mm in diameter were found attached to the gill filaments. Spherical or slightly oval, spores 4.8–5.2 μm in diameter, were present and possessed a thin outer mucous envelope which appeared as small conical protuberances at the ends of the equatorial axis. Polar capsules were pyriform in shape, equal in size and measured 1.6–2.0 × 1.0–1.2 μm; the polar filaments were 22–28 μm in length. There was a bean‐shaped sporoplasm measuring 3.5 × 1.5 μm. No iodine vacuole was detected when the parasite was stained with Lugol's iodine.
Reproduction in the greenback grey mullet, Liza subviridis (Valenciennes, 1836)
Authors: Chan E. H. , Chua T. E.
Published: January 2006

This paper presents data on the reproductive biology of Liza subviridis, a little studied mullet species. The fish is heterosexual, exhibiting external fertilization. Six maturity stages can be macroscopically identified in the testes and seven in the ovaries. The macroscopic changes in the gonads are manifestations of histological changes occurring in the development of sperm cells and oocytes. First sexual maturity is attained in the length ranges of 9.5–11.5 cm and 10.5–11.5 cm in male and female fish respectively. The fecundity for fish measuring 10.3–13.9 cm in standard length ranged from 40 000–145 000 eggs. The relationship between fecundity (F) and length (L) can be represented as: F= 1.9044 L4.2998. The spawning duration in L. subviridis is restricted to a short and definite period, with all ripe ova being released within a single spawning act. A pronounced spawning season can be detected to extend from June to November. However, during off‐seasons, some spawning also occurs. The correlations between spawning, rainfall and air temperature is discussed.
A note on the spaciousness of the cavity around the brain of the basking shark, Cetorhinus maximus (Gunner)
Authors: Stott F. C.
Published: January 2006

A description, including measurements, is given of the brain and cranial cavity of the basking shark, Cetorhinus maximus. The significance ofthe small brain and its enclosure by a relatively large cranial cavity in a thick cartilagenous skull is discussed.
The histology and calcification of regenerating scales in the blackspotted topminnow, Fundulus olivaceus (Storer)
Authors: Frietsche R. A. , Bailey C. F.
Published: January 2006

The regenerating scale and tissues comprising the scale pocket of Fundulus olivaceus were examined microscopically at specific intervals. Scale removal resulted in a thickening of the epidermis which persisted through the early stages of regeneration. This thickening was due in part to the appearance of columnar basal cells which divided producing cells that became mucous cells and squamous cells. The scale regenerated as a relatively large plate of bone which first appeared between layers of scleroblasts on the floor of the scale pocket and then grew producing circuli and radii. By the fourth day of regeneration, calcium was observed in the cytoplasm of the scleroblasts and at randomly distributed foci in the osseous portion of the scale. The osseous layer was completely calcified by 15 days of regeneration.
On the back‐calculation of fish lengths; modifications and extensions to the Fraser‐Lee equation
Authors: Duncan K. W.
Published: January 2006

The basis of the widely used Fraser‐Lee equation for back‐calculating lengths is discussed and a new algebraic method of calculating the constant is given. This algebraic method gave satisfactory results for the back‐calculation of European perch (Perca fluviatilis L.) lengths in Lake Mahinerangi, New Zealand. Errors in back‐calculation are much higher than regression techniques would suggest. Causes of the Rosa Lee phenomenon are discussed and methods are given for detecting it and compensating for it using a computer program, BACKCALC.
The effect of the anaesthetic benzocaine hydrochloride on red cell fragilities in Cyprinus carpio
Authors: Ferreira J. T. , Smit G. L. , Schoonbee H. J.
Published: January 2006

The effects of benzocaine HCl and neutralized benzocaine HCl anaesthesia were studied on osmotic fragilities in Cyprinus carpio. The differences observed in corpuscular fragility are ascribed to temperatures and pH effects. Further evaluation of such effects are required.
A comparison of methods used for the separation of fish lymphocytes
Authors: Blaxhall P. C.
Published: January 2006

A comparison is made of methods currently used in separating mammalian lymphocytes from whole blood when adapted for use with fish blood. The methods give good results but do require minor modifications. The use of Ficoll‐Paque, although requiring greater expertise, did result in obtaining good recovery rates of lymphocytes in a viable condition. The separation of cells without the addition of agents other than culture medium, while resulting in good yields of lymphocytes, was much more variable and did not result in the separation of such a pure cell line. The other methods compared were found to be unsuitable for fish blood.
Vascularization of the lateral muscle of some elasmobranchiomorph fishes
Authors: Totland G. K. , Kryvi H. , Bone Q. , Flood P. R.
Published: January 2006

The vascular bed of the locomotor muscle in three shark species and in a holocephalan is investigated and the capillarization quantified by morphometrical methods. The red muscle fibres of Scyliorhinus, Galeus, Etmopterus and Chimaera are well vascularized having respectively 25, 18, 23 and 5 per cent of fibre surface covered by capillaries. The white muscle fibres of Scyliorhinus are far better vascularized than white muscle fibres of Galeus, Etmopterus and Chimaera. The fibre surface covered by capillaries are 9, 1.4, 0.2 and 1.3 per cent, respectively. The intermediate muscle fibres have a vascular supply between that of red and white muscle fibres in all species. If the capillary contact area to the fibres are related to the mitochondrial volume, more similar values are obtained for the vascular supply to all fibres types in all animals. This parameter indicates that there is a definite relation between the capacity of the oxygen transport system and the aerobic metabolic machinery.
The distribution of perch, Perca fluviatilis L. throughout their first year of life in Llyn Tegid, North Wales
Authors: Coles T. F.
Published: January 2006

The distribution of 0+ perch, Perca fluviatilis L., in a lacustrine environment is described. Since the perch occupied many different habitats within the ecosystem throughout their first year of life a number of sampling techniques were required to sample the population. The early larvae and post larvae were planktonic and their distribution could be related to the effect of the winds. As soon as the young perch developed fins an inshore migration began. Virtually all the fish had completed this migration by the time they reached a total length of 19 mm but the majority of the population reached the shoreline before attaining this size. During June and August the 0+ perch formed large shoals around the shoreline especially in sheltered areas in water less than 3 m deep. At the end of August probably in response to falling lake temperatures the perch fry migrated into deeper water.
First record of a notacanth leptocephalus; a benthopelagic capture in the slope waters off Ireland
Authors: Merrett N. R.
Published: January 2006

A metamorphosing notacanth leptocephalus is reported from the Porcupine Sea‐Bight, southwest of Ireland. It is described and compared with juvenile Notacanthus chemnitzi and N. bonapartei from the same area. The adult diagnostic features evident are shown to conform with N. chmnitzi. The posterior location of the anus in the leptocephalus relative to the post‐metamorphic condition is noted. The ecological significance of the benthopelagic occurrence of this exceptional larva in slope waters is considered.
Haematological evaluation of the anaesthetic benzocaine hydrochloride in the freshwater fishCyprinus carpioL.
Authors: Ferreira J. T. , Smit G. L. , Schoonbee H. J.
Published: January 2006

The effects of anaesthetization with different concentrations of benzocaine hydrochloride (BH) and neutralized benzocaine hydrochloride (NBH) were studied on the haematology ofCyprinus carpio.Due to its acidic nature and resultant effects on aquarium water, BH produces haemoconcentration effects with disturbances in acid‐base function. The use of NBH, whereby water quality effects were drastically reduced, improved the general haematological profile. In contrast, haemodilution resulted when blood was sampled without the use of an anaesthetic agent.
Food and growth of hatchery‐produced chinook salmon, Oncorhynchus tshawytscha (Walbaum), in landlocked Lake Purrumbete, Victoria, Australia
Authors: Cadwallader P. L. , Eden A. K.
Published: January 2006

One‐year old hatchery‐produced chinook salmon were released into landlocked Lake Purrumbete, Victoria, in 1976 and specimens were recaptured at three‐monthly intervals during the next two years. Examination of their stomach contents revealed that fish, particularly Galaxias maculatus, formed the bulk of the food of the salmon. Other items eaten included Amphipoda, Cladocera, Ostracoda and Decapoda (Crustacea), Odonata, Coleoptera, Diptera, Trichoptera and Hemiptera (Insecta) and Gastropoda (Mollusca). At the end of their first three months in the lake the salmon had increased 85% in length and over 670% in weight. After two years in the lake, their length was 582 mm and their weight was 2.73 kg. Growth rate was lowest in spring when the relative amount of fish in the stomach contents was at its lowest and there was a greater diversity of food types in the dict.
Vitellogenesis and trace metals in a marine teleost
Authors: Shackley S. E. , King P. E. , Gordon S. M.
Published: January 2006

The concentration and loss of copper and cadmium over the spawning period in relation to vitellogenesis in Blennius pholis L. and the implications for the viability of the developing embryo are described and discussed.
Observations on the blood of the Chinese silver carp Hypophthalmichthys molitrix (Valenciennes)
Authors: Pieterse J. J. , Smit G. L. , Van Vliet K. , Schoonbee H. J. , Hattingh J.
Published: January 2006

The ranges and mean values for several blood parameters of adult specimens of Hypophthalmichthys molitrix were determined in order to establish a standard haematological profile for future investigations. Several significant correlations were established, the most important being between haematocrit, haemoglobin and erythrocyte counts. The data are discussed in relation to the general biology of this species.
Densities and swimbladder development of juvenile American eels, Anguilla rostrata (Lesueur) as related to energetics of migration
Authors: Hickman R. A.
Published: January 2006

Glass eels and elvers of the American eel were negatively buoyant. Those adapted to sea water were more dense (1.072 ± 0.001 g cm−3) than those adapted to fresh water (1.061 ± 0.001 g cm−3). Adaptation to fresh water increased relative body water content, but did not account for the observed decrease in total body density. Histological examination revealed the presence of a potentially functional swimbladder in the glass eels, although this hydrostatic organ did not becomegas‐filled until after freshwater residency had occurred. Calculation of lift as used in the selective tidal transport mechanism suggests that hydrodynamic compensation for horizontal swimming during the estuarine phase of migration is energetically adaptive.
Acclimation‐induced changes in toxicity of arsenic and cyanide to rainbow trout, Salmo gairdneri Richardson
Authors: Dixon D. G. , Sprague J. B.
Published: January 2006

Pre‐exposure of rainbow trout, Salmo gairdneri to sublethal levels of arsenic or cyanide, resulted in significant changes in the incipient lethal levels of the respective toxicants. Fish gradually increased their tolerance to arsenic (as arsenite) by 47% during a three week preexposure to 0.22 of the incipient lethal level. Mean whole‐body aresenic concentrations increased from 2 to 27 μg g−1 dry weight during the first week, then decreased to a stable level of 15 after two and three weeks. Fish decreased their tolerance to cyanide (as HCN) by 32 and 15% after one and two weeks of pre‐exposure to 0–35 of the incipient lethal level. This initial sensitization disappeared after three weeks. Renal tubular parenchymatous oedema was observed after two and three weeks of cyanide pre‐exposure. Neither arsenic nor cyanide affected growth at these levels of pre‐exposure.
A comparison of bottom trawl catch rates in the Kenya waters of Lake Victoria
Authors: Benda R. S.
Published: January 2006

A comparison of mean trawl catch rates (kg/h) from 128 collections in 1969 and 1970 and 63 collections in the fourth quarter of 1976 showed the following changes.

A reduction in mean total catch rates at all seven depth intervals from 1970–1976.

Reductions of 6.8, 6.1, 3.9, 6.2, 1.5, 2.9 and 5.9 times from shallow to deepest 10m depths respectively.

No Tilapiu esculenfu were collected in 1976.

The trend that emerges shows a marked reduction in mean total trawl catch rates in the Kenya waters of Lake Victoria which should sound a note of caution for proponents of a mechanized fishing industry.
Colour change and visual cues in the sand flathead, Platycephalus arenarius (Ramsay and Ogilby)
Authors: Douglas W. A. , Lanzing W. J. R.
Published: January 2006

This study investigates cryptic coloration and the phenomenon of colour change in the sand flathead, Platycephalus arenarius (Ramsay and Ogilby), a shallow‐water marine species. The chromatophore configurations of the dorsal integument are described and the responses to a range of artificial backgrounds studied. Certain visual cues used by this species in colour change are deduced, and the existence of a linear relationship between the shade of the integument and that of the background is proposed.