Frederick Beamish

• Professor (Associate) at Burapha University

Stream degradation increases with high anthropogenic activity and climate variability, while declines occur in biodiversity. However, few studies have been undertaken on tropical waterways, a major impediment to biodiversity conservation. The present study was conducted on 95 relatively pristine small streams in Eastern Thailand with 10 reasonably...

Seasonal change inferred to climate change inevitably influences Critical thermal maximum (CTmax) of riverine fishes. In this study, we investigated CTmax as thermal tolerance for four common riverine fishes, i.e., Danio regina, Channa gachua, Rasbora caudimaculata and Mystacoleucus chilopterus, in the Kwae Noi river system in western Thailand. The...

Tropical freshwaters support an immense diversity of fishes and invertebrates but are understudied in comparison to temperate systems. This is especially true of headwater streams, as only a small number of studies has assessed the trophic dynamics underpinning food web structure in these streams. We used stable isotopes of carbon, nitrogen and hyd...

Understanding gonadal development in lampreys is complicated by their complex life cycle, the long period during which their gonads remain histologically undifferentiated, and their lack of any close living relatives. This chapter synthesizes the available information related to lamprey sex determination, sex differentiation, sexual maturation, and...

Carbon and nitrogen stable-isotope ratios were compared of fin and muscle tissue from 15 fish species collected from seven headwater rivers in eastern and western Thailand. In addition, two-source stable-isotope mixing models were used to derive estimates of each fish's reliance on allochthonous and autochthonous energy based on fin and muscle tiss...

Gill, liver and kidney tissue in Oreochromis niloticus underwent histological alterations during a 90-day chronic exposure to metal complex dark green azo acid dye; anionic surfactant oil or mixtures of the two substances. Gill alterations following these chronic exposures included primary lamellae lifting, epithelial hypertrophy, secondary lamella...

Critical thermal maximum (CTmax) related positively with acclimation temperature between 20.0°C and a maximumthat varied with the four species; Devario acrostomus, Mystacoleucus chilopterus, Barbodes binotatus and Rasbora caudimaculata, between 30.0 and 35.0°C. Highest and lowest CTmax were 39.0±1.0°C at 35.0°C acclimation for B. binotatus and 34.6...

Fish species were collected by electrofishing from 96 sites, representing 79 species, in lightly exploited rivers in western Thailand. Significant chemical and physical environmental factors associated with species numbers and total fish abundance were identified using multiple linear regression. Total abundance correlated negatively with water dep...

Garra fluviatilis is a new species described herein from the Kwai Noi, Mae Khlong basin, in the Thong Pha Phum District of Kanchanaburi Province in western Thailand. It is diagnosed by the following combination of morphological characters: well developed upper lip with unculiferous papillae, mottled pigmentation pattern, a pleated papilliferous fol...

Environmental associations favorable for benthic loaches within the families Nemacheilidae and Balitoridae were the objective of this study that was conducted at 160 sites within five river systems: Southeastern, Mekong, Chao Phraya, Maeklong and Peninsula, in the central region of Thailand. Loaches in this study represented seven genera and 19 spe...

An 8-week feeding trial was conducted to examine effects of wheat naturally contaminated with Fusarium mycotoxins (deoxynivalenol, DON 41 mg·kg −1) on growth performance and selected health indices of red tilapia (Oreochromis niloticus × O. mossambicus; initial weight = 4.3 g/fish). Five experimental diets were formulated by replacement of clean wh...

Diets were estimated from stomach contents and the MixSIR model using stable isotope values for five co-existing and abundant benthic fishes in relation to potential prey from a riffle habitat in a tropical river in eastern Thailand. Collectively, aquatic insects were of greatest dietary importance based on stomach contents and, except for one fish...

Schistura crocotula, a new species, is described from Khanan River, Prachuap Khiri Khan Province, southern Thailand. It is distinguished from other species of Schistura in Southeast Asia by a depressed head; 6-11 dark brown bars against an orange background; the first bar is the widest, two bars are under dorsal fin; interspaces are often indistinc...

Abstract The experiment was conducted on Nile tilapia Oreochromis niloticus to determine the lethal concentration of textile metal complex dark green azo acid dye in the presence and absence of anionic surfactant oil during an exposure period of 96 hr. The design consisted of four treatments: control, metal complex dark green azo dye, a mixture of...

A new species of Schistura is described from the Kwai Noi, Mae Khlong basin, in the Thong Pha Phum District of Kanchanaburi Province in western Thailand. The species is distinguished from all other species of Schistura by a uniform dusky brown color pattern without marks on the dorsum or side of body and with many conspicuous supplementary neuromas...

Sexually dimorphic characteristics are described for four species of Schistura from the Mae Khlong basin and peninsular Thailand. Males of S. mahnerti have a suborbital flap and rows of unculi on the upper surfaces of the pectoral-fin rays. Females of S. mahnerti have a suborbital groove. None of the morphological measurements differ significantly...

We examined foraging adaptations and diet among dominant fishes within two species-rich riffle habitats in Thailand headwater rivers during the early and late portions of the dry season. All species exhibited diel temporal variations in feeding activity. Some species fed principally during daylight, while others fed mainly during darkness. Feeding...

Diversity of freshwater fishes is spatially heterogeneous but, for the most part, the reasons remain poorly understood in Thailand. This review attempts to promulgate factors linking freshwater fishes and habitats, particularly morphological, physiological and ecological, drawing on principles and information from elsewhere but with the focus being...

The influence of sublethal concentrations of total copper on the appetite, growth, and proximate body composition of rainbow trout (Salmo gairdneri) held in hard water (365 mg/liter) was measured over a 40-day interval. The initial response of trout exposed to concentrations of copper ranging from 0.0 to 0.3 mg/liter (the 96-h LC50 was 0.25–0.68) w...

Groups of sea lampreys (Petromyzon marinus) of 10–90 g initial weight were held at temperatures of 1–20 °C for 30 days and allowed to feed ad lib. on white suckers (Catostomus commersoni). Increases in water temperature and in lamprey size caused the rate of host mortality to increase in agreement with observations that mortality in the Great Lakes...

Observations on vertical patterns of migration were made on the Nova Scotian and Gulf of St. Lawrence fishing banks. The commercially important demersal species, cod, haddock, and redfish, were usually closely associated with bottom by day and moved off after dark. While this is the general pattern, variations occurred. Thus, on cloudy or dull days...

Endurance was determined in relation to swimming speed and temperature for Atlantic cod, Gadus morhua Linnaeus, redfish, Sebastes marinus (Linnaeus), winter flounder, Pseudopleuronectes americanus (Walbaum), and to swimming speed at 8 C for longhorn sculpin, Myoxocephalus octodecimspinosus (Mitchill), sea raven, Hemitripterus americanus (Gmelin), a...

Haddock were subjected to strenuous muscular exertion in capture by otter trawl. In each of seven tows, blood lactic acid followed a similar pattern with peak levels between 90 and 240 min after capture. Generally, in surviving fish, lactic acid subsided to preexercise levels within 12 hr after capture. Tagging fish immediately after capture had no...

In Atlantic cod, muscle glycogen was reduced by about 50% at moderate swimming speeds and over 80% at higher speeds. Muscle glycogen for a given swimming speed was generally lower after 30 min exercise than after 15 min exercise. During the 8-hr period after strenuous exercise, muscle glycogen increased but remained well below the level for unexerc...

Oxygen consumption of Tilapia nilotica (L.) at 25 C was measured for various swimming speeds at salinities of 0, 7.5, 11.6, 22.5, and 30‰.Oxygen consumption for a given swimming speed and salinity increased linearly with weight when expressed on a double logarithmic grid. Slopes of regression lines relating oxygen consumption and weight were less t...

When Tilapia nilotica was acclimated to temperatures of 15–35 C and salinities of 0–30‰ in a vertical gradient tank, maximum temperature preferenda occurred at acclimation temperatures of 20 and 25 irrespective of salinity. Preferenda declined as acclimation temperature was increased above 25 C and, except at 0 and 7.5‰, declined as acclimation tem...

In unexercised Atlantic salmon (Salmo salar), plasma osmolality and Na+ and Ca++ concentrations varied little at temperature-salinity combinations of 3, 5, 10, and 14 C and 0, 15, and 30‰. Plasma K+ tended to increase with increase in temperature. Cl− values were similar at 5 and 14 C. At 1 C and 0‰, lower plasma osmolalities indicated reduced abil...

Throughout the year, algae were the most frequently encountered organisms in the gut of larvae of landlocked and anadromous sea lamprey (Petromyzon marinus) and American brook lamprey (Lampetra lamottei). Relative abundance of organisms in the gut of both species was similar and did not change with length of larvae. In general, relative abundance o...

The incidence of attack by the sea lamprey (Petromyzon marinus) was studied on freshwater teleosts of similar and different size. Splake (Salvelinus namaycush × Salvelinus fontinalis), carp (Cyprinus carpio), and white suckers (Catostomus commersoni) were attacked a significantly greater number of times than lake whitefish (Coregonus clupeaformis),...

The logarithm of standard oxygen consumption of adult Petromyzon marinus increased linearly with the logarithm of weight at each of 5, 10, and 15 C. The proportionate change in standard oxygen consumption for a given change in temperature was independent of size, the mean regression coefficient being 0.949. Standard oxygen consumption for a sea lam...

The mean lengths of adult males and females of the sea lamprey (Petromyzon marinus) migrating into the Humber River from Lake Ontario in each of the years 1968–1972 varied little, and were similar to those found by other workers in recently established populations in the upper lakes. In contrast, the ratio of males to females, which lay within the...

Oxygen consumption attributable to apparent specific dynamic action (SDA) was measured in relation to feeding level and body weight in largemouth bass, Micropterus salmoides, forced to swim at 1.7 body lengths/s (BL/s). Apparent SDA rose curvilinearly with ration size, the coefficient increasing with weight of bass. For a ration of fixed percent bo...

A stochastic dynamic model was developed to evaluate the simulated and empirical interactions between sea lampreys (Petromyzon marinus) and two lake trout (Salvelinus namaycush) population structures, one without and the other with previous lamprey predation.An arithmetic increase in lampreys induced a geometric decline in trout, which was dependen...

Interannual growth variations were compared among neighbouring populations of lake sturgeon (Acipenser fulvescens) and white spruce (Picea glauca), white pine (Pinus strobus), and red pine (Pinus resinosa). Measures of growth were obtained by removing long-term trends from widths of rings in the hard tissues of both aquatic and terrestrial organism...

After 11 mo in the laboratory, significantly more sea lamprey, Petromyzon marinus, larvae from the Chippewa River, Michigan, metamorphosed in an ambient temperature regime (3 ± 2 animals∙tank−1) compared with a fixed 21 °C temperature (0 animals); photoperiod and food deprivation did not have detectable effects on the incidence of metamorphosis. Me...

We used annual increments in the pectoral fin rays of lake sturgeon (Acipenser fulvescens) to assess growth synchrony. We based our decision criteria on correlation among individual chronologies developed from samples collected in the Saskatchewan River, Saskatchewan, and Lake St. Clair and the Mattagami River, Ontario. Initially, correlations amon...

Anadromous Pacific lamprey, Lampetra tridentata, typically construct nests and reproduce in lotic environments. In the summer of 1984, Pacific lamprey were observed spawning in shallow lentic water in two regions of the Babine Lake system, British Columbia. Nests were subject to wave action but an obvious unidirectional flow was not observed.

Larval mountain brook lamprey, Ichthyomyzon greeleyi, were collected from Bent Creek in western North Carolina to provide information on the age structure of the population and to validate statolith banding patterns as an aging technique. Larvae were injected with oxytetracycline in winter and held in the laboratory at seasonally adjusted temperatu...

Juvenile lake trout, Salvelinus namaycush, of similar size were fed one of three isocaloric diets, each differing in protein and lipid content. Oxygen consumption and swimming performance were measured in a recirculating water flume at intervals throughout the 70-d feeding trials (10 °C). Swimming speed was increased by stepwise velocity increments...

Trophic dynamics between lake trout (Salvelinus namaycush) and cisco (Coregonus artedii) were examined in a set of 10 northwestern Ontario lakes that ranged in conductivity by nearly an order of magnitude. Diets revealed the possibility of interspecific competition for invertebrate prey prior to initiation of piscivory by lake trout at approximatel...

Nitrogen and energy loss in fecal and nonfecal excretions by lake trout, Salvelinus namaycush (171–268 g), varied directly with dietary protein (40 and 50% dry weight) and inversely with lipid (10 and 20%) among four test diets. Diets high in lipid increased dry matter digestibility resulting in reduced nitrogen and energy loss in feces. NH3-N cons...

Sex ratios were determined for 20 populations of southern brook lamprey larvae, Ichthyomyzon gagei, collected from throughout much of their range in the southeastern United States. Ratios varied between 9 and 49% males. Differential mortality was an unlikely factor, as sex ratios were similar among age groups within each population. Environmental s...

Hypolimnetic trophic interactions were examined among lake trout (Salvelinus namaycush), cisco (Coregonus artedi), zooplankton, and macroinvertebrates in six northwestern Ontario lakes varying sevenfold in conductivity. Faster growth and larger body size of lake trout in high-conductivity lakes were associated with larger meal sizes, earlier entry...

Morphological, biochemical, and behavioral criteria, from samples collected from 1969 to 1971, showed that metamorphosis in P. marinus is of a relatively short duration. In an analysis of sequential catches during 1971, the first external signs of transformation were observed only in samples caught between July 12 and 26, illustrating the marked sy...

The sea lamprey (Petromyzon marinus) in the western Atlantic Ocean adjacent to North America is usually found within a depth of 200 m between latitudes of 30 and 53°. Spawning size lampreys have been recorded in 116 rivers between 32 and 48° latitude. The upstream spawning migration which may extend to several hundred kilometres, takes place betwee...

Oxygen consumption and uptake of waterborne methylmercury were measured for rainbow trout (Salmo gairdneri) forced to swim at sustained swimming speeds at 10 and 20 °C. The concentrations of methylmercury used (< 8 μg Hg∙L−1) did not affect oxygen consumption. The log of mass specific oxygen consumption increased linearly with relative swimming spe...

Characters useful for the identification of ammocoetes of lampreys found in British Columbia were verified by rearing ammocoetes through metamorphosis to specifically identifiable adults. We developed a key that employs new as well as some previously published features. We showed that published descriptions previously thought to be characteristic o...

We measured the efficiency of uptake of waterborne methylmercury relative to oxygen consumption for rainbow trout, Salmo gairdneri, in hard or soft water and during exposure to sublethal concentrations of mercuric chloride or zinc sulphate. The relative efficiency of methylmercury uptake in soft water was more than double that measured in hard wate...

Oxygen uptake attributable to apparent heat increment (AHI) in rainbow trout, Salmo gairdneri (10–15 g), induced to swim at was influenced by dietary energy intake and diet composition. Twelve balanced diets were tested, with protein levels of , 40, 48 and 60% and lipid levels of , 15, and 23% factorally combined. Diets supplying 34% protein and 23...

Fishways have traditionally been designed to provide safe passage for jumping fish and only recently have nonjumping species been considered. Concern over dwindling populations of lake sturgeon, Acipenser fulvescens, has focused attention on fishway designs that accommodate its swimming abilities. The objective of this study was to derive a model t...

Seasonal and size-related changes in proximate composition and energy of lake sturgeon were examined for a population from the northern portion of the species' geographic distribution. Condition factor increased with total length of lake sturgeon but did not differ among seasons. Whole body and muscle water, protein, lipid, inorganic, and energy co...

American brook lamprey, Lampetra appendix, and physical habitat information were collected during the summer from 10 second-order streams throughout much of the species' geographical distribution. Larval density, several descriptors of larval length composition, particle size distribution, hydraulic conductivity, porosity, organic content, current...

Agnathans are the only vertebrates without a thymus, yet lampreys possess putative lymphocytes whose responses parallel those of T cells in gnathostomes. The phylogenetically conserved Thy-1 antigen is often associated with the thymus, thymocytes, and T cells. An immunohistochemical study, using commercial anti-rat brain Thy-1.1 antiserum and an im...

The standard rate of oxygen consumption for brook and brown trout acclimated to 10 °C and exposed to natural daylight varied seasonally. For male brook trout, standard oxygen consumption increased from a low of 30 mg/kg hour during March and April to a maximum of 63 mg/kg hour during the late fall spawning period. The standard rates of the females...

Standard oxygen consumption was determined in relation to various partial pressures of oxygen for eastern brook trout at 10° and 15 °C, and for carp and goldfish at 10° and 20 °C. Two conditions of oxygen acclimation were compared. In one case acclimation was to air saturation while in the other acclimation was to each of the partial pressures of o...

Oxygen consumption was determined in relation to spontaneous activity and standard metabolism estimated by extrapolating the values to zero activity, Standard oxygen consumption was determined in relation to different partial pressures of carbon dioxide and oxygen for brook trout. Salvelinus fontinalis (Mitchill), at 10 °C, and carp, Cyprinus carpi...

Organic dry weight, protein N, lipid, and energy of contents in the stomach of largemouth bass decreased curvilinearly with time after a meal of lake emerald shiners, Notropis atherinoides. Time to evacuate the stomach increased with ration size. The proportionate change in time for a given percentage of gastric emptiness was independent of ration...

Assimilation efficiency of energy in juvenile harp seals was 92.5–95.0% of gross energy intake when fed Atlantic herring and 72.2% when fed shrimp. Faecal energy losses increased directly with intake. Metabolizable energy (ME) ranged from 85.5 to 88.7% of gross energy intake for a diet of herring. Urinary energy losses increased directly with appar...

Assimilation efficiency of gross energy (±SD) in juvenile and adult grey seals fed Atlantic herring was 92.6 ± 2.1%. Metabolizable energy (ME) was 82.7 ± 4.8% of gross energy intake. Faecal energy losses increased directly with energy intake and urinary energy losses increased directly with apparent digestible nitrogen intake. Maintenance energy re...

Diatom colonies were established on glass slides in Rouge River and Wilmot Creek before application of the lamprecide 3-trifluoromethyl-4-nitrophenol and their abundance was monitored for 21 and 55 d, respectively, after treatment. A total of 105 species of diatoms were identified from the Rouge River; of these, 23 were particularly abundant. Sampl...

Approximately 20 to 25 individuals of the Irrawaddy dolphin (Orcaella brevirostris) were found in one school in the Bang Pakong estuary, Thailand. The estuary covers an area of 135 km 2 . The habitat characteristics of the Irrawaddy are waters which are rather turbid and with a depth of 2-5 metres. Within the school, it was found that individuals t...

Total length-weight regressions on logarithmic transformed data are provided for 33 species, with 26 apparently being first estimates. All regressions are highly significant with slope values between 2.5720 and 3.4436. Slopes and intercepts of length-weight regressions did not differ significantly with location for each of three species. Preservati...

The lengths, weights and condition factors of young adult lampreys caught feeding on Gaspereau, Alosa pseudoharengus. Shad, Alosa sapidissima, and White suckers, Catostomus commersoni, in the lake-like extensions of the St. John River system during May, suggest that many lampreys do not feed in the nine to ten months following the initiation of met...

Calcium oxalate (CaOx) can be crystallized in several forms and morphologies. In this research, we investigated the crystallization of CaOx by the precipitation of calcium chloride and sodium oxalate in the absence and presence of roselle (Hibiscus sabdariffa L.). The effects of roselle concentration and [Ca 2+ ]/[C 2 O 4 2-] concentration on CaOx...

Samples of larvae, metamorphosing and adult representatives of anadromous Petromyzon marinus were collected from rivers in New Brunswick to provide data on aspects of its life cycle. The proportional length of the prebranchial, branchial, trunk and tail regions changed throughout larval life, with the third of these lengths being greater than in La...

Total relative abundance of fish and species richness at 95 sites in small rivers varied significantly with physicochemical factors. Species richness was negatively and positively related with pH and dissolved oxygen, respectively. Relative abundance varied inversely with discharge and ambient ammonia and, directly with depth, substratum, ambient o...

Adaptive cluster sampling (ACS) provides researchers with an alternative technique to estimate the abundance of rare or spatially clustered organisms, but its application in field investigations has been limited to relatively few studies. We used ACS to estimate parameters of a spatially autocorrelated population of larval sea lampreys, Petromyzon...

Balitorids were collected, by electrofishing, from small rivers across central Thailand between October 2000 and March 2004. Total balitorid abundance for the 18 species averaged 3·8% of the cumulative total for all fishes. Balitorid species numbers and abundance varied directly with elevation to c. 400 m, substratum particle size and ambient silic...

Freshwater fishes from a diverse array of 11 families, some dominated by marine species and others containing only a few species, were collected by electrofishing from 84 locations on small rivers in central Thailand and their abundances related to habitat characteristics. Abundances were largest for Channa gachua, Dermogenys pusillus and Mastacemb...

This investigation was conducted in an area of oil spill along the east coast of Thailand to examine the relations among cytochrome P450 1A activity in liver and PAHs in the bile of the tonguefish and petroleum hydrocarbons in the sediments. PAH sediment concentrations in the reference and oil spill areas were 5.03 +/- 0.42 and 0.21 +/- 0.043 micro...

AChE was measured in brain, liver, muscle and gill tissues of hybrid catfish (Clarias macrocephalus x Clarias gariepinus) exposed to a sublethal concentration of an organophosphate, chlorpyrifos and a carbamate, carbaryl, for 4 days. AChE inhibition increased rapidly with insecticide concentration. Relative inhibition of AChE was higher in larger f...

Cyprinids were sampled, by electrofishing, from 159 sites on small rivers in four major watersheds across central Thailand. Total abundance, estimated by the depletion method, varied directly with water velocity and, inversely with discharge while species richness varied inversely with habitat width and, directly with ambient oxygen and alkalinity....

Oxygen consumption of juvenile rainbow trout (5 g at 13°C) at moderate swimming speeds did not change significantly when infected with Cryptobia salmositica. However, significant reductions of as much as 44% of the maximum aerobic scope for activity and 24% of the critical swimming speed were observed when the parasitaemia reached a maximum of 57.6...

This study examines the sequential pattern of bacterial colonization and the sequential development of branchial lesions during typical outbreaks of bacterial gill disease (BGD) among four groups of commercially reared rainbow trout fingerlings, Oncorhynchus mykiss (Richardson). During a 5-month monitoring regime, prior to the onset of natural outb...

The range of branchial lesions associated with bacterial gill disease (BGD) in rainbow trout, Oncorhynchus mykiss (Richardson), was investigated through the ultrastructural examination of 23 separate outbreaks of the disease condition within commercially reared stocks. Diseased branchial tissues had a large and diffusely distributed monomorphic pop...

Rainbow trout (Salmo gairdneri) were held at a ked ration and activity regime and were exposed to a number of copper, pH and hardness combinations. Growth rate, appetite and gross conversion efficiency were determined over three consecutive 10-day periods of exposure. Growth rate was most affected during the first 10 days of exposure and partial or...

Rainbow trout were exposed to sublethal concentrations of Permethrin in water (0.09, 0.18 and 0.35 μg l−1) and in food (85, 180 and 350 μg kg−1 dry diet) in 20–0 day experiments. Histological changes in the gills included epithelial separation or necrosis, mucus cell hyperplasia, clubbing of epithelial cells or hyperplasia and fusion of adjacent se...

Estimates were made of the growth rates and proximate body composition of larval and metamorphosing P. marinus (L.) collected at various times of the year from Shelter Valley Creek, Lake Ontario. Analysis of length-frequency data indicates that the average duration of larval life was 6 years, with metamorphosis occurring predominantly in the length...

Apparent SDA was defined as the energy expenditure associated with the ingestion of a meal. In the present study apparent SDA was equated to an increase in oxygen consumption above the postabsorptive level subsequent to the ingestion of a meal. The energy cost for physically processing a meal, mechanical SDA, was equated to the oxygen uptake associ...

While science has made extensive progress to enhance our understanding of the growth of sturgeon and paddlefish in North America there is still a great deal that remains unknown. This lack of knowledge, especially that pertaining to wild organisms, is likely to continue as numbers dwindle from human insults on populations and habitat. The value of...

Atlantic salmon (Salmo salar) was once native to Lake Ontario, however, its numbers rapidly declined following colonisation by Europeans and the species was extirpated by 1896. Government agencies surrounding Lake Ontario are currently undertaking a variety of studies to assess the feasibility of reintroducing Atlantic salmon. We released hatchery-...

We examined the physical habitat of nest sites chosen by hatchery Atlantic salmon, Salmo salar, in a recovery program for this extirpated species in Lake Ontario, Canada. We compared the sites used by these captive bred fish to a set of random locations in a wide range of available habitats. Compared to random locations in the stream, the nest site...

Morphological characteristics and intestinal content were analysed for five species of coexisting freshwater fishes in Thailand: Rasbora caudimaculata, Schistura desmotes, Dermogenys pusillus, Xenentodon cancila and Monopterus albus(all found in riffle habitats in Thai streams). Rasbora caudimaculata, S. desmotes and D. pusillus fed predominantly o...

Longitudinal and temporal distribution was determined for 40 species of cladocerans at sites between the headwaters and mouth of Khayeng Stream, a relatively pristine waterway in western Thailand. Cladocerans were confined mostly to lentic areas and abundance between April and September was highest in September, largely a consequence of a floodplai...

Abstract – We examined the effects of two salmonid species, chinook salmon (Oncorhynchus tschwaytscha) and brown trout (Salmo trutta), both exotic species to Lake Ontario, on behaviour and foraging success of juvenile Atlantic salmon (S. salar), a native species to Lake Ontario, in an artificial stream. We found that both exotic species have effect...

Gonadal biopsies of sea lamprey Petromyzon marinus larvae (118·5–142·5 mm) were examined quantitatively and categorized as ovaries, presumptive testes, or atypical gonads. Subsets of larvae were then killed 1, 2, 4, 8, 16 and 52 weeks following surgery at which time each larva was matched with its biopsy, and its gonad re–examined for quantifiable...

We examined the diet of Channa limbata, a predatory fish from western Thailand, in relation to mass, mouth and body morphology and intestine length. The cluster analysis we performed on the prey-specific abundance values of the dietary items yielded four size-classes based on diet. There was a shift from detritus and smaller benthic invertebrates i...

The fish described in this paper were sampled from four watersheds in the Eastern, Chao Phraya, Peninsular, and Maeklons regions of central Thailand, between the years 2000-2004. A total of 124 species were captured from 160 stream and river sites, using an electrofishing method. 33 of these species were captured in the Eastern region and 42 in the...

Modern North American sturgeons and paddlefish are the result of 100 million years of evolution. Once an integral part of aboriginal culture, their numbers were decimated by overfishing and habitat destruction during the past two centuries. This book details the extensive science aimed at helping these remarkable species recover from the brink of e...

Gonads of premetamorphosing larval (PML), transforming (TL) and newly metamorphosed (juvenile) sea lampreys (JL) (Petromyzon marinus) were incubated in vitro with tritiated pregnenolone ([(3)H]P(5)), progesterone ([(3)H]P(4)), and androstenedione ([(3)H]A(4)) to identify the major products of steroidogenesis in early developmental stages. Reverse-p...

We measured the growth and mortality characteristics of northern pike (Esox lucius) in a northern Ontario river and examined the influence of flow on these characteristics by comparing our measurements with those estimated for a lake at the same latitude based on published studies. Pike ranged in total length from 229 to 784 mm, in mass from 70 to...

Fish captured by electrofishing from lotic reaches within and immediately outside the North Selangor blackwater peat swamp forest were placed into six assemblages. Species richness varied among assemblages from 7 to 32 but most species were not regular members of an assemblage. Swamp water was low in dissolved oxygen and buffering capacity and high...

Use of the selective lampricide 3-trifluoromethyl-4-nitrophenol (TFM) and other alternative control methods (such as barriers which prevent sea lampreys, Petromyzon marinus, from reaching their spawning grounds) have succeeded in reducing sea lamprey abundance in the Great Lakes to a level that permits the survival of economically-valuable fish spe...

The main purpose of the study was to identify the principal gonadal steroids synthesized by male and female sea lampreys, Petromyzon marinus. To achieve this, we used high performance liquid chromatography to separate the steroids in the serum of sexually mature animals, and to separate the steroids produced by gonadal tissue incubated in the prese...

Abstract – Non-native species can have substantial impacts on successful restoration of native species. Here, we examined effects of chinook salmon (Oncorhychus tshawytscha), an exotic species introduced to Lake Ontario to enhance recreational angling, on reintroduced Atlantic salmon (Salmo salar) in a Lake Ontario tributary stream. Field enclosure...