bluuebunny/crossref_metadata_2025 huggingface dataset:
Tunnel-Digging in Mud by Newly-Settled American Lobsters, Homarus americanus
Authors: Berrill Michael , Stewart Robert
Published: April 2011

Newly settled lobsters (stages IV through VIII) appear well adapted to living on mud. In aquaria with mud substrates, they dig U-shaped tunnels by means of a combination of plowing and fanning activities.
An Improved Ekman-Type Grab
Authors: Burton W. , Flannagan John F.
Published: April 2011

An improved Ekman-type grab with top lids, which are locked open during descent and weighted to keep them closed during retrieval, is described. In comparative trials with a Wildco Tall 6-inch Birge-Ekman, the new grab collected significantly more chironomids and oligochaetes, and about the same number of the heavier and larger animals such as gastropods, sphaeriids, trichopterans, etc. The new design also improves the versatility and mechanical reliability of the grab.
Nutritional Factors in the Biochemical Pathology of Corynebacterial Kidney Disease in the Coho Salmon (Oncorhynchus kisutch)
Authors: Wedemeyer Gary A. , Ross A. J.
Published: April 2011

The influence of diet ingredient on the morbidity and biochemical pathogenesis of corynebacterial kidney disease was investigated using juvenile coho salmon (Oncorhynchus kisutch) fed the Abernathy dry ration made up with either corn gluten or cottonseed meal (isoprotein, isocaloric substitution). Evaluation of incidence of infection, pituitary activation and aspects of carbohydrate metabolism, acid-base balance, renal function, and hematopoietic activity showed that the actual disease incidence was about the same for both diets but the nonspecific stress of infection was more severe in fish fed the corn gluten.Discriminant function calculations combining four physiological parameters gave a probability of 0.86 for successfully diagnosing infected fish on the basis of these blood chemistry tests.
Age, Growth, and Maturity of Round Whitefish (Prosopium cylindraceum) From the Leaf River, Ungava, Quebec
Authors: Jessop B. M. , Power G.
Published: April 2011

Data on the age, growth, and maturity of round whitefish (Prosopium cylindraceum) from the Leaf River, Ungava, generally confirmed or extended observations previously reported for two other Ungava rivers. On the basis of back-calculated lengths, Leaf and Koksoak River round whitefish had similar growth rates except that the Leaf River specimens showed an atypical decrease in the second year. Scale increments in the year of the study suggested that the growing season extended from mid-June to mid-September. Both sexes matured at ages 4–6, but proportionately more females than males were mature at ages 4 and 5. Females matured at lengths between 190–199 mm and 240–249 mm while males matured at lengths 10–20 mm greater, as in the Koksoak River. Apparently, not all mature females spawned annually.
A Submersible Spectroradiometer and Data Acquisition System
Authors: Duval W. S. , Brown T. J. , Geen G. H.
Published: April 2011

A submersible light meter that measures and records irradiance versus wavelength over the range 400–750 nm is described. A data acquisition system coupled to the radiometer permits collection and processing of large numbers of field observations. The incident spectrum is determined by an optical system incorporating a wedge interference filter monochromator and photodiode. Recorded data are converted to spectral irradiance (μw cm−2 nm−1) at 5-nm intervals by applying standard lamp calibration and immersion factor corrections. Minimum detectable radiation varies from 0.05 to 0.016 μw cm−2 nm−1 depending on wavelength. Response of the meter is not affected by temperature in the range of 3.5–23.0 C and angular dependence of the light collector follows Lambert’s Cosine Law for incident angles less than 55° from the vertical.Changes in the spectral composition of incident light with depth are demonstrated for two lakes.
Influence of Appearance of Prey and Satiation of Predator on Food Selection by Northern Pike (Esox lucius)
Authors: Coble Daniel W.
Published: April 2011

Northern pike (Esox lucius) were put in tanks with fantail and regular-tail goldfish (Carassius auratus) or with goldfish of different colors. Physical appearance of prey did not affect the pike’s feeding. In experiments in plastic pools four species of fish were exposed to predation by northern pike that were satiated or deprived of food for either 2 or 4 weeks. The pike always selected carp (Cyprinus carpio) and fathead minnow (Pimephales promelas) over green sunfish (Lepomis cyanellus) and bluegill (L. macrochirus).
Speed, Stamina, and Muscles in Fishes
Authors: Gatz Jr. A. John
Published: April 2011

A new interpretation is offered of some of the classic experiments on swimming in fishes done by Bainbridge. It is suggested that certain aspects of his results can be explained best by recognizing the discrete functions of the red and white muscle fibers in fishes. Persons investigating swimming performance of fishes are cautioned to bear in mind these distinctions in future work.
Toxicity of TFM (Lampricide) to Six Early Life Stages of Rainbow Trout (Salmo gairdneri)
Authors: Olson L. E. , Marking L. L.
Published: April 2011

The lampricide TFM (3-trifluoromethyl-4-nitrophenol) was tested against the following life stages of rainbow trout (Salmo gairdneri): green eggs, eyed eggs, sac fry, swim-up fry, fry, and fingerlings in four water hardnesses (12, 44, 170, and 320 mg/liter as CaCO3). The eyed-egg stage was one of the most resistant stages tested, and the sac-fry stage was one of the least resistant. Increased water hardness decreases toxicity to all stages. The LC50’s range from 0.532 mg/liter to 40.0 mg/liter depending upon life stage, water hardness, and duration of exposure. The margin of safety for coexisting species exposed to TFM ranges from 3.2 to 4.1 in natural waters. The margin of safety for early life stages of rainbow trout and larval lamprey under controlled laboratory conditions ranges from 4.2 to 12.2. Therefore, all six early life stages of rainbow trout are safe in minimum lampricidal concentrations of TFM.
Biology of White Whales (Delphinapterus leucas) in Western Hudson Bay
Authors: Sergeant D. E.
Published: April 2011

The number of white whales inhabiting western Hudson Bay is about 10,000. In July and early August the herds are concentrated in river estuaries at 57° to 60° N, but a migration in mid-August through September takes them to between 62° and 66°N. Wintering occurs in the western part of the Bay. In the estuary of the Churchill River feeding, mainly on fish, is not heavy and the herds are believed to enter the river estuaries in this region for reproduction as much as feeding. Further north in late summer feeding is heavier and changes towards a diet of decapod Crustacea. It is believed that two dentinal layers are laid down in the teeth each year, each layer consisting of one opaque and one translucent zone of dentine, with the translucent material laid down during periods of reduced feeding. These may occur either at an autumn and a spring migration or during a summer fast at calving time and during winter deprivation. Females attain sexual maturity at 8–13 (mean 10) growth layers and males at 16–18 layers, i.e. at supposed mean ages of 4–7 (5) and 8–9 years. The skin loses all trace of grey color at 18–22 layers. Maximal duration of life is about 50 layers or a supposed age of 25 years in both sexes. The sexes are probably about equal in numbers. Gestation lasts 14 months and lactation about 20 months. Overlap of pregnancy and the previous lactation is infrequent so that calving occurs about once in 3 years. The annual crude birth rate is estimated at 0.12. Estimation of the maximal number of births from counts of corpora luteal scars is complicated by the frequent presence of accessory corpora lutea and luteinized follicles, estimated at about 32% of the total. The mean maximal number of scars retained in the ovaries during a female’s reproductive lifetime is 14.5. The full reproductive lifetime, on the basis of two growth layers per annum, is 20 years. Thus the mean ovulation rate is about 0.7 per annum. Reducing the number of scars by 32% gives 0.5 true (fertile) ovulations per annum, which would indicate a reproductive rate of one pregnancy in 2 years, and a maximal number of 10 pregnancies in a full reproductive lifetime
The Use of 17 α-methyltestosterone for Promoting Weight Increases in Juvenile Pacific Salmon
Authors: McBride J. R. , Fagerlund U. H. M.
Published: April 2011

The effect of 17 α-methyltestosterone feeding on the weight of juvenile coho salmon (Oncorhynchus kisutch) and on the weight, length, and condition factor of juvenile chinook salmon (O. tshawytscha) was determined. Significant increases in weight and length but not in condition factor were noted at all levels of steroid tested. Coho fed rations containing 10 mg/kg of the steroid for 42 days showed a 29% net weight gain and chinooks fed 1 mg/kg of the hormone for 84 days exhibited a 17% net weight gain over the respective control groups.A marked thickening of the skin was noted in the coho retained on diets containing 10 and 50 mg/kg of the steroid. This alteration was most evident in those fish fed the highest concentrations of hormone for the longest period.In the coho, diets containing 10 or 50 mg/kg of the hormone evoked marked degenerative changes in the testes. Less drastic alterations were noted in the testes of the chinooks retained on the 1 mg/kg test ration for 84 days. No apparent structural changes were noted in the ovary of any of the test fish.
Behavior of the Planktonic Coelenterates, Sarsia tubulosa, Phialidium gregarium, and Pleurobrachia pileus in Salinity Discontinuity Layers
Authors: Arai Mary Needler
Published: April 2011

The behavior of Sarsia tubulosa (M. Sars 1835), Phialidium gregarium (L. Agassiz 1862), and Pleurobrachia pileus (O. F. Müller 1776) was investigated in chambers where salinity discontinuity layers could be established. Sarsia tubulosa and P. pileus aggregated at the layer for salinity discontinuities of as little as 2‰ although P. gregarium showed more variable behavior. This aggregation was shown to be due to an active response rather than passive flotation in the density barrier set up when low salinity water is placed over high salinity water. Sarsia tubulosa also showed increased fishing activity in any column containing a discontinuity layer compared with any homogeneous control column.
Observations on Distribution and Intraspecific Variation in Pigmentation Patterns of Odontocete Cetacea in the Western North Atlantic
Authors: Mercer M. C.
Published: April 2011

This paper comprises sight records for nine species and morphometries, color descriptions, and miscellaneous notes on the food and parasites of seven species of small odontocetes observed from West Greenland to Florida 1967–72. Of interest are the first western Atlantic extralimital record of Monodon monoceros, first Newfoundland records of Stenella coeruleoalba, and extralimital records of Delphinapterus leucas from Newfoundland. Intraspecific variability is described in the pigmentation patterns of Phocoena phocoena.
Investigation of Iodothyronine Binding to Plasma Proteins in Brook Trout, Salvelinus fontinalis, Using Precipitation, Dialysis, and Electrophoretic Methods
Authors: Falkner N. W. , Eales J. G.
Published: April 2011

Over 95% of 3,5,3′-triiodo-L-thyronine (T3) or L-thyroxine (T4) up to added hormone levels of at least 5 μg/ml, were precipitated by trichloroacetic acid with plasma proteins of brook trout using a semimicro method. Hormone recovery in the precipitate was higher than with precipitation methods previously used on fish plasma.Equilibrium dialysis showed over 99% of T4 or T3 bound to plasma proteins of trout up to added hormone levels of at least 5 μg/ml.Acrylamide gel was superior to paper and particularly cellulose polyacetate as a medium for electrophoretic separation of proteins responsible for binding T3 or T4. In vitro studies at high hormone levels showed that T3 and T4 bound mainly to prealbumin-like proteins. In vivo studies at more physiological levels showed T4 bound to fast prealbumin-like, albuminlike, and β-globulin-like proteins, while T3 bound to slow prealbumin-like and probably the same albumin-like and β-globulin-like proteins as T4.
Interrelation of Feeding Behavior and Accommodative Lens Movements in Some Species of North American Freshwater Fishes
Authors: Sivak Jacob G.
Published: April 2011

Accommodation, in response to atropine and pilocarpine, was measured retinoscopically and photographically in seven species of freshwater fishes. These species accommodate in varying magnitudes and directions by means of lenticular movements. The common white sucker (Catostomus commersoni) and the goldfish (Carassius auratus) accommodate mainly in the lateral direction (5–10 diopters), whereas the common bluegill (Lepomis macrochirus), northern rock bass (Ambloplites rupestris), and yellow perch (Perca flavescens), exhibit a larger accommodative ability which occurs primarily along the rostral–caudal axis (up to 40 diopters in the yellow perch). The rainbow trout (Salmo gairdneri) accommodates equally along the lateral and rostral–caudal axes. No accommodative response occurs in the northern black bullhead (Ictalurus melas). Reference to the diets and feeding habits of the above species suggests that the magnitude and principal direction of accommodation is a response to the visual demands of a particular life history.
New and Previously Described Species of the Genus Lyrodiscus (Monogenoidea: Ancyrocephalinae) from Fishes of the Great Lakes
Authors: Dechtiar Alex O.
Published: April 2011

The following species of the genus Lyrodiscus are recorded from Great Lakes fishes, and comparatively or originally described: Lyrodiscus rupestris n.sp., from Ambloplites rupestris of lakes Ontario, Erie, and Huron: L. longibasus from Pomoxis nigromaculatus and P. annularis from lakes Erie and Ontario. Lyrodiscus seminolensis from Lepomis macrochirus of lakes Erie and Ontario, and L. minimus from Ambloplites rupestris of Lake Ontario. The genus Lyrodiscus is emended.
Preliminary Energy Budget of the Ninespine Stickleback (Pungitius pungitius) in an Arctic Lake
Authors: Cameron J. N. , Kostoris J. , Penhale P. A.
Published: April 2011

In a study of energy flow through the stickleback population of Ikroavik Lake, northern Alaska, oxygen consumption was related to weight and temperature by the equation Log Y = −2.795 +.823 W +.094 T where Y = μl∙min−1O2 uptake; W = log weight, mg; and T = temperature. Growth was fairly rapid, with fish reaching about 21 mm at the end of the first year, 42 mm by the second, and 65 mm by the third. No older fish were found. Food was primarily chironomid larvae and zooplankton, especially copepods and Daphnia. Estimates of daily ration were calculated from growth and metabolic data (23.4 cal/day for a 30-mm fish at 10 C), gastric clearing rate determinations (12.2 cal/day at 15 C), and laboratory feeding experiments (24 cal/day at 10 C). Population distribution was uneven. Higher densities were reached in early summer, up to 74 g/m2 in the marginal marsh areas. For specified days when temperatures were accurately known, an energy budget could be calculated for the population in given areas, including estimates of population biomass, respiration, growth, ration, and growth efficiency.
Effect of Temperature and Feeding Regime on the Specific Growth Rate of Sockeye Salmon Fry (Oncorhynchus nerka), with a Consideration of Size Effect
Authors: Shelbourn J. E. , Brett J. R. , Shirahata S.
Published: April 2011

Specific growth rates were obtained for sockeye fry (Oncorhynchus nerka) acclimated to four temperatures and fed excess ration over a 36-day period, starting at an initial weight of 0.4 g. The rates were 2.2 (5 C), 5.1 (10 C), 6.5 (15 C), and 6.1 (20 C)% wet weight/day. Continuous feeding for 15 hr/day at 20 C produced a significantly greater growth rate than feeding to satiation three times daily (P < 0.05). The growth rates are compared to those obtained for larger sockeye, determined in earlier experiments.
Growth Temperature Requirements and Lower Lethal Temperatures for Juvenile Smallmouth Bass (Micropterus dolomieui)
Authors: Horning II W. B. , Pearson R. E.
Published: April 2011

Maximum growth rate of juvenile smallmouth bass (Micropterus dolomieui), grown at constant temperatures of 16, 23, 26, 29, 32, and 35 C, occurred at approximately 26 C. Fish held at 35 C demonstrated a negative growth rate. The average 96-hr low temperature TL50 values (median tolerance limit) varied from 1.6 to 10.1 C for smallmouth bass acclimated to 15 and 26 C, respectively. Intermediate values were obtained for fish acclimated to 18 and 22 C. An important aspect of the study was the occurrence of a secondary fungous infection on the fish after 96-hr exposure to cold temperatures. In some cases the infection was severe enough to cause complete mortality within 7 days.
Preliminary Information on the Systematics, Distribution, and Abundance of the Dusky Rockfish, Sebastes ciliatus
Authors: Westrheim S. J.
Published: April 2011

Information is presented on the systematics, distribution, and abundance of the dusky rockfish, Sebastes ciliatus (Tilesius 1810). Morphological description of the taxon is provided, together with a translation into English of the original description. Geographic range is East Kamchatka (USSR) to Dixon Entrance (Canada). Maximum depth of capture in the Gulf of Alaska is 170 fath. Maximum size is 428 mm (17 inches), standard length. Relative abundance is low.
Absence of Acute Effects on Threespine Sticklebacks (Gasterosteus aculeatus) and Coho Salmon (Oncorhynchus kisutch) Exposed to Resuspended Harbor Sediment Contaminants
Authors: LeGore Richard S. , DesVoigne David M.
Published: April 2011

Threespine sticklebacks (Gasterosteus aculeatus) and coho salmon fry (Oncorhynchus kisutch) were challenged in static 96-hr bioassays with suspensions of sediment from the Duwamish Waterway, Seattle, Wash. Doses of up to 5% wet weight (28.8 g/liter dry weight basis) were used. No observable effect on the fish of contaminants released from the sediment was elicited, although high levels of these contaminants, such as volatile solids, COD, organic nitrogen, oil and grease, zinc, and lead, were present.
Rapid Decline of Olfactory and Gustatory Receptor Sensitivities of Wild Catfish (Ictaluridae) after Capture
Authors: Tucker D.
Published: April 2011

In several species of catfish (Ictaluridae), comparably high sensitivities of olfactory and gustatory receptors to α-amino acids as a class were confirmed. An important determinant of the frequency of successful electrical recording preparations was found to be the duration of fish captivity. The functional deterioration of olfactory and gustatory receptors may be a stress reaction caused by capture and confinement of the wild fish.
Comparison of Changes in Trimethylamine, Dimethylamine, and Extractable Protein in Iced and Frozen Gadoid Fillets
Authors: Castell C. H. , Neal W. E. , Dale J.
Published: April 2011

When fillets of Atlantic cod (Gadus morhua), pollock (Pollachius virens), cusk (Brosme brosme), and silver hake (Merluccius bilinearis) were iced and the opposite fillets frozen, large amounts of trimethylamine were rapidly produced in the iced fish but none was formed in the frozen fish within 60 days. Hake produced large, similar amounts of dimethylamine (DMA) in iced and frozen fillets. The other three species produced more DMA in the frozen than in the iced fillets, but always much less than in the hake. In both frozen and iced fish the production of DMA was accompanied by a corresponding decrease in extractable protein nitrogen.
Temperature Selection by Juvenile and Adult Yellow Perch (Perca flavescens) Acclimated to 24 C
Authors: McCauley R. W. , Read L. A. A.
Published: April 2011

Samples of juvenile and adult yellow perch (Perca flavescens) were obtained from the same habitat and at the same time from two separate water sources to study the differences, if any, in their preferred temperatures.The fish, acclimated to 24 C, were subjected to a vertical temperature gradient. Juveniles selected temperatures in the range 20.0–23.3 C and adults in the range 17.6–20.1 C. It is concluded that age plays an important role in temperature selection in this species.
Sexual Ripening of Pacific Halibut (Hippoglossus stenolepis) in Captivity
Authors: Tomlinson N. , Baker E. G.
Published: April 2011

Five female Pacific halibut, ranging between 89 and 105 cm long and between 10.4 and 17.9 kg, and three males, between 79 and 99 cm and 6.34 and 13.3 kg, became sexually ripe after being held in captivity for 21 months. This apparently is the first record of this development in the species in captivity.
Two Mechanisms That Make it Impossible to Maintain Peak-Period Yields From Stocks of Pacific Salmon and Other Fishes
Authors: Ricker W. E.
Published: April 2011

"Mechanism 1" has two aspects: catches taken at a given rate of exploitation are greater when rate of exploitation has been increasing than when it has been steady or decreasing; also, the yield taken from the progeny of a spawning of a given size is greater when rate of exploitation has been increasing than when it has been steady or decreasing. "Mechanism 2" is the fact that mixtures of stocks of unequal productivity, when harvested together, produce smaller recruitments than single stocks of the same original size and having the same optimum rate of exploitation. In addition, any fishery for a valuable species is likely to develop beyond the optimum rate of exploitation because there is no easily detectable symptom that the optimum is being passed. When this has happened, maximum sustainable yield (MSY) will not be achieved immediately if the optimum rate is imposed subsequent to a period of overexploitation; rather there will be a gradual approach to MSY that extends over several generations after the optimum rate is established. Both of the two mechanisms above, plus the likelihood of unrecognized overfishing, make for a catch maximum while fishing is still on the increase. For salmon this maximum is likely to be 30–60% greater than the sustainable yield. In addition, unavoidable difficulties of management make for even greater differences between the historical maximum and the mean equilibrium yield that can be achieved in practice. Good annual prediction of recruitment can improve this picture because rate of exploitation can then be adjusted to the quantity of fish available; however this procedure too is much less effective when mixtures of stocks are fished in common, because in general the recruitments to different stocks do not vary in exactly the same way. The phenomena described may also contribute to an historical early maximum of catch in fisheries for species such as cod, being independent of and additional to the maximum caused by "removal of accumulated stock."
Relation Between Total Body Weight and Concentrations of Manganese, Iron, Copper, Zinc, and Mercury in White Muscle of Bluefish (Pomatomus saltatrix) and a Bathyl-Demersal Fish Antimora rostrata
Authors: Cross F. A. , Hardy L. H. , Jones N. Y. , Barber R. T.
Published: April 2011

Concentrations of mercury (Hg) increased significantly with size (P < 0.001) in white muscle of bluefish (Pomatomus saltatrix) and a bathyl-demersal fish Antimora rostrata but concentrations of manganese (Mn), iron (Fe), copper (Cu), and zinc (Zn) either remained constant or decreased. These results indicate that fish residing in two different ecosystems in the Atlantic Ocean may be in a steady state with their environment with respect to Mn, Fe, Cu, and Zn but not Hg. The observed variations in accumulation patterns of trace metals in muscle of these two species as a function of size are discussed.
Uptake of Methyl Mercuric Chloride and Mercuric Chloride by Trout: A Study of Uptake Pathways into the Whole Animal and Uptake by Erythrocytes in vitro
Authors: Olson Kenneth R. , Bergman Harold L. , Fromm Paul O.
Published: April 2011

Twenty-four hour uptake rate of either 203HgCl2 or CH3203HgCl by rainbow trout (Salmo gairdneri) was not affected by esophageal ligation. Uptake of these two mercurials in non-feeding trout appears to be by way of the gills. Methyl mercury enters the fish at a faster rate than the inorganic form and anomalous tissue distribution of these two mercurials suggests that inorganic mercury does not require methylation prior to entry into the fish.In vitro experiments using radioactive mercurials demonstrated high affinity of methyl mercury for red cells (up to 90% was bound to red cells in 40 min). Only 9% of inorganic mercury was taken up by red cells, but, this percentage was increased up to 65% if the cells were washed and suspended in Ringer solution prior to incubation with mercury.
Coupling Carbon Flow Through Some Pelagic and Benthic Communities
Authors: Hargrave Barry T.
Published: April 2011

Sediment core oxygen uptake is correlated positively with primary production and inversely with mixed-layer depth in various aquatic ecosystems for which the input of organic matter is predominantly autochthonous. In these areas organic carbon sedimentation is proportional to the ratio of carbon input: mixed-layer depth, which reflects increased mineralization with increased depth of mixing. The ratio of primary production: mixed-layer depth is compared with the carbon equivalent of oxygen uptake by sediments to derive an expression which is used to calculate the amount of photosynthetically fixed carbon respired at the sediment surface.
Gastric Digestion, Food Consumption, Feeding Periodicity, and Food Conversion Efficiency in Walleye (Stizostedion vitreum vitreum)
Authors: Swenson William A. , Smith Jr. Lloyd L.
Published: April 2011

Gastric digestion of walleye, Stizostedion vitreum vitreum, and sauger, Stizostedion canadense, was measured by pumping stomachs at various intervals after experimental meals had been force-fed or voluntarily consumed. No significant differences in digestion rates were found between species or among walleye taken from three lakes. Repeated use of fish in digestion experiments failed to influence results. Gastric digestion rate increased with fish size, but was depressed by increased meal size, food particle size, and by force-feeding experimental meals.Food consumption rate and feeding chronology of the strong 1966 year-class of Lake of the Woods walleye were determined by applying results of laboratory digestion studies to stomach samples. An estimating technique that takes into account the effects of factors shown to influence digestion in the laboratory was developed and used to make calculations for the field population. Consumption averaged 1% of body weight during June, 2% during July, and 3% during August and September. Average temperatures were similar during June and September. Greater consumption during September resulted from higher food availability. Feeding was greatest during night and early morning hours in all months except June when it was continuous. Conversion efficiency of the 1966 year-class was described from estimates of growth and consumption rates for June through September and approximated 20% during each month.
Proecdysis, Setal Development, and Molt Prediction in the American Lobster (Homarus americanus)
Authors: Aiken D. E.
Published: April 2011

Setal development and proecdysial cuticular changes can be observed in the pleopods of the American lobster (Homarus americanus) from earliest D0 through stage D3, and with pleopod staging criteria it is possible to follow proecdysis from beginning to end. A technique is described for recognition of all stages and substages of proecdysis, for evaluating effects of various treatments on proecdysis, and for predicting time of ecdysis where holding temperature is known. Histological comparisons between the pleopods and the general integument suggest a universal criterion for stage D2, and a need for adjustment in some accepted molt stage criteria. Development plateaus occur in stage D0 instead of C4 in this species, and this suggests that the concept of stage C anecdysis may be incorrect.
Computer Program for Sample Sizes Required to Determine Disease Incidence in Fish Populations
Authors: Ossiander Frank J. , Wedemeyer Gary
Published: April 2011

A computer program is described for generating the sample size tables required in fish hatchery disease inspection and certification. The program was designed to aid in detection of infectious pancreatic necrosis (IPN) in salmonids, but it is applicable to any fish disease inspection when the sampling plan follows the hypergeometric distribution.
Reliability of an Ammonia Probe for Electrometric Determination of Total Ammonia Nitrogen in Fish Tanks
Authors: Barica Jan
Published: April 2011

The method involves an alkalization of a sample to pH 12 and subsequent measurement of liberated un-ionized ammonia with a gas-permeable membrane electrode. Total ammonia is measured directly rather than ammonium ion. Tests on different samples of water from aquaria and fish tanks showed a mean absolute difference of ±8.3% as compared with the phenolhypochlorite method in the concentration range of 0.5–5.1 mg/liter NH3-N. The lowest level of detection was 0.1 mg/liter NH3-N.
Supersaturation of Nitrogen in Water During Passage Through Hydroelectric Turbines at Mactaquac Dam
Authors: Macdonald J. Rod , Hyatt R. A.
Published: April 2011

Two fish kills occurred at the Saint John River, New Brunswick, below the Mactaquac Hydroelectric Station in the summer of 1968. Gas bubbles, commonly associated with nitrogen supersaturation, were observed on dead and dying salmon (Salmo salar) and eels (Anguilla rostrata). Tests showed that the concentrations of dissolved oxygen and nitrogen gases were substantially increased when water passed through the turbine generating system at low generating levels. Concentrations of dissolved nitrogen gas increased by as much as 20% above atmospheric equilibrium.
Métabolisme de l’iode et de la thyroxine chez Perca flavescens
Authors: Bibor V. , Leray C.
Published: April 2011

Two radioisotopes (Na125I and thyroxine125I) were used to investigate thyroid function in Perca flavescens. In the thyroid, if the hormonal fraction is very small (4% of total radioactive thyroid components, 5 days after injection of Na125I) the variation of this fraction with time suggests the existence of a rapid turnover of hormones (maximum level before 24 hr). The rapid incorporation of iodine into iodotyrosine compounds by the thyroid (60% of MIT + DIT after 12 hr) also suggests the involvement of a very important biosynthetic activity. At peripheral levels the rapid metabolism of T4125I ([Formula: see text] in the blood) confirms this view. In the plasma, the level of labelled hormones goes through two maxima followed (48 hr after injection of Na125I) by a steady increase. The second maximum observed is probably due to the release of thyroid hormones into the blood, but the first (6 hr after injection of Na125I) cannot be related to any known physiological process in fishes. The half-life of 125I in the plasma is the same as that in the whole body (4 days).
Eutrophication of Lake 227 by Addition of Phosphate and Nitrate: the Second, Third, and Fourth Years of Enrichment, 1970, 1971, and 1972
Authors: Schindler D. W. , Kling H. , Schmidt R. V. , Prokopowich J. , Frost V. E. , Reid R. A. , Capel M.
Published: April 2011

Lake 227, a small lake with extremely low concentrations of dissolved inorganic carbon, was fertilized with PO4 and NO3 for 4 years, beginning in 1969. The additions increased natural inputs of phosphorus and nitrogen about five times.Phytoplankton standing crop increased nearly two orders of magnitude, and the Cryptophyceae and Chrysophyceae present in natural lakes of the area were replaced by Chlorophyta and Cyanophyta. The standing crop of phytoplankton per square meter was near the maximum which could theoretically be maintained by surface light, in spite of the low carbon concentrations. Added phosphate and nitrate were rapidly removed by phytoplankton, so that concentrations in the lake remained low.Almost all of the added nutrient was retained by the lake, in spite of relatively fast water renewal times. An average of 80% of the phosphorus income of the lake was sedimented. There was no return of phosphorus from sediments in spite of anoxic conditions in the hypolimnion.Photosynthesizing plankton reduced dissolved inorganic carbon concentrations severely, causing a flux of atmospheric CO2 into the lake. From 69 to 95% of the inorganic + particulate carbon supplied to the lake was from the atmosphere. Results demonstrate that low carbon concentrations do not hinder eutrophication if phosphorus and nitrogen supplies are adequate.
Distribution and Uptake of Artificially Introduced Radium-226 in a Small Lake
Authors: Emerson S. , Hesslein R.
Published: April 2011

Radium-226 was added to lake 227 of the Experimental Lakes Area in August 1970 so that gas-exchange rates between the atmosphere and the lake could be traced by its gaseous daughter product radon-222. Although we expected the radium to remain in solution it did so for only about 1 month. An investigation to locate the radium after it left solution revealed that it was taken up on the bottom in the littoral zone. Further experiments indicated that it had adsorbed to the algal detrital material on the littoral sediment surface. Seasonal movement of this material could thus be monitored by following the movement of the radium with time.
Diurnal Variation of Dissolved Inorganic Carbon and its Use in Estimating Primary Production and CO2 Invasion in Lake 227
Authors: Schindler D. W. , Fee E. J.
Published: April 2011

Standard in situ measurements of phytoplankton production and 14C bottle bioassays gave erroneous results when applied to lake 227, a eutrophic softwater lake in the Canadian Shield. Errors were found to be due to diurnal variations in the degree of carbon limitation of phytoplankton, and to invasion of CO2 from the atmosphere and hypolimnion.A method based on diurnal measurements of dissolved inorganic carbon, community respiration, and invasion of CO2, using gas chromatography, is described. Production by phytoplankton in lakes fertilized with nitrogen and phosphorus was found to be several times higher than in natural lakes of the area. Net production during summer stratification was found to equal invasion of CO2 from the atmosphere.The new technique should have application in other eutrophic low carbon lakes, where 14C tracer techniques are encumbered by serious technical complications.
Measurement of Adenosine Triphosphate (ATP) in Two Precambrian Shield Lakes of Northwestern Ontario
Authors: Rudd John W. M. , Hamilton R. D.
Published: April 2011

Profiles of the adenosine triphosphate (ATP) concentrations occurring in the particulate material of two experimental shield lakes were obtained with respect to time. Large seasonal changes were evident, as were specific sites of high biological activity due either to natural stratification or to deliberate manipulation. Chlorophyll a, particulate carbon, and direct count data were found to be misleading in specifying the changes or the sites of biological activity. Analysis of the ATP data on the basis of the relative abundance of different size fractions was found to be useful. An ATP filtration error could not be demonstrated, indicating that cell breakage is not a source of the filtration error inherent in some 14C primary and secondary productivity studies.
Effects of Cadmium and Copper on the Oxidation of Lactate by Rainbow Trout (Salmo gairdneri) Gills
Authors: Bilinski E. , Jonas R. E. E.
Published: April 2011

The oxidative activity of gill filaments was determined by measuring the liberation of 14CO2 from Na-lactate-3-14C. In fish surviving the exposure to 10−5 M CdCl2 (1.12 mg Cd/liter) for 24 hr or to 10−6 M CuCl2 (0.064 mg Cu/liter) for 48 hr, the oxidation of lactate by gills was inhibited by over 50%. The exposure of trout to lower metal ion concentrations resulted in mortalities, but there was no detectable effect on the oxidative activity in gills.
Apparatus for Simulating Motion of Animals through the Geomagnetic Field
Authors: Rommel Jr. S. A.
Published: April 2011

An apparatus to simulate animal motion through the geomagnetic field was devised. The test animal can be rotated through a magnetic field produced by two coils of wire. With this equipment biologists may introduce motionally induced electric fields into laboratory experiments on electro- and magneto-sensitivity.
Redescription of Gaetanus intermedius Campbell (Calanoida: Copepoda) from the Type Locality
Authors: Park Taisoo
Published: April 2011

Gaetanus intermedius Campbell 1930, is redescribed from specimens taken in the type locality, the Vancouver Island region in the northeastern Pacific. Gaetanus simplex Brodsky 1950, is found to be a junior synonym of G. intermedius.
Microcultures of Brown Bullhead (Ictalurus nebulosus) Cells: Their Use in Quantitation of Channel Catfish (Ictalurus punctatus) Virus and Antibody
Authors: Gratzek John B. , McGlamery Merrill H. , Dawe Donald L. , Scott Trudy
Published: April 2011

A microculture system was applied to the culture of brown bullhead (Ictalurus nebulosus) cells and used for the titration of channel catfish (Ictalurus punctatus) virus and corresponding antibody. As few as 1.7 × 104 cells/well could be used for routine titrations. Simultaneous inoculation of virus with cells at the time of planting resulted in clearer endpoints as opposed to inoculation of preformed monolayers. When channel catfish virus antibodies were measured using plaque reduction and microculture titration assays as indicator systems, no significant differences in antibody titers were noted.
Digestive Enzyme Secretion After Dietary Variation in the American Lobster (Homarus americanus)
Authors: Hoyle R. J.
Published: April 2011

American lobsters, Homarus americanus, were fed diets containing 0, 5, and 20% starch for periods up to 37 days. Digestive enzymes in the stomach juices of these and fasted lobsters were assayed. The base-line, or true fasting enzyme level was considered to be those values found after feeding for 2 days on a 5% starch diet. Compared to this basal level both specific activities and absolute amounts of proteinase, lipase and, to a lesser extent, amylase were found to rise on prolonged feeding. Further feeding (all diets) allowed products of a greater proportion of proteinase than amylase or lipase; alteration of the starch content of the diet had no consistent effect.
Changes in the Population of Lake Whitefish (Coregonus clupeaformis) in Lake Winnipeg from 1944 to 1969
Authors: Davidoff E. B. , Rybicki R. W. , Doan K. H.
Published: April 2011

Whitefish catches have fluctuated since 1952, and except in 1964 each successive peak has decreased in magnitude. Recently the overall trend has been a diminishing fishery with increasing effort.There has been a drastic change in age composition with time. Age-groups 5, 6, and 7 accounted for 81% of the catch from 1944 to 1948, age-groups 4, 5, and 6 for 89% from 1949 to 1955, age-groups 4 and 5 for 86% from 1959 to 1968, and age-groups 3 and 4 for 88% in 1969. The fishery is now dependent upon two age-groups instead of three. Natural failure of one or more important year-classes would result in a serious decline in catch, and partial or complete collapse of this fishery.Annual survival rate decreased from 34%, 1944–48 to 12%, 1959–69. Instantaneous natural mortality rate was estimated to be 0.72, and may be overestimated. The 1938–39, 1945–47, 1949, and 1957 year-classes were strong, while the 1940–44, and 1956, 1958, and 1961 year-classes were weak. The 1959 and 1960 year-classes appeared to be somewhat above average. Examination of data on total dissolved solids and temperature indicated that ecological changes were not responsible for the decline of whitefish in Lake Winnipeg.We judge that the optimum rate of fishing has been exceeded, and that the fishery itself is largely responsible for the depleted condition of the whitefish stocks in Lake Winnipeg. Fishing effort must be reduced to the point where the fishery is again dependent upon three year-classes. This should result in higher catches, and provide less fluctuation in annual catches.
Temperatures Selected Seasonally by Four Fishes from Western Lake Erie
Authors: Barans Charles A. , Tubb Richard A.
Published: April 2011

When four species of fish were taken from western Lake Erie in each of four seasons and held usually for less than 7 days at ambient lake temperatures, the temperatures they selected during 2–3 days in a horizontal temperature gradient differed seasonally. The differences were largely attributable to the conditions at which the fish had been acclimatized in the lake, and were modified by acclimation during 2–3 days in the gradient.The selected temperatures provided insights into the temperatures that might be selected by these species each season if the lake basin or other waters with similar seasonal ambient temperatures were subjected to thermal discharges. Temperatures selected were above ambient lake temperatures except for emerald shiners (Notropis atherinoides) in summer and fall. In general, white bass (Morone chrysops) and smallmouth bass (Micropterus dolomieui) selected a high range in temperatures throughout the year (18–30 C and 18–31 C, respectively), yellow perch (Perca flavescens) an intermediate range (10–29 C) and emerald shiners the lowest range (6–23 C). Three of the species were distributed within a relatively precise temperature range in the summer and within a larger range during other seasons; emerald shiners selected a narrow range during all seasons. A fairly stable temperature preference was usually reached within several hours in summer, but the temperatures selected by three species generally increased with time in the gradient during the other seasons; emerald shiners selected constant temperatures in all seasons. Temperatures selected by young and adults differed mainly in yellow perch and emerald shiners in summer and winter, when the lake temperatures fluctuated least.
Use of Plastein Reaction in Recovering Protein from Fish Waste
Authors: Onoue Y. , Riddle V. M.
Published: April 2011

A high quality proteinaceous product is recoverable in 35% yield from fish waste by a process of peptic hydrolysis followed by a pepsin-catalyzed recombination of soluble peptides to form plastein. Hydrolysis is at pH 2.0 and 37 C for 6 hr. Soluble peptides are then separated from insoluble residue, adjusted to pH 4.5, concentrated at 45 C to 30% protein solids, and incubated for 24 hr at 37 C with additional pepsin. The insoluble plastein formed during incubation is filtered, washed, and dried. In a pilot experiment with fillet waste from Petrale sole (Eopsetta jordani), the yield was 35% of total original protein. Proximate composition of the product was: protein, 96.1%; moisture, 2.9%; ash, 0.5%; and lipid, 0.0%. The plastein contained a higher proportion of essential amino acids than did a hydrolysate of the whole waste, all except tryptophan exceeding FAO reference standards.
Some Aspects of Osmoregulation in Mysis stenolepis (Crustacea, Mysidacea)
Authors: Dormaar K. A. , Corey S.
Published: April 2011

Osmotic regulation of the mysid Mysis stenolepis was studied by gradually and suddenly exposing specimens to salinities from 0 to 30‰. Acclimation to all salinities other than 0‰ occurred under all conditions within 3 hr. All specimens exposed to 0‰ died. Mysis stenolepis is hyposmotic (Δt 1.363 C) at 22–3 C‰ and hyperosmotic at salinities less than 22‰. The osmoregulatory pattern and the ability to acclimate rapidly indicates an adaptation to the estuarine environment.
A Portable Wire–Speed Indicator for Use with Plankton Nets
Authors: Lusz Larry D. , Waldron K. D.
Published: April 2011

A system is described for measuring true wire speed during plankton tows, using commercially available electrical components attached to a standard metering wheel. The indicator increases uniformity between and during plankton tows where the wire speed does not exceed 50 m/min.
Inability to Detect Spores of Clostridium botulinum in Fish Protein Concentrates (FPC)
Authors: Hauschild A. H. W. , Pivnick H. , Regier L. W.
Published: April 2011

Samples of fish protein concentrates from a total of 124 production lots prepared in pilot plants by three different methods have been tested for the presence of viable Clostridium botulinum spores by incubating them in cooked meat medium and assaying the culture supernatant fluids for toxin. No spores of C. botulinum could be demonstrated with certainty in any of the 124 samples of FPC tested. Two of the supernatant fluids were lethal to mice, but their lethal effects appeared to be caused by factors other than C. botulinum toxin.
Light intensity and photosynthetic rates in phytoplankton
Authors: Harris Graham P. , Lott John N. A.
Published: April 2011

The physiological behavior of various phytoplankton species has been examined under increasing and decreasing light regimes. A marked asymmetry has been found, with photosynthesis rates under rising light intensities exceeding those under dimming lights. Photoinhibition has been observed at moderate light intensities (0.4–1.0 ly/min). Variations in the asymmetry and in photoinhibition appear to be correlated with the light regimes experienced by the population. Under constant illumination by full sunlight a steady decrease in the photosynthesis rate was observed. As a result of photosynthesis measurements in fluctuating light regimes there is now evidence for photorespiration as the controlling mechanism. Data are presented which show that prolonged exposure to high light has an adverse effect on photosynthesis and indicate that 14C moored bottle experiments may show reduced surface rates because of this.
Energy Expenditure of Sockeye Salmon, Oncorhynchus nerka, During Sustained Performance
Authors: Brett J. R.
Published: April 2011

Fingerling and adult sockeye salmon (Oncorhynchus nerka) were subjected to long periods of sustained swimming (10–20 days) in air-saturated fresh water. Energy expended was computed from change in body composition and compared with the metabolic equivalent from multiple determinations of oxygen-consumption rate. Caloric loss from body substance exceeded that estimated from total oxygen uptake by an average of 19.8%. The reasons for the difference, and the assumptions involved, are discussed. The difference apparently arises from slight excretion of partially metabolized fuels (anaerobic metabolism) and loss from sloughed body tissues. An oxycalorific equivalent of 4.8 kcal/liter O2 is considered an acceptable value for fish.
Abundance, Survival, and Vertical and Diurnal Distribution of Lobster Larvae in Northumberland Strait, 1962–63, and their Relationships with Commercial Stocks
Authors: Scarratt D. J.
Published: April 2011

Estimates of the abundance of the four planktonic stages of lobster larvae (Homarus americanus) taken in a large surface plankton net show that production and survival of larvae in Northumberland Strait in 1962 and 1963 were the lowest on record. Examination of diurnal fluctuations in abundance, and sampling below the surface and at various depths to the bottom, confirm that larvae are concentrated at the surface during daylight hours. The time to next molt of stage IV larvae, captured and retained alive, indicates that settlement takes place about midway through stage IV. Reexamination of earlier results together with these new data now suggests there is some evidence for a relationship between stage IV larval abundance and subsequent commercial lobster stocks, but that sampling errors are too great to permit accurate prediction.