The environmental requirements of salmon and trout in fresh water

This article is a summary for the general reader, rather than an in-depth review, and attempts to define, as quantitatively as possible, the habitat requirements of salmon and trout and then to relate them to the main ways in which man's activity can influence the survival and growth of these fishes. Frequent text references to an extensive body of published work have been avoided, although a selective bibliography has been included which lists some of the main work upon which the text depends. This article deals only with the freshwater part of the life cycle, and the coverage has some bias towards England and Wales.

Relationship of dimensions and weight in freshwater planktonic crustaceans. [Translation from: Doklady Akademii Nauk SSSR 84(1) 153-156, 1952. ]

There is no doubt that determination of the biomass of zooplankton (primarily of crustaceans) will be taken into consideration in practice and limnological works, especially after the recent publication of fairly comprehensive tables of weights of a whole range of species of freshwater copepods and cladocerans. The usefulness of applying formulae of determining the biomass of marine crustaceans for freshwater copepods is discussed.

Year class strengths of perch and pike in Windermere

The pike (Esox lucius) year classes are more stable than those of the perch (Perca fluviatilis), and have been shown to be closely correlated with temp conditions during the first few months of life. The perch year class strengths have been more variable; for success they require the presence of several positive conditions and the absence of many adverse conditions which could cause failure, a favourable combination of circumstances rarely occurs. The conclusions refer only to Windermere from 1941-1964.

Treading in Mortimer's footsteps: the geochemical cycling of iron and manganese in Esthwaite water

A study of the geochemical cycling of iron and manganese in a seasonally stratified lake, Esthwaite water is described. This work is based on speculative ideas on environmental redox chemistry of iron which were proposed by C.H. Mortimer in the 1940's. These observations have been verified and some speculations confirmed, along with a new understanding of the manganese cycle, and detailed information on the particulate forms of both iron and manganese. Details on the mechanisms and transformations of iron have also emerged.

Measurements of resistance and reactance in fish with the use of bioelectrical impedance analysis: sources of error

New technologies can be riddled with unforeseen sources of error, jeopardizing the validity and application of their advancement. Bioelectrical impedance analysis (BIA) is a new technology in fisheries research that is capable of estimating proximate composition, condition, and energy content in fish quickly, cheaply, and (after calibration) without the need to sacrifice fish. Before BIA can be widely accepted in fisheries science, it is necessary to identify sources of error and determine a means to minimize potential errors with this analysis. We conducted controlled laboratory experiments to identify sources of errors within BIA measurements. We concluded that electrode needle location, procedure deviations, user experience, time after death, and temperature can affect resistance and reactance measurements. Sensitivity analyses showed that errors in predictive estimates of composition can be large (>50%) when these errors are experienced. Adherence to a strict protocol can help avoid these sources of error and provide BIA estimates that are both accurate and precise in a field or laboratory setting.

Distribution and abundance of Dungeness crab and crangon shrimp, and dredging-related mortality of invertebrates and fish in Grays Harbor, Washington

The impacts of widening and deepening the existing navigation channel in Grays Harbor on Dungeness crab, crangon shrimp and fish was investigated. The spatial and temporal distribution of these organisms was studied using an otter trawl and ring nets, and the uptake of organisms by dredges was estimated from samples collected on working hopper and pipeline dredges. ... Impacts of the dredging project on crabs, shrimp and fish could be associated with entrainment, food loss and toxicants released from sediments. Scenarios are presented that predict impacts. Suggestions for reducing impacts are given.

Snow depth as an indicator of weather and climate in the Sierra Nevada

EXTRACT (SEE PDF FOR FULL ABSTRACT): The purpose of this study is to determine: (1) whether the cooperative station snow depth contains useful weather and climate information, (2) how cooperative snow depth variability is related to snowcourse variability, and (3) how it is related to other weather elements. From an examination of stations in the Sierra Nevada of California, it is clear that cooperative snow records and snowcourse records have consistent spatial and temporal variability. ... We show that high snow ratio (low density snow or high SD/Ppt) events have low temperatures and high amplitude atmospheric circulation patterns over the eastern North Pacific. In contrast, low snow ratio (high density or low SD/Ppt) events have warm temperatures and a zonal flow pattern with a southerly displaced storm track from Hawaii to the West Coast.

Interdecadal variability in the spatial structure of wind and SST in the California Current system

The physical environment of eastern boundary current systems is rarely uniform in time. ENSO and other perturbations produce profound anomalies in the atmosphere and ocean on interannual to decadal and century time scales. ... The objective of this paper is to describe the temporal variability in the spatial texture of the California Current system, a major eastern boundary current system off the west coast of North America, to provide a base from which to evaluate the effect of climate change - in the recent past, at present, and for the future.

Studies on the occurrence of coliforms and streptococci in coastal waters of Bombay

The distribution of coliforms and streptococci in Bombay coastal waters was investigated in order to determine the state of pollution in the area. Findings show the incidence of pollution to be of a recurring nature, primarily due to discharge of raw or improperly treated sewage; thus regular monitoring of the incidence of coliforms and streptococci is of importance in determining the public health safety of the beaches and coastal waters.

Control of crabs and snakes in freshwater fish seed farms

A design has been developed to adopt in freshwater fish seed farms for controlling crabs and snakes. The method is convenient and effective. It prevents the entry of crabs and snakes into the ponds.

Determination of ubiquinone and tocopherol in heart, liver and muscle tissues of fresh water fish, Rohu (Labeo rohita, Hamilton)

The liver, heart and muscle tissues of Rohu, (Labeo rohita, Hamilton) were examined for their ubiquinone (UQ) and tocopherol contents. These three tissues contained respectively 11.60, 3.94 and 0.19 mg of ubiquinone and 10.16, 5.32 and 3.58 mg of tocopherol per 100 g. The 4% (V/V) of diethyl ether (EE) in light petroleum ether (PE) fractions of all three tissues on paper chromatographic separation gave spots having the same Rf value as standard ubiquinone-50 (UQ 10). Both the 4% and 6% (V/V) diethyl ether in light petroleum ether fraction of liver, heart and muscle tissues gave a single spot with the same Rf value as α – tocopherol.

Biochemical differences between the red and white meat of tuna and changes in quality during freezing and storage

The differences between the white and red (dark) meat of tuna (Katsuwonus pelamis) in chemical, physical and organoleptic aspects and the rate and pattern of spoilage during freezing and subsequent storage are discussed in this communication. In the indices studied distinct difference is seen between the white and red meat as well as in the head, middle and tail portions of the same fish. The characteristic colour of tuna meat is due to the presence of haemoglobin and myoglobin, the concentrations of which are about 5 times more in red meat than in white meat. The shelf-life of the frozen material varies with the type of the pack, that is, whole fish>chunks>fillets; the fillets being adversely affected during frozen storage.