View of Paraiso Yard showing dredging equipment, Panama Canal. (ca. 1914)

Leonard Carpenter Panama Canal Collection. Photographs: Dredging, Soldiers, and Ships. [Box 1] from the Special Collections & Area Studies Department, George A. Smathers Libraries, University of Florida.

Technologies for Measuring Currents in Coastal Environments, Portland, Maine, October 26-28, 2005:workshop proceedings

The Alliance for Coastal Technologies (ACT) Workshop entitled "Technologies for Measuring Currents in Coastal Environments" was held in Portland, Maine, October 26-28, 2005, with sponsorship by the Gulf of Maine Ocean Observing System (GoMOOS), an ACT partner organization. The primary goals of the event were to summarize recent trends in nearshore research and management applications for current meter technologies, identify how current meters can assist coastal managers to fulfill their regulatory and management objectives, and to recommend actions to overcome barriers to use of the technologies. The workshop was attended by 25 participants representing state and federal environmental management agencies, manufacturers of current meter technologies, and researchers from academic institutions and private industry. Common themes that were discussed during the workshop included 1) advantages and limitations of existing current measuring equipment, 2) reliability and ease of use with each instrument type, 3) data decoding and interpretation procedures, and 4) mechanisms to facilitate better training and guidance to a broad user group. Seven key recommendations, which were ranked in order of importance during the last day of the workshop are listed below. 1. Forums should be developed to facilitate the exchange of information among users and industry: a) On-line forums that not only provide information on specific instruments and technologies, but also provide an avenue for the exchange of user experiences with various instruments (i.e. problems encountered, cautions, tips, advantages, etc). (see References for manufacturer websites with links to application and technical forums at end of report) b) Regional training/meetings for operational managers to exchange ideas on methods for measuring currents and evaluating data. c) Organize mini-meetings or tutorial sessions within larger conference venues. 2. A committee of major stakeholders should be convened to develop common standards (similar to the Institute of Electrical and Electronics Engineers (IEEE) committee) that enable users to switch sensors without losing software or display capabilities. (pdf contains 28 pages)

Fish tracking technology development. Phases 1 and 2, project definition desk study and equipment

The document reports on the major findings from a definition study to appraise the options to develop fish tracking equipment, in particular tags and data logging systems, in order to improve the effeciency of the Agency tracking studies and to obtain a greater understanding of fish biology. The definition study was in two parts. The first, Phase 1, collated and evaluated all the known tracking systems that may be suitable for studies of fish which are either produced commercially or have been constructed for specific in-house studies. Phase 2 was an evaluation of all the tracking equipment considered to merit further investigation in Phase 1. The deficiencies between existing and required technologies to improve the efficiency of Agency's tracking studies and to obtain a greater understanding of fish biology are also identified.

An investigation into the effects of electric fishing equipment on salmon and sea trout within the area of the Lancashire River Board.

The report looks at experiments into electric fishing equipment and effects on salmon and trout within the Lancashire River Board. Experiments include obtaining information on voltage gradients, ascertaining what damage to fish of the larger size groups resulted from electric fishing, determining whether or not fractures could occur in coarse fish and brown trout,similar to those occurring in salmon and sea trout, and effects low temperatures have on electrofishing techniques.

Electrical phase angle as a new method to measure fish condition

In this study, phase angle (the ratio of resistance and reactance of tissue to applied electrical current) is presented as a possible new method to measure fish condition. Condition indices for fish have historically been based on simple weight-at-length relationships, or on costly and timeconsuming laboratory procedures that measure specific physiological parameters. Phase angle is introduced to combine the simplicity of a quick field-based measurement with the specificity of laboratory analysis by directly measuring extra- and intracellular water distribution within an organism, which is indicative of its condition. Phase angle, which can be measured in the field or laboratory in the time it takes to measure length and weight, was measured in six species of fish at different states (e.g., fed vs. fasted, and postmortem) and under different environmental treatments (wild vs. hatchery, winter vs. spring). Phase angle reflected different states of condition. Phase angles <15° indicated fish in poor condition, and phase angles >15° indicated fish that were in better condition. Phase angle was slightly affected by temperatures (slope = – 0.19) in the 0–8°C range and did not change in fish placed on ice for <12 hours. Phase angle also decreased over time in postmortem fish because of cell membrane degradation and subsequent water movement from intra- to extracellular (interstitial) spaces. Phase angle also reflected condition of specific anatomical locations within the fish.

Preliminary experiments on electrical fishing in fresh watter [i.e. water]

Fishing using electricity is a new technique and is still in the experimental stages in many of the advanced countries. While no published records are available in India, considerable work has been done in Germany, United States, Canada, and United Kingdom. These papers mainly deal with the behavior of the fish in the electrical field, the physiological effects of electrical current on fishes, methods of electrofishing, electric fencing etc. The following experiments on electrical fishing were conducted with a view to studying the distribution of electrical field when an alternating current is passed through two fixed electrodes in fresh water and to study the reaction of different fresh water fishes to the field.

Impulse generator for electrical fishing

Since impulse current has been found to be more economical and more effective for conducting electrical fishing an impulse generator was designed and fabricated. The principle and description of the impulse generator are given in the paper. Even though it is not giving theoretical value of the impulse voltages it has been found that for conducting electrical fishing it is producing necessary voltages.

On the response of zooplankton in an electrical field

Zooplankton showed directional movement towards the positive electrode in an electrical field till the current continued to flow. Examination of the plankton 24 hours after their exposure for one minute to different current densities showed considerable mortality, the percentage of which was more in the case of the larger size groups.

On the response of Catla catla (Ham) and Cirrhinus mrigala (Ham) to the voltage gradient of electrical field

The threshold body voltage (voltage gradient between head and tail) required for first reaction, electro-taxis and electro-narcosis depended upon species, conductivity of the fish body, nature of current and wave shape. Larger fishes showed first reaction at a lower body voltage than smaller ones. All the three reactions were dependent on the accommodation of nerves to the electrical field and subsequent fatigue of the fishes. No significant change was observed in the period of narcosis and recovery after repeated stimulation.

On the effect of electrical field on Indian carps in captivity

Threshold current densities required for narcosis of fish in captivity differed in different species. Increased temperature of the water had greater effect on the fishes while changes of pH had no appreciable effect on narcosis in the fishes. Impulse currents of 50 V were found to have better effect on the fishes than continuous current of 180-220 V.