What are the security threats to further development of nuclear power plants in the U.S.?

What are the security threats to further development of nuclear power plants in the U.S.? The U.S. stands alone today in terms of the vast nuclear armory at its disposal. It is clear we know something about how to build nuclear weapons, and yet, we are not world leaders in the field of nuclear power. Nuclear energy has the potential to be an alternative fuel source that would be sustainable and economical. Nuclear power is controversial in the U.S. because it raises issues of domestic energy policy, funding, regulation, safety, and especially security. In turn it can affect U.S. investments, foreign policy, economy, and jobs. As America struggles with its dependence on foreign oil, we must seek alternative fuel sources. The President has made energy a priority and is pushing for a "clean energy economy." Not to pursue alternative fuel sources will directly impact our ability to be economically competitive, as other countries will have cheaper electricity for manufacturing and services. We need to protect the U.S. from economic and strategic risks associated with our reliance on foreign oil. We also need to address the destabilizing effects of a changing climate, Internet is heavily impacted by our energy use.http://archive.org/details/whatresecurityth109455440US Air Force (USAF) authorApproved for public release; distribution is unlimited

Extensive gas bubble release in Norwegian spring-spawning herring (Clupea harengus) during predator avoidance

Events of extensive gas bubble releases in overwintering Norwegian spring spawning herring (Clupea harengus) were repeatedly observed acoustically and visually in Vestfjorden, northem Norway, during attacks from killer whales (Orcinus orca) and saithe (Pollachius virens). Gas bubble production was so extensive that large areas of the sea surface were sometimes covered with white foam after an event. Gas bubbles were visually observed to come from the swimbladder of individual herring swimming very close to the surface. Acoustically, gas bubbles could be identified on the echosounder as strong echoes covering the upper 0-30 m of the water column. Schools of herring were forced from 30-100 m depth up to the surface by predatory killer whales and saithe. I suggest that herring expel gas near the surface as a concequence of the rapid change in depth, and that gas bubble release may confuse and deflect both visually and acoustically oriented predators due to increased scattering of light, reduced range of vision, and confusing effects of the reflection energy of the bubbles and the fish. Such events may have considerable effect on the target strength and estimated stock sizes during acoustic surveys

Evidence that whales (Balaenoptera borealis) visit drifting fish aggregating devices : do their presence affect the processes underlying fish aggregation ?

Evidence of the presence of a group of sei whales (Balaenoptera borealis) detected around drifting fish aggregating devices (FADs) was provided by omnidirectional multi-beam sonar during a survey off the Seychelles (Indian Ocean). The short visit by the sei whales produced a significant change in the behaviour of the fish assemblage associated with the FAD. There was first a significant increase in fish density when the whales approached the FAD, then a marked decrease after the whales had moved away from the FAD. Furthermore, the fish density was still low, 3 h after the whales had left the FAD. We assume that the presence and behaviour of the sei whales led some of the fish initially associated with the FAD to move away from it. There has been a considerable increase in the use of drifting artificial FADs in the Indian Ocean in recent decades. The frequency of cetacean visits to drifting FADs in the Indian Ocean is unknown, but they may have a major impact on assemblages of pelagic fish species around FADs. The effect of marine mammals on FAD-associated fish could be relevant to the ecological trap theory (FAD acting as a trap for their associated fish) because of their impact on the dynamics of fish aggregation processes, through commensalism and/or predatorprey interactions

Echotrace classification and spatial distribution of pelagic fish aggregations around drifting fish aggregating devices (DFAD)

This work presents a method to observe pelagic fish around drifting fish aggregating devices (DFADs). A triple-frequency vertical echosounder was employed to observe fish distributions in the vicinity of DFADs. Surveys were conducted in a star pattern that was centred at the DFADs. The objective of the study was to define a methodology for future acoustic studies. This goal was pursued by (i) studying the spatial distribution of fish aggregations, (ii) developing concepts for the grouping of observed aggregations and (iii) developing specifications for future autonomous acoustic tools. For this purpose 5 cruises were carried out in the western Indian Ocean. The multi-frequency approach proved useful as a means of separating acoustic detections into sound-scattering layers (e. g. plankton and micronekton), fish aggregations and individual fish. Fish target strength (TS) was measured. Four types of aggregations were found near DFADs: ( i) dense structure (ii) medium structure (iii) loose structure and (iv) structure consisting of separated targets. More than 90% of these structures were found within a radius of 400 m and about 75% within 200 m of the DFADs. The spatial configuration of DFAD fish aggregations appeared to be more dynamic compared to aggregations near moored FADs. The spatial distribution and structure of DFAD aggregations have direct implications for their catchability by tuna purse-seiner. We have carried out the first quantitative acoustic recordings around DFADs, and obtained a better understanding of the spatiotemporal dynamics of fish aggregations around DFADs in the Indian Ocean. Based on this knowledge we are now working on specifications for instrumented buoys that are intended as autonomous data recording observatories for such pelagic environments

Spawning of herring: day or night, today or tomorrow?

Diel variations in schooling patterns and spatial dynamics during spawning were studied in Norwegian spring-spawning herring (Clupea harengus) off south-western Norway by acoustic surveying, diel cycle experiments and school tracking by sonar, and bottom gillnet sampling. Herring formed horizontally extensive, loosely packed demersal layers shortly after darkness. At night, the fish disappeared in the acoustic dead zone, but lifted off the bottom early in the following mornings. At daytime the herring reorganised into dense pelagic schools. The evening descent to the spawning habitat was considered as part of a precautionary strategy towards visual predators, as the bottom is a high-risk zone for archetypal pelagic fish like herring. Large numbers of gadoids, which are potential herring predators, were present in the area. Herring not ready to spawn dominated the bottom samples in 4 out of 5 days, suggesting that pre-spawning herring followed the descent of ripe herring. The herring spawning layers shifted in a south-easterly direction from day to day in diel spawning waves