14 research outputs found

    Transmission loss patterns from acoustic harassment and deterrent devices do not always follow geometrical spreading predictions

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    Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Marine Mammal Science 25 (2009): 53-67, doi:10.1111/j.1748-7692.2008.00243.x.Acoustic harassment and deterrent devices have become increasingly popular mitigation tools for negotiating the impacts of marine mammals on fisheries. The rationale for their variable effectiveness remains unexplained but high variability in the surrounding acoustic field may be relevant. In the present study, the sound fields of one acoustic harassment device and three acoustic deterrent devices were measured at three study sites along the Scandinavian coast. Superimposed onto an overall trend of decreasing sound exposure levels with increasing range were large local variations in sound level for all sources in each of the environments. This variability was likely caused by source directionality, inter-ping source level variation and multi-path interference. Rapid and unpredictable variations in the sound level as a function of range deviated from expectations derived from spherical and cylindrical spreading models and conflicted with the classic concept of concentric zones of increasing disturbance with decreasing range. Under such conditions, animals may encounter difficulties when trying to determine the direction to and location of a sound source, which may complicate or jeopardize avoidance responses.The project was funded by the Swedish Fishermen Association, the Swedish Board of Fisheries, Aage V. Jensen Foundations, Danish Forest and Nature Agency, The Nordic Research Council and the Carlsberg Foundation. Additional logistical support was furnished by the Oticon Foundation and Reson A/S. A.D. Shapiro received financial support from the National Defense Science and Engineering Graduate Fellowship and the WHOI Academic Programs Office. 35

    Reactions in individual fish to strobe light. Field and aquarium experiments performed on whitefish (Coregonus lavaretus)

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    This study describes how individual whitefish Coregonus lavaretus react to strobe light. Field experiments were performed in a net enclosure on fish tagged with ultrasonic transmitters. A strobe light array was switched on near the tagged fish. The fish moved away from the light and increased their swimming speed. Aquarium experiments under controlled conditions were carried out in rearing tanks at Saimaa Fisheries and Aquaculture Station in Finland. A strobe light was directed from the side of the basin just ahead of, directly at, and behind the fish at a close range. In the first two cases fish responded by a distinct turn and a change in swimming direction away from the light. The fish did not change its swimming direction when light was aimed from behind. It is concluded that strobe light may be used to prevent fish from swimming into a specific area. Implications for development of new fishing equipment and research concerning fishes in areas with water power stations is briefly discussed

    Transition thresholds and transition operators for binarization and edge detection

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    Acoustic harassment and deterrent devices have become increasingly popular mitigation tools for negotiating the impacts of marine mammals on fisheries. The rationale for their variable effectiveness remains unexplained, but high variability in the surrounding acoustic field may be relevant. In the present study, the sound fields of one acoustic harassment device and three acoustic deterrent devices were measured at three study sites along the Scandinavian coast. Superimposed onto an overall trend of decreasing sound exposure levels with increasing range were large local variations in the sound level for all sources in each of the environments. This variability was likely caused by source directionality, inter-ping source level variation and multipath interference. Rapid and unpredictable variations in the sound level as a function of range deviated from expectations derived from spherical and cylindrical spreading models and conflicted with the classic concept of concentric zones of increasing disturbance with decreasing range. Under such conditions, animals may encounter difficulties when trying to determine the direction to and location of a sound source, which may complicate or jeopardize avoidance responses. " 2008 by the Society for Marine Mammalogy.",,,,,,"10.1111/j.1748-7692.2008.00243.x",,,"http://hdl.handle.net/20.500.12104/45450","http://www.scopus.com/inward/record.url?eid=2-s2.0-58349099098&partnerID=40&md5=2155719fc067f3fa33d0fa7fc0663403",,,,,,"1",,"Marine Mammal Science",,"5

    TMEM203 Is a Novel Regulator of Intracellular Calcium Homeostasis and Is Required for Spermatogenesis

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    Intracellular calcium signaling is critical for initiating and sustaining diverse cellular functions including transcription, synaptic signaling, muscle contraction, apoptosis and fertilization. Trans-membrane 203 (TMEM203) was identified here in cDNA overexpression screens for proteins capable of modulating intracellular calcium levels using activation of a calcium/calcineurin regulated transcription factor as an indicator. Overexpression of TMEM203 resulted in a reduction of Endoplasmic Reticulum (ER) calcium stores and elevation in basal cytoplasmic calcium levels. TMEM203 protein was localized to the ER and found associated with a number of ER proteins which regulate ER calcium entry and efflux. Mouse Embryonic Fibroblasts (MEFs) derived from Tmem203 deficient mice had reduced ER calcium stores and altered calcium homeostasis. Tmem203 deficient mice were viable though male knockout mice were infertile and exhibited a severe block in spermiogenesis and spermiation. Expression profiling studies showed significant alternations in expression of calcium channels and pumps in testes and concurrently Tmem203 deficient spermatocytes demonstrated significantly altered calcium handling. Thus Tmem203 is an evolutionarily conserved regulator of cellular calcium homeostasis, is required for spermatogenesis and provides a causal link between intracellular calcium regulation and spermiogenesis
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