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2 produkter
2 produkter
Häftad, Engelska, 1996
1 871 kr
Skickas inom 5-8 vardagar
Longlining is becoming increasingly more important as a method of fishing commercially for certain prime species of fish- particulary in the face of declining stocks. Longlining is much more selective that any other form of fishing and is thus more environmentally acceptable. Furthermore, longlining allows for the targeting of particular prime species and fish caught by this method are less damaged and thus hold a higher value. Despite the many major benefits of longlining, there are, as yet few books which address the technical and economic aspects of this method of commercial fishing. Written by an expert, this new book describes the principles and development of longlining fishing and explains the action of chemical sensing in fish and their behaviour towards baited hooks. Details of gear construction, the operation cycle for longlines, longline vessels and the different principles of mechanised baiting and on-board gear handling are provided and typical examples are given. The target species, gear parameters and catching efficiency, and the selective properties of longline gear are fully discussed whilst a concluding chapter compares longlining with other fishing methods.
E-bok
PDF, Engelska, 2014708 kr
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This Technical Report presents the outcome of a Working Group that was established to determine broadly applicable sound exposure guidelines for fishes and sea turtles. After consideration of the diversity of fish and sea turtles, guidelines were developed for broad groups of animals, defined by the way they detect sound. Different sound sources were considered in terms of their acoustic characteristics and appropriate metrics defined for measurement of the received levels. The resultant sound exposure guidelines are presented in a set of tables. In some cases numerical guidelines are provided, expressed in appropriate metrics. When there were insufficient data to support numerical values, the relative likelihood of effects occurring was evaluated, although the actual likelihood of effects depends on the received level. These sound exposure guidelines, which are based on the best scientific information at the time of writing, should be treated as interim. The expectation is that with more research the guidelines can be refined and more cells in the tables completed. Recommendations are put forward defining the research requirements of highest priority for extending these interim exposure guidelines.