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Fish spawning aggregations are vulnerable to overexploitation, which can have severe ecological, social, and economic consequences. Knowledge on the spatial ecology of aggregating species is often lacking, but is crucial for their effective conservation. This study explores the spawning site residency, interannual fidelity, and migration of black seabream Spondyliosoma cantharus using acoustic (n =  55) and conventional (n =  2397) tagging within and outside Marine Conservation Zones in the southern UK. Detections and recaptures of tagged fish indicated that black seabream display significant interannual fidelity to nesting areas, but that residency of individuals at nesting areas was short relative to current temporal management of these areas. Locations of detection and recapture during autumn/winter indicated migration by black seabream into deeper waters of the English Channel and coastal waters of France and the Channel Islands. The results indicate spatial structuring of black seabream populations maintained by homing of adults to previously occupied sites. However, short residency periods within protected reproductive sites, and evidence of transboundary migrations emphasize the importance of effective fisheries management, i.e. collaborative between European nations. These findings highlight the importance of international-scale telemetry studies and networks for informing ecosystem-based fisheries management of sensitive migratory species. [ABSTRACT FROM AUTHOR]

Absolute efficiency calibration of radiometric detectors is frequently difficult and requires careful detector modeling and accurate knowledge of the radioactive source used. In the past we have calibrated the β–γ coincidence detector of the Automated Radioxenon Sampler/Analyzer (ARSA) using a variety of sources and techniques which have proven to be less than desirable (Reeder et al., J Radioanal Nucl Chem, 235, 1989). A superior technique has been developed that uses the conversion-electron (CE) and X-ray coincidence of 131mXe to provide a more accurate absolute gamma efficiency of the detector. The 131mXe is injected directly into the beta cell of the coincident counting system and no knowledge of absolute source strength is required. In addition, 133Xe is used to provide a second independent means to obtain the absolute efficiency calibration. These two data points provide the necessary information for calculating the detector efficiency and can be used in conjunction with other noble gas isotopes to completely characterize and calibrate the ARSA nuclear detector. In this paper we discuss the techniques and results that we have obtained. [ABSTRACT FROM AUTHOR]