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We conducted an interdisciplinary review of available information (i.e., genetics, life-history, and movement) to evaluate the stock structure of a previously targeted shark species, the porbeagle (Lamna nasus), in the North Atlantic. Most available information supports the conclusion that porbeagle consist of a single genetic population in the North Atlantic, which is relevant for determining species conservation status. However, the observed movement rates between the Northwest, Northeast Atlantic, and the Mediterranean appear to be low enough to consider separate spatial units for stock assessment and fishery management. The review reveals different interpretations among the organizations involved with the conservation, management, and assessments of porbeagle in the North Atlantic regarding biological population and stock boundaries. Differences in the spatial definition of management units among management organizations may pose an impediment to conserving porbeagle populations and achieving management objectives. We recommend an increased collaboration between organizations involved in highly migratory shark species as it would be beneficial for data collection, data inclusiveness, the robustness of assessments, and provide clarity for fishery managers, scientists, and the public on stocks and status. This review demonstrates that the interdisciplinary approach to stock identification is particularly valuable for data-limited species because no single approach typically has enough information to be definitive. Clearly defining management units that reflect the biological populations of porbeagle in the North Atlantic is expected to reduce uncertainty in stock assessments and help achieve current management and conservation goals of rebuilding North Atlantic porbeagle stocks. [ABSTRACT FROM AUTHOR]

A masking-level-difference (MLD) paradigm was used to measure release from masking in a reverberant environment. The masking-level difference is specified in terms of the signal level in decibels at threshold for an experimental condition, relative to the signal level at threshold for the reference S0N0 condition where the maskee and masker are both binaurally in phase. Two types of masking situations were used: (1) incoherent masking-a signal (pulsed tone or speech in this study) had to be detected in a noise background; (2) coherent masking-the signal and masker were derived from the same source. Band-limited noise and speech were used in the coherent masking experiments. For both masking conditions, the MLD was found to be approximately 3 dB. Cross correlation of the late-echo structure of impulse responses taken at the left and right ears of a manikin show that the reverberant sound field is uncorrelated between the two ears. This is consistent with a 3-dB MLD result. [ABSTRACT FROM AUTHOR]