SUMMARY

• Main Authors: A. Z. Horodysky, D. W. Kerstetter, J. E. Graves
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.543.2503; http://www.iccat.int/Documents/CVSP/CV056_2004/no_1/CV056010160.pdf

To improve billfish assessments, researchers have applied habitat-based models that incorporate behavioral and oceanographic parameters to standardize historical catch-per-unit-effort time-series data, accounting for significant gear changes over time. However, there has been little behavioral data from Atlantic billfishes to support these models. We provide information on habitat preferences of white marlin released from recreational and commercial fisheries in the western North Atlantic. White marlin were tagged with pop-up satellite archival tags (PSATs) from recreational rod and reel (n=22) and commercial pelagic longline (n=2) fisheries between May-November 2002. Our data indicate that each surviving white marlin spent the majority of time at depths of 10m or less, with all fish displaying repetitive short duration diving behavior (less than 30 minutes) to depths of 60-100m. These dives were presumably related to foraging activities. Furthermore, the depths of many of the repetitive dives were within the range of deep-set pelagic longline gear. Longline sets targeting bigeye tuna may actually increase white marlin by-catch by placing baits at depths where this species may be highly motivated to feed. Until billfish feeding motivation is better understood, it may be premature to apply habitat-based stock assessment models to billfishes in the Atlantic Ocean.