Comparison of Vented and Ventless Trap Catches of American Lobster with Scuba Transect Surveys

Abstract

ABSTRACT Ventless trap surveys are becoming an increasingly common method to estimate American lobster (Homarus americanus) population structure and abundance. These surveys typically consist of strings of conventional commercial vented traps set alternately with experimental ventless traps, which lack escape vents and, as a result, capture higher proportions of sublegal-size lobsters. To determine how accurately ventless trap surveys reflect lobster populations on the seafloor, lobster density, size distribution, and sex ratios observed from scuba transect and tagging surveys were compared with ventless trap survey catches at 17 locations that varied by average temperature and dominant substrate. Diver surveys indicated that higher lobster densities were associated with increasing substrate complexity and constant temperature. Trap catch per unit effort increased with substrate complexity and decreased with increasing water temperatures. Comparisons of survey methods suggest ventless trap surveys overest...