A comparison of American lobster size structure and abundance using standard and ventless traps

Ventless (escape vents blocked) trap surveys are becoming increasingly common and provide data that are useful for making well-informed management decisions. The purpose of this study was to conduct ventless and standard trap surveys, in parallel with SCUBA surveys, to determine how lobster catch in both types of traps relates to the size structure and abundance of lobster populations on the bottom. Because trap saturation may affect catch-per-unit-effort, we also quantified how catch changed over time by pulling traps after a period of 10 distinct soak times, ranging from 2 to 96 h. All surveys were carried out in 2010 and 2011, at a study site along the coast of New Hampshire, USA. Ventless traps collectively captured 10 times as many lobsters as standard traps, but the mean size of the lobsters captured did not differ between the trap types. Catch in standard traps changed little over time and thus the time to saturate was difficult to assess. However, ventless traps saturated between 16 and 24h. Ventless traps saturated at all lobster densities, but had higher final catch values at times when lobsters were most abundant (as determined by SCUBA surveys). These data indicate that ventless traps provide valuable information about natural lobster populations, which can be useful in the assessment of this valuable fishery. (C) 2015 Elsevier B.V. All rights reserved.