LAUSR

Aggregations of egg bearing (ovigerous) American lobsters, Homarus americanus (H. Milne-Edwards, 1837), have been documented throughout the species range, but it is not clear why they tend to accumulate in these areas. One such aggregation occurs near the Isles of Shoals (IOS), New Hampshire, USA. The overall goal of our study was to determine if reproductive status, depth, temperature, and/ or current might explain their presence in this area. In 2013 and 2014, research traps were fished at three depth strata (5– 15, 16–25, and 26–35 m), on similar substrates, on both the eastern and western side of the IOS to quantify population demographics. Traps fished on the eastern side of the IOS caught significantly larger female lobsters and approximately 3 times more ovigerous lobsters than those on the western side. Interestingly, the catch rate of females carrying eggs that were hatching was significantly higher in the deep-water stratum (26–35 m) compared to shallow areas (5–15 m), when combining data from both sides of the IOS. In contrast, late stage prehatch animals were significantly more abundant in shallow water. Thus, it appears that female lobsters move to deeper water prior to to the time when their eggs are due to hatch. We hypothesize that lobsters accumulate in specific areas, like IOS, to brood their eggs in part because of their proximity to preferred deep water and high-current hatching locations.