Quantitative relationships between postlarval production and benthic recruitment in lobsters, Homarus americanus

Abstract

Relationships between lobster postlarval supply and benthic recruitment were evaluated within and between oceanographically distinct segments of the range of the American lobster. Postlarvae (PL) were sampled by neuston nets in western Rhode Island Sound and the western Gulf of Maine, USA, from June to September 1989–95. Benthic lobsters were sampled in sublittoral cobble habitat by using a diver-operated airlift at the end of the settlement season. Average annual recruitment densities of young-of-year (YOY) lobsters ranged from 0.3 to 1.7 m-2. YOY recruitment was positively correlated between areas. Integrated seasonal abundance of postlarvae was often much greater in Rhode Island than Maine, but production estimates (PL 1000 m-2 season-1), calculated from moult cycle stages and temperature-dependent growth rates, differed by a factor of <0.5. PL production was positively correlated between areas and explained ≥81% of the annual variation in recruitment in each area and 90% for the two areas combined. In Maine, among-site differences in YOY recruitment persisted for a year after settlement and then began to lessen, at least in part because larger individuals moved into areas of initially lower recruitment

A vessel‐deployed passive postlarval collector to assess settlement of the American lobsterHomarus americanus

“…Under this protocol, divers sampled twelve 0.5 m 2 quadrats per site. Newly settled young-of-year lobsters were defined as those <11 mm CL on the basis of previous studies (Wähle Incze et al 1997;Wähle et al 2004). …”

“…), so called "crevice collectors" made of stacked layers of plywood are more suitable (Booth & Tarring 1986). In other instances, natural substrates, such as shell hash or rocks, placed in deployable-retrievable units have proven effective (Eggleston & Armstrong 1995;Incze et al 1997;Moksnes & Wennhage 2001).…”

“…Since the late 1980s, diver-based suction sampling of both natural and artificial habitats has been widely used to quantify recruitment of recently settled American lobster (e.g., Wähle & Incze 1997;Incze et al 1997;Wähle et al 2004). Currently, some 70 sites are sampled annually along the coast of New England, United States, and Atlantic Canada to assess young-of-year recruitment and the abundance of older juveniles (Incze et al 2006).…”

“…For example, Incze et al (1997) deployed a collector made of standard trap wire mesh lined with a finer mesh and filled with cobble stones. Another design described by Palma et al (1998Palma et al ( , 1999 and Wilson (1999) was constructed of stacked cross-wise layers of PVC tubing fastened to a wire mesh tray lined with a finer mesh.…”

The geography and bathymetry of American lobster benthic recruitment as measured by diver-based suction sampling and passive collectors

“…Developing sampling methods to quantify newly settled cohorts in benthic population studies can be a powerful way of understanding processes operating before and after larval settlement that drive subsequent recruitment and population dynamics (Roughgarden et al 1988;Pineda 2000;Balch & Scheibling 2000;Cowen et al 2000;Navarrete et al 2005). Studies of lobsters and crabs that track the fate of early benthic cohorts have provided critical insights into larval transport leading to benthic recruitment and the strength of inter-and intraspecific interactions influencing the fate of cohorts after settlement (Eggleston & Armstrong 1995;Pile et al 1996;Incze et al 1997;Moksnes & Wennhage 2001;Gardner et al 2001;BrionesFourzan et al 2008). The western rock lobster, Panulirus cygnus George 1962, is a noteworthy example of a species for which annual monitoring of postlarval settlement has been an integral part of fishery management for more than four decades (Caputi et al 1995).…”