An overview of the LEAR (Lobster Ecology and Recruitment) project: results of field and experimental studies on the juvenile ecology of Homarus gammarus in cobble

Abstract

Field and experimental studies were undertaken in four European countries on clawed lobster (Homarus gammarus) ecology and recruitment. The aims were to assess: (a) abundance of early benthic phase (EBP) lobsters and other benthic species at cobble sites, (b) the effect of these species on EBP growth and survival, and (c) influence of these factors on recruitment and/or viability of restocking. Suction sampling of cobble sites revealed a wide diversity and abundance of potential competitors but no EBP lobsters. Hatchery-produced EBPs were therefore used for small-scale mesocosm experiments. In nature, predation on EBP was rapid without shelter, whereas in-vitro mortality, growth, and behaviour experiments showed that cover potentially increases survival. Scarcity per se may not completely explain the apparently absence of EBP, given that not a single EBP lobster was located either during this study or during any other of the extensive benthic investigations. The present paper discusses the implications of their apparent absence and whether it arises because EBPs are very scarce, cannot be captured by suction sampling, are not within lobster habitat, or occupy a specialized niche within adult habitat outside the range of current sampling methods.

Desktop study on autecology and productivity of European lobster (Homarus gammarus, L) in offshore wind farms

“…For the relation between TL and CL, We calculated a slope of 0.37 (R² = 0.9963) from the data of Schmalenbach (2009). Kristiansen et al (2004) calculated a slope of 0.35 (R 2 = 0,9519) for reared juvenile European lobsters from Norway, Mercer et al (2001) a slope of 0.36 for reared lobster from Ireland and Scotland. Table 2.…”

“…European lobsters are usually located at lower than mean low water neaps (sublittoral fringe) to depths of 165m; usually not deeper than 50 m ( (Mercer et al, 2001).…”

“…The animals are nocturnal and territorial, living in holes or crevices (Holthuis, 1991, Lawton & Lavalli, 1995, Jensen et al, 2000, Turner et al, 2009, Phillips, 2013, Seitz et al, 2014, Skerrit et al, 2015. Holes and crevices are especially important for the younger stages that are vulnerable to predation and cannibalism (Table 4, Jensen et al, 2000, Mercer et al, 2001, Phillips, 2013. As lobsters grow they gain a size-refuge from predators, and in turn their association with shelter tends to relax.…”

“…Based on indirect measurements and extrapolations, larval settlement strength of H. gammarus is associated with local sea temperatures (production and mortality) and onshore winds (transport and availability) as is described for H. americanus as well (Sheehy andBannister, 2002, Phillips, 2013). Mercer et al (2001) observed that predation on unprotected EBO lobsters was generally rapid. They suggested that time can be a critical factor during settlement, and high mortality can occurs where suitable shelter or substrate is unavailable.…”

Using camouflage for conservation: colour change in juvenile European lobster

“…Unlike their wild counterparts, hatchery-reared juveniles are naïve to predators, which often puts them at greater risk (28). The lack of habitat enrichment limits shelter-seeking behaviour in released European lobster, Homarus gammarus and those reared alone are slow to seek shelter (29), making them more vulnerable to predation (30). While training individuals alongside conspecifics can mitigate this (31), European lobsters are often reared individually to prevent agonistic interactions between individuals (32).…”