A mark-recapture study of hatchery-reared juvenile European lobsters, Homarus gammarus, released at the rocky island of Helgoland (German Bight, North Sea) from 2000 to 2009

Abstract

a b s t r a c tFrom 2000 to 2005 about 5400 one-year-old hatchery-reared lobsters (Homarus gammarus) were tagged and released at the rocky island of Helgoland, North Sea. To date, 1-8% of the different release cohorts were recaptured in the field and 8-19% of these lobsters were recaptured from the semi-open area of the outer harbour. The recaptured lobsters indicated good development and growth conditions. The smallest berried females caught were 83 mm carapace length and 4 years old. The proportion of cultured lobsters to all measured lobsters captured around the island was 3-8% in the years [2007][2008][2009]. The population size of two cohorts was assessed using the Lincoln-Peterson method and the estimated survival rate averaged 30% and 40%. Minimum landing size of cultured lobsters was reached after 4-7 years. Cultured lobsters showed strong fidelity to their release sites, and thus remained around the island of Helgoland. A basis has been laid to enhance this endangered lobster population by means of a large scale restocking programme.

Effects of temperature on the moulting and locomotory activity of hatchery-reared juvenile lobsters (Homarus gammarus) at Helgoland (North Sea)

“…The lobsters used in this study were released at Helgoland within the markÁrecapture programme Schmalenbach et al 2011).…”

“…During this phase the risk of predation is high. The survival of released juvenile lobsters in the wild may be influenced by the presence of sufficient shelter, suitable substratum, abundance of competitors and predators, and the release techniques as the transportation conditions, time of release and seasonal water temperature (Van der Meeren 1993, 2000Schmalenbach et al 2011).…”

“…Furthermore, locomotory activity of nocturnal lobsters of Homarus spp. may depend on their size, sex and specific behavioural patterns (foraging, moulting, mating, dominance and territorial behaviour) (Branford 1979;Lawton 1987;Karavanich & Atema 1998;Mehrtens et al 2008;Schmalenbach et al 2011). So far, field studies that quantified movement in adult lobsters reported no significant differences in home ranges between lobster size and sex (Scopel et al 2009;Moland et al 2011b).…”

Morphological and histochemical examination of male and female gonads in Homarus gammarus (L. 1758)

“…These include: growth, reproduction, movement and abundance of the European lobster, H. gammarus, at the rocky island of Helgoland, North Sea [8], improvement of rearing conditions for juvenile lobsters by co-culturing with juvenile isopods (Idotea emarginata) [3], growth, reproductive cycle, and movement of berried European lobsters in a local stock off southwestern Norway [9], reproduction in the European Lobster [10], studies on the developmental conditions of the European lobster [8], and variation on size at onset of egg production [11]. However, basic studies concerning the male and female reproductive system, gonad structure and histochemistry are missing.…”

Potential impact of climate warming on the recruitment of an economically and ecologically important species, the European lobster (Homarus gammarus) at Helgoland, North Sea

“…Up to the 1930s, there was an important lobster fishery at Helgoland, yielding up to 50 tons per year (Klimpel 1965). Since a dramatic decline in landings in the 1950s and 1960s, the numbers of lobsters landed per year have been fluctuating at an extremely low level of only a few hundred individuals per year (Goemann 1990;Schmalenbach 2009). As no fishery-independent data on lobster abundance are available from past decades, we do not know to what extent the population actually declined.…”