Landings of European lobster (Homarus gammarus) and edible crab (Cancer pagurus) from 1615 to 2009, Helgoland, North Sea

From 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 2007-2009. 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.

European lobsters (Homarus gammarus) captured around the rocky island of Helgoland (German Bight, North Sea) from 2005 to 2015 - A mark-recapture program -

European lobsters were captured by employees of the Marine Biological Station and local fishermen from the rocky subtidal zone around the island of Helgoland (North Sea, 54°11.3'N, 7°54.0'E) and from the Helgoland Deep Trench, located south west of the island. The animals were captured by pots, traps, trawl and divers. All measured lobsters were tagged and released. A tagged lobster was classified by the absence or presence of colour tag and/or T-bar tag. Data of lobsters contains capture date, fresh weight, carapace lengths, sex and the information if lobsters were egg-bearing and tagged. Furthermore, data of commercial landed lobsters are included.

qPCR counts of mRNA for hepatic reference gene selection in adult female Atlantic salmon from perturbation experiments under artificial temperature conditions

The dataset contains raw data (quantification cycle) for a study which determined the most suitable hepatic reference genes for normalisation of qPCR data orginating from adult (entire reproductive season) Atlantic salmon (14 days) exposed to 14 and 22 degrees C. These results will be useful for anyone wanting to study the effects of climate change/elevated temperature on reproductive physiology of fish (and perhaphs other vertebrates). In addition, a target gene (vitellogenin) has normalised using an inappropriate and an 'ideal' reference gene to demonstrate the consequences of using an unstable reference gene for normalisation. For the adult experiment, maiden and repeat adult females were held at the Salmon Enterprises of Tasmania (SALTAS) Wayatinah Hatchery (Tasmania, Australia) at ambient temperature and photoperiod in either 200 (maidens) or 50 (repeats) m3 circular tanks at stocking densities of 12-18, and 24-36 kg m-3 for maidens and repeats, respectively, until transfered to the experimental tanks.

Seawater carbonate chemistry and biological processes during experiments with early life stages of the blue mussel Mytilus edulis, 2010

Several experiments have shown a decrease of growth and calcification of organisms at decreased pH levels. There is a growing interest to focus on early life stages that are believed to be more sensitive to environmental disturbances such as hypercapnia. Here, we present experimental data, acquired in a commercial hatchery, demonstrating that the growth of planktonic mussel (Mytilus edulis) larvae is significantly affected by a decrease of pH to a level expected for the end of the century. Even though there was no significant effect of a 0.25-0.34 pH unit decrease on hatching and mortality rates during the first 2 days of development nor during the following 13-day period prior to settlement, final shells were respectively 4.5±1.3 and 6.0±2.3% smaller at pHNBS~7.8 (pCO2~1100-1200 µatm) than at a control pHNBS of ~8.1 (pCO2~460-640 µatm). Moreover, a decrease of 12.0±5.4% of shell thickness was observed after 15d of development. More severe impacts were found with a decrease of ~0.5 pHNBS unit during the first 2 days of development which could be attributed to a decrease of calcification due to a slight undersaturation of seawater with respect to aragonite. Indeed, important effects on both hatching and D-veliger shell growth were found. Hatching rates were 24±4% lower while D-veliger shells were 12.7±0.9% smaller at pHNBS~7.6 (pCO2~1900 µatm) than at a control pHNBS of ~8.1 (pCO2~540 µatm). Although these results show that blue mussel larvae are still able to develop a shell in seawater undersaturated with respect to aragonite, the observed decreases of hatching rates and shell growth could lead to a significant decrease of the settlement success. As the environmental conditions considered in this study do not necessarily reflect the natural conditions experienced by this species at the time of spawning, future studies will need to consider the whole larval cycle (from fertilization to settlement) under environmentally relevant conditions in order to investigate the potential ecological and economical losses of a decrease of this species fitness in the field.