Schmalenbach, Isabel

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0 10 20 30 40 5001234Calendar week 20100 10 20 30 40 500.000.020.040.060.080.100.120.140.160.180.000.020.040.060.080.100.12close seasondata are calculated: 1 kg=1 crabCPUE (N)9,904 pots203 lobsters = 286 kg15,572 pots29,744 kg = 1,695 crabsmissing data are calculated: 1 lobster=1.5 kgN and kg per pot lift 2010CPUE (kg)CPUE (N and kg)2006 2007 2008 2009 2010CPUE 0.000.020.040.060.080.100.122006 2007 2008 2009 2010012340.27t 0.28t 0.45t 0.35t 0.29t 42 t 51 t 42 t 34 t 30 tKg per pot lift and day 2006-20101960 1970 1980 1990 2000 2010Catch (kg)01000200030004000500060001960 1970 1980 1990 2000 201001000020000300004000050000Catch (kg) 1960-2010n. s.The catchability of the European lobster (Homarus gammarus) and the edible crab (Cancer pagurus) around the island of Helgoland (North Sea, German Bight)Isabel Schmalenbach, Michael Janke & Heinz-Dieter FrankeBiologische Anstalt Helgoland, Alfred Wegener Institute for Polar and Marine Research, 27498 Helgoland, GermanyReferences: (1) Schmalenbach, I., Mehrtens, F., Janke, M., Buchholz, F. (2011). 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. Fisheries Research 108, 22-30, see doi:10.1594/PANGAEA.727206 for supplementary data. (2) Schmalenbach, I. (2011). Landings of European lobster (Homarus gammarus) and edible crab (Cancer pagurus) in 2010, Helgoland, North Sea. Alfred Wegener Institute for Polar and Marine Research - Biological Institute Helgoland, doi:10.1594/PANGAEA.755534.  Pictures: T. Meyer, U. Nettelmann, B.  Rauch, I.  Schmalenbach, C. WankeAcknowledgments: The study was supported by the Ministry of Fisheries and Agriculture of the State of Schleswig-Holstein, Germany. We would like to thank the captain H.-C. Lührs and the crew of the research vessel FK Uthörn for their support in the field.Helgoland0 40 8020 Kilometers0 2,200 4,4001,100 MetersSteingrundSellebrunnknollMessstation ElbeCommercial pot fishery (1, 2)Monitoring 2010H. gammarus C. pagurusAt Helgoland waters, the population size of H. gammarus has declined dramatically since the 1960s, and commercial landingsof lobsters have been fluctuating over the past decades at a lowlevel of only a few hundred kg per year. The main competitor of the lobster for food and shelter is theedible crab, C. pagurus.In 2010, lobsters and crabs were sampled with pots from February to November at three different stations. The catch per unit effort of lobsters and crabs varied from 0 lobster and 0.04 crabs per pot in winter to 0.08 lobsters and 11 crabs in summer. Data on catch rates of lobsters and crabs and their seasonal changes around Helgoland may be helpful for fishery and management regulations.The size of crabs increased while the percentage of females decreased with increasing water temperature. Berried crabs were not captured around Helgoland.The catchability of lobsters and crabsis related to several environmentalvariables such as the water temperature and is dependent on their size, sex andspecific behavioural patterns.H. gammarus C. pagurusH. gammarus C. pagurus279 pots; 4 lobsters6 10 15 23 26 28 38 39 47 CPUE0.00.10.20.30.40.56 10 15 23 26 28 38 39 4705101520SST (°C)05101520N per pot lift299 pots; 9 lobsters323 pots; 8 lobsters279 pots; 1,062 crabs299 pots; 1,121 crabs323 pots; 1,197 crabsSteingrundSellebrunnknollSea surface water temperature (SST) MessstationTemperature (°C)0 5 10 15 20CPUE (N lobster)0.000.020.040.060.08CPUE (N crab)0246810CPUE vs. temperatureH. gammarus:y=-0.0013+0.0022x; r²=0.5160, p<0.05C. pagurus:y=-1.7367+0.5192x;r²=0.8916; p<0.0001not fished n. f. n. f.6 10 15 23 26 28 38 39 47Sex ratio (%)02550751006 10 15 23 26 28 38 39 47Size (cm)0510156 10 15 23 26 28 38 39 4705101520Carapace length per pot lift Carapace width per pot lift  female: 10.2cm; male: 11.4-13.1cm  female: 11.1cm; male: 9.1-15.5cm        female: 10.0-10.8cm; male: 11.2-14.0cmfemale: 8-18cm; male: 5-21.5cmfemale: 7-19cm; male: 8-20.5cm female: 7-17cm; male: 6-21.5cmSex ratio per pot lift (all stations)6 10 15 23 26 28 38 39 470255075100malefemaleCalendar week 2010n. f.

The catchability of the European lobster (Homarus gammarus) and the edible crab (Cancer pagurus) around the island of Helgoland (North Sea, German Bight)

The catchability of the European lobster (Homarus gammarus) and the edible crab (Cancer pagurus) around the island of Helgoland (North Sea, German Bight)

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