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Spawning season and food habits of the deep-water stomatopod crustacean Squilloides leptosquilla (Squillidae) in Kagoshima Bay, Japan
2004
Ohtomi, J. (Kagoshima Univ. (Japan). Faculty of Fisheries) | Yokomura, H. | Hamano, T.
The spawning season and food habits of the deep-water stomato-pod crustacean Squilloides leptosquilla (Squillidae) were examined using samples collected on board the small-scale bottom trawlers in Kagoshima Bay, southern Japan. From the reproductive analyses, the size at sexual maturity of female S. leptosquilla was estimated to be 10 mm in carapace length and the spawning season was estimated to continue from May to September with a peak during July and September. Gut analysis showed that this species is a typical carnivore and mainly ate shrimps, especially the deep-water mud shrimp Solenocera melantho which is one of the most important target species for the small-scale bottom trawlers in Kagoshima Bay.
Mostrar más [+] Menos [-]Effects of salinity on survival, daily food intake and growth of juvenile round goby Neogobius melanostomus (Pallas, 1814) from a brackish water system Texto completo
2015
Hempel, M. | Thiel, R.
The growth response of juvenile round gobies was tested in various salinities to assess the potential performance of the species in widely differing salinities in the Baltic Sea and adjacent waters. An experimental approach analysed the survival, daily food intake and growth of juvenile Neogobius melanostomus from the brackish water region of the Kiel Canal, Germany. Round gobies (TL = 61.5 ±5.3 mm; n = 40) were fed ad libitum (diet = mysid shrimp; energy content = 4.7 cal per mg dry weight) at salinity levels of 0.1, 7.5, 15 and 30 over 12 weeks. Two replicate tanks (125 × 30 × 30 cm; 100 L) were maintained for each salinity level, each holding five specimens at a mean temperature of 19.90°C (±0.64°C; n = 136). Survival at all levels was 100%, except for 0.1 with 90%. Mean daily food intake (% of body weight) increased from salinity level 0.1 to 15 (from 17.76% to 19.95%); specimens at level 30 showed a more diversified and lower mean food intake (18.44%). Mean cumulative body weight gain appeared greatest at a level of 7.5 (224.52%), closely followed by 0.1 (206.57%) and 15 (191.92%). In contrast, fish growth was significantly lower at a salinity level of 30 (100.57%). Results of the experiment indicate that salinity tolerance estimates of the round goby made by other authors are too low regarding specimens that stem from brackish habitats. Growth patterns of some specimens, even in the salinity 30 treatment, show that a further spread of this species into regions with higher salinities is quite possible.
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