激励
发表于 2025-3-23 12:20:42
Rudolf Ratzel,Hans-Dieter Lippert Atlantic coast, as well as in the Mediterranean and Adriatic Seas, which is concluded to represent the origin of the species range. Contrastingly, the diversity was low on the European Atlantic and the North Sea coasts as well as in the Black Sea, suggesting that these areas were colonized only recently.
cultivated
发表于 2025-3-23 15:38:19
Rudolf Ratzel,Hans-Dieter Lippertrly twentieth century. In addition to the European sturgeon, Atlantic sturgeon (.), beluga (.) and Adriatic sturgeon (.) are discussed as presumably former endemic species. Such status remains open given that the occurrence of isolated specimens is not taken as conclusive evidence for the upgrading of these taxa to a native species status.
ARC
发表于 2025-3-23 21:38:05
Rudolf Ratzel,Hans-Dieter Lippertradient. They show common denominators in the subtidal area as far as depth, muddy or sandy sediment are concerned, and similar current velocity. These habitats constitute an important feeding ground rich in tube-dwelling polychaetes (. sp. and .), which have been identified as the dominant prey items of European sturgeon juveniles.
手铐
发表于 2025-3-23 23:08:13
Rudolf Ratzel,Hans-Dieter Lippertsess the evolution of landings and caviar production. According to our estimates, with the intensive fishing of juveniles, landings reached 120 t in 1920, with a production of 3,000 kg of caviar. The sharp decrease after World War II up to 1980 is described.
显赫的人
发表于 2025-3-24 03:04:06
Rudolf Ratzel,Hans-Dieter Lippertter 1840 in Germany. The endpoint of a targeted fishery occurred in the early twentieth century for the majority of rivers. River constructions to improve navigation, pollution, as well as overharvest interlinking with insufficient protection led to the extirpation of the species in the North Sea and its tributaries.
尽忠
发表于 2025-3-24 07:45:17
Rudolf Ratzel,Hans-Dieter Lippertne and disappearance in the 1920s, due to increasing fishing and pollution. In Italy, sturgeon fishing was declared illegal in the 1980s, but in a few years the species disappeared. Nowadays, a reintroduction plan could take advantage of the experience gained with the recovery plan carried out for ..
Anthem
发表于 2025-3-24 11:46:27
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能得到
发表于 2025-3-24 17:09:11
Morphological Distinction Between Juvenile Stages of the European Sturgeon , and the Atlantic Sturgein fish of 4–20 cm is assessed. We outline valid diagnostic characteristics in juveniles (number of dorsal and lateral scutes, surface/type of scutes, presence of fontanelle), giving comments on their usefulness with regard to the diagnostic significance in adults.
朋党派系
发表于 2025-3-24 21:33:13
Ontogeny of the European Sturgeon, ,ally oriented spikes are very prominent. In older juveniles the spikes regress; in 30 cm long juveniles the spikes have nearly disappeared. The ontogeny of the incomplete cover of the gills by the operculum is shown. The distribution of the ampullary electroreceptors in a 27-day-old larva is described.
Customary
发表于 2025-3-25 01:50:34
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