Daily Archives: 14 May 2009

From sturgeons to round gobies

A while ago, I commented on the capture of a Russian sturgeon Acipenser gueldenstaedti, in southern Sweden. The fish now has a home in an aquarium at Universeum, where it moved in 5 May. Universeum is a Science center in Göteborg, located on the Swedish west coast. They have a web cam of their shark tank. I rather want to see the sturgeon!

Meanwhile it appears that German fishery biologists have indeed released plenty of Atlantic Sturgeon, Acipenser oxyrinchus, imported and reared from North American stock. The idea is to re-introduce an extirpated species. Without eliminating any of the adverse factors that killed the sturgeon and threatens all other life in the Baltic: fishery and pollution is just the first name. Will the introduced sturgeon become a further complication in a disturbed ecosystem or will they peacefully die away? Stay tuned.

German newspapers now report on catches (Berliner Morgenpost, 14 May 2009), and a tagged sturgeon (Acipenser oxyrinchus) was caught off Bornholm, a Danish island in the southern Baltic, on 6 May, the identification supported by newspaper photograph.

These sturgeons are apparently from a small number of large meter long sturgeons initially from Canada in 2005 but reared in Germany and recently released into the Baltic. Thousands of baby sturgeon have also been released this Spring according to the article in Berliner Morgenpost. 50 small tagged sturgeons were released in the Elbe in April. All the larger A. oxyrinchus released are tagged, and should be released again if caught — at least if you are a sturgeon fan. If the fish lacks the tag and has a very short snout, it is more likely a totally alien species; it is up to you what to do if you catch one. The expectation is that these fishes shall feed upon the rich benthic fauna in the Baltic and in ten years or so migrate up the Odra River on the border between Poland and Germany, and breed there, so re-establishing the sturgeon in the Baltic. The German Society for Saving the Sturgeon is one active organisation in this work with updated information on Sturgeon releases.

Whatever one may think of these experiments, fishing in the Baltic, always report your sturgeon, irrespective of species, to the nearest museum or other competent authority. Dead or alive there will be use for the information.

Another alien fish species is also coming up here. Last year, in July, a sport fisherman in Karlskrona, on the Baltic coast of southern Sweden, caught a strange fish which he kept in his freezer for a while. In November it was reported to the right scientist, and made some headlines. It was the first Swedish representative of the round goby, Neogobius melanostomus, a Black Sea species which has made itself at home in select locations in the Polish section of the Baltic since about 1990. Just a few days ago, the second specimen was reported, also this time near Karlskrona, which has both an important harbour and archipelago. It will be interesting to follow also the spread of this alien, which unfortunately will not go away as easily as the sturgeons may.

Neogobius melanostomus from Karlskrona, May 2009, NRM 51437.
Photo Bodil Kajrup, Swedish Museum of Natural History, CC-BY-NC.