Prof. Dr. Gunther Lachsmann
Institute of Coastal and Aquaculture Technology, Saaremaa (CATS), ET
Fish, the first known true chordates, have a long evolutionary history. Early jawless fish started diversifying during the middle Silurian period, but during the Devonian – sometimes referred to as the “Age of Fishes” - the variety of fish boomed. Towards the end of the Devonian the first tetrapods had evolved, an important intermediate step in the evolutionary transition from fish to terrestrial animals. This transition has lead to a slow but significant decrease of the fish population. Predation by other fish, as well as by marine mammals and birds, further decimates the fish population. In addition to the natural sinks, anthropogenic factors such as fisheries, pollution and domestic felines, aggravate the dramatic decline (well-known inversed “hockey stick”; Jungfrau, 1989). Reproduction, which occurs in species-specific locations, is the only significant source of fish known to date. A new infrared satellite tracking system has given us the opportunity to locate and quantify the sources of 23 different fish species over 3 years. Several fish communities were found to congregate in ocean gyre centres, due to the convergence of ocean currents, forming so-called “love pools”. Still, production rates in these coupling hotspots derived from the Pesci-Terminatov law, are still too low to sustain current levels of fish. The main question addressed in this talk will be: With more sinks than sources of fish identified, how come healthy fish populations are still widely observed in oceans and lakes?
*** Abstract realizzato in collaborazione con J.U. e S.G.
Institute of Coastal and Aquaculture Technology, Saaremaa (CATS), ET
Fish, the first known true chordates, have a long evolutionary history. Early jawless fish started diversifying during the middle Silurian period, but during the Devonian – sometimes referred to as the “Age of Fishes” - the variety of fish boomed. Towards the end of the Devonian the first tetrapods had evolved, an important intermediate step in the evolutionary transition from fish to terrestrial animals. This transition has lead to a slow but significant decrease of the fish population. Predation by other fish, as well as by marine mammals and birds, further decimates the fish population. In addition to the natural sinks, anthropogenic factors such as fisheries, pollution and domestic felines, aggravate the dramatic decline (well-known inversed “hockey stick”; Jungfrau, 1989). Reproduction, which occurs in species-specific locations, is the only significant source of fish known to date. A new infrared satellite tracking system has given us the opportunity to locate and quantify the sources of 23 different fish species over 3 years. Several fish communities were found to congregate in ocean gyre centres, due to the convergence of ocean currents, forming so-called “love pools”. Still, production rates in these coupling hotspots derived from the Pesci-Terminatov law, are still too low to sustain current levels of fish. The main question addressed in this talk will be: With more sinks than sources of fish identified, how come healthy fish populations are still widely observed in oceans and lakes?
*** Abstract realizzato in collaborazione con J.U. e S.G.
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