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Μια σειρά άρθρων με τίτλο "Endangered cichlids of Lake Tanganyika" άρχισε να γράφει ο Ad Konings στο fb.
Το πρώτο :

Maswa Duboisi
The cichlid at most risk of extinction is the so-called Maswa Duboisi. This particular form was discovered about 40 years ago by Pierre Brichard near a place known from old maps as Maswa. It is the name of an old fortress, later monastery, located on the shore south of the Malagarasi Delta, though nothing of it now remains. Since its introduction into the hobby late 1950s, Tropheus duboisi has always been an extremely popular cichlid mainly because of it polka-dotted juveniles. The species is very old, estimated at about 2 million years, and seems less capable of holding territory in the prime rocky habitat as other members of the genus. We therefore find only a few relict populations of this species in the northern half of the lake. By extracting major numbers of this species from such surviving populations, we likely push this cichlid quickly to extinction. This has nearly happened with the Maswa Duboisi which used to live at a few select places around Cape Kabogo. The initially discovered population was virtually wiped out by the end of the previous century and after I found another population near Halembe also that population is nearly gone. T. duboisi is very slowly regenerating species that usually spawns just two times a year when it produces on average nine young. The challenges juvenile cichlids face in the lake are such that almost none of these juveniles make it to maturity. The adults are already challenged by the presence of more successful members of the genus, so that over-collecting this species is a lose lose situation.
There is absolutely no need to extract this species from the wild as it is bred in quantities far greater than can be found in the lake. So, to completely stop collecting the Maswa variant of T. duboisi is a no-brainer.

και μια επισήμανση του :

A quote from Ad Konings
"I would like to clarify some of the misconceptions readers may have about over-fishing and extinction. Some believe that when not the last individual of a certain species/population has been fished out of the lake, there is still hope that the species may recover. Of course it is true that it is almost impossible to catch the very last individual of a species/population when the ornamental fish collectors are extracting fish from the lake, BUT you don’t need to catch the very last to exterminate a species. Every species has a critical minimum population density and below that, it is gone forever. With so many species competing for the same piece of real estate in the lake it is easy to see that each species needs a certain density to hold on to their share. In particular T. duboisi, who shares everywhere the habitat with a more successful congeneric, critical density is likely much higher than β€œthe last individual”.
Another misconception has been raised by those who believe that exporters manage their collection quotas by not extracting a certain species/population when they notice the numbers are dwindling. Chris knows of at least nine (!) different teams that extract cichlids from the lake. Even if there was one that would refrain from collecting a certain species/population, the other eight teams won’t! Believe me, there is NOBODY who would not collect a fish so that it can recover. As long as we want to buy a certain species/form from an exporter, there will be extractors trying to get it, even just a single individual. The local fishermen continue to catch till EVERY fish is gone. There is no alternative for these people. Some studies have been done in Africa’s lakes towards the sustainability of fisheries, words have been spoken, and laws have been made by the country’s fisheries departments, but on the ground it is a free for all with very little measure of control. They even prevent recruitment of young fish by also collecting these with mosquito nets in the very shallow water. Dream on if you think African catchers are β€œmanaging their quotas”. Regarding ornamental fish it is OUR demand that drives certain species into extinction; WE have to regulate collections, not the workers in Africa. There are about 200 cichlid species and variants that are or have been exported from the lake; all we ask is to refrain from buying a few of these, less than 3%.
There was a question about the validity of information given on this page because if it was only me saying so it was not acceptable. I wonder whom we should ask about the cichlids in the lake, somebody who has been traveling, observing, and publishing about these fish in the lake for the last 30 years, scientists who have made detailed studies of particular populations, concerned citizen of Tanzania who actually live on the shores of the lake, OR an importer of these fish in the United States who perhaps has never seen a cichlid in its natural habitat? To answer the question about how often Tropheus species breed please read the study by Yanagisawa & Sato (1990) who found in their study area that T. duboisi mouthbroods for about 31 days and females recuperate for about 76 days before they spawn again. For T. moorii/T. sp. ‘black’ the interval is even much longer. It is possible that in the aquarium, where fish get fed twice a day and there are no predators, T. duboisi may spawn perhaps 4 times a year, but in their natural habitat things are a little more competitive. Also during the rainy season hardly any cichlid species breeds because of poor visibility. So, in the wild a Tropheus female spawns on average 2-3 times a year. Therefore catching 50% of a population in a single year is NOT sustainable for Tropheus."