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Within an earlier project, Kvarkenharr (The Kvarken Grayling) (Interreg IKM3.4-23-02), the potential sea-spawning grayling fry-production areas in the Kvarken were presented in the form of a ready-made albeit non-verified GIS-model. The model is based on the fry studies conducted in the Holmögadd Archipelago in the summer of 2005. Newly hatched grayling fry were found along shallow clean stony beaches, which are exposed and colder than the surrounding shallow areas, at least at the start of the summer. The method used was direct observation from the shoreline at several different habitats. Holmögadd was the only area where grayling fry were observed. Therefore, Holmögadd is the only known area where the sea-spawning grayling has a nursery… in the entire world. Since the sea-spawning grayling is indigenous to the Gulf of Bothnia, the project responds directly to the environmental quality goals stipulated by the Swedish Parliament, “Hav i balans och levande kust och skärgård” (A Balanced Marine Environment, Flourishing Coastal Areas and Archipelagos). This project aims to follow these environmental quality goals as well as international agreements concerning the maintaining of biodiversity. Furthermore, this project provides a necessary tool to be able to meet these environmental quality goals. In our model, we strive to discover factors that can be measured everywhere and form the base of a functional GIS-tool. This tool should be good enough to be used on both the Finnish and Swedish side of the Kvarken. There will be a great need in the future for a working tool/model to
evaluate and define both spawning- and fry-production areas, for example,
when future regional planning will include use of marine areas, via the
marine framework directive.
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Despite the fact that there is no real follow-up of stocks, it is possible to say that the sea-grayling has declined in number and spread, and that the majority of the sub-stock has already disappeared. In interviews with researchers, fishery administrators, fishery organisations and fishmongers with regard to their views on the development of the fish stock along the Finnish coast, they all had the opinion that the grayling population had collapsed in Finland. Lately, this same decline has been seen in Sweden. In combination with the report “ Harrfiskets omfattning och karaktär vid kusten i Kvarkenregionen” (The Size and Characteristics of Grayling fishing along the Coast in the Kvarken Region), an enquiry was sent out to professional- and sport fishermen in order to gain an overview of the history and development of the grayling populations in the Kvarken. A comparison between sports fishermen and professional fishermen shows a certain difference in their experience of how fishing has changed. Professional fishermen don’t think that the supply has changed very much, it has always been “small” or “good”, but the sports fishermen think that grayling fishing used to be very bad during the 1960s and that there has been a clear decline during the 1990s. Despite some differing views, the end result of the research is that the grayling population has obviously declined during the past 10 years, also on the Swedish side of the Kvarken.
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All the documentation concerning the grayling population in the Gulf of Bothnia shows that the situation for sea-spawning grayling is very critical. All criteria are fulfilled for the term "critically endangered", which is the highest degree of threat according to the IUCN classification (http://www.iucnredlist.org/info/categories_criteria2001) for endangered organisms on the earth. The next step is extinction from the nature. At this point, we can only speculate that there is a connection between the environmental demands of the species and the dramatic development of the population. Among other things, the common eutrophication of the Gulf of Bothnia has increased the algae production. Some of the shore zone algae are even seen as being poisonous by some researchers. Such algae are fairly common in areas that are typical grayling spawning areas and they can then be toxic during the early development stages of grayling. When the algae die and decompose, the growing environment for the fry becomes worse. Drifting, decomposing algae is a common sight along the shores today. A large population of algae benefit the three-spined stickleback that can be a serious predator to newly hatched grayling fry. Through the inventory of fry habitats, it was shown that sticklebacks were more or less missing in areas where grayling fry could be found. An increased spread of algae can benefit the three-spined stickleback and worsen the survival of grayling fry. Acidification, in particular in areas where the rivers run through acid clay, can also be a contributing factor to the population crash. Such water courses are mostly found in the Gulf of Bothnia. Since river water runs on top of sea water, acidic water can reach far out into the sea. In the acidic water, there are also lots of metals, which are especially poisonous in the change between fresh water and brackish water. Aluminium is such a metal, which is also very poisonous for fish. Unfortunately, there has been too little research made concerning what happens in the change zones where acidic metal-rich river water meets sea water, or where the waters meet the fish surface or their roe surface. However, the phenomenon is known chemically and geologically.
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