identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
038787C8FF81FF9CCD8F615122DDFF32.text	038787C8FF81FF9CCD8F615122DDFF32.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Astacus astacus (Linnaeus 1758)	<div><p>Noble crayfish Astacus astacus (Linnaeus, 1758)</p><p>The noble crayfish is obviously the only local species in Latvian waters. It has been found in many lakes and rivers throughout the territory of Latvia (Bērziņš 1936, Mazītis 1955, 1967, 1971).</p><p>In surveys undertaken from 1962 to 1968 (Jurane 1967, Jurane &amp; Dzene 1969), 31 lakes where noble crayfish could be found were mentioned. These lakes were distributed fairly evenly throughout the territory of Latvia.</p><p>In parallel to this, a survey of local fishermen was undertaken via questionnaires. From the collated data, crayfish were ascribed to 163 lakes and 109 rivers in Latvia. From the sites indicated on the map included in the publication (Jurane 1967), noble crayfish could be found in 95% of them, with narrow-clawed crayfish in the rest.</p><p>Judging from the Baltic Fish Conservation and Reproduction Administration’s archival materials from the 1970s and 1980s, distinguishing between the species of crayfish has not always been correct. The local residents and crayfish fishermen’s surveyed called the smaller sized noble crayfish “swamp crayfish”, and the specimens with regenerated claws, as narrow-clawed crayfish. Therefore, the data from various surveys and questionnaires, as can be observed nowadays too, is not certain enough in relation to the systemic affiliation of the crayfish found in this or that water body.</p><p>In the surveys that we conducted from 1992 to 2018, noble crayfish was found in a total of 158 lakes, 52 rivers, 6 reservoirs on rivers and 5 quarry reservoirs throughout the territory of Latvia, in all of the largest river basins, (Fig. 2.).</p><p>In general, a trend can be observed, that the occurrence and local distribution of noble crayfish is decreasing, which is caused by their periodical mass mortality, and the increased distribution and occurrence of other species of crayfish.</p><p>In neighboring Estonia, noble crayfish are the only local species (Paaver &amp; Hurt 2010, Kouba et al. 2014). Similarly, in Lithuania too, it is considered to be the only local crayfish species (Burba 1994, Taugbøl 1998, Arbačiauskas et al.</p><p>2012). In Belarus, the noble crayfish populations have co-existed with narrow-clawed crayfish (Šteinfeld 1957, Aklehnovich &amp; Razlutskij 2013).</p></div>	https://treatment.plazi.org/id/038787C8FF81FF9CCD8F615122DDFF32	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aleksejevs, Ēriks;Birzaks, Jānis	Aleksejevs, Ēriks, Birzaks, Jānis (2020): Distribution Of Freshwater Crayfish In Latvia. Acta Biologica Universitatis Daugavpiliensis 20 (1): 1-11, DOI: 10.5281/zenodo.10602038
038787C8FF80FF9ECD5C602422EAFF7F.text	038787C8FF80FF9ECD5C602422EAFF7F.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Astacus leptodactylus (Eschscholtz 1823)	<div><p>Narrow-clawed crayfish Astacus leptodactylus (Eschscholtz, 1823)</p><p>The distribution of narrow-clawed crayfish is mainly linked with the south-eastern region of the country and more rarely in the rest of Latvia (Bērziņš 1936, Mazītis 1955, 1967, 1971).</p><p>Earlier evaluations of the distribution of this species have been quite inconsistent. Thus, in one of the publications, where survey data has also been used, 14 sites along Latvia’s southern border were mentioned (Jurane 1967). Whereas, a map in another publication (Jurane &amp; Dzene 1969) shows 50 narrow-clawed crayfish sites, which also include the central and northern part of Latvia. Even though, the number of lakes surveyed directly, compared to prepublication, fundamentally doubled (80), this is still not mentioned as an increase in the number of sites in the text of the article, but is portrayed graphically on the map. It shows that narrow-clawed crayfish can be found mainly in the southern part of Latvia and 3 lakes are mentioned in which they can be found in large numbers.</p><p>In the most recent surveys from 1992 to 2018, narrow-clawed crayfish were found in 33 lakes, 4 rivers, 3 reservoirs on rivers and 2 quarry reservoirs (Fig. 3.).</p><p>Of the largest rivers, individual examples were found only in the Lielupe, but were also encountered in reservoirs in the Daugava and Gauja rivers basins.</p><p>The early origin of the narrow-clawed crayfish in Latvia is unclear. In the literature (Bērziņš 1936, Mazītis 1955, 1967, 1971) the presence of species is mentioned early in the previous century, without mention of it as having developed as a result of their introduction.</p><p>In later publications (Jurane 1967, Jurane &amp; Dzene 1969), the assumption that narrow-clawed crayfish were brought into Latvia from Belarus or Lithuania was expressed, but no specific facts were mentioned. This may be why it tends to be described as being a local species in all three neighboring countries (Holdich 2002), or even mentioned as a local European species which has been introduced into Latvia and Lithuania relatively recently (Holdich et al. 2009).</p><p>The assumption that it was introduced into Lithuania from Latvia or Belarus in the late 19 th century has also been expressed (Burba 1994).</p><p>In the Pskov region of Russia which borders Latvia, narrow-clawed crayfish, which were introduced from Belarus, can only be found in a few lakes and rivers (Rahmanov 1976).</p><p>In Belarus, narrow-clawed crayfish are considered to be a local species with its area of distribution having increased in a northerly and north-westerly direction (Šteinfeld 1957, Aklehnovich &amp; Razlutskij 2013).</p><p>The greatest number of narrow-clawed crayfish populations in Latvia is in the south and southeast part of the country in the border zone with neighboring countries Lithuania and Belarus. The character of its distribution leads to the assumption that, historically, narrow-clawed crayfish have not been a local species in Latvia. At the same time, the distribution of narrow-clawed crayfish in neighboring countries (Arbačiauskas et al. 2012, Kouba et al. 2014) provides evidence, that the artificial spread of its natural habitat to Latvia has, in actual fact, taken place.</p><p>Narrow-clawed crayfish have not been found further to the north of Latvia and in Estonia (Paaver &amp; Hurt 2010, Kouba et al. 2014).</p><p>Compared to the first half of the previous century, there has been an increase in their occurrence and distribution, caused by their illegal introduction from Belarus into individual lakes in the northeastern part of Latvia in the 1980s. From unofficial information, the unsanctioned spread of narrow-clawed crayfish is taking place nowadays too. However, a particularly rapid increase in their occurrence and distribution will not, most likely take place. Just like the noble crayfish, mass mortality is characteristic to this species and was observed in four lakes from 1993 to 2010. The narrow-clawed crayfish may possibly lose in competition with the spiny cheek crayfish, the distribution area of which is rapidly increasing. Thus, 212 spiny cheek crayfish and only one narrow-clawed crayfish were caught during test fishing at 5 sites in a 25 km long section of the Lielupe in 2005 and 2006.</p></div>	https://treatment.plazi.org/id/038787C8FF80FF9ECD5C602422EAFF7F	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aleksejevs, Ēriks;Birzaks, Jānis	Aleksejevs, Ēriks, Birzaks, Jānis (2020): Distribution Of Freshwater Crayfish In Latvia. Acta Biologica Universitatis Daugavpiliensis 20 (1): 1-11, DOI: 10.5281/zenodo.10602038
038787C8FF82FF9ECD5C61E92149FCBE.text	038787C8FF82FF9ECD5C61E92149FCBE.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Pacifastacus leniusculus (Dana 1852)	<div><p>Signal crayfish Pacifastacus leniusculus (Dana, 1852)</p><p>Signal crayfish were introduced into Latvia from Lithuania in 1983 and 1984 and released into Primmas Lake in 1983-1985 (Mjasischev 1991). They were raised in a fish farm on the Gauja’s tributary, the Brasla, from which it entered this river.</p><p>The signal crayfish have successfully acclimatized and formed a naturally reproducing population in Primmas Lake. The signal crayfish may possibly have reached the adjacent Kliķu Lake via the ditch system and along the KorĢe River into the Salaca River and the rivers in its basin, where a particularly large population of signal crayfish has developed.</p><p>In total, signal crayfish were found in one lake and 9 rivers from 1992 to 2018, where, according to unofficial information, they ended up mainly as a result of their unsanctioned spread from a fish farm, where they were bred, or from the lake where they acclimatized. (Fig. 4.).</p><p>Their legal catching in the Salaca River, which commenced in 2007, has obviously facilitated this process even more.</p><p>Up till now, they have been found in natural water bodies only in the Salaca and Gauja rivers basins, but from unofficial information they were also released in the Daugava River basin, as well as in 2 small rivers flowing into the Gulf of Riga. The species is bred artificially in fish farms and introduced into artificial water bodies. The signal crayfish, an alien species, the natural area of distribution of which is not associated with Europe, is considered to be an invasive species in Latvia. Its further distribution in lakes has not been observed, but its presence in rivers is linked to the river basins of the Salaca and the Gauja.</p><p>Bearing in mind that the mass mortality of the signal crayfish, as opposed to the noble and narrow-clawed crayfish, has not been observed in Latvia, managers of individual natural waters are interested in their illegal introduction, which will obviously gradually increase their distribution area.</p></div>	https://treatment.plazi.org/id/038787C8FF82FF9ECD5C61E92149FCBE	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Aleksejevs, Ēriks;Birzaks, Jānis	Aleksejevs, Ēriks, Birzaks, Jānis (2020): Distribution Of Freshwater Crayfish In Latvia. Acta Biologica Universitatis Daugavpiliensis 20 (1): 1-11, DOI: 10.5281/zenodo.10602038
