Hydroacoustics and concurrent experimental trawling reveal extreme annual variation in the density of 0+ pikeperch in late summer

The density and mean size of 0 + pikeperch (Sander lucioperca) were studied in late summer in 2004-2017 in clay-turbid and eutrophic Lake Tuusulanjarvi in southern Finland. Hydroacoustics and simultaneous experimental trawling were used to estimate the density of 0 + pikeperch. In some autumns, 0 + pikeperch was the most abundant species in the pelagic fish assemblage. However, the annual amplitude of pikeperch density was extremely high (1,300 -19,900 individuals ha(-1)). The density and size variations of 0 + pikeperch were analysed in relation to air temperature sums and degree days. Unexpectedly, the density of 0 + pikeperch showed no correlation with the air temperature sums or degree days, but both the mean length and weight of 0 + pikeperch correlated positively with these temperature variables. The highest correlation coefficients between mean size and temperature were found with temperature sums over 10 degrees C and degree days over 5 degrees C. The correlation between density and condition of 0 + pikeperch was negative but non-significant. The high density of 0 + pikeperch in some autumns suggests that pikeperch may play a central role in the pelagic food web in eutrophic lakes - not only as a predator of planktivores but also by its own planktivory.Peer reviewe

Individual identification of Black-throated Divers (Gavia arctica)

The potential to identify individual Black-throated Divers (Gavia arctica) on the basis of breeding plumage features was explored using 278 photos, including two paired birds followed during the years 2007-2015 at a specific breeding location. Observations were focused on: 1) white lines on the sides of neck, 2) mantle having rows of sharply contrasting white squares, and 3) small white spots on lesser andmedian coverts. In photos, the number ofwhite lines on the sides of neck varied from four to seven (mean = 5.0, n = 278), and the second line from the head was the highest in 92.1% of the photos. The number of " white square" rows on the mantle varied from 11 to 14 and the small white spots on coverts from 27 to 67. Identification of individual Black-throated Divers was potentially easiest if the plumage had some special patterns (19.4% of birds, n = 278). Plumage remained the same in the followed pair between years, as was also shown by the discriminant analysis, since the followed pair was correctly classified by sex but not by sides showing that sides are similar. To estimate whether it is possible to separate these two birds from other birds, a second discriminant analysis was accomplished. Thus, 125 other birds were added to analysis as a third group together with the followed pair (female andmale, nine years and n = 18 per sex). The linear discriminant analysis yielded a classification rate of 70.8% in original analysis and 69.6% based on the leave-one-out analysis (n = 161). These analyses were based on the relative height of the neck lines, their average relative height and standard deviation. When the number ofwhite spotswere added to this discriminant analysis, a correct classification rate of 77.4% in original analysis and 75.7% in the leave-one-out analysis was obtained (n = 115). These following nesting pairs during their breeding seasons in different years. Presumed female andmaleBlack-throatedDiver could be distinguished based on the shape of the forehead.Peer reviewe

Yksilöllinen vaihtelu kuikkien (Gavia arctica) reviirihuudoissa

Kuikkien (Gavia arctica) kuuluva reviirihuuto on tunnetuimpia luonnonääniä pohjoisilla alueilla. Tutkimuksen tavoitteena oli selvittää, voidaanko koiraskuikkia tunnistaa yksilöllisesti huudon perusteella. Vuosina 2018–2021 äänitettiin 19 urospuolisen kuikan reviirihuuto, 10 niistä 2–4 peräkkäisenä vuotena ja yhdeksän yhtenä vuotena. Äänitykset tehtiin samalla järvialueella Suomessa. Huuto koostuu yhdestä johdanto-osasta ja yhdestä tai useammasta toisto-osasta. Johdanto-osan ja ensimmäisen toisto-osan spektrogrammeista mitattiin 17 eri parametriä. Nämä koostuivat spektrogrammin eri osien taajuuksista ja kestoista. Valitut parametrit analysoitiin tilastollisesti. Erotteluanalyysiä käytettiin tutkittaessa kuikkayksilöiden yksilöllistä tunnistamista reviirihuutojen (n = 297) spektrianalyysin perusteella eri reviireillä (n = 19). Analyysit osoittivat, että käytettäessä 14 muuttujaa ja ristiinvalidointia, pystyttiin reviirit luokittelemaan huudon perusteella lähes 98 prosenttisesti oikein. Tämä viittaa siihen, että samat yksilöt puolustavat reviiriään vuodesta toiseen.The intention of the study was to determine whether male Black-throated Divers (Gavia arctica) can be distinguished individually by their vocalization. The songs of 19 male Black-throated Divers (BTDs) were recorded in their territories in the same lake area in 2018–2021 in Finland. The songs were recorded in one year in nine territories and in 2–4 consecutive years in ten territories. The song consists of one introductory phrase and one or more repeat phrases. Seventeen variables were measured from the spectrograms of the introductory phrase and the first repeat phrase. These variables included the frequencies and duration of different parts of the spectrogram. The discriminant analyses were used to examine the recognition of individual BTDs based on the spectral analysis of the male yodels (n = 297) in different territories (n = 19). The discriminant analysis showed that when using 14 of the variables of the yodels, the discriminant analysis classified the yodels to correct territories at a rate of almost 98% based on the cross-validation of all data. This suggests that the same individuals defend their territory from year to year.Peer reviewe

Can fish introductions alter nutrient cycles in previously fishless high-latitude lakes?

The additional input and enhanced cycling of nutrients derived from introduced fish can be a significant factor altering nutrient dynamics in oligotrophic lakes. To test this, we used a bioenergetic model to estimate the fish-derived nutrient load in Lake Kuutsjurvi, a historically fishless boreal lake of northern Fennoscandia. The lake was selected because of the absence of other anthropogenic stressors, a known stocking history and the possibility of quantitatively estimating the size-structure and biomass of the fish population through a mass removal. Subsequently, we used a mass balance model to compare fish-derived nutrients with other nutrient load pathways. For comparison over longer timescales, we used lake sediment records of diatoms, chlorophyll and carotenoid pigments, C: N ratios and stable isotopes to infer whether fish introduction produced detectable changes in the lake trophic state, primary productivity and terrestrial nutrient input. Based on the nutrient mass balance model, we found that phosphorus and nitrogen derived from fish were 0.46% and 2.2%, respectively, of the total load to the lake, suggesting that fish introduction could not markedly increase the nutrient load. Accordingly, the palaeolimnological record indicated little increase in primary production but instead a shift from pelagic to benthic production after fish introduction.Peer reviewe

Density and temperature dependent growth of pikeperch (Sander lucioperca) in the Archipelago Sea

In the Archipelago Sea, pikeperch (Sander lucioperca) is an important species in both commercial and recreational fisheries. Pikeperch is caught mainly with small mesh size gillnets, and annual fishing mortality is high. The possible effects of such fisheries, as well as temperature or density on pikeperch growth have not been studied earlier. The first hypothesis of this study was that the effect of temperature on growth is positive and that of density is negative. The second hypothesis was that size-selectivity of gillnets causes the fast-growing individuals to be caught at younger ages than the slow-growing ones. The results showed that temperature had a significant positive effect on growth, and this was greater than the negative effect of year-class density, which was also significant. The gillnet selectivity caused a difference of up to 60 mm in back-calculated lengths in the fully recruited age groups within the same year class, between pikeperch caught at age 6+ and age 9+. Thus, the Rosa Lee phenomenon caused by gillnet size-selectivity led to the removal of faster growing specimens from the population at younger ages. This can potentially cause underestimation of real growth, and thus, poor fishery management

34. Rakennuttajakoulutuksen tutkielmat

Julkaisu koostuu kolmestatoista 34. rakennuttajakoulutuksen tutkielmasta: (1) Markus Aaltonen: Suunnitelmien yhteensovittaminen tietomallia hyödyntävässä rakennushankkeessa (2) Tapani Heiskanen: Turvallisuuskoordinaattorin tehtävät (3) Tero Kanervo: Suunnittelun ohjaus allianssiurakassa (4) Seppo Lappalainen: Turvallisuuskoordinaattorin tehtävät - Rakennuttajakonsultti turvallisuuskoordinaattorina (5) Jyrki Latvala: Tietomallinnuksen hyödyntäminen työmaatoiminnassa (6) Juha Lehtonen: Arkkitehtitoimiston rakennuttamispalvelu - Palvelun kehittäminen erilliseksi liiketoiminnaksi (7) Reijo Markkanen: Rakennuttajan sivu-urakoiden alistamismenettelyn mahdollisuuksia ja kehitysehdotuksia rakennusprojektin hallinnassa (8) Janne Pietarinen: Laadunvarmistusmittaukset tietomallipohjaisessa väylärakentamisessa (9) Petri Pirttilahti: Turvallisuuskoordinaattorin työturvallisuustehtävät ja -vastuut (10) Anni Rouvinen: Asiakaslähtöinen hankekehitys ja suunnittelu (11) Pekka Saarnio: Rakennuttajan määrälaskenta: Vaatimukset LVIA -töiden määrälaskenta-asiakirjoille (12) Pekka Salla: Rakennuttajan kustannusarvioiden laadinta (13) Satu Salonsaari: Turvallisuuskoordinaattorin tehtävät kohteessa Fazer Suklaa O

Russia of Transformations

The reader is holding the second, more comprehensive study on developments in Russia commissioned by the Ministry of Defence. The first, published in 2008, focused on society and domestic politics, the economy, traffic and transport, the environment and energy, and foreign and security policy. At the time, this project represented a new approach. Extensive use was made of expertise outside the defence establishment, while reports submitted for publication were drawn up by thematic working groups, based on the preliminary research question and their own work. From the Finnish security perspective, the ‘Russia of Challenges’ publication demonstrated a clear need to gather knowledge on Russia produced, analysed and processed in a practical manner. Three editions were published. Of these, around 13,000 copies in Finnish and 2,700 in English were downloaded from the internet. Over a period of four years, developments in both Russia and the international community have once again created the need for a survey of Russia by Finnish experts and specialists in various fields

Muutosten Venäjä

Lukijalla on nyt kädessään järjestyksessään toinen puolustusministeriön tilaama laajempi tutkimus Venäjän kehityksestä. Vuonna 2008 julkaistussa Venäjä–tutkimuksessa tarkastelun kohteena olivat yhteiskunta ja sisäpolitiikka, talous liikenne ja kuljetus, ympäristö ja energia sekä ulko- ja turvallisuuspolitiikka. Hankkeen toteuttamismalli oli uusi: siinä hyödynnettiin laajasti puolustushallinnon ulkopuolista osaamista ja teemaryhmät tuottivat annettujen kysymysten ja työskentelynsä pohjalta raportit, jotka toimitettiin julkaisuksi. Haasteiden Venäjä -julkaisu osoitti selvän tarpeen Suomen turvallisuuden näkökulmasta tuotetun, analysoidun ja käytännönläheisen Venäjä-tiedon kokoamiselle. Julkaisusta otettiin kolme painosta ja suomenkielisten Internet-latausten määrä oli noin 13 000 ja englanninkielisten noin 2 700. Neljän vuoden aikana sekä Venäjällä että kansainvälisessä yhteisössä tapahtunut kehitys ovat jälleen kannustaneet kokoamaan yhteen eri alojen kotimaisen Venäjä-asiantuntemuksen