Keinänen, M., Uddström, A., Mikkonen, J., Casini, M., Pönni, J., Myllylä, T., Aro, E., and Vuorinen, P. J. 2012. The thiamine deficiency syndrome M74, a reproductive disorder of Atlantic salmon (Salmo salar) feeding in the Baltic Sea, is related to the fat and thiamine content of prey fish. – ICES Journal of Marine Science, 69: 516–528. This study clarifies how the diet of Baltic salmon leads to thiamine deficiency in eggs, and consequently to M74 mortality of yolk-sac fry. The main prey species, sprat (Sprattus sprattus) and herring (Clupea harengus membras), and their biomass in the Baltic Proper (BPr) and the Bothnian Sea, the two feeding grounds of salmon originating from the northern Gulf of Bothnia rivers, are compared. The thiamine concentration of both prey species is lowest in the youngest age groups. Because average fat content and energy density are greater in sprat than in herring, and greatest in youngest sprat, the supply of thiamine per unit energy is least in a diet containing many young sprat. Also, the greater is the supply of thiamine and fat from sprat in the southern BPr in the preceding year, the lower the concentration of thiamine in salmon eggs. Thiamine deficiency in eggs results from an unbalanced diet abundant in fatty prey fish, such as young sprat, from which the supply of thiamine is insufficient in proportion to the supply of energy and unsaturated fatty acids for salmon, which must undergo a long prespawning fasting period.

The magnitude of inbreeding depression is often larger in traits closely related to fitness, such as survival and fecundity, compared to morphological traits. Reproductive behaviour is also closely associated with fitness, and therefore expected to show strong inbreeding depression. Despite this, little is known about how reproductive behaviour is affected by inbreeding. Here we show that one generation of full‐sib mating results in a decrease in male reproductive performance in the least killifish (Heterandria formosa). Inbred males performed less gonopodial thrusts and thrust attempts than outbred males (δ = 0.38). We show that this behaviour is closely linked with fitness as gonopodial performance correlates with paternity success. Other traits that show inbreeding depression are offspring viability (δ = 0.06) and maturation time of males (δ = 0.19) and females (δ = 0.14). Outbred matings produced a female biased sex ratio whereas inbred matings produced an even sex ratio.

Microbisium suecicum Lohmander, 1945 is reported from Finland for the first time. The characters that distinguish it from the closely related M. brevifemoratum (Ellingsen, 1903) are given. A checklist of the 17 species of Finnish pseudoscorpions is presented. A brief history of research on pseudoscorpions in Finland is also presented. ÐÅÇÞÌÅ. Âïåðâûå äëÿ ôàóíû Ôèíëÿíäèè îò-ìå÷åí ëîaeíîñêîðïèîí Microbisium suecicum Lohmander, 1945. Óêàçàíû åãî îòëè÷èÿ îò áëèçêîãî M. brevifemoratum (Ellingsen, 1903). Ïðèâåäåí ñïèñîê ëîaeíîñêîðïèîíîâ çàðåãèñòðèðîâàííûõ â Ôèíëÿíäèè. Ïðèâåä¸í êðàòêèé èñòîðè÷åñêèé îáçîð èçó÷åíèÿ ãðóïïû â ñòðàíå.