Effect of static magnetic field on the hatching success, growth, mortality, and yolk-sac absorption of larval Northern pike Esox lucius D.P. Fey a, ⁎, M. Greszkiewicz a , Z. Otremba b , E. Andrulewicz a a Department of Fisheries Oceanography and Marine Ecology, National Marine Fisheries Research Institute, ul. Kołłątaja 1, 81-332 Gdynia, Poland b Maritime University, ul. Morska 81-87, 81-332 Gdynia, Poland HIGHLIGHTS • Norther pike embryos and larvae ex- posed to static magnetic field of 10 mT. • No effect on the hatching success and the size of larvae at hatch. • No effect on larvae mortality and growth rate during the first six days of life. • Earlier hatching time and faster yolk-sac absorption in magnetic field. GRAPHICAL ABSTRACT abstract article info Article history: Received 17 April 2018 Received in revised form 26 June 2018 Accepted 30 July 2018 Available online 31 July 2018 Editor: Henner Hollert The effect of anthropogenic magnetic field on water ecosystems has been constantly growing as a result of an in- creasing number of underwater cables transferring electric current. Northern pike were subjected to a static mag- netic field (emitted by DC cables) of 10 milliteslas (mT) during the embryonic phase and in the first six days post- hatching (DPH), in the period when larvae of this species in the natural environment are attached to artificial sub- strate. No statistically significant effect of a magnetic field was recorded on the hatching success (87.1% in the magnetic field and 83.3% in the control) or on larvae mortality (54.5% in magnetic field and 54.3% in control). The size of larvae at hatching (9.84 mm SL in a magnetic field and 9.86 mm SL in a control) and their growth rate during the first six days of life (0.52 mm·day -1 in a magnetic field and 0.53 mm·day -1 in a control) were also almost the same – no statistically significant differences. A significant effect of a magnetic field, however, was observed on the time of hatching (one day earlier in a magnetic field than in a control), yolk-sac size on 1 DPH (smaller in a magnetic field), and yolk-sac absorption time (faster in a magnetic field). Faster yolk-sac ab- sorption time in a magnetic field was interpreted as an indication of increased metabolic rate. Even if some neg- ative consequences may be expected as a result of shorter time until first feeding, the actual risk for increased Northern pike larvae mortality due to those factors seems to be negligible. Although it cannot be excluded that higher than 10 mT magnetic field values are hazardous for fish larvae, such values do not occur in the natural en- vironment (e.g. along underwater cables). © 2018 Elsevier B.V. All rights reserved. Keywords: Fish larvae Anthropogenic impact Underwater cables Wind farms Science of the Total Environment 647 (2019) 1239–1244 ⁎ Corresponding author. E-mail address: dfey@mir.gdynia.pl (D.P. Fey). https://doi.org/10.1016/j.scitotenv.2018.07.427 0048-9697/© 2018 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv