Effects of the environment and the spawning stock structure on the distribution of Northeast Arctic cod larvae

The spatial distribution and abundance of early life stages of fish can shape survival to later stages and, consequently affect population structure, dynamics and resilience. The Northeast Arctic (NEA) cod spawning occurs along the Norwegian coast, and eggs, larvae and pelagic juveniles drift near-surface towards the Barents Sea nursery area. It has previously been shown that high average age and size of the spawning stock of NEA cod result in high egg abundance and widespread egg distribution. A wide egg distribution increases the variability in conditions experienced by early life stages of fish, thereby increasing the probability that a significant fraction reaches the recruitment stage. NEA cod larvae data from two Russian ichthyoplankton surveys (1959-1993), one in spring and one in summer, are analyzed in combination with factors that potentially may affect the distribution of spawners, eggs and larvae. These factors include biological aspects, such as biomass and mean weight of the spawning stock, and environmental variables, such as water temperature, wind and currents. Using spatio-temporal statistical analysis we assess how these factors associate with the abundance and distribution of NEA cod larvae. Preliminary results show that the physiological condition of the spawners, measured as the liver condition index, associates positively with the distributional extent of NEA cod larvae. The mean weight of the spawners shows no association with larval distribution or abundance, in contrast to the findings for cod eggs.