Henrik has successfully completed his master on bearded goby growth

Henrik Christiansen has been a visiting student taking his master's project at BIO and exam in Germany. Henrik has been working with his master project on growth of bearded goby since February 2013. The project reached a happy end with the examination of Henrik's thesis "Age and growth of the bearded goby (Sufflogobius bibarbatus) in the northern Benguela upwelling" on Friday, August 31 at the Leibniz Center for Tropical Marine Ecology (ZMT), University of Bremen.

Henrik has done age readings on otoliths from 314 specimens and established von Bertalanffy growth curves for gobies from northern, central, and southern parts of the Namibian coast, and for sneakers and territorial males. Henrik has worked meticulously with otoliths that were photographed and measured for numerous dimensions, such as size, weight, zone width and perimeter. Results regarding latitudinal variations were contradictory, but it seems that the southern part of the Benguela around Lüderitz provides better conditions for growth than farther north.

Henrik has found male-biased sexual size dimorphism. Females of the same age as males are smaller and have a slower growth. Within males sneakers appeared to be approximately 1+ to 3+ years of age, notably younger than territorials. It is likely that sneaking and territorial behaviour are consecutive tactics following ontogeny. Yet it remains unclear if transition stages occur or if sneakers experience higher mortality.