Escape performance in the sub-Antarctic notothenioid fish Eleginops maclovinus

Fast-start performance associated with escape behaviour was investigated in the sub-Antarctic notothenioid Eleginops maclovinus from the Beagle Channel, Tierra del Fuego, Argentina (mean winter water temperature 4degreesC, mean summer water temperature 10degreesC). Fish acclimated to 8.5degreesC for 2 months were filmed at 2, 4, 6, 8 and 10degreesC. Escape responses were temperature dependent over the range of temperatures tested. Maximum length-specific velocity ((V) over cap (max)), maximum length-specific acceleration ((A) over cap (max)) and inertial power output (P-iner) increased significantly with temperature. Q(10) values for (V) over cap (max), (A) over cap (max) and P-iner were 1.90, 3.27 and 8.90, respectively. Non-dimensional curvature of the spine ((c) over cap) also varied significantly with temperature, but was higher at low temperatures. The values of (c) over cap were threefold lower than previously reported for Antarctic notothenioids and similar to the values for temperate species. The results indicate that the high values of observed during escape behaviour in Antarctic notothenioids are not a universal feature of the suborder. A greater flexion of the body during fast starts is therefore a promising candidate for a specialised feature of behaviour linked to low-temperature performance.