This strong swimmer is an opportunistic predator that attacks schools of fish such as cod, herring, sardines and whiting (3) (4). Although it feeds primarily on bony fish, it also consumes bottom-dwelling animals such as crustaceans and molluscs (3). Tope themselves are prey for larger sharks such as the great white shark (Carcharodon carcharias) (4). Tope sharks occur in small schools that migrate long distances in the higher latitudes of their range where they move towards the equator in winter, and poleward in the summer (4). The schools are known to segregate by sex and age (4), making them especially vulnerable to the effects of fishing (6). Tope are ovoviviparous (4), a method of reproduction in which embryos develop within eggs that remain inside the mother's body until they hatch. No placenta is formed, and instead the embryo depends on its own egg yolk for nourishment (3). Gestation is thought to last for about 12 months, and females move inshore to coastal nursery areas in the late summer to give birth (3) (7). Between 6 and 52 pups are born in a litter (4), each measuring about 40 centimetres in length (3). Tope are believed to have a life expectancy of up to 55 years (8).