Most abundant in cold to warm temperate continental seas, from the surfline and very shallow water to well offshore (Compagno in prep b). In G. galeus occurs over the continental shelf from shallow, inshore bays (mainly juveniles) to about 800 m depth on the continental slope. At least in some areas (Northeast Atlantic, Tasman Sea) they also extend offshore up to 1,610 km from the coast (Fitzmaurice 1979, Brown et al. 2000). The species is primarily found near the bottom but ranges through the water column even into the pelagic zone. Similar to the Australian and South American populations, the South African population inhabits cool waters from the coastal surfline to the continental shelf (>400 m).

The life history parameters of G. galeus varies between regions. For a review of life history from different regions see Walker (1999) which draws on a number of sources including: Ripley (1946), Olsen (1954, 1959, 1984), Freer (1992), Capape and Mellinger (1988) and Peres and Vooren 1991). For a summary of life history characteristics by regional population see the tables at the end of this assessment (these will be specifically drawn upon for regional reports).

The maximum size varies considerably: the maximum size recorded is ~200 cm total length (female) in the Mediterranean (Capape and Mellinger 1998), but is somewhat smaller in the Southwest Atlantic with a maximum size of 155 cm (female); 148 cm (male) (Peres and Vooren 1991). Differences are also apparent in the size at maturity in different regions. The smallest sizes at sexual maturity are in the Southwest Atlantic where males attain sexual maturity at 107?117 cm and females at 118 to 128 cm (Peres and Vooren 1991), elsewhere the range is generally between 120 and 135 cm for males and 134 to 140 cm for females (Olsen 1954, Capape and Mellinger 1988, Peres and Vooren 1991, Freer 1992), although Ripley (1946) noted 150 cm for females and McCord (2005) reports 101 cm for males.

Reproduction is aplacental viviparity with average litters of 20 to 35 pups, with as few as six and as many as 52 observed with an average of 35 in the Eastern North Pacific (Ripley 1946, Ebert 2003)) produced in spring or early summer after a gestation period of ~12 months; the young vary in length at birth between 26 and 40 cm, depending on the region. The litter size increases in larger females. Males appear to breed every year but individual females have been reported to breed every year in the Mediterranean, every second year in Australia, and every third year in Brazil (Capape and Mellinger 1988, Peres and Vooren 1991, Olsen 1954). These may reflect real differences or may be due to the difficulties of sampling a species, which shows marked temporal and spatial sexual and size segregation, and which makes extensive movements.

These animals are very long-lived and are estimated to live for up to 60 years, although estimates vary (from around 22 years to around 40 years to up to 60 years) with region and ageing methods used. In Australia, tags have been returned from animals at liberty for more than 40 years. Age at maturity is 8 to 10 for males and 10 to 15 for females (Olsen 1954, Peres and Vooren 1991, Freer 1992, Walker 1999, Ebert 2003). The annual rate of population increase has been estimated by Cortes (2002) at 1.077 ( 95% C.I. 1.037 to 1.128) and the natural mortality by Smith et al. (1998) at 0.113.

The species feeds mainly on teleost fish, most often on bottom-associated species although pelagic fish are also taken (Walker 1999). Cephalopods, mostly squid and octopus, are also important in their diet. Small juveniles include a high proportion of crustaceans and other prey such as annelids and gastropods in their diet (Olsen 1954, Stevens and West 1997, Walker and Punt 1998). Predators (especially of juveniles) include the great white shark Carcharadon carcharias, sevengill shark Notorynchus cepedianus, and possibly marine mammals (Ripley 1946; Ebert 2001, 2003).