Western Blue Groper

Interesting Info

• The Western Blue Groper is the largest reef-dwelling bony fish in southern Australia, capable of reaching 1.75 m (5 ft 9 in) in length and weighing over 40 kg (88 lb).
• It is found only in southern Australia, from Shark Bay in Western Australia around to South Australia.
• Despite the name, it is actually a wrasse, not a true groper—its closest relatives are other wrasses such as the Eastern Blue Groper.
• Adults are striking deep blue to blue-green, while females and juveniles are green-brown to yellow-brown with scattered blotches.
• They are protogynous hermaphrodites—meaning all individuals start life as females, and the largest, dominant females eventually change into males.
• Males develop bright blue colouration and dominate reef territories, often attended by harems of females.
• They live for decades, with some individuals estimated at over 70 years old, making them among the longest-lived of all wrasses.
• Western Blue Gropers are powerful reef predators that feed mainly on hard-shelled invertebrates such as abalone, sea urchins, crabs, lobsters, and molluscs, which they crush with strong jaws and peg-like teeth.
• Juveniles often inhabit seagrass beds and sheltered bays, while adults move to exposed reefs, kelp beds, and rocky coastlines.
• They are usually solitary or in small groups, with large males patrolling territories and females staying close to shelter.
• Breeding occurs in winter when pairs or small groups spawn, releasing eggs that drift with the currents.
• Their slow growth, late maturity, and long lifespan make them very vulnerable to overfishing – They can live over 70 years.
• They are curious around divers and snorkellers, often approaching slowly to inspect intruders on their reefs.
• Western Blue Gropers were heavily overfished in the past, with spearfishing and line fishing causing dramatic declines in some regions.
• Thanks to protections, populations have begun recovering, and today they are often seen on shallow reefs, making them a conservation success story.
• In South Australia, it is the official marine emblem, symbolising the importance of protecting temperate reef habitats.
• Other common names include Blue Groper, Western Groper, and Giant Blue Wrasse.