The Migration And Life Cycle Of Snapper

  The Australian snapper is the same species as the New Zealand snapper and the red sea bream found in the coastal waters around Japan and Indonesia, and the closest relative to snapper in our waters is the black bream. Depending on where you fish, and the age and size of the snapper, they are known by a range of vernacular names including reds, cockney, pinkies, red bream, rugger, cobs and squire.
Bill Athanasslie  with a whopper -a 13.1kg snapper.

Bill Athanasslie with a whopper -a 13.1kg snapper.

Fish Facts

The following information was sourced from Fisheries Victoria. Anglers in other States will find similarities, however, for more detailed information I suggest they visit the various websites. For many years the migration and life cycle of Victoria’s snapper stocks were a mystery, however, a determined research effort by scientists at Victoria’s Marine Science laboratory solved the mystery. A few years back I interviewed fisheries scientist Paul Hamer, who said snapper spawned in Port Phillip Bay were the mainstay of Victoria’s western snapper stock. The statement was the result of a decade of research. It meant that all snapper from Wilsons Promontory to the mouth of the Murray River, had their origins in Port Phillip Bay. Snapper caught from the Lee Breakwater at Portland, or in Western Port, can trace their origins back to Port Phillip Bay.

Spawning Time

This was amazing given that before the research program began, researchers could not say for certain where snapper spawned. Now they know: The bulk of the spawning effort in the bay takes place along the eastern seaboard from mid-December to mid-January. “Key spawning areas took in Hobsons Bay, Beaumaris, Frankston and Mornington,” Paul said, adding that successful spawning and survival of young snapper in the bay varied from year to year, and that 10 to 20 fold variations were common. “It is this variation that shapes future catches,” Paul said.
Hump heads and bulbous noses, the true profile of an Old Man Snapper.

Hump heads and bulbous noses, the true profile of an Old Man Snapper.

Slow Growers

Snapper are slow growing. Paul said it takes about 3-4 years for snapper to reach legal size, 7-8 years to make 40cm, and 10-12 years to become big snapper. Ageing data suggested the majority of snapper in the 2 to 2.5kg size ranges were about eight years old, and 6 to 7 kg fish about 13 years-old. Fish of about 10kg can be 30 years or older. The oldest Victorian snapper aged was a 10kg fish from Western Port that was 39 years-old. Snapper in Victorian waters on average reach sexual maturity from about 28cm in length, and all snapper are mature by the time they reach 40cm. When spawning, schools of snapper have been seen to congregate on the surface. The activity consists of a slow circular movement of the tightly bunched school and the discharge of large quantities of ova and sperm into the water column. The spawning ritual is believed to have a strong bearing on the movement of snapper from deep to shallower water.
Pinkies have the same shape as their close relatives bream, only the colour is different.

Pinkies have the same shape as their close relatives bream, only the colour is different.

Snapper Eggs

The eggs are spherical in shape and about 1mm in diameter and look like fine boiled sago. Each tiny sphere contains a buoyant globule of clear oil and a yolk. Within 48 hours of fertilisation the drifting embryo is fully developed, the eggs are planktonic or free-floating. After fertilisation, they rise to the surface and drift with the currents until they hatch. The young fish then descend to the seabed for safety and make their way into estuaries and similar protected waters to develop. Major nursery areas for baby snapper in Victoria have been identified in Port Phillip Bay, the Gippsland Lakes, Corner Inlet/Nooramunga and Mallacoota Inlet. Western Port Bay does not appear to be a major nursery area for baby snapper. Smaller Gippsland inlets and estuaries that remain open during the summer spawning season, such as the Snowy River estuary, also act as nursery areas for baby snapper. The baby snapper that are found in these estuaries are spawned in adjacent coastal waters. Snapper use these smaller estuaries as juvenile nurseries, with most snapper migrating out to the ocean before they reach two years of age. Few estuaries along the west Victorian coast are permanently open and none have been identified as important snapper nurseries.
Marine scientists Ross Winstanley (left) admires this 4.2kg snapper caught by Bob Hart.

Marine scientists Ross Winstanley (left) admires this 4.2kg snapper caught by Bob Hart.

Growth Rate Data

The growth rate of snapper is not as fast as most of us would like it to be. Water temperatures appear to influence the growth rate to some extent in that a series of warm summers will greatly increase it. Data from studies carried out by the Central Ageing Facility at the Marine and Freshwater Resources Institute, Queenscliff, show the age structure of snapper as follows:
Marine scientists Ross Winstanley with a 5kg snapper

Marine scientists Ross Winstanley with a 5kg snapper

  • 1 year – 12-25cm, average 16cm
  • 2 years – 15-25cm, average 21cm
  • 3 years – 25-36cm, average 28cm
  • 4 years – 29-44cm, average 35cm
  • 5 years – 32-44cm, average 37cm
  • 6 years – 27-47cm, average 42cm
  • 7 years – 33-56cm, average 49cm
  • 8 years – 46-63cm, average 54cm
  • 10 years – 46-66cm, average 57cm
  • 12 years – 52-71cm, average 61cm
  • 14 years – 57-72cm, average 63cm
  • 16 years – 59-80cm, average 68cm
  • 18 years – 69-71cm, average 70cm
  • 20-years – 72cm
  • 24-years – 75cm

Old Hump Head

After years of growth, some snapper develop a large hump on their head, and sometimes even a big fleshy nose. It is at this stage that they become known as an Old Man snapper. There is a suggestion snapper that are habitual diggers develop this nose, which is normally slightly hooked underneath. The nose may be the result of infection, a small piece of shell or grit penetrating the fish’s skin. But there is no proof of this. As for the hump, its sole purpose is to help stabilise the fish as it acquires the habit of feeding and moving nose down and tail up, groping for crabs and other bottom dwellers.

Tag Details

Tracing snapper movements is done with tagging, and some of the results are spectacular. A 22.8cm snapper tagged in Corio Bay in was recaptured nine years later. It was 70 cm (47cm growth) and weighed 4.5 kg. A 34cm snapper that weighed less than 500g was tagged and released near Portland and recaptured 14 years later off the Seaford Pier. It weighed just over 6kg, and its age was estimated at about 20 years.  
Bob Hart with a handy red caught in the middle of the day in Port Phillip Bay

Bob Hart with a handy red caught in the middle of the day in Port Phillip Bay

Steve Cooper

About Steve Cooper

Cooper is now a freelance travel and fishing writer with no fixed abode - his home being his cleverly appointed Jayco caravan which is packed to the pop-top with fishing gear. He has has towed the rig the length and breadth of Australia behind his diesel-powered Toyota Landcruiser which of course is topped with a small, flexible fishing boat.

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