Fisheries Victoria
'A fortnightly round-up of recreational fisheries management issues'

Fish-Fax issue 168, 30th March 2006

Predicting Port Phillip Bay snapper seasons

In 2005, Port Phillip Bay experienced the best snapper season in the last 10 to 15 years. While keen fishers caught snapper of all sizes (from small pinkies to large 10kg trophy fish) most were taking 2 to 6 kg snapper.

Funded by Fisheries Victoria, fisheries scientists from DPI Research survey selected habitats in Port Phillip Bay each March after the snapper spawning season to determine numbers of newly settled juvenile snapper less than 10 cm in length.

The numbers of fish caught in these surveys give the scientists an indication of the success of the previous spring/summer spawning season. This information, in turn, has allowed them to forecast the strength of year classes entering the fisheries several years into the future.

Results from studies of otoliths (ear bones), to age fish currently being caught, can then be used to validate predictions about strong year classes entering the fishery.

The ageing suggests:

•  The majority of snapper in the 2 to 2.5 kg size ranges are from the 1997/98 spawning season, so they will be nine years old this summer.

•  Snapper around the 4 to 5 kg marks are from two spawning seasons - 1994/95 and 1995/96 - so they will be 11or 12 years old this summer.

•  Many of the snapper around 6 to 7 kg are from the 1992/93 spawning season, so they're about 14 years old this summer.

Juvenile snapper surveys indicate there have been several exceptionally successful spawning seasons in the last five years, indicating good fishing in the future. In particular, the 2000/01 spawning season was very successful and fisheries scientists have been monitoring this age group of snapper closely. There was also another good spawning season in 2003/04, and provided the spring migrations of adult snapper into the bay from coastal waters remains consistent, the future prospects of Port Phillip Bay's snapper fishery are bright.

Being able to forecast strong or weak year classes entering the fisheries is vital to ensure that fishery management arrangements are ‘adapted' to suit the circumstances. Fishing controls will allow fishers to take advantage of times when spawning has been successful and snapper are abundant (such as now), but may need to be tightened in future to protect declining adult stocks if the surveys indicate persistent poor spawning success.

Enforcement News

Two men, one from Portland and the other from Warrnambool, were fined a total of $4000 in Warrnambool Magistrates' Court after pleading guilty to trafficking abalone and using commercial equipment to take more than twice the legal bag limit of abalone.

The two men were observed by Fisheries officers as they carried two bags up steep cliffs west of Childers Cove. They were seen to place two bags in some bushes before returning to the base of the cliff to retrieve diving gear. The men were intercepted by Fisheries officers and when asked about the two bags they admitted they contained abalone.

The Magistrate ordered the men's snorkelling gear and vehicle to be forfeited and the abalone sold.

Summary of February 2006 fish stockings

DPI – Fisheries Victoria

Snobs Creek Fish Hatchery

Summary of fish releases for February 2006

* - Yearling Murray cod that are dart tagged