Gavin Partridge

Snapper is an iconic recreational and commercial fish species across its range in southern Australia and northern New Zealand. In many of these locations, stocks have been reduced to low levels by fishing. The ability to economically restock or enhance the species, while ensuring genetic diversity, would be improved if fertilised eggs could be collected from the wild during their spawning aggregations. This project developed effective techniques to collect snapper eggs from the extensively studied spawning aggregations in Cockburn Sound in Western Australia and to assess the genetic diversity of the offspring produced. Optimum weather conditions, times of day, methods and locations for egg collection were identified during the project. The selection of snapper eggs based on their diameter and oil globule size proved to be a reliable method of separating potential snapper from other eggs within the collections. Samples of these eggs were confirmed to be snapper using real-time PCR, comprising a snapper specific probe and a general fish probe. A microsatellite-based comparison of a sample of juveniles raised in the hatchery from wild spawned eggs with a sample of wild-caught individuals from Cockburn Sound tested the genetic integrity of this collection and culture method. A number of snapper cultured from this project were marked with alizarin complexone and retained in the hatchery to test for mark integrity over time.