What can recreational fishing research tell us about fish biodiversity in Western Port? Greg Jenkins

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1 What can recreational fishing research tell us about fish biodiversity in Western Port? Greg Jenkins

2 Recreational fishing in Western Port Second largest recreational fishery in Victoria. Primarily trailer-boat based fishery. Main species: King George Whiting Snapper Flathead Elephant Fish Calamari Australian Salmon Gummy Shark Garfish

3 Onsite (boat ramp) surveys Surveys conducted 1998 to Weekends from October to May. >13,000 interviews conducted Primarily provides information for stock assessment (e.g. catch rates, size structure). Over time additional biodiversity information added (fishing location, depth, habitat).

4 Aims Need for the research comes from the Western Port Science Review. Aim is to analyse recreational fishing data to increase our knowledge of fish biodiversity and habitat relationships in Western Port. Results are related to factors that could influence fish biodiversity such as: Habitat distribution Catchment inputs Human activities Marine National Parks

5 Survey area All ramps surveyed but mainly Hastings, Stony Point, Rhyll, Corinella Fishing locations were recorded from a spatial grid.

6 Seagrass distribution in Western Port

7 King George Whiting Whiting in Western Port are juveniles up to 4 years age Spawning occurs on the open coast, 100 s kms to the west Small larvae (2 cm length) settle in shallow seagrass in spring Numbers of larvae depends on winds, water temp in Bass Strait Catches fluctuate year to year, related to abundance of larvae 3 years prior

8 King George Whiting Catch rates tend to match seagrass distribution Under legal length fish more common in the SE

9 Percentage of trips King George Whiting Habitat Kept Release 0 Habitat

10 Percentage of trips King George Whiting Depth Kept Released Depth (m)

11 Snapper Snapper up to 40 years age can occur in Western Port Migrate between bays and also coast (including pinkies ) Major spawning area in Port Phillip Bay Importance of Western Port for spawning unknown Spawning success fluctuates based on river flow and nutrients Catches fluctuate year to year, related to spawning success

12 Snapper Catch rates tend to match deeper channels Under legal size fish more common in SE

13 Percentage of trips Snapper Habitat Kept Release Habitat

14 Percentage of trips Snapper Depth Kept Released Depth (m)

15 Elephant Fish Live up to 20 years, 100 cm in length Migrate between Bass Strait and bays, broad southern stock Enter Western Port in autumn Western Port largest known egg laying aggregation in Australia Eggs cases deposited in fine sediments Major recreational / charter boat fishery in early 2000 s Bag limit was reduced from 2 fish to 1 fish per day in 2008

16 Elephant Fish Area of catch contracts to Rhyll basin over time

17 Percentage of trips Elelphant Fish Habitat & Depth Kept Habitat Depth (m)

18 Gummy Shark Live at least 16 years, up to 180 cm in length Broad offshore stock in southern Australia Enter Western Port, pupping in summer Up to 40 live pups per litter Population fluctuation linked to number of females Bag limit of two sharks per day

19 Gummy Shark Widespread distribution juveniles in Rhyll basin

20 Percentage of trips Gummy Shark Habitat & depth Total Kept Depth (m) Habitat

21 Calamari Fast growing, 1 year life cycle Spawning in spring Lays eggs on seagrass (Amphibolis) and algae Large year to year fluctuations in catch Increasingly popular recreational species

22 Calamari Similar to seagrass, including Amphibolis

23 Percentage of trips Calamari Habitat & depth Kept Kept Depth (m) Habitat

24 Conclusions Valuable tool for understanding biodiversity values in Western Port Distributions of some species associated with seagrass (e.g. Whiting, Calamari, Garfish) Other species with deeper reef habitat (Snapper, Gummy Shark) Rhyll basin important for juveniles of a number of species Rhyll basin strongly influenced by catchment inputs in NE Study provides new information on spatial distribution and habitat use essential for management