Gladstone Fish Health Investigation 2011 - 2012 - Western Basin ...

Size structure of mud crabs observed at each site during Phase 1.Legal Male Crabs Large Female Crabs Undersize Crabs90%80%70%60%Percentage50%40%30%20%10%0%Fitzroy River(n = 140)Narrows(n = 607)Port DevelopmentArea(n = 150)LocationCalliope River(n = 108)South Trees Inlet(n = 55)Rodds Bay(n = 375)Figure 17. The size structure of mud crabs observed at each site during the Gladstone Fish HealthMonitoring Program Phase 1, December 2011 – January 2012. Note, (n) refers to the total number ofcrabs examined at each site.Phase 2: During Phase 2, mud crab sampling was conducted between April 2012 and July2012. A total of 1599 crabs were caught, with their size and sex recorded. Results show thata large proportion of the crabs caught within the Gladstone region were undersized crabs(43.59%) (Figure 18). The percentage of undersized crabs varied between sites withinGladstone, with numbers of undersized crabs ranging between 35% (Rodds Bay) and 55%(Port Development Area). The percentage of undersized crabs caught in the Fitzroy Riverand Bundaberg were 49% and 78% respectively (Figure 19).90%80%70%Size structure of mud crabs observed in the Gladstone region and reference sitesduring Phase 2.Legal Male Crabs Large Female Crabs Undersize CrabsPercentage60%50%40%30%20%10%0%Fitzroy River(n = 387)Gladstone(n = 959)Bundaberg(n = 253)LocationFigure 18. The size structure of mud crabs observed in the Gladstone region (sites combined) and thereference sites during the Gladstone Fish Health Monitoring Program Phase 2, April 2012 – July 2012.Note, (n) refers to the total number of crabs examined at each site.39