Q4 (11 marks) Changes in the population structure of a freshwater fish, the silver perch, was investigated in the Murray-Darling river. The fish is a popular target for sports fisherman, and the researchers wanted to know whether the relative numbers of big vs. small fish had changed since recreational fishing at the river had been allowed. The researchers examined the reports of fish that had been caught in the river in 1984 (the first year of fishing) with a similar survey conducted in 1998. Reported were the numbers of fish caught in 5 different size categories (in increasing order of size: Stock, Quality, Preferred, Memorable and Trophy). The observed values were: Stock Quality Preferred Memorable Trophy 1984 6571 161 62 42 5 1998 1597 387 47 14 The researchers analysed these data in a 2 x 5 contingency table, obtaining a x2 value of 781.17 and a P value of