Continuous Crayfishing Tests: Pelsart Group, Houtman Abrolhos, Western Australia, 1953

Abstract

The continuous crayfishing test at the Pelsart Group, Houtman Abrolhos, conducted in 1948, was repeated in 1953. The numbers of crayfish available within the tested area had been reduced from 90 per haul in 1948 to 37 per haul in 1953. There was also a decrease in the commercial catch in 1953 as compared with that of 1948 in the proportion of 90 to 72; and in the catch per man in the proportion 90 to 66. The ratio of the commercial catch in 1950 (the year of maximum production and one of high fishing intensity) to that of 1953 was 90 to 34. In 1953, there were relatively fewer very small and very large crayfish than in 1948. The effects of the 4 years of intensive fishing between 1948 and 1953 on the composition and the numbers of crayfish available at the Pelsart Group are discussed. The period of the test from March 15 to August 26 was divided into three catch phases, characterized by changes in the catch rates. Except for three long-distance movements of tagged crayfish, movements were limited to a distance of approximately 2 miles. Mating commenced on July 1 and by the end of August the majority of mature females were mated. Spawning commenced on August 22. Few females below a carapace length of 2.9 in. were mated.