Date of Award

2007

Degree Type

Thesis

Degree Name

Bachelor of Science Honours

Faculty

Faculty of Communications, Health and Science

First Advisor

Dr Ute Mueller

Abstract

The Shark Bay Managed Scallop Fishe1y is Western Australia's most important scallop fishery with an annual value of between $2 and $58 million. In addition to this the fishery is an important source of regional employment with approximately 160 skippers and crew employed during the 2005 season. Two separate fleets are permitted to fish for scallops in this fishery, the first consisting of dedicated scallop fishing vessels (Class A licences) and the second of prawn fishing vessels (Class B licences) that are allowed to take scallops under a catch sharing arrangement. Concerns exist over the interactions between these two fleets and in particular how the catch of the Class A fleet is affected by the fishing activity of the Class B fleet. This thesis discusses the results obtained from a statistical analysis of the relationship between the fishing effort used by the Class B fleet, and the size of the subsequent scallop catch. Geostatistical estimation (kriging) has been used on survey data to allow for comparisons to be made with catch and fishing effort data. Spatial maps of these data have been constructed and investigated for the presence of spatial patterns. Measurements of correlation and spatial association have also been used to quantify the relationship between the level of fishing effort used by the Class B fleet and the size of the scallop catch achieved by the Class A fleet and by both fleets combined. Finally, an investigation has also been conducted on the effect that fishing by the Class B fleet has on the subsequent scallop recruitment. The results presented in this thesis do not indicate the presence of a marked or consistent relationship between the level of fishing effort applied by the Class B fleet and the size of the subsequent scallop catch during the 2000 to 2005 fishing seasons. As such, this thesis has found no evidence that the fishing activity of the Class B fleet, over the entire season, during the spawning period or prior to the start of scallop fishing, has a direct effect on the scallop catch achieved by the Class A fleet.

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