The objective of this thesis was to determine if there were any correlations in the distribution of cetaceans, especially sperm whales (Physeter macrocephalus), pantropical dolphins (Stenella attenuata), bottlenose dolphins (Tursiops truncatus), and Risso’s dolphins (Grampus griseus) in the northern Gulf of Mexico because of the influence of oil and gas production and exploration. This research is important because of the lack of knowledge about the impact of anthropogenic sounds from oil and gas exploration and production (E&P) on cetacean distribution in the Gulf of Mexico. I analyzed cetacean visual line-transect survey results from the Gulf of Mexico for period of 1992 – 2001. I divided this time span into an early period (1992 – 1997) and a late period (1998 – 2001). I overlayed the locations of cetacean sightings and the locations of oil and gas E&P platforms to demonstrate their close association in space, and tested a hypothesis that distribution would shift south correlated with changes in distribution of E&P. I compared the distributions of cetacean sightings in the entire Gulf of Mexico, and separated the Gulf of Mexico into east and west, between the early period and the late period. The east Gulf of Mexico represents an area without oil and gas E&P platforms and the west Gulf of Mexico is the area where oil and gas E&P platforms are located. The null hypothesis for these tests was that there was no difference in cetacean distribution between the early period and the late period. I also compared the distribution of sperm whales, pantropical dolphins, bottlenose dolphins, and Risso’s dolphins in the entire Gulf of Mexico, both east and west, between the early and late periods. I expect if distribution changes were correlated with changes in E&P distribution, then there will be a shift south in the western Gulf. Changes in distribution in the eastern Gulf would not be correlated with E&P. I found that the sightings per unit effort (SPUE) of all cetacean sightings in the entire Gulf of Mexico shifted to the south in the late period, as compared to the early period .The distribution of all cetacean sightings for the late period (1998-2001) was significantly different compared to the distributions of all cetacean sightings in the early period (1992-1997). The SPUE of sperm whale and bottlenose dolphin distributions were shifted to the north in the late period (1998-2001) compared to the early period (1992-1997). While pantropical dolphin distributions were significantly shifted to the south between the two time periods. I observed that the SPUE of all cetaceans sightings in the east Gulf of Mexico for the early period (1992-1997) were shifted to the south compared to the west, which were not different. The SPUE for sperm whales in the east for the early period were marginally shifted to the north in comparison to the west, which were also shifted further north. The SPUE for Risso’s dolphins in the east were shifted further north while in the west SPUE were shifted to the south. The SPUE for pantropical dolphin sightings were shifted to the north in both the east and west regions. While the SPUE for bottlenose dolphin sightings were shifted to the north in both the east and west Gulf of Mexico. My SPUE results suggest that pantropical dolphins, like the total cetaceans examined here, have shifted their distributions in the entire northern Gulf of Mexico to the south. However, in areas of high oil and gas E&P platforms the distributions of sperm whales and bottlenose dolphins did not shift their distributions from the early period to the late period to the south even though these E&P activities have shifted to the south over the past two decades as they expanded into the deeper waters of the northern Gulf of Mexico. Therefore, there is little evidence that large scale changes in the latitudinal distribution of marine mammals in the Northern Gulf have occurred as a result of greater offshore E&P activity.

This thesis is presented as a collection of five papers and one report, each of which has been either published after peer review or submitted for publication. It covers a broad range of applied statistical methods, from deterministic modelling to integrated Bayesian modelling using MCMC, via bootstrapping and stochastic simulation. It also covers a broad range of subjects, from analysis of recreational fishing diaries, to genetic mark recapture for wombats. However, it focuses on practical applications of statistics to the management of wild populations. The first chapter (Hoyle and Jellyman 2002, published in Marine and Freshwater Research) applies a simple deterministic yield per recruit model to a fishery management problem: possible overexploitation of the New Zealand longfin eel. The chapter has significant implications for longfin eel fishery management. The second chapter (Hoyle and Cameron 2003, published in Fisheries Management and Ecology) focuses on uncertainty in the classical paradigm, by investigating the best way to estimate bootstrap confidence limits on recreational harvest and catch rate using catch diary data. The third chapter (Hoyle et al., in press with Molecular Ecology Notes) takes a different path by looking at genetic mark-recapture in a fisheries management context. Genetic mark-recapture was developed for wildlife abundance estimation but has not previously been applied to fish harvest rate estimation. The fourth chapter (Hoyle and Banks, submitted) addresses genetic mark-recapture, but in the wildlife context for estimates of abundance rather than harvest rate. Our approach uses individual-based modeling and Bayesian analysis to investigate the effect of shadows on abundance estimates and confidence intervals, and to provide guidelines for developing sets of loci for populations of different sizes and levels of relatedness. The fifth chapter (Hoyle and Maunder 2004, Animal Biodiversity and Conservation) applies integrated analysis techniques developed in fisheries to the modeling of protected species population dynamics - specifically the north-eastern spotted dolphin, Stenella attenuata. It combines data from a number of different sources in a single statistical model, and estimates parameters using both maximum likelihood and Bayesian MCMC. The sixth chapter (Hoyle 2002, peer reviewed and published as Queensland Department of Primary Industries Information Series) results directly from a pressing management issue: developing new management procedures for the Queensland east coast Spanish mackerel fishery. It uses an existing stock assessment as a starting point for an integrated Bayesian management strategy evaluation. Possibilities for further research have been identified within the subject areas of each chapter, both within the chapters and in the final discussion chapter.