i THE SARDINE RUN: INVESTIGATING SARDINE AND PREDATOR DISTRIBUTION IN RELATION TO ENVIRONMENTAL CONDITIONS USING GIS AND REMOTELY SENSED PRODUCTS. by SEAN HENRY O’DONOGHUE Submitted in fulfilment of the academic requirements for the degree of Doctor of Philosophy in the School of Biological & Conservation Sciences, University of KwaZulu-Natal, Durban July 2009 As the candidate’s supervisor I have approved this thesis/dissertation for submission. 23 rd December 2009 ii ABSTRACT The sardine run is a spectacular but poorly understood natural phenomenon. This research aims to broaden scientific knowledge pertaining to sardine, Sardinops sagax , distribution, both in relation to their predators and environmental conditions. Sardine distribution was closely related to sea temperature. Sardines were sighted every year along the Lower Wild Coast, where continental shelf conditions were cooled by the Port Alfred upwelling cell. To the north of Mbashe River, shelf conditions were dominated by the warm Agulhas Current, and sardine distribution varied annually in close relation with sea temperature conditions. Along this coastline sardine abundance always peaked between Waterfall Bluff and Port St Johns with favourable conditions caused by the westward inflection of the coastline and the shelf bathymetry. Topographically-induced upwelling was concluded to be the cause of cooler sea temperatures and elevated chl a concentrations. Although chl a concentration appeared to be associated with east coast sardine distribution, the uncertainty with regards data accuracy hindered their usefulness as a predictor of suitable biological conditions for sardine. Sardine northward movement along the KZN coastline was impeded adjacent to the Durban Eddy, where they were forced shorewards by the warm conditions. This coincided with the peak in beach seine catches. The Cape Gannet, Morus capensis , was very closely associated with sardine along the entire east coast. Their abundance declined substantially adjacent to the Durban Eddy. Prevailing atmospheric conditions affected gannet behaviour: they travelled more frequently during strong alongshore winds and foraged more upon cessation of such winds. Gannets were closely associated with feeding dolphins at both coarse and fine scales, and responded to changes in dolphin behaviour. Common dolphin, Delphinus capensis , abundance and group size peaked between Waterfall Bluff and Port St Johns. Along this stretch of coastline they travelled more slowly, and in pods more perpendicular to the bathymetry of the region. Bottlenose dolphin, Tursiops aduncus , abundance increased during the sardine run with the influx of a migrant stock which reached the KZN Mid South Coast. Humpback Whale, Megaptera novaeangliae , and sardine distributions did not appear to be related. iii PREFACE The experimental work described in this thesis was carried out in the School of Biological and Conservation Sciences, University of KwaZulu-Natal, from July 2005 to July 2009, under the supervision of Professor Victor M Peddemors. These studies represent original work by the author and have not otherwise been submitted in any form for any degree or diploma to any tertiary institution. Where use has been made of the work of others it is duly acknowledged in the text. iv DECLARATION 1 - PLAGIARISM I, Sean O’Donoghue, declare that 1. The research reported in this thesis, except where otherwise indicated, is my original research. 2. This thesis has not been submitted for any degree or examination at any other university. 3. This thesis does not contain other persons’ data, pictures, graphs or other information, unless specifically acknowledged as being sourced from other persons. 4. This thesis does not contain other persons' writing, unless specifically acknowledged as being sourced from other researchers. Where other written sources have been quoted, then: a. Their words have been re-written but the general information attributed to them has been referenced b. Where their exact words have been used, then their writing has been placed inside quotation marks, and referenced. 5. This thesis does not contain text, graphics or tables copied and pasted from the Internet, unless specifically acknowledged, and the source being detailed in the thesis and in the References sections. Signed: ………………………………………………………… v DECLARATION 2 - PUBLICATIONS DETAILS OF CONTRIBUTION TO PUBLICATIONS that form part and/or include research presented in this thesis (include publications in preparation, submitted, in press and published and give details of the contributions of each author to the experimental work and writing of each publication) Publication 1: O’Donoghue SH, Drapeau L and Peddemors VM (in press) An investigation of broad-scale distribution patterns of sardines and their predators in relation to remotely sensed environmental conditions. African Journal of Marine Science . O’Donoghue – data collection (aerial surveys), data capture, analyses, writing, intellectual input Drapeau – data collection (remote sensing time series), writing (remote sensing methods) Peddemors – data collection (aerial surveys), writing, intellectual input Publication 2 O’Donoghue SH, Drapeau L, Dudley SFJ and Peddemors VM (in press) The KwaZulu-Natal sardine run: shoal distribution in relation to near-shore environmental conditions, 1997 to 2007. African Journal of Marine Science . O’Donoghue – data collection (climate), data capture, analyses, writing, intellectual input Drapeau – analyses (GLM and GAM modelling), writing Dudley – data collection (KZNSB oceanographic), writing, intellectual input Peddemors – writing, intellectual input Publication 3 O’Donoghue SH, Whittington P, Peddemors VM and Dyer BM (submitted) The 2005 sardine run survey II: Avian and marine mammal predators associated with the sardine run. African Journal Marine Science. O’Donoghue – data collection (remote sensed time series), data capture, analyses, writing, intellectual input Whittington – data collection (ornithological survey), data capture, analyses, writing, intellectual input (bird data) Peddemors – data collection (mammal survey), writing, intellectual input Dyer – data collection (ornithological survey) vi Publication 4 O’Donoghue SH, Peddemors VM (submitted) Fine-scale sardine run distribution and predator behaviour along the Eastern Cape ‘Wild Coast’ in relation to environmental conditions. O’Donoghue – data collection (aerial survey, climate data), data capture, analyses, writing, intellectual input Peddemors – writing, intellectual input Publication 5 O’Donoghue SH, Peddemors VM (in prep) Differences in predator behaviour along the Eastern Cape ‘Wild Coast’ in relation to the annual sardine run. African Zoology O’Donoghue – data collection (point survey), data capture, analyses, writing, intellectual input Peddemors – data collection (CTD survey), writing, intellectual Signed: vii CONTENTS CHAPTER ONE …………………………………………………………… 1 Introduction CHAPTER TWO …………………………………………………………... 9 An investigation of broad-scale distribution patterns of sardines and their predators in relation to remotely sensed environmental conditions CHAPTER THREE …………………………………………………………... 30 The KwaZulu-Natal sardine run: shoal distribution in relation to near-shore environmental conditions, 1997 to 2007 CHAPTER FOUR ………………………………………………………….. 52 The 2005 sardine run survey II: Avian and marine mammal predators associated with the sardine run. CHAPTER FIVE …………………………………………………………… 75 Fine-scale sardine run distribution and predator behaviour along the Eastern Cape ‘Wild Coast’ in relation to environmental conditions CHAPTER SIX …………………………………………………………… 98 Differences in predator behaviour along the Eastern Cape ‘Wild Coast’ in relation to the annual sardine run. CHAPTER SEVEN …………………………………………………………… 120 Conclusion REFERENCES …………………………………………………………... 127 viii ACKNOWLEDGEMENTS This thesis would not have been possible without the energy and enthusiasm that Professor Vic Peddemors brought to the University of Durban, Westville, in 2002. Vic’s interest in the sardine run has been long-term, and his motivation and hard work resulted in the initiation of the UKZN sardine run research programme. I would like to thank him both for his role as the programme director, and for his guidance and tireless dedication as my supervisor and in preparing this thesis. Finally, I would like to thank him for the six wonderful years of sardine run research that I’ve been fortunate enough to participate in. Following Professor Peddemors’ emigration to Australia, I remained under the care of Doctor AJ Smit. I gratefully acknowledge Dr Smit’s selfless assistance with matters pertaining to university life as a UKZN student. The three examiners of this thesis are also thanked for their effort, particularly for their helpful criticism and their attention to the integrity of the methods used in the analysis of data. This research was conducted as part of project URD2005070100039 under the auspices of the NRF University Research Development Programme - their support is gratefully acknowledged. I would like to express special gratitude to the South African Government, Department of Labour, for the financial support that I received via the D.O.L. Scarce skills Scholarship programme. Further financial assistance was received from the UKZN School of Biological and Conservation Sciences through a Special Award and an award to attend an international conference. Finally, I would like to thank the Oppenheimer Trust for the supplementary grant to attend an international