Population structure and morphology of the serratus (Pennant, 1777) in Welsh coastal waters with a consideration of two options for regulating the fishery

Richard Huxley

July 2011

Abstract The prawn fishery contributes over half a million pounds annually to the Welsh economy. Despite its importance, the commercial exploitation of the in Welsh waters remains unregulated. Fishermen and their Associations have long recognised that legislation is crucial if the fishery is to remain economically sustainable. Because regional variations in the morphology and structure of the population could compromise the universal applicability of legislation, sample populations from four locations around the Welsh coast were examined with a view to testing the hypothesis that there were morphologically or structurally distinct groups of P. serratus that could be regarded as separate populations of the species around the Welsh coast.

Significant differences in size were found between the sexes in all samples, confirming that because females were larger they were the main target of the fishery. Sexual dimorphism was also evident in the analysis of rostral morphology. Relative to carapace length, the length of the rostrum was found to be significantly longer in males than in females. No evidence of separate populations around the Welsh coast was found; regional variations in the morphology and structure of the sample populations were thought to reflect the depth at which samples were collected and known seasonal migratory patterns of the species.

Data relating to the effect of pot mesh size on catch quantity were examined to determine what the differences in the quantities of saleable and discarded were between 9mm and 14mm mesh pots. The mean number of prawns captured by the 14mm mesh pots was significantly less than the mean number captured by the 9mm mesh pots, but significantly less discard and marginally more saleable prawns were captured by the 14mm mesh pots.

Most commercial prawn fishing takes place during the winter months. The main income of pot fishermen during the summer months comes from the capture of species such as the common (). Therefore, catch data for both P. serratus and H. gammarus were examined to determine if there was a period during which the prawn fishery could be closed without having an adverse effect on fishing incomes. No evidence was found in the analysis of catch data to suggest that a closed season between 1st June and 1st September would have any adverse effect on fishing incomes.

i DECLARATION

This work has not previously been accepted in substance for any degree and is not being concurrently submitted in candidature for any degree.

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Date ......

STATEMENT 1

This thesis is the result of my own investigations, except where otherwise stated. Other sources are acknowledged by explicit references. A bibliography is appended.

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STATEMENT 2

I hereby give consent for my thesis, if accepted, to be available for photocopying and for inter-library loan, and for the title and summary to be made available to outside organisations.

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ii Acknowledgements I would like to express gratitude to the Welsh Federation of Fishermen’s Associations (WFFA) for providing financial support for this project. With respect to this thanks are due to Jerry Percy of the WFFA, Ben Fothergill from Cardigan Bay Fisherman’s Association (CBFA) and Dr John , (project supervisor) for finding the fishermen to collect prawn samples. Thanks are also due to Barbara Newborough from the CBFA for her invaluable assistance in finding the “lost” data used for the analysis of the effect of pot mesh size on catch. The time, advice and efforts of all the fishermen involved in the project is also gratefully acknowledged, with special thanks to; Harry Parry, Dave Slater, Brian Wotton, Chris Hicks, Dan Parry, Dai Bray and Dave Samson.

Special thanks are due to Barrie John, senior fisheries officer from the Wales Marine Fisheries Agency (WMFA), for advice and help in acquiring fisheries data and for his sound advice. Thanks are also due to Colin Charman and Tim Croucher from the WMFA for their prompt responses to my various enquiries.

Special thanks are due to Dr David Causton from the Institute of Biological Environmental and Rural Sciences (IBERS) for advice on statistics and the use of his non-orthogonal ANOVA software. Dr Joel Allainguillaume from IBERS is acknowledged for help with translation of papers written in French. I would like to thank Dr Sue Fish, Dr Helen Marshall, Dr Ian Scott and the late Professor John Barratt from IBERS for all their advice and encouragement during my time at the institute. Thanks are also due to the following technical staff at IBERS for their assistance, advice and support; Rob Darby, Rory Geoghegan, Julie Hirst, Dr Mike Holland, Gwen Jenkins, Helen McAnulty-Jones, and Gareth Owen. Finally, thanks to Katy Peat and Liz Daniel from IBERS for being such good listeners and to Louise Birch for keeping the home fires burning.

iii Abbreviations used in the text

ANOVA - Analysis of variance

ANCOVA - Analysis of covariance

BIM - Bord Iascaigh Mhara/Irish Sea Fisheries Board

CBFA - Cardigan Bay Fisherman’s Association

CCW - Countryside Council for Wales

CL - Carapace length

CPU - Catch per unit effort

CW - Carapace width

EU – European Union

EV - Egg volume

IFCA - Inshore Fisheries and Conservation Authority

IFG - Inshore Fisheries Group

ITIS - Integrated Taxonomic Information System

MMO - Marine Management Organisation

NAW - National Assembly for Wales

NWNWSFC - North Western and North Wales Sea Fisheries Committee

RL - Rostral length

SAG - Stakeholder Advisory Group

SWSFC - South Wales Sea Fisheries Committee

UK - United Kingdom

WAG - Welsh Assembly Government

WFFA - Welsh Federation of Fishermen’s Associations

WMFA - Wales Marine Fisheries Agency

WMFAG - Wales Marine Fisheries Advisory Group

WoRMS - World Register of Marine Species

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Contents Section Title Page Abstract i Declaration ii Acknowledgements iii Abbreviations used in the text iv

INTRODUCTION 1

1 THE COMMON PRAWN: Palaemon serratus 3

1.1 4 1.1.1 Taxonomic hierarchy 5

1.2 MORPHOLOGY 6 1.2.1 Size 7 1.2.2 Sexual dimorphism 8 1.2.3 Age 10

1.3 REPRODUCTION 11 1.3.1 Spawning 11 1.3.2 Fecundity 12 1.3.3 Larval development and dispersal 12 1.3.4 Size at sexual maturity 13

1.4 EPIDEMIOLOGY 14 1.4.1 Bopyrus squillarum 14 1.4.2 Indosporus octospora 14 1.4.3 Nectonema agile 15 1.4.4 Ascophrys rodor 15

2 THE WELSH PRAWN FISHERY 16

2.1 HISTORICAL CONTEXT & ECONOMIC IMPORTANCE 17

2.2 MANAGEMENT 19 2.2.1 Structure of the WMFAG 20 2.2.2 Structure of the regional IFGs 21 2.2.3 Regulation 22 2.2.4 Market driven practices 22 2.2.5 Practical limitations and problems 23 2.2.6 Future management; regulatory options 24

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3 AIMS AND METHODS 28

3.1 AIMS 29

3.2 SAMPLING 31 3.2.1 Sampling frequency 31 3.2.2 Location of sample ports 33 3.2.3 Sampling equipment 34 3.2.4 Sample collection 35 3.2.5 Storage 35 3.2.6 Preservation 35

3.3 IDENTIFICATION & MEASUREMENT 36 3.3.1 Weight 36 3.3.2 Determination of species and sex 36 3.3.3 Linear measurements 37 3.3.4 Rostral teeth 38 3.3.5 Egg number 38 3.3.6 Egg volume 38

3.4 STATISTICAL ANALYSIS 40 3.4.1 Population structure 40 3.4.2 Morphology 41 3.4.3 Size at sexual maturity 42 3.4.4 Fecundity, egg number, egg volume and carapace length 42 3.4.5 Estimates of total biomass of the samples 43 3.4.6 Saleable proportion of catch samples 44 3.4.7 Minimum carapace length of saleable prawns 44 3.4.8 Pot mesh size 44 3.4.9 Seasonal trends in catch records for P. serratus and H. gammarus 45

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4 RESULTS 46

4.1 POPULATION STRUCTURE 47 4.1.1 The proportion of male, female and ovigerous female prawns and 48 prawn biomass in the catch samples 4.1.2 Age 54

4.2 MORPHOLOGY 63 4.2.1 Carapace length 64 4.2.2 Wet weight 72 4.2.3 Carapace width and carapace length 80 4.2.4 Carapace length and rostral length 89 4.2.5 Carapace length and wet weight 99 4.2.6 The number of dorsal teeth on the rostrum 109 4.2.7 The number of ventral teeth on the rostrum 112 4.2.8 Size at sexual maturity 115

4.3 FECUNDITY; EGG NUMBER & EGG VOLUME 122 4.3.1 Egg number 123 4.3.2 Egg volume 128

4.4 THE SALEABLE PROPORTION OF THE CATCH SAMPLES 133 4.4.1 Estimated minimum carapace length of saleable prawns 140

4.5 POT MESH SIZE 141 4.5.1 Numerical differences in the catch between the 9mm and 14mm mesh 142 pots 4.5.2 Differences in the mean carapace width of prawns captured by the 145 9mm and 14mm mesh pots 4.5.3 Comparison between this study and the pot mesh trial of the 147 saleable/non-saleable proportion of prawns in the catch samples 4.5.4 Estimates of the mean and minimum carapace length of prawns 148 captured by the 9mm and 14mm mesh pots

4.6 CATCH RECORDS 149 4.6.1 Quantity and value of P. serratus landed in Wales 2006 to 2009 150 4.6.2 Quantity and value of H. gammarus landed in Wales 2006 to 2009 153

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5 DISCUSSION 164

5.1 POPULATION STRUCTURE 156 5.1.1 The sex ratio 157 5.1.2 The sex ratio and biomass 158 5.1.3 The proportion of ovigerous females 158 5.1.4 Age 158

5.2 MORPHOLOGY 160 5.2.1 Size and sex 160 5.2.2 Regional and seasonal variations in size 160 5.2.3 Carapace width and carapace length 161 5.2.4 Carapace length and rostral length 163 5.2.5 Carapace length and wet weight 165 5.2.6 Rostral teeth 166 5.2.7 Size at sexual maturity 167 5.2.8 Additional observations 168

5.3 FECUNDITY; EGG NUMBER & EGG VOLUME 169 5.3.1 Egg number 169 5.3.2 Egg volume 169

5.4 THE SALEABLE PROPORTION OF THE CATCH SAMPLES 170

5.5 MINIMUM POT MESH SIZE 171 5.5.1 The pot mesh trial 171 5.5.2 Practicalities of a minimum pot mesh size 172

5.6 CLOSED SEASON 174 5.6.1 Practicalities of a closed season 175

5.7 GENERAL CONCLUSIONS 177

5.7.1 Suggestions for further work 179

REFERENCES/BIBLIOGRAPHY 181

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List of figures Number Legend Page 1 Schematic diagram of a caridean decapod 6 2 The inner endopodite on the second pleopod of a typical male P. 8 serratus, showing the appendices masculina and interna 3 The inner endopodite on the second pleopod of a typical female P. 8 serratus, showing the appendix interna 4 The ventral surface of a typical male P. serratus showing the small 9 protuberance between the posterior pereiopods 5 The ventral surface of a typical female P. serratus showing the 9 smooth ridge between the posterior pereiopods 6 Annual quantity of P. serratus landed in UK from 2006 to 2009 18 7 Annual value of P. serratus landed in UK from 2006 to 2009 18 8 Schematic diagram of the Stakeholder Engagement Model for the 19 management of Welsh marine fisheries 9 Location of the ports adjacent to where samples were collected 33 10a Schematic diagram of typical sampling rig 34 10b Typical Roscoff style prawn pot used in the sampling rigs 35 11 The cephalothorax of a typical female p. serratus 37 12 Proportion of male, non-ovigerous female and ovigerous female 48 prawns in samples: Newquay 2008/9 13 Proportion of male, non-ovigerous female and ovigerous female 48 biomass in samples: Newquay 2008/9 14 Proportion of male, non-ovigerous female and ovigerous female 49 prawns in samples: Aberystwyth 2009 15 Proportion of male, non-ovigerous female and ovigerous female 49 biomass in samples: Aberystwyth 2009 16 Proportion of male, non-ovigerous female and ovigerous female 50 prawns in samples: Morfa Nefyn 2009 17 Proportion of male, non-ovigerous female and ovigerous female 50 biomass in samples: Morfa Nefyn 2009 18 Proportion of male, non-ovigerous female and ovigerous female 51 prawns in samples: Amlwch 2009 19 Proportion of male, non-ovigerous female and ovigerous female 51 biomass in samples: Amlwch 2009 20-23 Length-frequency distributions from Mixture analyses with group fits: 54 Newquay males 2008/9 24 Summary of mean carapace lengths of male cohorts, Newquay 2008/9 54 25-28 Length-frequency distributions from Mixture analyses with group fits: 55 Newquay females 2008/9 29 Summary of mean carapace lengths of female cohorts, Newquay 55 2008/9 30-33 Length-frequency distributions from Mixture analyses with group fits: 56 Aberystwyth males 2008/9 34 Summary of mean carapace lengths of male cohorts, Aberystwyth 56 2009 35-38 Length-frequency distributions from Mixture analyses with group fits: 57 Aberystwyth females 2008/9

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List of figures cont/ Number Legend Page 39 Summary of mean carapace lengths of female cohorts, Aberystwyth 57 2009 40-43 Length-frequency distributions from Mixture analyses with group fits: 58 Morfa Nefyn males 2009 44 Summary of mean carapace lengths of male cohorts, Morfa Nefyn 58 2009 45-48 Length-frequency distributions from Mixture analyses with group fits: 59 Morfa Nefyn females 2009 49 Summary of mean carapace lengths of female cohorts, Morfa Nefyn 59 2009 50-51 Length-frequency distributions from Mixture analyses with group fits: 60 Morfa Nefyn males and females, October 2009 52 Summary of mean carapace lengths of male cohorts, Morfa Nefyn 60 2009 53 Summary of mean carapace lengths of female cohorts, Morfa Nefyn 60 2009 54-55 Length-frequency distributions from Mixture analyses with group fits: 61 Amlwch males 2009 56 Summary of mean carapace lengths of male cohorts, Amlwch 2009 61 57-58 Length-frequency distributions from Mixture analyses with group fits: 62 Amlwch females 2009 59 Summary of mean carapace lengths of female cohorts, Amlwch 2009 62 60 Mean carapace lengths: all locations, February and March 2009 64 61 Mean carapace lengths: Aberystwyth and Morfa Nefyn, February to 66 May 2009 62 Mean carapace lengths: Newquay, December to March 2008/9 68 63 Mean carapace lengths: Morfa Nefyn, February to May plus October 70 2009 64 Mean log wet weights: all locations, February and March 2009 72 65 Mean log wet weights: Aberystwyth and Morfa Nefyn, February to 74 May 2009 66 Mean log wet weights: Newquay, December to March 2008/9 76 67 Mean log wet weights: Morfa Nefyn, February to May plus October 78 2009 68 The relationship between carapace width and carapace length: both 80 sexes, all locations 2008/9 69 Mean carapace width/carapace length ratios: all locations, February 81 and March 2009 70 Mean carapace width/carapace length ratios: Aberystwyth and Morfa 83 Nefyn, February to May 2009 71 Mean carapace width/carapace length ratios: Newquay, December to 85 March 2008/9 72 Mean carapace width/carapace length ratios: Morfa Nefyn, February 87 to May plus October 2009 73 The relationship between carapace length and rostral length: both 89 sexes, all locations

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List of figures cont/ Number Legend Page 74 The relationship between log carapace length and log rostral length: 90 both sexes, all locations 2008/9 75 Mean log carapace length/rostral length ratios: all locations, February 91 and March 2009 76 Mean log carapace length/rostral length ratios: Aberystwyth and 93 Morfa Nefyn, February to May 2009 77 Mean log carapace length/rostral length ratios: Newquay, December to 95 March 2008/9 78 Mean log carapace length/rostral length ratios: Morfa Nefyn, February 97 to May plus October 2009 79 The relationship between carapace length and wet weight both sexes, 99 all locations 2008/9 80 The relationship between log carapace length and log wet weight: both 100 sexes, all locations 2008/9 81 Mean log carapace length/wet weight ratios: all locations, February & 101 March 2009 82 Mean log carapace length/wet weight ratios: Aberystwyth & Morfa 103 Nefyn, February to May 2009 83 Mean log carapace length/wet weight ratios: Newquay, December to 105 March 2008/9 84 Mean log carapace length/wet weight ratios: Morfa Nefyn, February 107 to May plus October 2009 85 Mean number of dorsal teeth on the rostrum for all locations, February 109 + March 2009 86 Mean number of dorsal teeth on the rostrum: Newquay, December to 111 March 2008/9 87 Mean number of ventral teeth on the rostrum for all locations February 112 + March 2009 88 Mean number of ventral teeth on the rostrum: Newquay, December to 114 March 2008/9 89 Logistic fit, ovigerous females: Newquay, February 2009 115 90 Logistic fit, ovigerous females: Newquay, March 2009 115 91 Logistic fit ovigerous females: Aberystwyth, March 2009 116 92 Logistic fit, ovigerous females: Aberystwyth, April 2009 116 93 Logistic fit, ovigerous females: Aberystwyth, May 2009 117 94 Logistic fit, ovigerous females: Morfa Nefyn, March 2009 117 95 Logistic fit, ovigerous females: Morfa Nefyn, April 2009 118 96 Logistic fit, ovigerous females: Morfa Nefyn, May 2009 118 97 Logistic fit, ovigerous females: Amlwch, February 2009 119 98 Logistic fit, ovigerous females: Amlwch, March 2009 119

99 Summary of CL50 values of ovigerous females for all sample 120 populations 2009 100 Summary of the minimum carapace lengths of ovigerous females for 121 all sample populations 2009 101 Relationship between carapace length and egg number: Newquay 123 February + March 2009

xi List of figures cont/ Number Legend Page 102 Relationship between carapace length and egg number: Aberystwyth, 124 February + March 2009 103 Relationship between carapace length and egg number: Morfa Nefyn, 125 February + March 2009 104 Relationship between carapace length and egg number: Amlwch, 126 February + March 2009 105 Mean egg numbers, all locations, February + March 2009 (adjusted 127 for length by ANCOVA) 106 Relationship between carapace length and egg volume: Newquay, 128 February + March 2009 107 Relationship between carapace length and egg volume: Aberystwyth, 129 February + March 2009 108 Relationship between carapace length and egg volume: Morfa Nefyn, 130 February + March 2009 109 Relationship between carapace length and egg volume: Amlwch, 131 February + March 2009 110 Mean log egg volumes, all locations, February + March 2009 132 111 Proportion of saleable/non-saleable prawns in samples: Newquay 134 2008/9 112 Proportion of saleable/non-saleable prawn biomass in samples: 134 Newquay 2008/9 113 Proportion of saleable/non-saleable prawns in samples: Aberystwyth 135 2009 114 Proportion of saleable/non-saleable prawn biomass in samples: 135 Aberystwyth 2009 115 Proportion of saleable/non-saleable prawns in samples: Morfa Nefyn 136 2009 116 Proportion of saleable/non-saleable prawn biomass in samples: Morfa 136 Nefyn 2009 117 Proportion of saleable/non-saleable prawns in samples: Amlwch 2009 137 118 Proportion of saleable/non-saleable prawn biomass in samples: 137 Amlwch 2009 119 Number of saleable and non-saleable prawns captured by the 9mm 142 and 14mm mesh pots 120 Relative proportion of saleable and non-saleable prawns captured by 142 the 9mm and 14mm pots 121 Mean number of saleable and non-saleable prawns captured in 9mm 143 and 14mm pots 122 Mean carapace widths of prawns <10mm carapace width and ≥10mm 145 carapace width captured by 9mm and 14mm pots 123 Comparison between mesh trial and current study of the proportion of 147 saleable/non-saleable prawns using pooled data from all samples 124 Comparison between mesh trial and current study of the proportion of 147 saleable/non-saleable prawns using pooled data from February to May 125 Quantity of P. serratus landed in Wales/month 2006 to 2009 150 126 Mean quantity of P. serratus landed in Wales/month 2006 to 2009 150 127 First sale value of P. serratus landed in Wales 2006 to 2009 151

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List of figures cont/ Number Legend Page 128 Mean first sale value of P. serratus landed in Wales/month 2006 to 151 2009 129 Quantity of H. gammarus landed in Wales/month 2006 to 2009 153 130 Mean quantity of H. gammarus landed in Wales/month 2006 to 2009 153 131 First sale value of H. gammarus landed in Wales/month 2006 to 2009 154 132 Mean first sale value of H. gammarus landed in Wales/month 2006 to 154 2009

List of tables Number Title Page 1 Summary of the quoted maximum total length of P. serratus 7 2 Structure of the WMFAG 20 3 Structure of regional IFGs 21 4 Summary of potential options for regulating the Welsh prawn fishery 24 5 Summary of haul dates and soak-times of prawn pots 32 6 Approximate depths of sample locations 33 7 Mean carapace lengths: all locations, February and March 2009 64 8 Mean carapace lengths: Aberystwyth and Morfa Nefyn, February to 66 May 2009 9 Mean carapace lengths: Newquay, December to March 2008/9 68 10 Mean carapace lengths: Morfa Nefyn, February to May plus October 70 2009 11 Mean log wet weights: all locations, February and March 2009 72 11.1 Mean wet weights: all locations, February and March 2009 73 12 Mean log wet weights: Aberystwyth and Morfa Nefyn, February to 74 May 2009 12.1 Mean wet weights: Aberystwyth and Morfa Nefyn, February to May 75 2009 13 Mean log wet weights: Newquay, December to March 2008/9 76 13.1 Mean wet weights: Newquay, December to March 2008/9 76 14 Mean log wet weights: Morfa Nefyn, February to May plus October 78 2009 14.1 Mean wet weights: Morfa Nefyn, February to May plus October 2009 78 15 Mean carapace width/carapace length ratios: all locations, February 81 and March 2009 16 Mean carapace width/carapace length ratios: Aberystwyth and Morfa 83 Nefyn, February to May 2009 17 Mean carapace width/carapace length ratios: Newquay, December to 85 March 2008/9 18 Mean carapace width/carapace length ratios: Morfa Nefyn, February 87 to May plus October 2009 19 Mean log carapace length/rostral length ratios: all locations, February 91 and March 2009

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List of tables cont/ Number Title Page 19.1 Mean carapace length/rostral length ratios: all locations, February and 92 March 2009 20 Mean carapace length/rostral length ratios: Aberystwyth and Morfa 93 Nefyn, February to May 2009 20.1 Mean carapace length/rostral length ratios: Aberystwyth and Morfa 94 Nefyn, February to May 2009 21 Mean log carapace length/rostral length ratios: Newquay December to 95 March 2008/9 21.1 Mean carapace length/rostral length ratios: Newquay December to 96 March 2008/9 22 Mean log carapace length/rostral length ratios Morfa Nefyn, February 97 to May plus October 2009 22.1 Mean carapace length/rostral length ratios Morfa Nefyn, February to 98 May plus October 2009 23 Mean log carapace length/wet weight ratios: all locations, February & 101 March 2009 23.1 Mean carapace length/wet weight ratios: all locations, February & 102 March 2009 24 Mean log carapace length/wet weight ratios: Aberystwyth & Morfa 103 Nefyn, February to May 2009 24.1 Mean carapace length/wet weight ratios: Aberystwyth & Morfa 104 Nefyn, February to May 2009 25 Mean log carapace length/wet weight ratios: Newquay, December to 105 March 2008/9 25.1 Mean carapace length/wet weight ratios: Newquay, December to 106 March 2008/9 26 Mean log carapace length/wet weight ratios Morfa Nefyn, February to 107 May plus October 2009 26.1 Mean carapace length/wet weight ratios Morfa Nefyn, February to 108 May plus October 2009 27 Mean numbers of dorsal teeth on the rostrum for all locations, 109 February + March 2009 28 Mean number of dorsal teeth on the rostrum: Newquay, December to 111 March 2008/9 29 Mean numbers of ventral teeth on the rostrum for all locations, 112 February + March 2009 30 Mean number of ventral teeth on the rostrum: Newquay, December to 114 March 2008/9 31 Summary of egg volumes for all locations, February + March 2009 132

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Number Page APPENDICES 188 I Summary of the number of prawns captured/sample 189 II Summary of the number of prawns captured/pot 190 III Estimated prawn biomass in samples 191 IV Estimated prawn biomass/pot 193 V Estimated mean weight of individual prawns captured 194 VI Multiple regression coefficients used to calculate biomass estimates 195 VII NWNWSFC Byelaw 30 196 VIII Carapace length ANOVAS and Tukeys post hoc test results 198 IX log Wet weight ANOVAS and Tukeys post hoc test results 209 X Carapace width/carapace length ratio ANOVAS and Tukeys post hoc 220 test results XI log Carapace length/rostral length ratio ANOVAS and Tukeys post 231 hoc test results XII log Carapace length/wet weight ratio ANOVAS and Tukeys post hoc 242 test results XIIIi ANOVA of the number of teeth on the rostrum and Tukeys post hoc 253 test results XIIIii ANCOVA of the number of rostral teeth and carapace length vs 258 location XIV Egg number and egg volume 260 XV ANOVAS of the number of prawns and carapace width vs pot mesh 262 size, and Tukeys post hoc test results

List of tables in Appendices Number Title Page I Summary of the number of male, female and ovigerous prawns 189 captured/sample 2008/9 II Summary of the number of male, female and ovigerous prawns 190 captured/pot 2008/9 III Estimated prawn biomass in samples: Newquay 2008/9 191 IV Estimated prawn biomass in samples: Aberystwyth 2009 191 V Estimated prawn biomass in samples: Morfa Nefyn 2009 192 VI Estimated prawn biomass in samples: Amlwch 2009 192 VII Estimated prawn biomass/pot: all samples 2008/9 193 VIII Estimated mean weight of individual male, female and ovigerous 194 prawns captured 2008/9 IX Multiple regression coefficients used to calculate biomass estimates 195 X ANOVA table for carapace length vs location, month and sex: all 198 locations, February and March 2009 XI ANOVA table for carapace length vs location, month and sex: 198 Aberystwyth and Morfa Nefyn February to May 2009 XII ANOVA table for carapace length vs month and sex: Newquay 199 December to March 2008/9 XIII ANOVA table for carapace length vs month and sex: Morfa Nefyn 199 February to May plus October 2009

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List of tables in Appendices cont/ Number Title Page XIV ANOVA table for log wet weight vs location, month and sex: all 209 locations, February and March 2009 XV ANOVA table for log wet weight vs location, month and sex: 209 Aberystwyth and Morfa Nefyn February to May 2009 XVI ANOVA table for log wet weight vs month and sex: Newquay 210 December to March 2008/9 XVII ANOVA table for log wet weight vs month and sex: Morfa Nefyn 210 February to May plus October 2009 XVIII ANOVA table for carapace width/carapace length ratio vs location, 220 month and sex: all locations, February and March 2009 XIX ANOVA table for carapace width/carapace length ratio vs month, 220 location and sex: Aberystwyth and Morfa Nefyn February to May 2009 XX ANOVA table for carapace width/carapace length ratio vs month and 221 sex: Newquay December to March 2008/9 XXI ANOVA table for carapace width/carapace length ratio vs month and 221 sex: Morfa Nefyn February to May plus October 2009 XXII ANOVA table for log carapace length/rostral length ratio vs location, 231 month and sex: all locations, February and March 2009 XXIII ANOVA table for log carapace length/rostral length ratio vs location, 231 month and sex: Aberystwyth and Morfa Nefyn February to May 2009 XXIV ANOVA table for log carapace length/rostral length ratio vs month 232 and sex: Newquay December to March 2008/9 XXV ANOVA table for log carapace length/rostral length ratio vs month 232 and sex: Morfa Nefyn February to May plus October 2009 XXVI ANOVA table for log carapace length/wet weight ratio vs location, 242 month and sex: all locations, February and March 2009 XXVII ANOVA table for log carapace length/wet weight ratio vs location, 242 month and sex: Aberystwyth and Morfa Nefyn February to May 2009 XXVIII ANOVA table for log carapace length/wet weight ratio vs month and 243 sex: Newquay December to March 2008/9 XXIX ANOVA table for log carapace length/wet weight ratio vs month and 243 sex: Morfa Nefyn February to May plus October 2009 XXX ANOVA table for the number of dorsal teeth vs location, month and 253 sex: all locations, February and March 2009 XXXI ANOVA table for the number of ventral teeth vs location, month and 253 sex: all locations, February and March 2009 XXXII ANOVA table for number of dorsal teeth vs month and sex: Newquay, 256 December 2008 to March 2009 XXXIII ANOVA table for number of ventral teeth vs month and sex: 256 Newquay, December 2008 to March 2009 XXXIV ANCOVA table for the number of female dorsal teeth and carapace 258 length vs location XXXV Supplementary results from ANCOVA of number of female dorsal 258 teeth and carapace length vs location XXXVI ANCOVA table for the number of male dorsal teeth and carapace 258 length vs location

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List of tables in Appendices cont/ Number Title Page XXXVII Supplementary results from ANCOVA of number of male dorsal teeth 258 and carapace length vs location XXXVIII ANCOVA table for the number of female ventral teeth and carapace 259 length vs location XXXIX Supplementary results from ANCOVA of number of female ventral 259 teeth and carapace length vs location XL Results of error check of egg counts 260 XLI ANCOVA table for egg number and carapace length vs location 260 XLII Supplementary results from ANCOVA of egg number and carapace 260 length vs location XLIII ANOVA table for the number of prawns captured/pot vs mesh size 262 and the split between saleable and non-saleable portions of the catch XLIV ANOVA table for carapace width vs mesh size and the split between 263 saleable and non-saleable portions of the catch

List of boxes in Appendices Number Legend Page 1 Tukey’s pairwise test results for carapace length: all locations, 200 February and March 2009 2 Tukey’s pairwise test results for carapace length: Aberystwyth and 203 Morfa Nefyn February to May 2009 3 Tukey’s pairwise test results for carapace length: Newquay December 206 to March 2008/9 4 Tukey’s pairwise test results for carapace length: Morfa Nefyn 207 February to May plus October 2009 5 Tukey’s pairwise test results for log wet weight: all locations, 211 February and March 2009 6 Tukey’s pairwise test results for log wet weight: Aberystwyth and 214 Morfa Nefyn February to May 2009 7 Tukey’s pairwise test results for log wet weight: Newquay December 217 to March 2008/9 8 Tukey’s pairwise test results for log wet weight: Morfa Nefyn 218 February to May plus October 2009 9 Tukey’s pairwise test results for carapace width/carapace length ratio: 222 all locations, February and March 2009 10 Tukey’s pairwise test results for carapace width/carapace length ratio: 225 Aberystwyth and Morfa Nefyn February to May 2009 11 Tukey’s pairwise test results for carapace width/carapace length ratio: 228 Newquay December to March 2008/9 12 Tukey’s pairwise test results for carapace width/carapace length ratio: 229 Morfa Nefyn February to May plus October 2009 13 Tukey’s pairwise test results for log carapace length/rostral length 233 ratio: all locations, February and March 2009 14 Tukey’s pairwise test results for log carapace length/rostral length 236 ratio: Aberystwyth and Morfa Nefyn February to May 2009 15 Tukey’s pairwise test results for log carapace length/rostral length 239 ratio: Newquay December to March 2008/9

xvii List of boxes in Appendices cont/ Number Legend Page 16 Tukey’s pairwise test results for log carapace length/rostral length 240 ratio: Morfa Nefyn February to May plus October 2009 17 Tukey’s pairwise test results for log carapace length/wet weight ratio: 244 all locations, February and March 2009 18 Tukey’s pairwise test results for log carapace length/wet weight ratio: 247 Aberystwyth and Morfa Nefyn February to May 2009 19 Tukey’s pairwise test results for log carapace length/wet weight ratio: 250 Newquay December to March 2008/9 20 Tukey’s pairwise test results for log carapace length/wet weight ratio: 251 Morfa Nefyn February to May plus October 2009 21 Tukey’s pairwise test results for dorsal teeth: all locations, February 254 and March 2009 22 Tukey’s pairwise test results for ventral teeth: all locations, February 255 and March 2009 23 Tukey’s pairwise test results for ventral teeth: Newquay, December 257 2008 to March 2009 24 ANOVA table for log egg volume vs location 261 25 Results of Tukey’s pairwise post hoc test of location log egg volume 261 means 26 Results of Tukey’s pairwise post hoc test of mean number of 262 prawns/pot vs mesh size and the split between saleable and non- saleable portions of the catch 27 Results of Tukey’s pairwise post hoc test of mean carapace width of 263 prawns/pot vs mesh size and the split between saleable and non- saleable portions of the catch

xviii INTRODUCTION

The Palaemon serratus prawn fishery is an important component in the mosaic of fishing activities pursued by the Welsh inshore fishing fleet. The vessels which fish for P. serratus also rely on the capture of the common lobster (Homarus gammarus), brown (Cancer pagarus) and the spiny spider crab (Maja squinado) among other species. The first sale value of landings from the 60+ vessels currently fishing for P. serratus in Welsh waters contributes more than half a million pounds annually to the Welsh economy (Marine Management Organisation (MMO) Fisheries Statistics Unit, 2010). The need for legislation to regulate this entirely unregulated fishery has long been recognised by fishermen and their Associations as being essential if the fishery is to remain economically sustainable. Without legislation, over-exploitation of the stock and excessive competition between fishermen are likely to result in falling sales incomes and perhaps conflict between fishermen.

The universal applicability and equity of any proposed legislation for regulating the fishery could be compromised by the existence of separate populations of the species around the Welsh coast. Because some of the regulatory options under consideration are based on morphological characteristics, such as size, and/or structural parameters, such as seasonality, the existence of morphologically and/or structurally distinct populations could require separate regional, rather than pan-Wales legislation. This could introduce undue complexity, potential controversy and additional costs to the implementation and enforcement of legislation that a pan-Wales approach would avoid. The primary aim of this project was, therefore, to test the hypothesis that there were morphologically or structurally distinct groups of P. serratus that could be regarded as separate populations of the species around the Welsh coast. The secondary aim was to examine two of the potential options for regulating the fishery; a minimum pot mesh size and a closed season.

To provide background information to inform the examination of the population structure and morphology of the species in Wales, this thesis begins with a brief review of the biology of P. serratus. This is followed by an outline of the Welsh prawn fishery to inform the consideration of a minimum pot mesh size and closed season as potential options for Byelaws. In Section 3 the project aims are reiterated and the methods described. The results of the analyses of population structure, morphology, fecundity etc

1 are presented in Section 4. Section 4 also contains the results of the analysis of data relating to pot mesh size and of the analysis of catch data that was undertaken to determine if there was a particularly favourable time for a closed season. The results are discussed in Section 5 followed by general conclusions and suggestions for further work. The detailed output of the data analyses and other supplementary information is contained in the Appendices, and a copy of the raw data are provided on a separate compact disc.

2 1 THE COMMON PRAWN: Palaemon serratus (Pennant, 1777)

3 1.1 TAXONOMY

Prawns, along with , and belong to the taxonomic order . Traditionally, order Decapoda was divided into separate swimming and crawling forms by the suborders Natantia and Reptantia respectively (e.g. Barrett & Yonge, 1958; Smaldon et al., 1993 and Fish & Fish, 1996). Although it was noted (Smaldon et al., 1993) that the classification of the order in this manner was unsettled. The traditional division of the Decapoda has now been superseded by the two suborders and Pleocyemata in popular guides (Waller et al., 1996), general text books (Ruppert & Barnes, 1996) and in specialist classifications of the Crustacea (Martin & Davis, 2001). However, the traditional distinction is still to be found acknowledged alongside the use of Dendrobranchiata and Pleocyemata in some standard works and field guides which deal with the identification of species (e.g. Hayward & Ryland, 2007).

The re-classification of and prawns, based on sound morphological and molecular data, has separated Palaemon serratus and the other caridean shrimps from the superficially similar penaeid shrimps and prawns (Martin & Davis, 2001). The Penaeoidea is now regarded as a superfamily within the Dendrobranchiata (Martin & Davis, 2001) rather than an infraorder within the Natantia (Holthuis, 1980; Smaldon et al.., 1993), or as an infraorder within the Dendrobranchiata (Hayward & Ryland, 2007). Infraorders such as Astacidea (lobsters and crayfish), Brachyura (crabs) and are now brought together within the taxon Pleocyemata; thereby grouping together some formerly separate natant and reptant decapods in a single Suborder (Martin & Davis, 2001). The shared feature of all members of the Pleocyemata is that their eggs remain attached to the female pleopods and their larvae hatch at an advanced developmental state as zoeae. This is in contradistinction to the eggs of the Dendrobranchiata taxa which are not brooded and hatch as more primitive naupliar larvae (Anger, 2006).

4 The general taxonomy produced by Martin & Davis (2001) only extends down to the level of family, but a complete taxonomic hierarchy for P. serratus is given in the Integrated Taxonomic Information System (ITIS) Standard Report on the species (ITIS, 2009). This incorporates both the updated crustacean classification (Martin & Davis, 2001) and the uncontroversial parts of the traditional classification from the level of family down to species (Smaldon et al., 1993).

1.1.1 Taxonomic hierarchy for Palaemon serratus

Kingdom: Animalia Phylum: Arthropoda Subphylum: Crustacea (Brünnich, 1772) Class: (Latreille, 1802) Subclass: Eumalacostraca (Grobben, 1892) Superorder: Eucarida (Calman, 1904) Order: Decapoda (Latreille, 1802) Suborder: Pleocyemata (Burkenroad, 1963) Infraorder: Caridea (Dana, 1852) Superfamily: Palaemonoidea (Rafinesque, 1815) Family: (Rafinesque, 1815) Subfamily: Palaemoninae (Rafinesque, 1815) : Palaemon (Weber, 1795) Species: Palaemon serratus (Pennant, 1777)

(ITIS, 2009)

5 1.2 MORPHOLOGY

Figure 1: Schematic diagram of a caridean decapod (Hayward & Ryland, 2007)

The broad designation of P. serratus as a decapod derives from the five pairs of walking appendages (pereopods) found at the posterior of the cephalothorax of these (Smaldon et al., 1993). The most distinctive feature of P. serratus is its toothed rostrum which has an upward curve normally terminating in a bifid tip (Smaldon et al., 1993), although specimens with undivided and even quadrafid rostral tips are sometimes found (pers. ob. 2009). The number of teeth on the rostrum is generally 6 to 7 on the dorsal margin, two of which occur behind the posterior edge of the orbit, and 4 to 5 on the ventral margin (Smaldon et al., 1993). Although colouring can vary according to its habitat, P. serratus is generally translucent with red/brown lines on the carapace and abdomen. The first two pairs of pereopods are chelate and often have yellow and red banding (Neal, 2008), with the second pair being larger than the first (Fish & Fish, 1996; Hayward & Ryland, 2007). When small, P. serratus can resemble both and varians (Fish & Fish, 1996). Consequently, identification of smaller specimens may require dissection and microscopic examination of the mandible. The mandible of P. serratus has clearly separate incisor and molar processes and a palp with three segments (Smaldon et al., 1993).

6 1.2.1 Size Total length is the parameter generally chosen to describe the maximum size of P. serratus. However, the reported size, and method by which it is measured, is subject to variation between authors. A summary of a selection of sources is given in Table 1.

Table 1: Summary of the quoted maximum total length of P. serratus

Size(mm) Measurement method Source(s) 85 From the tip of the rostrum to the base Guerao & Ribera, 2000 of the spines on the telson Nt td 100 Not reported Fish & Fish, 1996 104.22 From the tip of the rostrum to the tip of Campillo, 1979a the telson 104.65 Not reported Desbrousses, 1951 106 Not reported Nouvel, 1934 106.12 From the tip of the rostrum to the tip of Figueras, 1986 the telson 107.5 From the tip of the rostrum to the base Forster, 1951 of the spines on the telson 110 Not reported Smaldon et al., 1993 110 Not reported Hayward & Ryland, 2007 120 An approximation from a carapace Cole, 1958 length of 24.4mm 120 From the tip of the rostrum to the tip of Sollaud, 1923 the telson 120 From the tip of the rostrum to the base Fahy & Gleeson, 1996 of the spines on the telson

Alternatively, the maximum size attained by the species can be expressed by carapace length, the “standard measurement” of prawns and shrimps (Cole & Mistakidis, 1953). Measured from the posterior margin of the orbit to the mid dorsal posterior edge of the carapace, the maximum carapace length reported is 24.4mm (Cole, 1958).

Irrespective of whether total length or carapace length is used, the maximum sizes quoted in the literature on the species universally refer to female specimens; females have been found (by e.g. Cole, 1958, and Campillo, 1979a) to attain a greater size than males.

7 1.2.2 Sexual dimorphism P. serratus is thought to be dioecious (Smaldon et al., 1993) with no evidence having been found of protandrous hermaphrodism in the species (Campillo, 1979a). Below a certain size (i.e. a carapace length of 5mm) the sexes cannot be distinguished (Cole, 1958). However, once above this size the sex of P. serratus can be determined by a number of secondary morphological features.

In males, the absence or presence of the appendix masculina, a small appendage to the inner endopodite of the second pleopod, is the diagnostic feature most commonly referred to in the literature (Cole, 1958; Forster, 1951; Campillo, 1979b; Smaldon et al., 1993, and Hayward & Ryland, 1996). The inner endopodite of a typical male and female P. serratus are shown in Figures 2 and 3, and their location can be seen in Figure 1.

Figure 2: The inner endopodite on the second pleopod of a typical male P. serratus, showing the appendices masculina and interna

Figure 3: The inner endopodite on the second pleopod of a typical female P. serratus, showing the appendix interna

8 The presence of a small protuberance on the ventral surface of the cephalothorax between the posterior pereopods is also a feature of male specimens. Although noted by Cole (1958) and Campillo (1979a), both of whom provide good clear diagrams, this feature is curiously not mentioned elsewhere in the main literature. The female counterpart to the small protuberance found in males is a smooth curved ridge on the ventral surface between the posterior pereopods; no reference to this feature could be found in the literature. The location on the ventral surface of P. serratus of the male protuberance and female ridge is shown in Figures 4 and 5.

Figure 4: The ventral surface of a typical male P. serratus showing the small protuberance between the posterior pereopods

Figure 5: The ventral surface of a typical female P. serratus showing the smooth ridge between the posterior pereopods

9 1.2.3 Age Because crustacean growth is accomplished by successive moulting of the exoskeleton (ecdysis) no easily available record of the age of individual animals is left behind following a moult. Consequently, the age classification of small has traditionally been dealt with indirectly through the analysis of size-frequency distributions. This approach relies on identifying modes in the distribution, which can be equated with year classes or with recruitment cohorts. An individual sample may be analysed to detect a series of year classes, or several samples may be collected to follow the progression of modes over time (Hartnoll, 2001).

There is a range of conclusions with respect to the maximum age attained by the species. Sollaud (1916) considered the species to live for 5 or 6 years. Cole (1958) believed the species lived for 4 or 5 years, Forster (1951) thought it was 3 years, but argued that a definite conclusion of an age limit was impossible. Campillo (1979a) thought that the maximum age to be no more than 4 years, and Figueras (1986) thought the life span was 2 to 3 years. Fahy & Gleeson (1996) believed the species to have a 2 year life cycle, but that some individuals may exceed 24 months.

10 1.3 REPRODUCTION

Copulation takes place subsequent to the female moulting and involves the male extruding spermatophores from openings in the gonads located on the coxae between his posterior pereopods and depositing them on the sternum of the female between her posterior pereopods. A short time later, the female extrudes eggs from openings in her oviducts located on the coxae between the third pair of pereopods. As they are extruded the eggs pass over the spermatophores and are fertilized. The eggs are then passed backwards by the endopods of the first pleopods and attached by sticky cement to the setae of the endopods of pleopods 1 to 4 which form a brood chamber (Smaldon et al., 1993).

1.3.1 Spawning Females are thought to be capable of spawning at around 12 months of age (Campillo, 1979a). Those in their second year are capable of spawning twice in one year and larger females, probably in their third year, may spawn three times in a year (Forster, 1951; Campillo, 1979a). Considerable regional variation in the time and frequency of spawning and in the period of brooding has been observed in populations in north Wales (Cole, 1958), Plymouth (Forster, 1951), Roscoff-Garantec and the Bay of Biscay (Campillo, 1979a). Water temperature is thought to be the most influential factor in both the development of the ovaries and the incubation time of the eggs, with colder temperatures inhibiting both processes (Cole, 1958; Campillo, 1979a). The earliest time of year spawning occurred in a population studied in north Wales was from mid April (Cole, 1958). This was some three months later than that observed in the Plymouth population by Forster (1951). Both authors attribute this to lower winter water temperatures in north Wales. Conversely, the 2.5 to 3 months incubation period observed in the population from north Wales (Cole, 1958) was shorter than the 4 month average observed at Plymouth (Forster, 1951). This was because prawns in their second year at Plymouth spawned more than once which had the effect of extending the incubation period for their winter brood. However, some of the populations observed in north Wales did spawn during the winter months (i.e. for a second time) but it was not common and was thought to be limited to a small percentage of the largest females (Cole, 1958).

11 In recent years, the regional differences observed by Cole (1958) and Forster (1951) during the 1950s seem to have changed. It is now normal to find berried females throughout the winter months not only in the English Channel at Plymouth and Roscoff, but also around the coasts of (Fahy & Gleeson, 1996) and in north Wales (pers. ob., 2009). The increase in average sea temperatures recorded around the since the 1950s (Cannaby & Hüsrevoğlu, 2009) may have contributed to the recent growth of the Irish and Welsh prawn fisheries by facilitating an extended breeding season and subsequent growth in the size of prawn stocks.

1.3.2 Fecundity The reproductive capacity of caridean decapods is usually estimated with reference to egg production. Reports on the number of eggs produced by P. serratus vary considerably according to the size of the female. Sollaud (1923), stated that egg numbers produced by P. serratus range between 550 and 7,000. According to Forster (1951), the range of egg numbers produced by the smallest to largest prawn was between 1523 and 4282. Campillo (1979a) states that females will produce between 900 and 5000 eggs per laying according to their size, and a study of a population in northern Portugal found that the range was between 550 and 6100 (Felicio et al., 2002).

Extensive field and laboratory studies conducted in France showed general fecundity of P. serratus to be relatively low due to the large number of eggs which did not hatch (Campillo, 1979a). Consequently, assessments of fecundity purely in terms of egg production must be treated with caution and perhaps supplemented by other information such as, mean egg volume and/or egg mass volume. This approach has been used in estimates of early stage fecundity in decapod crustaceans (Reid & Corey, 1991), but no specific values for P. serratus could be found.

1.3.3 Larval development and dispersal The eggs of P. serratus hatch as zoea and go through a number of developmental stages until they metamorphose into post-larval juvenile prawns. Under laboratory conditions, as many as nine larval stages have been observed (Fincham, 1983), but, in wild populations, fewer stages are often found due to variable environmental conditions (Fincham & Figueras, 1986). During the early larval stages, moulting, growth and morphogenesis are synchronous and phenotypic variation is minimal (Fincham & Figueras, 1986). However, in later stages, morphological variation can become evident

12 and larvae with a similar moulting history may be quite different in size (Fincham & Figueras, 1986).

There is very little precise information regarding the dispersal and metamorphosis of larvae available with respect to British populations, but larval dispersal seems to follow a shoreward migration of berried females in the spring and, according to Forster (1951), metamorphosis appears to take place in the littoral zone. The actual rhythm of larval release is synchronised with the nocturnal/diurnal cycle, the lunar cycle, tidal amplitude and the time of high tide (Goncalves et al., 2003). As would be expected the combination of these variables differs from region to region, but most larval release is generally thought to be concentrated around nocturnal ebb tides (Goncalves et al., 2003). For example, a study of larval dispersal of P. serratus in the Mondego estuary in Portugal found that maximum larval emission occurred during nocturnal ebb tides with a low amplitude characteristic of the first quarter of the lunar cycle (Goncalves et al., 2003).

1.3.4 Size at sexual maturity Size at sexual maturity generally refers to the size of ovigerous females. With respect to P. serratus, the minimum size is often quoted in the literature, although there is not always agreement as to the parameter chosen to represent size. Examples include; 38mm from the rear of the orbit to the tip of the telson (Sollaud, 1923); 14.4mm carapace length (Cole, 1958); 60mm total length (Desbrosses, 1951); 5.5cm total length (Forster, 1959) and 25mm cephalothorax length (Lct1) (Campillo, 1979a). A more objective measure found in crustacean biology (e.g. Oh & Hartnoll, 1999, and Felicio et al., 2002) is to estimate the size at 50% maturity from a logistic curve fitted to a cumulative probability plot of the lengths of ovigerous females. This method was used (by Felicio et al., 2002) to estimate the carapace lengths at 50% of ovigerous females from a population of P. serratus in northern Portugal over a period of six months. However, it is curious that the size at sexual maturity quoted in the study is for total length (74.6mm from the tip of the rostrum to the tip of the telson) rather than carapace length.

13 1.4 EPIDEMIOLOGY

With the exception of Deroux et al. (1975), De Bhaldraithe (1972) and Azevedo et al. (2000) there is little literature devoted exclusively to the effect of named parasites on P. serratus. Although reference is made to specific organisms by authors such as Cole (1958) and Smaldon et al. (1993), descriptions of the symptoms of infections given by others such as Forster [J. R. M.] & Wickens (1972) are not linked to a clearly identified parasite. Having said this, there are four parasites mentioned in the literature which are known to infect P. serratus and these are outlined in Sections 1.4.1 to 1.4.4.

1.4.1 Bopyrus squillarum Bopyrus squillarum is a parasitic isopod crustacean which invades the branchial cavity of the host prawn and feeds on its body fluids after “piercing the body with its sharp mandible” (De Bhaldraithe, 1972). In the host prawn it causes “a distortion in the form and an obvious swelling on one side of the carapace” (Smaldon et al., 1993). This is evidently why the condition is sometimes known as “face ache” (Fish & Fish, 1996). The documented distribution B. squillarum did not extend to the full geographical range within which P. serratus is found. Of 4500 female and 1,600 male prawns trapped in Co. Galway in southern Ireland, infection rates were 4.5% and 8.9% respectfully (De Bhaldraithe, 1972). No sign of the parasite was found in the 12,000 specimens examined in north Wales, nor was it recorded in the Isle of Man (Cole, 1958). However, the parasite did occur regularly on P. serratus in various parts of Plymouth Sound, with fluctuating abundance during the same period (Marine Biological Association, 1957) and was considered common in the P. serratus population at Roscoff (Nouvel Van Rysselberge, 1937). Curiously, there is no mention of the parasite by Campillo (1979a, 1979b) whose extensive studies of P. serratus during the 1970s included Roscoff. B. squillarum is not thought to significantly affect the mortality of P. serratus because it is outlived by the host (De Bhaldraithe, 1972). There may, however, be some concern regarding the aesthetic quality of infected stock affecting its commercial value.

1.4.2 Indosporus octospora Indosporus octospora is a fungal parasite from the phylum Microsporidia which belongs to the family Thelohaniidae (WoRMS, 2009). It causes ultrastructural alterations in the muscle fibres of the host (Azevedo et al., 2000). Infected specimens can be distinguished from healthy specimens by the localized white zones in the muscle

14 of adult prawns (Azevedo et al., 2000). Microsporidia are generally considered to be significant pathogens and may cause parasitic castration of wild-stocks and reduce the market value of prawns with heavy infections (Bower, 1995). The samples examined by Azevedo et al. (2000) were from northern Brittany and the Portuguese Atlantic coast. No information regarding the infection of P. serratus in UK waters by I. octospora could be found.

1.4.3 Nectonema agile Nectonema agile is an endoparasite belonging to the phylum Nematomorpha (, 2000a). The larvae of this parasitic worm either penetrate the body wall of the host or are ingested as cysts and penetrate the gut wall. The young then enter the host’s haemocoel where development is completed (Ruppert & Barnes, 1996). The parasite absorbs nutrition from the host directly through its body wall and emerges as a free living adult worm after several weeks or months (Ruppert & Barnes, 1996). One record of infection of P. serratus by N. agile was found (Nouvel Van Rysselberge, 1937), but this was not from British waters. No further records or information on the specific effects of this parasite on P. serratus could be found.

1.4.4 Ascophrys rodor Ascophrys rodor is a member of the protozoan phylum Ciliaphora (Systema Naturae, 2000b). It is a common external parasite whose life cycle is adapted to the molting cycle of prawns. It feeds on the exoskeleton without penetrating the host’s tissues (Deroux et al., 1975). The infection manifests as brown spots/blisters on the exoskeleton and sometimes innumerable small white spots on the cuticle (especially the carapace) which becomes rough to the touch and tears easily. The infection can also extend into the brachial chambers and gills (Deroux et al., 1975). From studies of specimens reared in aquaculture the severity of the infection in terms of stock mortality at molting is related to low oxygen and elevated temperature and nutrient levels (Deroux et al., 1975). As such, the main concern for those exploiting wild fisheries with respect to this parasite (and others like it) is where the need arises for prolonged live storage and transportation of stock. This is not merely in terms of potential mortality, but how the aesthetic quality of infected stock may affect its commercial value. Visual signs of A. rodor were found in some samples collected for this study, but no definite identification was possible, nor was a systematic record kept of its occurrence.

15 2 THE WELSH PRAWN FISHERY

16 2.1 HISTORICAL CONTEXT & ECONOMIC IMPORTANCE

P. serratus has been commercially exploited using prawn trawls along the south coast of England and to a lesser extent along the Welsh coast up to the Menai Straight for many years, certainly since the early 20th Century (Cole, 1958). However, it was not until the 1970s, when lobster fishermen found the species appearing in their pots in sufficient numbers to interest them, that commercial potting for prawns started in Wales.

The 1990s saw the advent of live “vivier” transport systems and the Welsh fishery grew rapidly in response to a demand for live product in Spain, Portugal and France. What started as a small winter supplement to the incomes of some lobster and crab fishermen has become an increasingly important part of the annual incomes of Welsh inshore fishermen. A recent (unpublished) study of the Cardigan Bay fishery, found that prawn sales accounted for approximately 38% of the annual income of those vessels which fish for the species, and approximately 18% of the annual income of the Bay’s lobster fishing fleet (Huxley, 2008).

Demand for P. serratus as a high quality, high value meal component in the European hotel and restaurant sector has grown steadily during the early 21st Century, particularly from the Iberian Peninsula. Although much of this demand has been satisfied by the considerably larger prawn fishery of the Republic of Ireland, which has produced in excess of 200 tonnes annually since 1990 (Fahy et al., 2006), the Welsh fishery makes an important contribution. Because of the ongoing demand from Europe most of the prawns landed in Wales are exported (pers. ob.). Consequently, the Welsh prawn fishery is largely dependent on overseas markets for its survival.

In terms of the UK, the largest regional prawn fishery is in Wales. The number of vessels for which landings of P. serratus are recorded in Wales has increased from 56 in 2006 to 63 in 2009 (MMO, 2011). It was calculated from data obtained from the MMO statistics unit that the Welsh fishery accounts for an average of 90.2% by weight and 94.2% by value of all P. serratus landed in mainland UK.

Summaries of the annual landings/sales of the species for mainland UK for the past four years are shown in Figures 6 and 7.

17 QUANTITY OF Palaemon serratus LANDED IN MAINLAND UK: 2006 to 2009

40

35

30

25

20

15 Quantity (t) Quantity 10

5

0

-5 2006 2007 2008 2009

WALES 23.95 33.97 28.85 25.86 ENGLA ND 3.46 2.42 4.10 1.63 SCOTLAND 0.01 0.12 0.04 0.44 Year

Figure 6: Annual quantity of P. serratus landed in UK from 2006 to 2009 (Data source; MMO statistics unit, 2010)

FIRST SALE VALUE OF Palaemon serratus LANDED IN MAINLAND UK: 2006 to 2009

650

550

450

350

Value (£k) 250

150

50

-50 2006 2007 2008 2009

WALES 403.98 571.31 489.77 500.64 ENGLA ND 38.81 25.31 38.36 8.83 SCOTLAND 0.00 2.30 0.77 7.20 Year

Figure 7: Annual value of P. serratus landed in UK from 2006 to 2009(Data source; MMO statistics unit, 2010)

18 2.2 MANAGEMENT

Up until April 2010, the responsibility for inshore fisheries regulation and enforcement in Welsh waters fell to the two UK Sea Fisheries Committees which had Welsh coastline within their boundaries. In April 2010, the South Wales Sea Fisheries Committee (SWSFC) and the Welsh part of the North West and North Wales Sea Fisheries Committee (NWNWSFC) were absorbed by the Welsh Assembly Government (WAG) Fisheries Unit. The transfer of the paid staff from the Sea Fisheries Committees to WAG ensured a degree of continuity in that much of day-to-day enforcement responsibilities remained unchanged. There is now one management organisation with responsibility for Welsh marine fisheries with legal competence “out to the median line with the Republic of Ireland to the West, to the Isle of Man in the north, and to a small area in the southwest” (WAG, 2010). Subsequent to these changes, a Stakeholder Advisory Group (SAG) was formed to “design this new model for ensuring local and national input in the future” (WAG, 2010). As of January 2011, the new structure pertaining to the management of marine fisheries in Wales (aka, the “Stakeholder Engagement Model”) has been in place. This is shown in Figure 8.

Figure 8: Schematic diagram of the Stakeholder Engagement Model for the management of Welsh marine fisheries (WAG, 2011).

19 2.2.1 Structure of the WMFAG The WMFAG consists of individuals and groups with both statutory and non-statutory responsibility to advise on fisheries management in Wales, with the chair appointed and funded by WAG. This “in house” model contrasts strongly with the devolved management structure in place in England (since April 2011) which consists of Inshore Fisheries and Conservation Authorities (IFCAs) based on a revised and strengthened Sea Fisheries Committee model.

The provisional membership structure of the WMFAG is shown in Table 2.

Table 2: Structure of the WMFAG Interest Represented by Chair Independent WAG WAG Fisheries & Marine Branch (X3) Environmental – statutory CCW Environmental bodies – non- Wales Environment Link statutory Sustainable Development Wales Coastal Maritime Partnership Water Quality/Fisheries Environment Agency Wales Management Local Authorities Wales Local Government Association Recreational Anglers Welsh Federation of Sea Anglers Aquaculture Welsh Association of Aquaculture Producers Welsh Fishermen’s Associations Welsh Fishermen’s Associations (X2) IFG North IFG Chair North IFG Mid IFG Chair Mid IFG South IFG Chair South (WAG, 2011)

20 2.2.2 Structure of the regional IFGs Each IFG consists of regional stakeholders with an interest in fisheries, either directly or indirectly. The chair is elected from within the group and although IFGs do not receive any direct funding, the expenses of the chair are covered by WAG. Being new bodies their final constitution has yet to be fully decided, but the proposed membership structure is outlined in Table 3.

Table 3: Structure of regional IFGs 1 Chair 11 Boat Angler 2 WAG Fisheries 12 Charter vessels 3 WAG recognised local 13 Bait/tackle retailer Fishermen’s Association 4 Shellfish (hand gatherer) 14 Science 5 Shellfish (cultivated) 15 Local environmental concerns 6 Towed gear 16 Local environmental concerns 7 Static gear 17 Harbour masters/Maritime officer 8 Commercial netsman 18 Water quality/estuaries 9 Processor 19 Local Authorities 10 Shore angler 20 Land owners (WAG, 2011)

The first meetings of the IFGs and the WMFAG were held in the spring of 2011, so it is too soon to comment on how fit for purpose the new management structure is. However, it is clear that the effectiveness of the new structure is crucial to the success of the management of fisheries in Wales, particularly the traditional inshore and coastal fisheries.

21 2.2.3 Regulation There are no Statutory Instruments or Byelaws directly relating to the commercial exploitation of P. serratus in Wales (or the UK). The only legislation applicable to the species in Wales is Byelaw 30, confirmed by the NWNWSFC in 2007 (NWNWSFC, 2007) to regulate the non-commercial (i.e. recreational) exploitation of shellfish species (see Appendix VII). The Welsh prawn fishery is, therefore, almost entirely unregulated with current management being a combination of market driven practices, initiatives instigated by fishermen’s associations, and loose voluntary agreements between fishermen.

Until the Registration of Fish Buyers and Sellers and Designation of Fish Auction Sites Regulations (NAW, 2006) were passed in June 2006 there was no systematic record of the quantity of P. serratus landed. Consequently, much of the commercial catch of P. serratus in Wales is now recorded. However, it was noted in a recent (unpublished) study of the Cardigan Bay fishery that official catch records still underestimate the actual quantity of the species landed (Huxley, 2008).

2.2.4 Market driven practices The market demand for live prawns of a certain minimum size and quality has encouraged fishermen meet minimum product requirements. Most prawn fishermen currently either grade their catch by riddling it at sea, or leave it to merchants to grade with a mechanical riddle on the quayside (pers. ob., 2010). A riddle allows prawns under a certain carapace width (approximately 10mm) to pass through it, and retains the larger prawns. The smaller prawns which pass through the riddle are discarded either at sea or on the quayside as they are of no commercial value, and therefore constitute a loss to the fishery (pers. ob., 2010).

Some fishermen have adopted more selective fishing practices in the form of pots with a larger mesh size to meet market demand (pers. ob., 2010). Until recently, most commercially-available prawn pots had a 6mm or 9mm mesh as standard (a typical prawn pot is shown in Figure 10a, Section 3.2.3 ). The adoption of a larger mesh size (typically 14mm), either throughout the pot, in the end entrance cones, or in a dedicated escape panel, is intended to select for larger prawns, thereby, obviating the need for riddling.

22 2.2.5 Practical limitations and problems Fishing effort is limited by the distance fisherman can travel to their fishing grounds, the handling capacity of their vessel in terms of how many pots can be fished, and the cost of fuel. Being a predominantly winter activity, prawn fishing is also subject to limitations imposed by adverse weather conditions. The smaller vessels currently used by the majority of pot fishermen are subject to greater limitation than larger vessels with respect to distance, handling capacity and weather. The lack of port/quayside facilities around the Welsh coast for washing and holding live prior to its onward transport can also be a limiting factor. However, some new facilities, such as the provision of cold storage at Aberystwyth harbour, have been made possible thanks to funding provided by the WAG Interim Aid Programme to the industry.

Other problems flagged up by fishermen (pers. com.) include;  Unfairly holding ground  Loss of gear due to other fishing practices 

Unfairly holding ground By failing to remove pots when not actively fishing for prawns (e.g. during June, July and August), some fishermen unfairly hold on to ground which would otherwise be open to their competitors. This is definitely an area of potential conflict between fishermen.

Loss of gear due to other fishing practices Large-scale scallop dredging in inshore waters has been responsible for the loss of pots, buoys, anchors and ropes. The spectre of potential losses of gear associated with the controversial and poorly policed scallop fishery has imposed both temporal and geographical limits on many prawn fishermen in Wales, particularly those fishing in Cardigan Bay. An attempt to address these concerns with new legislation has recently been made by WAG in the form of The Scallop Fishing (Wales) (No.2) Order 2010 (WAG, 2010a). Whether long-term damage caused to the benthic substrata by scallop dredging, particularly habitat which may be critical for P. serratus and other commercial species, can be mitigated by the 2010 Scallop Fishing Order remains to be seen.

23 Overfishing The exploitation of P. serratus using pots is highly unlikely to reduce spawning biomass to levels below that required to maintain recruitment into the stock. However, fishing does exaggerate natural fluctuations in stock levels. From an economic perspective, overfishing occurs when the level of fishing effort (e.g. the number of pots deployed) results in decreasing yield per unit effort. Unless checked, overfishing could condemn the fishery to a boom-bust scenario and all the economic uncertainty it entails for both the fishermen and the merchants. If fishermen and merchants are unable to plan for a reasonably predictable catch then it becomes difficult for them to sustain their businesses and for the market for their product to develop to its full potential. A precautionary approach to the management of the fishery, backed by legislation, is, therefore, seen by many fishermen and their associations (pers. comm., 2010) as the best way to ensure the long-term economic sustainability of the fishery.

2.2.6 Future management; regulatory options A selection of options for regulating the fishery is outlined in Table 4. The selection of these particular options resulted from consultations between the author, prawn fishermen, their associations (e.g. CBFA) and officers from the Welsh Marine Fisheries Agency (WMFA) over the past four years.

Table 4: Summary of potential options for regulating the Welsh prawn fishery

Option Description Minimum landing The prohibition of landing prawns under a certain size (e.g. size 10mm carapace width). Minimum pot The prohibition on the use of any pots in the fishery with mesh mesh size size smaller than the specified minimum (e.g. 14mm).

Riddling Compulsory on-board riddling of catch using a standard size riddle (e.g.10mm). Minimum mesh The prohibition of the use of store trays in keep cages with a size in keep cage mesh size smaller than a specified minimum (e.g. 10mm). store trays Closed season The prohibition of fishing for and landing of the species during and gear removal certain periods of the year (probably during mid summer); to include removal of pots from the water during the closed season. Limit on the A limit on the number of pots fished within defined areas of the number of pots fishery, and/or the number of pots/vessel fishing defined areas within the fishery. Maximum quantity A limit to the annual quantity of prawns landed in the fishery as a whole by imposing a limit or total allowable catch (i.e. a quota) on individual vessels.

24 The first four options outlined in Table 4 are concerned with size selectivity and the other options with effort limitation. Each size selectivity option represents intervention at different stages of the fishing process to achieve a specific target size at which prawns are landed. Each effort limitation option represents a different way of reducing fishing pressure in order to protect the stock. The main pros and cons of the various options are briefly outlined in turn.

Minimum landing size A compulsory minimum landing size for P. serratus appears to be an attractive option because it is relatively easy to define unambiguously and is also consistent with what the market already demands. Unfortunately, the prohibition of landing prawns under a certain size (e.g. 10mm carapace width) will not per se ensure more selective fishing practices, only that the catch is sorted before it is landed and sold. The effectiveness that such a prohibition would have in reducing discard is therefore highly questionable. There are also questions regarding how a minimum landing size would be policed and what level of resources would be required for enforcement. A definition of size may be unambiguous, but translating it into practice is unlikely to be so. Because of the small size of the species and the relatively large number of individuals in a haul, questions about the percentage of a catch that could be allowed to be “undersized” would have to be addressed. Attempting this is likely to result in excessive complexity and to introduce ambiguity.

Riddling Compulsory on-board riddling of the catch using a standard size riddle (e.g.10mm) is also a questionable option for regulating the fishery because it will not ensure more selective fishing practices. In fact, making riddling compulsory would merely penalise the fishermen who have ceased to riddle because they have adopted more selective practices such as the use of larger mesh pots. If these fishermen are forced to riddle their catch, then the time savings and quality improvements gained by using a more selective pot mesh will be negated by the extra handling. There is also no hard evidence that the prawns discarded after riddling survive for sufficient time to re-join the population. Furthermore, even some of the fishermen who gave their qualified support for riddling in a recent study of the Cardigan Bay fishery (Huxley, 2008) also expressed the view that there was probably no need for riddling if a larger mesh size was used in pots.

25 Minimum mesh size in keep cage store trays Many fishermen store their daily haul in cages at sea in order to accumulate a reasonable quantity prior to landing their catch for onward transport by the merchants. The prawns are kept in plastic mesh trays within the store cages to ensure the free circulation of water. This keeps the catch in good condition and prevents any build-up of waste material; it also allows prawns below a certain size to escape through the mesh. Some fishermen use the mesh trays in store cages as a means of grading their catch in preference to riddling. In principle, the enforcement of a compulsory minimum mesh size (e.g. 10mm) in the store cage trays in order to allow the escape of small prawns would be relatively straightforward; however, this option has one of the main disadvantages associated with riddling. Although grading the catch in store cages is passive rather than active as it is with riddling, there is no evidence that the small prawns which manage to escape actually survive. In fact it is far more likely that they are subject to opportunist predation upon escape.

Limit on the number of pots A limit on the number of pots fished within defined areas of the fishery, and/or the number of pots/vessel fishing defined areas within the fishery would seem to have merit as a management option. Indeed, of all the regulatory options examined in a recent study of the Cardigan Bay fishery this was the most popular, with over 80% of fishermen expressing their support (Huxley, 2008). According to many of the fishermen interviewed (pers. comm.), the steady increase in the number of pots being deployed, especially by the larger vessels, has already resulted in a falling catch per unit effort (CPU) for all. A pot limit of some sort may therefore offer a way of arresting the trend of deploying more and more pots for the same or less saleable catch. It may also go some way toward avoiding conflict among fishermen because it would automatically limit the amount of ground that could be held by any particular vessel during the prawn season. Enforcement would also be relatively straightforward if pots were clearly identified and numbered. The main problem is how to instigate such a regulation. Should it be done using some sort of permit scheme, as a condition of the vessel licence or as entirely separate legislation? Further research is obviously required to explore fully the scope for action on this particular option.

26 Maximum landing quantity A limit the annual quantity of prawns landed in the fishery as a whole by imposing a limit or total allowable catch (i.e. a quota) on individual vessels should only be considered if evidence were forthcoming that the stock is being over-exploited to the point at which current level of fishing effort is unsustainable and the biological integrity of the stock is threatened. While the level of fishing effort may be leading to an (economically) unsustainable fishery, there is no evidence that the biological integrity of the stock is under threat from pot fishing.

Minimum pot mesh size A minimum mesh size in pots is a measure designed to reduce the proportion of discard in the catch (i.e. prawns of no commercial value). Ideally, a minimum pot mesh size should achieve this aim while not having a negative impact on the commercial value of the catch. In a recent (unpublished) study of the Cardigan Bay fishery just over 60% of the fishermen interviewed indicated that they would be supportive of a 14mm mesh as the minimum (Huxley, 2008). However, many fishermen were concerned over the practicality and cost of changing the mesh ends in existing pots to a larger size. This option is discussed in more detail in Section 5.5 in relation to the results of a re-analysis of data relating to a pot mesh trial previously conducted by the Cardigan Bay Fisherman’s Association (CBFA) in Cardigan Bay.

Closed season The prohibition of fishing for and landing of the species during certain periods of the year is a measure intended to protect the stock during biologically-critical periods such as, for example, the period of maximum egg carriage. Theoretically, a closed season should help stabilise or even increase the size of a population and thereby ensure the maximum yield per recruit for the fishery. However, many fishermen (pers. comm.) think the breeding season is subject to a significant degree of variability around the Welsh coast. Consequently, finding an equitable time period for a closed season is seen by many as being problematic. This option is discussed in more detail in Section 5.6 in relation to the results of an analysis of recent catch data for the Welsh prawn fishery.

27 3 AIMS & METHODS

28 3.1 AIMS

The primary aim of the project was to test the hypothesis that there were morphologically or structurally distinct groups of P. serratus that could be regarded as separate populations of the species around the Welsh coast. The secondary aim was to examine two of the potential options for regulating the fishery; a minimum pot mesh size and a closed season.

With respect to the first aim, it was intended to collect samples from a number of locations around the Welsh coast. The samples were then to be measured and the data analysed to determine if there were any notable sexual, seasonal and regional variations with respect to; size, morphology, rostral dentition, the size at sexual maturity, the sex ratio, the proportion of ovigerous females, fecundity, and the proportion of saleable biomass. The parameters measured in order to analyse variations in size were carapace length (mm) and wet weight (g). The other morphological variations analysed were; the ratio between carapace width and carapace length, the ratio between carapace length and rostral length, and the ratio between carapace length and wet weight. Differences in the mean number of dorsal and ventral teeth on the rostra of selected samples were also analysed. This was because it was considered possible that variations in rostral dentition might reflect sexual, seasonal and/or regional differences in the population. This idea was inspired by a study of the closely-related species Palaemonetes varians in which evidence of a latitudinal difference in the number of dorsal teeth on the rostrum was found (De Grave, 1999).

With respect to the second aim it was intended to re-examine a selection of data collected by Ben Fothergill of (CBFA) for a previous study on the effect of different pot mesh sizes on prawn catch (Fothergill, 2006). This was done with a view to informing a discussion on pot mesh size. The particular focus of the discussion was the utility of adopting a 14mm pot mesh throughout the Welsh fishery. It was also intended to review and compare official catch data for P. serratus and H. gammarus with a view to determining if there was a particularly favourable period for a closed season for prawn fishing.

The selection of H. gammarus for the comparison was because virtually all prawn fishermen are members of a sub-set belonging to a larger set comprising lobster

29 fishermen. Most pot fishing vessels concentrate on lobster (and crab) fishing during the summer and those which also fish for prawns tend to do so during the winter months. By comparing official catch data for P. serratus and H. gammarus the question of whether a temporal window of opportunity for a closed season already existed could be addressed; namely whether there was a period during which the incomes of pot fishermen would not be adversely affected because they were not reliant on the capture and sale of prawns.

30 3.2 SAMPLING

Studies of morphological variation and population dynamics ideally require examination of specific samples collected regularly over an appropriate time cycle, preferably weekly over an entire annual cycle. However, because the resources available to the project were limited to the sampling equipment (pots etc) and the professional fishermen who volunteered to deploy the equipment and collect the samples, this was not possible.

The selection of fishermen to collect samples was done by officers from the CBFA and the Welsh Federation of Fishermen’s Associations (WFFA). Once selected and supplied with the equipment to collect the samples, the fishermen were given a sampling protocol to follow and briefed by the author.

Originally, five volunteer fishermen from a selection of locations, deemed to provide sufficient coverage of the Welsh coastline to fulfil the primary aim of the project, were found. However, shortly after commencement one of these had to withdraw due to ill health and so sampling was confined to four locations (see Figure 9). Although the area sampled was smaller than originally intended, it was felt by the project supervisor, Dr John Fish, that it was still sufficient to fulfil the primary aim of the project.

3.2.1 Sampling frequency A combination of factors, including the priorities of the fishermen and the vagaries of the weather, affected the frequency with which samples could be collected. Consequently, the sampling frequency and deployment period (soak time) of the pots at each sample location and between locations were variable. Because it was not possible to collect regular weekly samples at each of the four locations, it was decided that the samples collected should be grouped into monthly categories prior to analysis. This entailed pooling some of the samples collected from Aberystwyth in February and March and from Morfa Nefyn in April. The frequency with which the pots used for sampling were hauled, and their soak times is summarised in Table 5.

31 Table 5: Summary of haul dates and soak-times of prawn pots

SAMPLING FREQUENCY LOCATION HAUL DATE SOAK TIME (DAYS) 14/12/08 7 NEWQUAY 13/01/09 30

21/02/09 39 18/03/09 25 ABERYSTWYTH 04/02/2009 * ? 17/02/2009 * 13 06/03/2009 ** 17 16/03/2009 ** 10 13/04/09 13 21/05/09 38 MORFA NEFYN 24/02/09 6 04/03/09 8 03/04/2009 *** 3 12/04/2009 *** 9 02/05/09 20 05/10/09 7 AMLWCH 19/02/09 7 01/03/09 10 (The asterisks indicate which samples were pooled prior to analysis)

32 3.2.2 Location of sample ports The location of the ports where samples were landed is shown in Figure 9.

Figure 9: Location of the ports adjacent to where samples were collected

The exact positions of the sample locations (i.e. latitudes and longitudes) have been withheld due to commercial sensitivity, but the approximate depths are given in Table 6.

Table 6: Approximate depths of sample locations

APPROXIMATE DEPTHS OF SAMPLE LOCATIONS LOCATION NEWQUAY ABERYSTWYTH MORFA NEFYN AMLWCH DEPTH (m) 15 12 7 14

Depths are approximate because they were derived from the nearest Admiralty chart sounding to the lat/long positions provided by the volunteer fishermen.

33 3.2.3 Sampling equipment Each volunteer fisherman was provided with a pot rig consisting of the following:  10 standard “Roscoff” prawn pots fitted with 9mm end cone mesh.  150m of 14mm leaded polypropylene rope.  70m of 12mm plain polypropylene rope.  Two anchors & two buoys. The fishermen were also provided with:  30cm X 40cm plastic bags for each pot sample.  100cm X 50cm plastic bags for each sample set.  Permanent marker pens to label samples.

The basic set-up of the sampling rig is shown in Figure 10a.

Figure 10a: Schematic diagram of typical sampling rig

The spacing between each pot attachment dropper was approximately 12m and each dropper was approximately 2m long. The exact length between the buoys and anchors varied according to the depth and type of ground fished and was decided by the fishermen.

34 Figure 10b: Typical Roscoff style prawn pot used in the sampling rigs

3.2.4 Sample collection The pots used for sampling were baited with mackerel or scad depending on what was available. The pots were then taken by boat to a set location chosen by the fishermen and deployed for a period of days prior to being hauled. Once hauled, the contents of each pot were emptied into a tray and any bye-catch likely to damage the sample (e.g. crabs/dogfish) or of species for which a minimum size applied (e.g. common lobster) removed and discarded. The remaining contents (i.e. all prawn, etc) of each individual pot were then placed in individual plastic bags with as much care as possible to avoid damage to the contents. The ten bags from each haul were then put into a single bag which was labelled with a permanent marker pen. In some cases, due to time constraints, the contents from all ten pots were placed in a single bag and labelled rather than in separate bags.

3.2.5 Storage The labelled plastic bags containing the contents of each sample haul were frozen on return to port by the volunteer fishermen. The samples were stored locally until collection and transfer to the University deep freeze, where they were stored until required for measurement.

3.2.6 Preservation Subsequent to thawing, identification and measurement some individual prawns were either fixed in 4% Formalin buffered in sea water and stored in 70% Ethanol, or re- frozen, depending on the intended use.

35 3.3 IDENTIFICATION & MEASUREMENT

The parameters measured for the study were:

 Sex  Wet weight (g)  Carapace length (mm)  Carapace width (mm)  Rostral length (mm)  Number of dorsal and ventral teeth on the rostrum  Egg number  Egg volume (mm3)

The following descriptions of the various processes leading up to and including the measurement of samples are given in the order they were performed in the laboratory.

3.3.1 Weight Frozen samples were thawed in sea water at room temperature and individual prawns removed and placed on a tissue paper for 5 minutes to absorb excess moisture prior to weighing. The wet weight to the nearest 0.001g was measured using a Fisherbrand PF- 153 digital balance. Only intact specimens were weighed.

3.3.2 Determination of species and sex When required, the keys in Coastal Shrimps and Prawns (Smaldon et al., 1993) or the Handbook of the Marine Fauna of North-west Europe (Hayward & Ryland, 2007) were used to determine species. The overwhelming majority of the samples consisted entirely of P. serratus, although on very rare occasions Pandalus montagui and were also found. The occurrence of P. montagui was limited to three individuals in the December sample from Newquay and three individuals in the March samples from Aberystwyth. The occurrence of C. crangon was limited to two individuals in the February sample from Morfa Nefyn and one individual in the April sample from Morfa Nefyn. All nine individuals were excluded from the analyses as their extremely small number was considered unlikely to have any effect on the results.

36 Unless specimens were ovigerous (and hence female) determining their sex was done by examination of the inner endopodite on the second pleopod for the presence/absence of the appendix masculina. A Leica CME stereoscopic compound microscope was used for this purpose. Alternatively, the presence of a small protuberance in males, or a smooth ridge in females, on the ventral surface of the cephalothorax between the posterior pereopods was used to determine sex. Details of these anatomical features can be found in Section 1.2.2.

3.3.3 Linear measurements

Figure 11: The cephalothorax of a typical female P. serratus (The superimposed lines indicate the line of measurement of carapace and rostral length.)

Carapace length (CL) was measured from the posterior margin of the orbit to the mid- dorsal posterior edge of the carapace. The length of the cephalothorax (Lct 1) was measured from the tip of the rostrum to the mid dorsal posterior edge of the carapace (see Figure 11 above). The length of the rostrum (RL) was calculated by subtracting carapace length from the length of the cephalothorax (i.e. RL = Lct 1 - CL). Carapace width (CW) was measured at the widest point 90° to the longitudinal axis of the carapace. All of the above were measured to the nearest 0.01mm using digital vernier

37 callipers. Carapace length and width were measured for all samples, but specimens with damaged rostra were excluded from the measurement of the cephalothorax.

3.3.4 Rostral teeth The numbers of dorsal and ventral teeth on the rostrum were counted with the aid of a three diopter 18w magnifying lamp and probe.

3.3.5 Egg number Females of a range of sizes were selected for egg counting and stored in 70% ethanol subsequent to being weighed and measured. After removing a preserved specimen from the ethanol the egg mass was detached from the prawn by cutting longitudinally in a posterior direction through the pleura and pleopods with scissors. The detached egg mass and attached severed appendages were placed in a petri dish filled with sea water. The pleopods and pleura were carefully removed from the egg mass using a probe and forceps. A sub-sample of approximately 20 eggs was then removed for measurement of egg volume. The remaining egg mass was spread evenly in a petri dish and divided into four even fractions using two glass slides. One quarter fraction of each egg mass was then counted using a Zeiss Stemi SV6 stereoscopic dissection microscope. The resulting number was multiplied by four and added to the number taken for the sub-sample to give an estimate of the total number of eggs for that female. Manual counts of a small sub-sample of five egg masses found an average error of 2.1% in the estimated counts. Although this represented a slight overestimate of the number of eggs the results were still considered reasonable. A Table of the error check results can be found in Appendix XIV.

3.3.6 Egg volume Eggs from the sub-sample were placed on a glass slide with a little seawater to prevent dehydration. The long and short axis of each intact egg in the sub-sample was measured using an eyepiece graticule in a stereoscopic compound microscope at a magnification of 100×. Individual egg volume (EV) was calculated using the formula EV = π lh2/6, (after Odinetz et. al., 1996) where l and h are, respectively, the long and short axes of the ellipsoidal egg. Mean egg volume was calculated by dividing the sum of the individual egg volumes by the number of eggs measured.

38 All eggs counted and measured were at an early stage of development. These, stage 1 eggs (after Guerao & Ribera, 2000) were characterised by an even opacity with the vitellus occupying all or most of the egg volume and the absence of pigmented eyes.

39 3.4 STATISTICAL ANALYSIS

3.4.1 Population structure Two aspects of the population structure were considered; the sex ratio (including the proportion of ovigerous females), and the number of age classes present in each sample population.

Sex ratio The relative proportions of male, female and ovigerous female prawns in the catch samples were calculated as percentages of the total number of prawns in each sample, and as percentages of the estimated total weight of each sample. This was done to allow both numerical and volumetric comparison between sample populations.

Age The irregular sampling frequency, the limited time period which the samples covered, and highly variable sample numbers made attempting an analysis of the age structure of the sample populations difficult, and possibly inadvisable. Nevertheless, an indication of the age structure of the sample populations was gained by analysis of the data as described below.

The number of potential age classes present in the sample populations was examined indirectly through the analysis of size-frequency distributions. Carapace length was chosen as the size parameter for the analyses. The analyses were undertaken using the Mixture Analysis option in the statistical software PAST 2.03 (Hammer et al., 2001). This method was selected because it can be used to study differences between size classes, when no independent information about group membership is available (Hammer et al., 2001).

The selection of the best option in terms of the number of groups present in each sample was done on the basis of the distribution fit with the least negative log likelihood value and the lowest Akiake Information Criterion (AIC) of the alternatives (Hammer et al., 2001). The number of groups present was equated with possible age cohorts.

40 3.4.2 Morphology The parameters analysed in the examination of morphology were;  Carapace length  Wet weight  Carapace width/carapace length  Carapace length/rostral length  Carapace length/wet weight  The number of dorsal teeth on the rostrum  The number of ventral teeth on the rostrum

In order to ascertain the degree of linearity in the relationship between each set of variables, trend lines were fitted to scatter plots of the raw data. In the case of the relationship between carapace width and carapace length, least squares regression fits were adequate to describe the relationship between variables. However, the relationships between carapace length and rostral length and between carapace length and wet weight were found to be curvilinear, with power trendlines producing the best fits to the data. Scatter plots of the log-transformed data were, therefore, produced in order to improve linearity. In both cases it was found that reduced major axis regression fits best described the relationship between variables.

The ratios between each pair of variables were analysed by non-orthogonal ANOVA in order to determine if there were any sexual, seasonal or regional differences in the relationships. The carapace lengths, wet weights, and the numbers of dorsal and ventral teeth on the rostrum were also analysed by non-orthogonal ANOVA. In the cases of the ratio between carapace length and rostral length, the ratio between carapace length and wet weight, and wet weight, the data were log-transformed (log10) prior to analysis to minimise variance heterogeneity.

The non-orthogonal ANOVA software used for the analyses was written by Dr David Causton (Causton, unpublished). Dr Causton advised the use of this particular software because it accounted for the often widely varying numerical size of the groups being compared in the analyses by employing a weighted means approach to the analysis of variance. All analyses were run on the University mainframe computer. When significant results were found post-hoc testing was done using Tukey’s pairwise test in Minitab 14.

41 With the exception of rostral dentition, all analyses were undertaken on data grouped as follows: All four locations from February and March, Aberystwyth and Morfa Nefyn from February to May, Newquay from December to March, and Morfa Nefyn from February to May plus October. The ANOVA of rostral dentition were undertaken on data from all four locations collected in February and March, and on data from Newquay collected between December and March. In order to rule out that size affected the number of teeth on the rostra analyses of covariance (ANCOVA) using PAST 2.03 (Hammer et al., 2001), with carapace length as the covariate, were used post-hoc to analyse variations in the mean number of teeth. The results of the ANCOVA are given in Appendix XIIIii.

3.4.3 Size at sexual maturity

Size at sexual maturity was determined by the carapace length of 50 % (CL50) of ovigerous females in the sample populations. In order to calculate the CL50 values each set of data was ranked according to size and a cumulative percentage distribution calculated. The paired data were then used to produce scatter plots to which logistic curves were fitted using the equation y = a/ (1 + be-cx). This follows the approach used on caridean prawns by Oh & Hartnoll (1999) and Felicio et al. (2002).

The “logistic model” option in the statistical software PAST 2.03 (Hammer et al., 2001) was used to calculate the parameter values for the logistic curves and bootstrapped confidence intervals. It was found that the “Levenberg-Marquardt nonlinear optimisation” option in PAST produced the best fitting curves and so this was selected for all logistic fits. The numerical output from PAST was used to re-plot the logistic curves in the dedicated graphing software Graph 4.3 (Johansen, 2009), and the CL50 values were then read from the resulting graphs.

Unless otherwise stated, locational and seasonal variations in the mean carapace lengths of ovigerous females were analysed using Dr. Causton’s non-orthogonal ANOVA software.

3.4.4 Fecundity, egg number, egg volume and carapace length Because of insufficient sample numbers to perform separate analyses for each month, the egg number and volume data from February and March were pooled prior to analysis.

42 The relationship between egg number and carapace length for each sample population was analysed using Spearman's rank-order correlation in the statistical software PAST 2.03 (Hammer et al., 2001). The same approach was used to analyse the relationship between carapace length and egg volume for each sample population. The significance of the correlations was determined with reference to Tables containing critical values for Spearman’s rs.

An analysis of covariance (ANCOVA) using PAST 2.03 (Hammer et al., 2001) was used to analyse variations in the number of eggs between sample locations with carapace length as the covariate. This was done to account for the effect of length on egg number. Variations in the egg volume between sample locations were analysed using a one–way ANOVA in Minitab 14. The egg volume data were log transformed

(log10) prior to analysis to minimise variance heterogeneity. When significant results were found post hoc testing was done using Tukey’s pairwise test in Minitab 14.

3.4.5 Estimates of total biomass of the samples The wet weight of 1789 individual prawns was recorded. This represented 62% of the 2902 prawns measured in total. Estimates of the “missing” 38% wet weight values were calculated using the multiple regression option in Microsoft Excel. Carapace length (x1) and carapace width (x2) were selected as the independent variables and wet weight (y) was the dependent variable in the equation: y = a + bx1 + cx2 (where a = intercept, and b and c = the two regression coefficients).

Because the relationship between length and mass is allometric (i.e. curvilinear), all data were log-transformed prior to doing the regressions. Separate calculations were performed for each sex in each sample and the resulting log values back-transformed. Estimates of the total biomass for each catch sample were then calculated by adding the known wet weight values to the “missing” values estimated from the regression equations. The detailed estimates of the total biomass for each sample can be found in Appendix III, and the regression coefficients can be found in Appendix VI.

43 3.4.6 Saleable proportion of catch samples The riddles used by fishermen and merchants to grade prawns for sale have a 10mm spacing. The widest part of a prawn is its carapace, therefore catch samples were split according to a carapace width of 10mm. Prawns ≥10mm carapace width were considered saleable. Those with a carapace width <10mm were considered to comprise the non-saleable proportion of the samples (i.e. discard). The relative proportions of saleable to non-saleable (male and female) prawns in each catch sample were calculated as percentages of the total number of prawns in each sample, and as percentages of the estimated total wet weight of each sample.

3.4.7 Minimum carapace length of saleable prawns The estimated minimum carapace length of saleable prawns was calculated using the least squares regression equations describing the relationship between carapace width and carapace length. A separate calculation was done for each sex. This was done so the size of saleable prawns of each sex could be expressed in terms of carapace length.

3.4.8 Pot mesh size Data collected between February and May 2006 near Aberystwyth for a study of the effect of a series of pot mesh sizes on catch (Fothergill, 2006) were obtained from the CBFA. From these data the carapace widths and numbers of prawns captured by the 9mm and 14mm mesh pots were selected for analyses. The data from all four months were pooled prior to analysis.

The total numbers of prawns captured by the 9mm and 14mm mesh pots was summarised, and the relative proportions of saleable to non-saleable prawns were expressed as percentages of the total number of prawns caught. This was done to aid comparison with the proportions of saleable and non-saleable prawns found by the current study.

Variations in the number of prawns caught/pot with respect to the 9mm and 14mm mesh size, and the split between the saleable and non-saleable portions of the catch, were analysed with non-orthogonal ANOVA. Variations in the carapace widths of prawns caught with respect to the 9mm and 14mm mesh size, and the split between the saleable and non-saleable portions of the catch were also analysed with non-orthogonal

44 ANOVA. When significant results were found by the ANOVA post hoc testing was done using Tukey’s pairwise test in Minitab 14.

The saleable and non-saleable prawns caught by each mesh size were determined by splitting the data at 10mm carapace width. Following the approach outlined in Section 3.4.6, prawns with a carapace width ≥10mm were regarded as saleable, and those with a carapace width <10mm were regarded as non-saleable. The main difference in the treatment of these data was that it was not possible to include sex in the analyses as this had not been recorded in the CBFA study.

The mean and minimum carapace length of prawns captured by the two mesh sizes was estimated from the known mean and minimum carapace widths using the regression equation describing the general relationship between carapace width and carapace length of both sexes from this study (see Section 4.2.1). This was done to assess the effect of the two mesh sizes on the number of sexually mature prawns captured.

Calculation of these estimates assumed that the general relationship between the carapace width and carapace length of the sample populations from the pot mesh trial was not different to that of the population sampled for this study.

3.4.9 Seasonal trends in catch records for P. serratus and H. gammarus Catch records for P. serratus and H. gammarus were obtained from the MMO Fisheries Statistics Unit via requests made to the Senior Fishery Officer of the WMFA. The mean annual quantity (tonnes) and value (£) of P. serratus landings for England, Scotland and Wales (i.e. mainland UK) between 2006 and 2009 were calculated from these data. This was done to place the Welsh prawn fishery within a UK context.

Catch data from 2006 to 2009 for both H. gammarus and P. serratus landings in Wales were summarised. Monthly percentages of the annual catch quantity (tonnes) and first sale value (£) for each year, and the mean for all four years, were calculated for both species. This was done in order to reveal and compare the seasonal trends for the capture of the two species to inform a discussion of the most favourable time for a closed season.

45 4 RESULTS

46 4.1 POPULATION STRUCTURE

47 4.1.1 The sex ratio and the proportion of ovigerous females

PROPORTION OF MALE, NON-OVIGEROUS FEMALE & OVIGEROUS FEMALE PRAWNS: NEWQUAY 2008/9

100

80

60

40 Percentage

20

0 DECEMBER JA NUA RY FEBRUA RY MA RCH

N 130 51 61 192 MA LE 29.2 56.9 37.7 65.1 NON-OV IGEROUS FEMA LE 67.7 39.2 39.3 15.1 OVIGEROUS FEMALE 3.1 3.9 23.0 19.8 Month

Figure 12: Proportion of male, non-ovigerous female and ovigerous female prawns in samples: Newquay 2008/9

PROPORTION OF MALE, NON-OVIGEROUS FEMALE & OVIGEROUS FEMALE PRAWN BIOMASS: NEWQUAY 2008/9

100

80

60

40 Percentage

20

0 DECEMBER JA NUA RY FEBRUA RY MA RCH

N 130 51 61 192 MA LE 17.7 41.8 24.9 51.2 NON-OV IGEROUS FEMA LE 78.5 51.6 44.3 19.3 OVIGEROUS FEMALE 3.8 6.6 30.8 29.6 Month

Figure 13: Proportion of male, non-ovigerous female and ovigerous female biomass in samples: Newquay 2008/9

48 PROPORTION OF MALE, NON-OVIGEROUS FEMALE & OVIGEROUS FEMALE PRAWNS: ABERYSTWYTH 2009

100

80

60

40 Percentage

20

0 FEBRUA RY MA RCH A PRIL MA Y

N 39 445 486 111 MA LE 17.9 40.0 47.3 39.6 NON-OV IGEROUS FEMA LE 74.4 34.2 5.8 0.9 OVIGEROUS FEMALE 7.7 25.8 46.9 59.5 Month

Figure 14: Proportion of male, non-ovigerous female and ovigerous female prawns in samples: Aberystwyth 2009

PROPORTION OF MALE, NON-OVIGEROUS FEMALE & OVIGEROUS FEMALE PRAWN BIOMASS: ABERYSTWYTH 2009

100

80

60

40 Percentage

20

0 FEBRUA RY MA RCH A PRIL MA Y

N 39 445 486 111 MA LE 11.2 25.1 31.9 25.4 NON-OV IGEROUS FEMA LE 78.0 39.4 6.5 0.2 OVIGEROUS FEMALE 10.8 35.5 61.6 74.4 Month

Figure 15: Proportion of male, non-ovigerous female and ovigerous female biomass in samples: Aberystwyth 2009

49 PROPORTION OF MALE, NON-OVIGEROUS FEMALE & OVIGEROUS FEMALE PRAWNS: MORFA NEFYN 2009

100

80

60

40 Percentage

20

0 FEBRUA RY MA RCH A PRIL MA Y OCTOBER

N 102 121 384 164 224 MA LE 86.3 63.6 53.4 47.6 13.4 NON-OV IGEROUS FEMA LE 10.8 25.6 3.4 3.7 86.6 OVIGEROUS FEMALE 2.9 10.7 43.2 48.8 0.0 Month

Figure 16: Proportion of male, non-ovigerous female and ovigerous female prawns in samples: Morfa Nefyn 2009

PROPORTION OF MALE, NON-OVIGEROUS FEMALE & OVIGEROUS FEMALE PRAWN BIOMASS: MORFA NEFYN 2009

100

80

60

40 Percentage

20

0 FEBRUA RY MA RCH A PRIL MA Y OCTOBER

N 102 121 384 164 224 MA LE 79.5 51.3 37.4 29.0 8.6 NON-OV IGEROUS FEMA LE 15.3 31.3 3.1 4.0 91.4 OVIGEROUS 5.2 17.4 59.4 67.0 0.0 Month

Figure 17: Proportion of male, non-ovigerous female and ovigerous female biomass in samples: Morfa Nefyn 2009

50 PROPORTION OF MALE, NON-OVIGEROUS FEMALE & OVIGEROUS FEMALE PRAWNS: AMLWCH 2009

100

80

60

40 Percentage

20

0 FEBRUA RY MA RCH

N 184 208 MA LE 15.2 15.9 NON-OV IGEROUS FEMA LE 54.3 63.0 OVIGEROUS FEMALE 30.4 21.2 Month

Figure 18: Proportion of male, non-ovigerous female and ovigerous female prawns in samples: Amlwch 2009

PROPORTION OF MALE, NON-OVIGEROUS FEMALE & OVIGEROUS FEMALE PRAWN BIOMASS: AMLWCH 2009

100

80

60

40 Percentage

20

0 FEBRUA RY MA RCH

N 184 208 MA LE 10.6 10.0 NON-OV IGEROUS FEMA LE 54.6 65.3 OVIGEROUS FEMALE 34.8 24.7 Month

Figure 19: Proportion of male, non-ovigerous female and ovigerous female biomass in samples: Amlwch 2009

51 Summary of seasonal variations

Newquay It can be seen from Figure 12 that although the ratio between males and females fluctuated between December and March, there was a general decline in the proportion of females in the samples. The decline was from over 70% to approximately 34% of the total from December to March. During the same period, there was also a notable increase in the proportion of ovigerous females; in December just over 4% of females were ovigerous, but by March it was over 50%.

Aberystwyth It is evident from Figure 14 that there was a decline in the proportion of females in the samples between February and May. In February just over 82% of the total number of prawns captured were female, by May it was just over 60%. During the same period there was a considerable increase in the proportion of ovigerous females in the sample populations. In February just over 9% of females were ovigerous, by May it was over 98%.

Morfa Nefyn It can be seen from Figure 16 that the proportion of female prawns in the samples steadily increased from February to May; just over 20% were female in February whereas it was over 70% by May. During the same period, the proportion of females that were ovigerous increased from just over 21% in February to approximately 93% in May. In October over 91% of the prawns captured were female, but none were ovigerous.

Amlwch It can be seen from Figure 18 that there was only a minimal difference between February and March in the proportion of females in the samples, with only a very slight decline being evident. However there was a more noticeable decline in the proportion of ovigerous females between February and March. In February almost 39% of females captured were ovigerous, but by March it was just over 27%.

52 Summary of regional differences

February and March The proportion of females in the samples from all locations except Morfa Nefyn declined between February and March whereas the proportion of females in the samples from Morfa Nefyn increased during this period.

Amlwch stands out for two reasons. Firstly, the proportion of females that were ovigerous declined between February and March, whereas the opposite was true of samples from all the other locations during these months. Secondly, the proportion of males in the samples collected in February and March was consistently lower in the Amlwch samples than in those from any other location during the same period.

Aberystwyth and Morfa Nefyn With respect to Aberystwyth and Morfa Nefyn, the proportion of females fell between March and April in the samples collected from Aberystwyth, whereas the opposite was true of samples from Morfa Nefyn. However, between April and May the proportion of females in the samples from both locations increased. Despite these differences it is also evident that for any given month the proportion of male prawns was consistently higher in the samples from Morfa Nefyn than those from Aberystwyth and the other locations.

Number biomass and sex With respect to all locations, it can be seen from Figures 12 to 19 that the numerical proportion of males in the samples was always greater than the proportion of male biomass. Conversely, the numerical proportion of females in the samples was always less than the proportion of female biomass. In other words the contribution made by female prawns (i.e. ovigerous and non-ovigerous combined) to the total biomass of the samples was proportionally greater than that made by male prawns.

53 4.1.2 Age

Figures 20 to 23 (from left to right): Carapace length-frequency distribution with group fits: Newquay males 2008/9

Figure 24: Summary of the number of male cohort groups detected and their mean carapace lengths, Newquay 2008/9

54

Figures 25 to 28 (from left to right): Carapace length-frequency distribution with group fits: Newquay females 2008/9

Figure 29: Summary of the number of female cohort groups detected and their mean carapace lengths, Newquay 2008/9

55

Figures 30 to 33 (from left to right): Carapace length-frequency distribution with group fits: Aberystwyth males 2008/9

Figure 34: Summary of the number of male cohort groups detected and their mean carapace lengths, Aberystwyth 2009

56

Figures 35 to 38: (from left to right): Carapace length-frequency distribution with group fits: Aberystwyth females 2008/9

Figure 39: Summary of the number of female cohort groups detected and their mean carapace lengths, Aberystwyth 2009

57 Figures 40 to 43: (from left to right): Carapace length-frequency distribution with group fits: Morfa Nefyn males 2009

Figure 44: Summary of the number of male cohort groups detected and their mean carapace lengths, Morfa Nefyn 2009

58

Figures 45 to 48: (from left to right): Carapace length-frequency distribution with group fits: Morfa Nefyn females 2009

Figure 49: Summary of the number of female cohort groups detected and their mean carapace lengths, Morfa Nefyn 2009

59

Figures 50 to 51: (from left to right): Carapace length-frequency distribution with group fits: Morfa Nefyn males and females, October 2009

Figure 52: Summary of the number of male cohort groups detected and their mean carapace lengths, Morfa Nefyn 2009

Figure 53: Summary of the number of female cohort groups detected and their mean carapace lengths, Morfa Nefyn 2009

60

Figures 54 to 55: (from left to right): Carapace length-frequency distribution with group fits: Amlwch males 2009

Figure 56: Summary of the number of male cohort groups detected and their mean carapace lengths, Amlwch 2009

61

Figures 57 to 58: (from left to right): Carapace length-frequency distribution with group fits: Amlwch females 2009

Figure 59: Summary of the number of female cohort groups detected and their mean carapace lengths, Amlwch 2009

62 4.2 MORPHOLOGY

63 4.2.1 Carapace length

MEAN CARAPACE LENGT HS +/- 95 % C I' s ︵ ︶ Car apac e l engt h mm ︵ ︶

18. 5

18

17. 5

17 FEMALE FEBRUARY FEMALE MARCH 16. 5 MALE FEBRUARY MALE MARCH 16

15. 5

15

14. 5

14

13. 5 NE WQUAY ABERYST WYTH MORFA NEFYN AML WCH Loc ati on 13

Figure 60: Mean carapace lengths: all locations, February and March 2009 (error bars indicate 95% confidence intervals for the means).

Table 7: Mean carapace lengths: all locations, February and March 2009

MEAN CARAPACE LENGTHS (mm) FEBRUARY & MARCH 2009 LOCATION NEWQUAY ABERYSTWYTH MORFA NEFYN AMLWCH SEX/MONTH N MEAN N MEAN N MEAN N MEAN FEBRUARY ♂ 23 14.29ab 7 14.77ab 88 14.03a 28 15.80bc

MARCH ♂ 125 15.10b 178 14.17a 77 14.28a 33 15.06ab FEBRUARY ♀ 38 18.04de 32 18.38de 14 16.82cd 156 18.46e MARCH ♀ 67 18.40e 267 18.28e 44 17.22d 175 18.34e

Means sharing the same superscript letter did not differ significantly from one another in Tukeys pairwise post hoc test (P<0.05).

64 Summary of the analysis of carapace length: all locations, February and March 2009 The difference between the mean carapace length of males and females from all locations was highly significant (ANOVA, F1,1336 = 1878.03, P<0.001). It is clear from the plot of means in Figure 60 and the post hoc test results in Table 7 that the there were no variations between the mean carapace length of female prawns between months, or between female samples from Newquay, Aberystwyth and Amlwch in either February or March. However, the mean carapace length of female prawns from Morfa Nefyn in February and March did vary from the other locations in both months. In February, the differences were statistically significant between the female prawns from Morfa Nefyn and Amlwch (Tukey’s adjusted P-value = 0.0157). In March the differences within the female samples were statistically significant between Morfa Nefyn and Newquay (Tukey’s adjusted P-value = 0.0091), Morfa Nefyn and Aberystwyth (Tukey’s adjusted P-value = 0.0029), and Morfa Nefyn and Amlwch (Tukey’s adjusted P-value = 0.0019).

There was no variation in the mean carapace length of male prawns between months at any location. However, there was a statistically significant difference in the mean carapace length of male prawns between Morfa Nefyn and Amlwch in February (Tukey’s adjusted P-value = 0.0001), with those from Morfa Nefyn being the smaller. In March, the mean carapace length of male prawns from Newquay was significantly greater than it was for males from Aberystwyth (Tukey’s adjusted P-value = 0.0001) and Morfa Nefyn (Tukey’s adjusted P-value = 0.0287).

NB: The full ANOVA and post hoc test results can be found in Appendix VII.

65 MEAN CARAPACE LENGT HS +/- 95 % CI' s ︵ ︶ Carapace length (mm) 20

19. 5

19

18. 5

18

17. 5 FEMALE ABERYSTWYTH FEMALE MORFA NEFYN 17 MALE ABERYSTWYTH MALE MORFA NEFYN 16. 5

16

15. 5

15

14. 5

14

13. 5 FEBRUARY MARCH APRI L MAY 13 Month

Figure 61: Mean carapace lengths: Aberystwyth and Morfa Nefyn, February to May 2009 (error bars indicate 95% confidence intervals for the means).

Table 8: Mean carapace lengths: Aberystwyth and Morfa Nefyn, February to May 2009

MEAN CARAPACE LENGTHS (mm) ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY 2009 MONTH FEBRUARY MARCH APRIL MAY LOCATION/SEX N MEAN N MEAN N MEAN N MEAN ABERYSTWYTH ♂ 7 14.77ab 178 14.17a 230 15.19b 44 15.52bc MORFA NEFYN ♂ 88 14.03a 77 14.28a 205 15.28b 78 15.22b ABERYSTWYTH ♀ 32 18.38efh 267 18.28e 256 19.01f 67 19.03fg MORFA NEFYN ♀ 14 16.82cdh 44 17.22d 179 18.99f 86 19.68g Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

66 Summary of the analysis of carapace length: Aberystwyth and Morfa Nefyn, February to May 2009 It can be seen from Figure 61 that the difference between the mean carapace length of males and females from both locations was highly significant (ANOVA F1,1836 = 3050.26, P<0.001).

Although the Figure 61 and Table 8 show an increase in the mean carapace length of female prawns from Aberystwyth between February and May, it was not statistically significant. There was, however, a significant increase in the mean carapace length of female prawns from Aberystwyth between March and April (Tukey’s adjusted P-value = <0.0001).

In contrast to Aberystwyth, the mean carapace length of female prawns from Morfa Nefyn increased significantly between February and May (Tukey’s adjusted P-value = <0.0001). Although the difference between February and March was not statistically significant, the difference between March and April was significant (Tukey’s adjusted P-value = <0.0001) as was the difference between April and May (Tukey’s adjusted P- value = 0.039).

There was a general increase in the mean carapace length of male prawns from Aberystwyth between February and May, but the increase was only statistically significant between March and April (Tukey’s adjusted P-value = <0.0001).

The mean carapace length of male prawns from Morfa Nefyn increased significantly between February and May (Tukey’s adjusted P-value = 0.0001), although the mean for May was slightly lower than for April. Within this overall increase the difference between February and March was not statistically significant, but there was a significant difference between March and April (Tukey’s adjusted P-value = 0.0001).

NB: The full ANOVA and post hoc test results can be found in Appendix VII.

67 MEAN CARAPACE LENGT HS +/- 95 % CI' s ︵ ︶ Carapace length (mm) 20

19. 5

19

18. 5

18

17. 5

17 FEMALE 16. 5 MALE

16

15. 5

15

14. 5

14

13. 5

13

12. 5 FEBRUARY MARCH DECEMBER JANUARY 12 Month

Figure 62: Mean carapace lengths: Newquay, December to March 2008/9 (error bars indicate 95% confidence intervals for the means).

Table 9: Mean carapace lengths: Newquay, December to March 2008/9

MEAN CARAPACE LENGTHS (mm) NEWQUAY DECEMBER TO MARCH 2008/9 MONTH DECEMBER JANUARY FEBRUARY MARCH SEX N MEAN N MEAN N MEAN N MEAN MALE 38 13.90a 29 14.96ab 23 14.29ab 125 15.10b FEMALE 92 17.78c 22 18.91c 38 18.04c 67 18.40c Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

68 Summary of the analysis of carapace length: Newquay, December to March 2008/9 The difference between the mean carapace length of males and females from Newquay between December and March was highly significant (ANOVA F1,426 = 487.85, P<0.001).

It is evident from Figure 62 and Table 9 that there were no significant differences in the mean carapace length of female prawns from Newquay between months. With respect to the mean carapace length of male prawns from Newquay, the only significant difference found was between the December and March means (Tukey’s adjusted P- value = 0.0011).

NB: The full ANOVA and post hoc test results can be found in Appendix VII.

69 MEAN CARAPACE LENGT HS +/- 95 % C I' s ︵ ︶ Carapace length (mm) 20

19. 5 FEMALE 19 MALE

18. 5

18

17. 5

17

16. 5

16

15. 5

15

14. 5

14

13. 5

13

12. 5 FEBRUARY MARCH APRIL MAY OCTOBER 12 Month

Figure 63: Mean carapace lengths: Morfa Nefyn, February to May plus October 2009 (error bars indicate 95% confidence intervals for the means).

Table 10: Mean carapace lengths: Morfa Nefyn, February to May plus October 2009 MEAN CARAPACE LENGTHS (mm) MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009 MONTH FEBRUARY MARCH APRIL MAY OCTOBER SEX N MEAN N MEAN N MEAN N MEAN N MEAN MALE 88 14.03a 77 14.28a 205 15.28bc 78 15.22bc 30 14.33ab FEMALE 14 16.82d 44 17.22d 179 18.99e 86 19.68f 194 17.46d Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

70 Summary of the analysis of carapace length: Morfa Nefyn, February to May plus October 2009 The difference between the mean carapace length of males and females from Morfa

Nefyn was highly significant (ANOVA, F1,985 = 1266.03, P<0.001).

It is evident from the plot of means in Figure 63 and the post hoc results in Table 10, that the mean carapace length of female prawns captured in October was significantly less than that it was for both May (Tukey’s adjusted P-value = <0.0001) and April (Tukey’s adjusted P-value = <0.0001). There was also a statistically significant difference in the mean carapace length of female prawns between April and May (Tukey’s adjusted P-value = 0.022), but there were no significant differences between October and February or between October and March.

It is evident from the plot of means in Figure 63 and the post hoc results in Table 10, that the mean carapace length of male prawns captured in February were significantly less than the mean values for both April (Tukey’s adjusted P-value = <0.0001) and May (Tukey’s adjusted P-value = <0.0001). The mean carapace length of male prawns captured in and March were significantly less than the mean values for April (Tukey’s adjusted P-value = 0.0001) and May (Tukey’s adjusted P-value = 0.0064). No other significant differences were found.

NB: The full ANOVA and post hoc test results can be found in Appendix VII.

71 4.2.2 Wet weight

MEAN l og WET WEI GHTS +/- 95 % C I' s ︵ ︶ Wet wei ght l og g ︵ ︶

0.85

0.8

0.75

FEMALE FEBRUARY 0.7 FEMALE MARCH MALE FEBRUARY MALE MARCH

0.65

0.6

0.55

0.5

0.45 NE WQUAY ABERYST WYTH MORFA NEFYN AML WCH Locati on

Figure 64: Mean log wet weights: all locations, February and March 2009 (error bars indicate 95% confidence intervals for the means).

Table 11: Mean log wet weights: all locations, February and March 2009

MEAN log WET WEIGHTS (g) FEBRUARY & MARCH 2009 LOCATION NEWQUAY ABERYSTWYTH MORFA NEFYN AMLWCH SEX/MONTH N MEAN N MEAN N MEAN N MEAN FEBRUARY ♂ 18 0.536a 6 0.570ab 60 0.507a 7 0.679abc MARCH ♂ 94 0.545a 140 0.508a 48 0.532a 22 0.593a FEBRUARY ♀ 33 0.812c 23 0.810c 12 0.710bc 58 0.813c MARCH ♀ 44 0.801c 208 0.811c 34 0.734bc 129 0.815c Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

72 Table 11.1: Mean wet weights: all locations, February and March 2009

MEAN WET WEIGHTS (g) FEBRUARY & MARCH 2009 LOCATION NEWQUAY ABERYSTWYTH MORFA NEFYN AMLWCH SEX/MONTH N MEAN N MEAN N MEAN N MEAN FEBRUARY ♂ 18 3.555a 6 3.739ab 60 3.291a 7 4.871abc MARCH ♂ 94 3.545a 140 3.405a 48 3.469a 22 3.986a FEBRUARY ♀ 33 6.558c 23 6.552c 12 5.374bc 58 6.917c MARCH ♀ 44 6.450c 208 6.751c 34 5.800bc 129 6.788c Means sharing the same superscript letter did not differ significantly from one another in Tukeys pairwise post hoc test of the log transformed data (P<0.05).

Summary of the analysis of log wet weight: all locations, February and March 2009 The mean log wet weight of female prawns caught at all locations in February and March was found to be significantly greater than the mean log wet weight of male prawns (ANOVA, F1,920 = 1003.66, P<0.001). However, Tukey’s post hoc test revealed one exception to the general picture; no difference was found in the mean log wet weight between males and females captured at Amlwch in February.

It can be seen from Figure 64 and Table 11, that the mean log wet weight of female prawns from Morfa Nefyn in both February and March was less than that of females from all other locations; however, the differences were not found to be statistically significant. No monthly or locational differences were found between the mean log wet weights of males.

NB: The full ANOVA and post hoc test results can be found in Appendix IX.

73 MEAN l og WET WEI GHTS +/- 95 % C I' s ︵ ︶ 0.95 Wet wei ght l og g ︵ ︶

0.9

0.85

0.8

0.75 FEMALE ABERYST WYTH FEMALE MORFA NEFYN MALE ABERYST WYTH 0.7 MALE MORFA NEFYN

0.65

0.6

0.55

0.5

0.45 FEBRUARY MARCH APRIL MAY Locati on

Figure 65: Mean log wet weights: Aberystwyth and Morfa Nefyn, February to May 2009 (error bars indicate 95% confidence intervals for the means).

Table 12: Mean log wet weights: Aberystwyth and Morfa Nefyn, February to May 2009

MEAN log WET WEIGHTS (g) ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY 2009 MONTH FEBRUARY MARCH APRIL MAY LOCATION/SEX N MEAN N MEAN N MEAN N MEAN ABERYSTWYTH ♂ 6 0.570def 140 0.508f 70 0.564ef 25 0.603de MORFA NEFYN ♂ 60 0.507f 48 0.532ef 134 0.576def 46 0.529ef ABERYSTWYTH ♀ 23 0.810abc 208 0.811bc 68 0.862ab 44 0.869ab MORFA NEFYN ♀ 12 0.710cd 34 0.734c 128 0.866a 47 0.875ab Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

74 Table 12.1: Mean wet weights: Aberystwyth and Morfa Nefyn, February to May 2009

MEAN WET WEIGHTS (g) ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY 2009 MONTH FEBRUARY MARCH APRIL MAY LOCATION/SEX N MEAN N MEAN N MEAN N MEAN ABERYSTWYTH ♂ 6 3.739def 140 3.405f 70 3.812ef 25 4.060de MORFA NEFYN ♂ 60 3.291f 48 3.469ef 134 3.883def 46 3.603ef ABERYSTWYTH ♀ 23 6.552abc 208 6.751bc 68 7.413ab 44 7.664ab MORFA NEFYN ♀ 12 5.374cd 34 5.800c 128 7.594a 47 7.890ab Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test of the log transformed data (P<0.05).

Summary of the analysis of log wet weight: Aberystwyth and Morfa Nefyn, February to May 2009 It can be seen from Figure 65 that the mean log wet weight of female prawns caught at both Aberystwyth and Morfa Nefyn was significantly greater than that of male prawns in all months (ANOVA, F1,1077 = 1309.92, P<0.001).

There were no significant differences in the mean log wet weight of male or female prawns between Aberystwyth and Morfa Nefyn in any particular month. However, there was a difference between Aberystwyth and Morfa Nefyn in the rate at which the mean log wet weight of female prawns increased between February and May. The increase in the mean log wet weight of female prawns from Morfa Nefyn between February and May was statistically significant (Tukey’s adjusted P-value = 0.0124), whereas the increase in the mean log wet weight of female prawns from Aberystwyth between February and May was not.

NB: The full ANOVA and post hoc test results can be found in Appendix IX.

75 MEAN l og WET WEI GHTS +/- 95 % C I' s ︵ ︶ Wet wei ght l og g ︵ ︶

0.9

0.85

0.8

0.75

0.7 FEMALE MALE 0.65

0.6

0.55

0.5

0.45

0.4 DECEMBER JANUARY FEBRUARY MARCH Mont h

Figure 66: Mean log wet weights: Newquay, December to March 2008/9 (error bars indicate 95% confidence intervals for the means).

Table 13: Mean log wet weights: Newquay, December to March 2008/9

MEAN log WET WEIGHTS (g) NEWQUAY DECEMBER TO MARCH 2008/9 MONTH DECEMBER JANUARY FEBRUARY MARCH SEX N MEAN N MEAN N MEAN N MEAN MALE 27 0.485a 18 0.588a 18 0.536a 94 0.545a FEMALE 75 0.784b 15 0.849b 33 0.812b 44 0.801b Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

Table 13.1: Mean wet weights: Newquay, December to March 2008/9

MEAN WET WEIGHTS (g) NEWQUAY DECEMBER TO MARCH 2008/9 MONTH DECEMBER JANUARY FEBRUARY MARCH SEX N MEAN N MEAN N MEAN N MEAN MALE 27 3.315a 18 3.910a 18 3.555a 94 3.545a FEMALE 75 6.512b 15 7.127b 33 6.558b 44 6.450b Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test of the log transformed data (P<0.05).

76 Summary of the analysis of log wet weight: Newquay, December to March 2008/9 The mean log wet weight of female prawns from Newquay in all months was greater than that of male prawns in all months and the difference was highly significant

(ANOVA, F1,316 = 339.28, P<0.001).

It can be seen from Figure 66 and the results of the post hoc analysis in Table 13 that there was some variation between December and March in the mean log wet weight of both male and female prawns and a slight peak in January in the weight of both sexes, but none of these seasonal differences were statistically significant.

NB: The full ANOVA and post hoc test results can be found in Appendix IX.

77 MEAN l og WET WEI GHTS +/- 95 % C I' s ︵ ︶ Wet wei ght l og g ︵ ︶

0.9 FEMALE MALE

0.85

0.8

0.75

0.7

0.65

0.6

0.55

0.5

0.45

FEBRUARY MARCH APRIL MAY OCTOBER Mont h 0.4

Figure 67: Mean log wet weights: Morfa Nefyn, February to May plus October 2009 (error bars indicate 95% confidence intervals for the means).

Table 14: Mean log wet weights: Morfa Nefyn, February to May plus October 2009 MEAN log WET WEIGHTS (g) MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009 MONTH FEBRUARY MARCH APRIL MAY OCTOBER SEX N MEAN N MEAN N MEAN N MEAN N MEAN MALE 60 0.507a 48 0.532ab 134 0.576b 46 0.529ab 18 0.532ab FEMALE 12 0.710c 34 0.734c 128 0.866d 47 0.875d 138 0.759c Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc (P<0.05).

Table 14.1: Mean wet weights: Morfa Nefyn, February to May plus October 2009

MEAN WET WEIGHTS (g) MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009 MONTH FEBRUARY MARCH APRIL MAY OCTOBER SEX N MEAN N MEAN N MEAN N MEAN N MEAN MALE 60 3.291a 48 3.469ab 134 3.883b 46 3.603ab 18 3.436ab FEMALE 12 5.374c 34 5.800c 128 7.594d 47 7.890d 138 5.840c Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test of the log transformed data (P<0.05).

78 Summary of the analysis of log wet weight, Morfa Nefyn: February to May plus October 2009 The mean log wet weight of female prawns from Morfa Nefyn in all months was greater than that of male prawns and the difference was highly significant (ANOVA, F1,655 = 817.66, P<0.001).

The plot of means in Figure 67 and the post hoc results in Table 14 indicate that the mean log wet weight of female prawns was greater in both April and May than in all other months, and the differences were statistically significant. There was no difference between the mean log wet weights of the females captured in April and May.

The only significant difference found in the mean log wet weight of male prawns between February and October was between the samples captured in February and April (Tukey’s adjusted P-value = 0.0067).

NB: The full ANOVA and post hoc test results can be found in Appendix IX.

79 4.2.3 Carapace width and carapace length

RELATIONSHIP BETWEEN CARAPACE WIDTH & CARAPACE LENGTH: BOTH SEXES, ALL LOCATIONS 2008/9 Carapace length (mm)

y = 1.4642x + 0.8412 24 R2 = 0.92

22

20

18

16 FEMALE N = 1689 MALE N = 1213

14

12

10

8 y = 1.5478x + 0.0455

R2 = 0.93 6

Carapace width (mm) 4 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Figure 68: The relationship between carapace width and carapace length: both sexes, all locations 2008/9. (The linear trend lines were fitted to male and female data using least squares regression, where y = carapace length and x = carapace width).

The result of Pearson’s correlation tests of the relationship between carapace width and carapace length was r = 0.96 for each sex. This indicated that there was a very strong positive correlation between the parameters for each of the sexes. With respect to both males and females the Ho that the data were not correlated was therefore rejected and it was concluded that the correlations between the variables were very highly significant. The slope of the regression line in Figure 68 describing the relationship between carapace width and carapace length of male prawns was slightly steeper than that describing the relationship of females, and the two lines also cross at the point where carapace width = 9.52mm and carapace length = 14.78mm.

The regression equation describing the relationship between the carapace width and carapace length of both sexes combined was: y = 1.4738x + 0.7386 (y = carapace length, x = carapace width).

80 MEAN CARAPACE WI DTH/ CARAPACE LENGT H RATI OS +/- 95 % C I' s ︵ ︶ Rati o

0. 685

FEMALE FEBRUARY 0. 68 FEMALE MARCH MALE FEBRUARY 0. 675 MALE MARCH

0. 67

0. 665

0. 66

0. 655

0. 65

0. 645

0. 64

0. 635

0. 63

0. 625 ABERYST WYTH MORFA NEFYN NE WQUAY AML WCH Loc ati on 0. 62

Figure 69: Mean carapace width/carapace length ratios: all locations, February and March 2009 (error bars indicate 95% confidence intervals for the means).

Table 15: Mean carapace width/carapace length ratios: all locations, February and March 2009.

MEAN CARAPACE WIDTH/CARAPACE LENGTH RATIOS FEBRUARY & MARCH 2009 LOCATION NEWQUAY ABERYSTWYTH MORFA NEFYN AMLWCH SEX/MONTH N MEAN N MEAN N MEAN N MEAN FEBRUARY ♂ 23 0.668ab 7 0.653abdef 88 0.647e 28 0.648de MARCH ♂ 125 0.632c 178 0.653de 77 0.647e 33 0.651de FEBRUARY ♀ 38 0.673a 32 0.651de 14 0.651bde 156 0.655bd MARCH ♀ 67 0.634cf 267 0.653de 44 0.648de 175 0.649de

Means sharing the same superscript letter did not differ significantly from one another in Tukeys pairwise post hoc test (P<0.05).

81 Summary of the analysis of carapace width/carapace length ratios: all locations, February and March 2009 It is clear from Figure 69 and Table 15 that variations in the mean ratio between carapace width and carapace length were either between the Newquay sample means and those from the other locations, or within the Newquay sample means. Differences between sex and month in the Aberystwyth, Morfa Nefyn and Amlwch means were minimal, as were differences between these locations.

It is clear from Figure 69 that there was no variation in the carapace width/carapace length ratio between the sexes in the Newquay samples collected in either February or March. However, there were significant differences between February and March in both males (Tukey’s adjusted P-value = <0.0001) and females (Tukey’s adjusted P- value = <0.0001) from Newquay.

It can be seen from Table 15 that, with just one exception, the mean carapace width/carapace length ratios for both male and female prawns from Newquay were significantly different to the mean ratios from all other locations. The exception was between the male prawns from Newquay in February and the male prawns from Aberystwyth in February.

NB: The full ANOVA and post hoc test results can be found in Appendix X.

82 MEAN CARAPACE WI DTH/ CARAPACE LENGT H RATI OS +/- 95 % C I' s ︵ ︶ Ratio

0. 665 FEMALE ABERYST WYTH FEMALE MORFA NEFYN

0. 66 MALE ABERYST WYTH MALE MORFA NEFYN

0. 655

0. 65

0. 645

0. 64

0. 635

0. 63

FEBRUARY MARCH APRI L MAY 0. 625 Month

Figure 70: Mean carapace width/carapace length ratios: Aberystwyth and Morfa Nefyn, February to May 2009 (error bars indicate 95% confidence intervals for the means).

Table 16: Mean carapace width/carapace length ratios: Aberystwyth and Morfa Nefyn, February to May 2009

MEAN CARAPACE WIDTH/CARAPACE LENGTH RATIOS ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY 2009 MONTH FEBRUARY MARCH APRIL MAY LOCATION/SEX N MEAN N MEAN N MEAN N MEAN ABERYSTWYTH ♂ 7 0.653bcdef 178 0.653def 230 0.642bc 44 0.650def MORFA NEFYN ♂ 88 0.647cd 77 0.647cd 205 0.639b 78 0.632a ABERYSTWYTH ♀ 32 0.651def 267 0.653ef 256 0.648d 67 0.658f MORFA NEFYN ♀ 14 0.651cdef 44 0.648cde 179 0.646d 86 0.649de

Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

83 Summary of the analysis of carapace width/carapace length ratios: Aberystwyth and Morfa Nefyn, February to May 2009 It can be seen from Figure 70 and Table 16 that, in February there, was no difference in the mean carapace width/carapace length ratio between the male and female prawns from either Aberystwyth or Morfa Nefyn, or any differences between the two locations.

In March, there were no differences between the sexes in samples from either Aberystwyth or Morfa Nefyn, nor were there differences between locations.

In April there were no significant differences between locations with respect to either sex, however significant differences were found between the sexes at both Aberystwyth (Tukey’s adjusted P-value = <0.0001) and Morfa Nefyn (Tukey’s adjusted P-value = <0.0001). In both cases the carapace of male prawns were significantly longer relative to their widths than the female prawns.

In May there was a significant difference between the male and female ratios in the samples from Morfa Nefyn (Tukey’s adjusted P-value = <0.0001), but no difference between the sexes in the samples from Aberystwyth. There was also a significant difference between Aberystwyth and Morfa Nefyn with respect to the male ratios (Tukey’s adjusted P-value = <0.0001) and the female ratios (Tukey’s adjusted P-value = 0.0056).

NB: The full ANOVA and post hoc test results can be found in Appendix X.

84 MEAN CARAPACE WI DTH/ CARAPACE LENGT H RATI OS +/- 95 % C I' s ︵ ︶ Ratio

0. 675

0. 67

0. 665 FEMALE MALE 0. 66

0. 655

0. 65

0. 645

0. 64

0. 635

0. 63 DECEMBER JANUARY FEBRUARY MARCH

0. 625 Month

Figure 71: Mean carapace width/carapace length ratios: Newquay, December to March 2008/9 (error bars indicate 95% confidence intervals for the means).

Table 17: Mean carapace width/carapace length ratios: Newquay, December to March 2008/9 MEAN CARAPACE WIDTH/CARAPACE LENGTH RATIOS NEWQUAY DECEMBER TO MARCH 2008/9 MONTH DECEMBER JANUARY FEBRUARY MARCH SEX N MEAN N MEAN N MEAN N MEAN MALE 38 0.662bc 29 0.648c 23 0.668b 125 0.632a FEMALE 92 0.664bd 22 0.648cd 38 0.673b 67 0.634a Means sharing the same superscript letter did not differ significantly from one another in Tukeys pairwise post hoc test (P<0.05).

85 Summary of the analysis of carapace width/carapace length ratios: Newquay, December to March 2008/9 It is clear from Figure 71 and Table 17 that there were no significant differences between the male and female carapace width/length ratios of prawns from Newquay in any month.

With respect to both sexes carapace length increased relative to carapace width from December to January, decreased from January to February and then increased again between February and March. The carapace width/carapace length ratios of female prawns captured in December were significantly different to the female ratios in March (Tukey’s adjusted P-value = <0.0001), but not those of January or February.

The mean carapace width/carapace length ratios of the male prawns captured in December were significantly different to the ratios of the male prawns captured in March (Tukey’s adjusted P-value = <0.0001). Differences between December and January and between December and March were not significant.

NB: The full ANOVA and post hoc test results can be found in Appendix X.

86 MEAN CARAPACE WI DTH/ CARAPACE LENGT H RATI OS +/- 95 % C I' s ︵ ︶ Ratio

0. 675 FEMALE MALE 0. 67

0. 665

0. 66

0. 655

0. 65

0. 645

0. 64

0. 635

0. 63

FEBRUARY MARCH APRI L MAY OCTOBER 0. 625 Month

Figure 72: Mean carapace width/carapace length ratios: Morfa Nefyn, February to May plus October 2009 (error bars indicate 95% confidence intervals for the means).

Table 18: Mean carapace width/carapace length ratios: Morfa Nefyn, February to May plus October 2009 MEAN CARAPACE WIDTH/CARAPACE LENGTH RATIOS MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009 MONTH FEBRUARY MARCH APRIL MAY OCTOBER SEX N MEAN N MEAN N MEANN MEAN N MEAN MALE 88 0.647d 77 0.647d 205 0.639c 78 0.632a 30 0.665b FEMALE 14 0.651bd 44 0.648d 179 0.646d 86 0.649d 194 0.659b Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

87 Summary of the analysis of carapace width/carapace length ratios: Morfa Nefyn, February to May plus October 2009 It is evident from Figure 72 and Table 18, that there were no differences in the mean carapace width/length ratio between the male and female prawns in February, March and October. There were, however, significant differences between the sexes in both April (Tukey’s adjusted P-value = <0.0001) and May (Tukey’s adjusted P-value = <0.0001).

The carapace length of males in October was significantly less, relative to carapace width, than it was in February (Tukey’s adjusted P-value = <0.0001), March (Tukey’s adjusted P-value = <0.0001), April (Tukey’s adjusted P-value = <0.0001) and May (Tukey’s adjusted P-value = <0.0001). The carapace length of females in October was significantly less, relative to carapace width, than it was in March (Tukey’s adjusted P- value = 0.001), April (Tukey’s adjusted P-value = <0.0001), and May (Tukey’s adjusted P-value = <0.0001).

NB: The full ANOVA and post hoc test results can be found in Appendix X.

88 4.2.4 Carapace length and rostral length

RELATIONSHIP BETWEEN CARAPACE LENGTH & ROSTRAL LENGTH: BOTH SEXES, ALL LOCATIONS 2008/9 Rostral length (mm) 34

32

y = 1.8927x0.9075 30 R2 = 0.71

28

26

24

MALE N = 890 FEMALE N = 1277 22 y = 2.5258x0.7519

20 R2 = 0.61

18

16

14

12

10

Carapace length (mm) 8 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Figure 73: The relationship between carapace length and rostral length: both sexes, all locations 2008/9. (The trend line which the best fitted the data was produced by a power function).

It can be seen from the trend lines fitted to the data in Figure 73 above that the relationship between carapace length and rostral length was slightly curvilinear. It is also clear from the divergence of the two lines that there was a clear difference between the sexes with respect to the relationship between carapace length and rostral length; females were generally larger than males, and for any given carapace length the rostra of males was longer than the rostra of females.

89 RELATIONSHIP BETWEEN log CARAPACE LENGTH & log ROSTRAL LENGTH: BOTH SEXES, ALL LOCATIONS 2008/9 Rostral length (log mm)

1.5

1.45

y = 1.078x + 0.077772

1.4 R2 = 0.71

1.35

1.3 MALE N = 890 FEMALE N = 1277 1.25

y = 0.9057x + 0.13911 1.2 R2 = 0.61

1.15

1.1

1.05

1

Carapace length (log mm) 0.95 0.9 1 1.1 1.2 1.3 1.4

Figure 74: The relationship between log carapace length and log rostral length: both sexes, all locations 2008/9. (The linear trend lines were fitted using reduced major axis regression)

It can be seen from Figure 74 above that log transformation increased linearity, reduced the spread (i.e. variance heterogeneity) of the data and reduced the divergence of the two fitted trend lines.

90 MEAN log CARAPACE LENGTH/ROSTRAL LENGTH RATIOS (+/- 95% C I's) Log ratio

-0.07

-0.08

-0.09

-0.1

-0.11

-0.12 FEMALE FEBRUARY FEMALE MARCH

-0.13 MALE FEBRUARY MALE MARCH

-0.14

-0.15

-0.16

-0.17

-0.18

-0.19 NE WQUAY ABERYST WYTH MORFA NEFYN AML WCH Location -0.2

Figure 75: Mean log carapace length/rostral length ratios: all locations, February and March 2009 (error bars indicate 95% confidence intervals for the means).

Table 19: Mean log carapace length/rostral length ratios: all locations, February and March 2009

MEAN log CARAPACE LENGTH/ROSTRAL LENGTH RATIOS FEBRUARY & MARCH 2009 LOCATION NEWQUAY ABERYSTWYTH MORFA NEFYN AMLWCH SEX/MONTH N MEAN N MEAN N MEAN N MEAN FEBRUARY ♂ 18 -0.175bc 6 -0.171bc 62 -0.173bc 11 -0.162bc MARCH ♂ 100 -0.163b 142 -0.177c 53 -0.167bc 26 -0.156b FEBRUARY ♀ 33 -0.087a 24 -0.088a 12 -0.089a 99 -0.093a MARCH ♀ 51 -0.085a 210 -0.092a 36 -0.089a 138 -0.085a Means sharing the same superscript letter did not differ significantly from one another in Tukeys pairwise post hoc test (P<0.05).

91 Table 19.1: Mean carapace length/rostral length ratios: all locations, February and March 2009

MEAN CARAPACE LENGTH/ROSTRAL LENGTH RATIOS FEBRUARY & MARCH 2009 LOCATION NEWQUAY ABERYSTWYTH MORFA NEFYN AMLWCH SEX/MONTH N MEAN N MEAN N MEAN N MEAN FEBRUARY ♂ 18 0.669bc 6 0.676bc 62 0.672bc 11 0.690bc MARCH ♂ 100 0.688b 142 0.666c 53 0.682bc 26 0.700b FEBRUARY ♀ 33 0.821a 24 0.819a 12 0.824a 99 0.810a MARCH ♀ 51 0.824a 210 0.810a 36 0.819a 138 0.823a Means sharing the same superscript letter did not differ significantly from one another in Tukeys pairwise post hoc test of the log transformed data (P<0.05).

Summary of the analysis of carapace length/rostral length ratios: all locations, February and March 2009

The difference between the male and female mean log ratios was highly significant

(ANOVA, F1,1005 = 1925.98, P<0.001). This indicates that for any given carapace length male rostra were longer than female rostra.

It is clear from Figure 75, that there was some variation between the mean log ratios of prawns from Aberystwyth and the mean log ratios from the other locations. However, as Table 19 shows, the differences were only statistically significant between the males from Aberystwyth and Newquay in March (Tukey’s adjusted P-value = 0.0146) and between males from Aberystwyth and Amlwch in March (Tukey’s adjusted P-value = 0.0442).

NB: The full ANOVA and post hoc test results can be found in Appendix XI.

92 MEAN log CARAPACE LENGTH/ROSTRAL LENGTH RATIOS (+/- 95% C I's) Log ratio

-0.05

-0.06

-0.07

-0.08

-0.09

-0.1

-0.11

FEMALE ABERYSTWYTH -0.12 FEMALE MORFA NEFYN MALE ABERYSTWYTH -0.13 MALE MORFA NEFYN

-0.14

-0.15

-0.16

-0.17

-0.18

-0.19 FEBRUARY MARCH APRI L MAY Month -0.2

Figure 76: Mean log carapace length/rostral length ratios: Aberystwyth and Morfa Nefyn, February to May 2009 (error bars indicate 95% confidence intervals for the means).

Table 20: Mean log carapace length/rostral length ratios: Aberystwyth and Morfa Nefyn, February to May 2009

MEAN log CARAPACE LENGTH/ROSTRAL LENGTH RATIOS ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY 2009 MONTH FEBRUARY MARCH APRIL MAY LOCATION/SEX N MEAN N MEAN N MEAN N MEAN ABERYSTWYTH ♂ 6 -0.171bc 142 -0.177c 153 -0.169bc 34 -0.167bc MORFA NEFYN ♂ 62 -0.173bc 53 -0.167bc 160 -0.166b 54 -0.167bc ABERYSTWYTH ♀ 24 -0.088a 210 -0.092a 157 -0.092a 55 -0.085a MORFA NEFYN ♀ 12 -0.089a 36 -0.089a 143 -0.085a 58 -0.081a Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

93 Table 20.1: Mean carapace length/rostral length ratios: Aberystwyth and Morfa Nefyn, February to May 2009 MEAN CARAPACE LENGTH/ROSTRAL LENGTH RATIOS ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY 2009 MONTH FEBRUARY MARCH APRIL MAY LOCATION/SEX N MEAN N MEAN N MEAN N MEAN ABERYSTWYTH ♂ 6 0.676bc 142 0.666c 153 0.678bc 34 0.682bc MORFA NEFYN ♂ 62 0.672bc 53 0.682bc 160 0.683b 54 0.682bc ABERYSTWYTH ♀ 24 0.819a 210 0.809a 157 0.810a 55 0.825a MORFA NEFYN ♀ 12 0.824a 36 0.819a 143 0.824a 58 0.831a Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test of the log transformed data (P<0.05).

Summary of the analysis of carapace length/rostral length ratios: Aberystwyth and Morfa Nefyn, February to May 2009

It can be seen from Figure 76, that the difference between the male and female mean log ratios of prawns from both Aberystwyth and Morfa Nefyn was highly significant

(ANOVA, F1,1343 = 2781.75, P<0.001). This indicates that for any given carapace length male rostra were longer than female rostra.

It can also be seen from Figure 76 and Table 20, that, although there were some minor seasonal variations, there were no statistically significant differences in either the male or female mean ratios between Aberystwyth and Morfa Nefyn in any particular month.

NB: The full ANOVA and post hoc test results can be found in Appendix XI.

94 MEAN l og CARAPACE L ENGT H/ ROST RAL L ENGTH RATI OS +/- 95 % C I' s ︵ ︶ Log r ati o

-0. 07

-0. 08

-0. 09

-0. 1

-0. 11

-0. 12

FEMALE -0. 13 MALE

-0. 14

-0. 15

-0. 16

-0. 17

-0. 18

-0. 19

DECEMBER JANUARY FEBRUARY MARCH Loc ati on -0. 2

Figure 77: Mean log carapace length/rostral length ratios: Newquay, December to March 2008/9 (error bars indicate 95% confidence intervals for the means).

Table 21: Mean log carapace length/rostral length ratios: Newquay December to March 2008/9 MEAN log CARAPACE LENGTH/ROSTRAL LENGTH RATIOS NEWQUAY DECEMBER TO MARCH 2008/9 MONTH DECEMBER JANUARY FEBRUARY MARCH SEX N MEAN N MEAN N MEAN N MEAN MALE 29 -0.179a 21 -0.167a 18 -0.175a 100 -0.163a FEMALE 77 -0.088b 16 -0.088b 33 -0.087b 51 -0.085b Means sharing the same superscript letter did not differ significantly from one another in Tukeys pairwise post hoc test (P<0.05).

95 Table 21.1: Mean carapace length/rostral length ratios: Newquay December to March 2008/9.

MEAN CARAPACE LENGTH/ROSTRAL LENGTH RATIOS NEWQUAY DECEMBER TO MARCH 2008/9

MONTH DECEMBER JANUARY FEBRUARY MARCH SEX N MEAN N MEAN N MEAN N MEAN MALE 29 0.664a 21 0.683a 18 0.669a 100 0.688a FEMALE 77 0.818b 16 0.817b 33 0.821b 51 0.824b Means sharing the same superscript letter did not differ significantly from one another in Tukeys pairwise post hoc test of the log transformed data (P<0.05).

Summary of the analysis of carapace length/rostral length ratios: Newquay December to March 2008/9 It can be seen from Figure 77, that the difference between the male and female mean log ratios of prawns from Newquay was highly significant (ANOVA, F1,1343 = 2781.75, P<0.001). This indicates that for any given carapace length male rostra were longer than female rostra.It is also clear from Figure 77 and Table 21 that there were no differences in either the male or female log ratios between months.

NB: The full ANOVA and post hoc test results can be found in Appendix XI.

96 MEAN l og CARAPACE L ENGT H/ ROST RAL L ENGTH RATI OS +/- 95 % C I' s Log r ati o ︵ ︶

-0.05

-0.06

-0.07

-0.08

-0.09

-0.1

-0.11

-0.12 FEMALE MALE -0.13

-0.14

-0.15

-0.16

-0.17

-0.18

-0.19 FEBRUARY MARCH APRIL MAY OCTOBER Mont h -0.2

Figure 78: Mean log carapace length/rostral length ratios: Morfa Nefyn, February to May plus October 2009 (error bars indicate 95% confidence intervals for the means).

Table 22: Mean log carapace length/rostral length ratios Morfa Nefyn, February to May plus October 2009 MEAN log CARAPACE LENGTH/ROSTRAL LENGTH RATIOS MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009 MONTH FEBRUARY MARCH APRIL MAY OCTOBER SEX N MEAN N MEAN N MEAN N MEAN N MEAN MALE 62 -0.173a 53 -0.167a 160 -0.166a 54 -0.167a 21 -0.165a FEMALE 12 -0.089bc 36 -0.089bc 143 -0.085c 58 -0.081c 168 -0.095b Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

97 Table 22.1: Mean carapace length/rostral length ratios Morfa Nefyn, February to May plus October 2009 MEAN CARAPACE LENGTH/ROSTRAL LENGTH RATIOS MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009 MONTH FEBRUARY MARCH APRIL MAY OCTOBER SEX N MEAN N MEAN N MEAN N MEAN N MEAN MALE 62 0.672a 53 0.682a 160 0.683a 54 0.682a 21 0.685a FEMALE 12 0.824bc 36 0.819bc 143 0.824c 58 0.831c 168 0.805b Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test of the log transformed data (P<0.05).

Summary of the analysis of carapace length/rostral length ratios: Morfa Nefyn, February to May plus October 2009 The difference between the male and female mean log ratios of prawns from Morfa

Nefyn was highly significant (ANOVA, F1,757 = 1500.74, P<0.001). This indicates that for any given carapace length male rostra were longer than female rostra.

It can be seen from Figure 78 and Table 22, that there was no seasonal variation between the mean log ratio values of males. However, there was some variation in the female mean log ratio values between months. Relative to their carapace female prawns had significantly longer rostra in October than they did in April (Tukey’s adjusted P- value = 0.0498) and May (Tukey’s adjusted P-value = 0.0346).

NB: The full ANOVA and post hoc test results can be found in Appendix XI.

98 4.2.5 Carapace length and wet weight

RELATIONSHIP BETWEEN CARAPACE LENGTH & WET WEIGHT: BOTH SEXES, ALL LOCATIONS 2008/9 Wet weight (g)

15 y = 0.0016x2.8549 14 R2 = 0.94

13

12

11

10

9 FEMALE N = 1056 MALE N = 733 8

7

6

5

4

3 y = 0.0028x2.6613

2 R2 = 0.93

1

Carapace length (mm) 0 7 8 9 10111213141516171819202122232425 Figure 79: The relationship between carapace length and wet weight both sexes, all locations 2008/9 (The trend lines were fitted using the power function).

It can be seen from Figure 79 that females were generally larger than males and that the relationship between carapace length and wet weight of both sexes was clearly curvilinear (i.e. allometric). Although the difference in the curves of the two fitted lines was not great, the two lines do cross (at the point where carapace length = 18mm and wet weight = 6.138g). This indicates that the weight of females increased at a greater rate than males as size increased.

99 RELATIONSHIP BETWEEN log CARAPACE LENGTH & log WET WEIGHT: BOTH SEXES, ALL LOCATIONS 2008/9 Wet weight (log g)

1.3

1.2

1.1

1 y = 2.9398x -2.8913

R2 = 0.94 0.9

0.8

0.7 FEMALE N = 1056 0.6 MALE N = 733

0.5

0.4

0.3

0.2

0.1 y = 2.7663x -2.6783

0 R2 = 0.93

-0.1

-0.2

-0.3

Carapace length (log mm) -0.4 0.9 1 1.1 1.2 1.3 1.4

Figure 80: The relationship between log carapace length and log wet weight: both sexes, all locations 2008/9. (The linear trend lines were fitted using reduced major axis regression)

It can be seen from Figure 80 that log transformation increased linearity and reduced the spread of the data. It is clear that the linear trend line fitted to the female data is very slightly steeper than the trend line fitted to the male data. This indicates more clearly than the plot of untransformed data shown in Figure 79 that the weight of females increased at a greater rate than males as size increased.

100 MEAN l og CARAPACE L ENGT H/ WET WEI GHT RATI OS +/- 95 % C I' s ︵ ︶ Log r ati o

0.65

0.6

MALE FEBRUARY 0.55 MALE MARCH FEMALE FEBRUARY FEMALE MARCH

0.5

0.45

0.4 NE WQUAY ABERYST WYTH MORFA NEFYN AML WCH Locati on

Figure 81: Mean log carapace length/wet weight ratios: all locations, February & March 2009 (error bars indicate 95% confidence intervals for the means).

Table 23: Mean log carapace length/wet weight ratios: all locations, February & March 2009

MEAN log CARAPACE LENGTH/WET WEIGHT RATIOS FEBRUARY & MARCH 2009 LOCATION NEWQUAY ABERYSTWYTH MORFA NEFYN AMLWCH SEX/MONTH N MEAN N MEAN N MEAN N MEAN FEBRUARY ♂ 18 0.618ad 6 0.597ad 60 0.640a 7 0.523ab MARCH ♂ 94 0.631a 140 0.638a 48 0.624a 22 0.583ad FEBRUARY ♀ 33 0.446bc 23 0.454bc 12 0.516bcd 58 0.447bc MARCH ♀ 44 0.465bc 208 0.446bc 34 0.500bc 129 0.445c Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

101 Table 23.1: Mean carapace length/wet weight ratios: all locations, February & March 2009

MEAN CARAPACE LENGTH/WET WEIGHT RATIOS FEBRUARY & MARCH 2009 LOCATION NEWQUAY ABERYSTWYTH MORFA NEFYN AMLWCH SEX/MONTH N MEAN N MEAN N MEAN N MEAN FEBRUARY ♂ 18 4.236ad 6 3.967ad 60 4.426a 7 3.362ab MARCH ♂ 94 4.291a 140 4.503a 48 4.245a 22 3.857ad FEBRUARY ♀ 33 2.814bc 23 2.863bc 12 3.373bcd 58 2.914bc MARCH ♀ 44 2.949bc 208 2.885bc 34 3.280bc 129 2.858c Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test of the log transformed data (P<0.05).

Summary of the analysis of carapace length/wet weight ratios: all locations, February & March 2009 The mean log carapace length/wet weight ratios of female prawns caught at all locations in February and March was found to be significantly different to the mean log carapace length/wet weight ratios of male prawns (ANOVA, F1,920 = 931.55, P<0.001). However, Tukey’s post hoc test revealed one exception to the general picture; no difference was found between males and females captured at Amlwch in February.

It can be seen from Figure 81 and Table 23 that there were no statistically significant differences between the monthly means of either sex at any of the locations, nor between any of the location means.

NB: The full ANOVA and post hoc test results can be found in Appendix XII.

102 MEAN l og CARAPACE L ENGT H/ WET WEI GHT RATI OS +/- 95 % C I' s ︵ ︶ Log r ati o

0.65

0.6

0.55

MALE ABERYST WYTH MALE MORFA NEFYN FEMALE ABERYST WYTH 0.5 FEMALE MORFA NEFYN

0.45

0.4

0.35 FEBRUARY MARCH APRI L MAY Locati on

Figure 82: Mean log carapace length/wet weight ratios: Aberystwyth & Morfa Nefyn, February to May 2009 (error bars indicate 95% confidence intervals for the means).

Table 24: Mean log carapace length/wet weight ratios: Aberystwyth & Morfa Nefyn, February to May 2009

MEAN log CARAPACE LENGTH/WET WEIGHT RATIOS ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY 2009 MONTH FEBRUARY MARCH APRIL MAY LOCATION/SEX N MEAN N MEAN N MEAN N MEAN aef a af af ABERYSTWYTH ♂ 6 0.597 140 0.638 70 0.609 25 0.587 MORFA NEFYN ♂ 60 0.640a 48 0.624a 134 0.602af 46 0.646a ABERYSTWYTH ♀ 23 0.454bcd 208 0.446cd 68 0.413bc 44 0.407bc def de b bc MORFA NEFYN ♀ 12 0.516 34 0.500 128 0.411 47 0.411 Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

103 Table 24.1: Mean carapace length/wet weight ratios: Aberystwyth & Morfa Nefyn, February to May 2009

MEAN CARAPACE LENGTH/WET WEIGHT RATIOS ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY 2009 MONTH FEBRUARY MARCH APRIL MAY LOCATION/SEX N MEAN N MEAN N MEAN N MEAN aef a af af ABERYSTWYTH ♂ 6 3.967 140 4.503 70 4.158 25 3.886 MORFA NEFYN ♂ 60 4.426a 48 4.245a 134 4.066af 46 4.612a ABERYSTWYTH ♀ 23 2.863bcd 208 2.886cd 68 2.610bc 44 2.630bc MORFA NEFYN ♀ 12 3.373def 34 3.280de 128 2.618b 47 2.689bc Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test of the log transformed data (P<0.05).

Summary of the analysis of carapace length/wet weight ratios: Aberystwyth & Morfa Nefyn, February to May 2009 It can be seen from Figure 82 that the difference between the mean log carapace length/wet weight ratios of female prawns caught at both Aberystwyth and Morfa Nefyn was significantly different to the male ratios in all months (ANOVA, F1,1077 = 1229.80, P<0.001).

Seasonal variation in the mean log carapace length/wet weight ratios was most pronounced in the female samples from Morfa Nefyn. The mean log ratio values clearly declined from February to May, but the only statistically significant difference found was between March and April (Tukey’s adjusted P-value = 0.0001). There were no statistically significant seasonal variations in the mean log carapace length/wet weight ratios of female prawns from Aberystwyth, nor any statistically significant seasonal variations in the mean log carapace length/wet weight ratio of male prawns from Aberystwyth or Morfa Nefyn.

NB: The full ANOVA and post hoc test results can be found in Appendix XII.

104 MEAN l og CARAPACE L ENGT H/ WET WEI GHT RATI OS +/- 95 % C I' s ︵ ︶ Log r ati o

MALE FEMALE

0.65

0.6

0.55

0.5

0.45

0.4 DECEMBER JANUARY FEBRUARY MARCH Mont h

Figure 83: Mean log carapace length/wet weight ratios: Newquay, December to March 2008/9 (error bars indicate 95% confidence intervals for the means).

Table 25: Mean log carapace length/wet weight ratios: Newquay, December to March 2008/9 MEAN log CARAPACE LENGTH/WET WEIGHT RATIOS NEWQUAY DECEMBER TO MARCH 2008/9 MONTH DECEMBER JANUARY FEBRUARY MARCH SEX N MEAN N MEAN N MEAN N MEAN MALE 27 0.596a 18 0.530ac 18 0.570a 94 0.553a FEMALE 75 0.465bc 15 0.420b 33 0.446b 44 0.459b Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

105 Table 25.1: Mean carapace length/wet weight ratios: Newquay, December to March 2008/9

MEAN CARAPACE LENGTH/WET WEIGHT RATIOS NEWQUAY DECEMBER TO MARCH 2008/9

MONTH DECEMBER JANUARY FEBRUARY MARCH SEX N MEAN N MEAN N MEAN N MEAN MALE 27 4.288a 18 3.397ac 18 3.833a 94 3.620a FEMALE 75 3.109bc 15 2.638b 33 2.809b 44 2.897b Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test of the log transformed data (P<0.05)

Summary of the analysis of carapace length/wet weight ratios: Newquay, December to March 2008/9 It can be seen from Figure 83, and the results of the post hoc analysis in Table 25, that the difference in mean log carapace length/wet weight ratios between the sexes was highly significant (ANOVA, F1,316 = 99.41, P<0.001).

Although there was some variation between December and March in the mean log carapace length/wet weight ratios of both male and female prawns, none of the differences were statistically significant.

NB: The full ANOVA and post hoc test results can be found in Appendix XII.

106 MEAN l og CARAPACE L ENGTH/ WET WEI GHT RATI OS +/- 95 % C I' s ︵ ︶ Log r ati o

0.65

0.6

0.55 MALE FEMALE

0.5

0.45

0.4

0.35 FEBRUARY MARCH APRIL MAY OCTOBER Mont h

Figure 84: Mean log carapace length/wet weight ratios: Morfa Nefyn, February to May plus October 2009 (error bars indicate 95% confidence intervals for the means).

Table 26: Mean log carapace length/wet weight ratios: Morfa Nefyn, February to May plus October 2009 MEAN log CARAPACE LENGTH/ROSTRAL LENGTH RATIOS MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009 MONTH FEBRUARY MARCH APRIL MAY OCTOBER SEX N MEAN N MEAN N MEAN N MEAN N MEAN MALE 60 0.640a 48 0.624a 134 0.602a 46 0.646a 18 0.621a FEMALE 12 0.516b 34 0.500b 128 0.411c 47 0.411c 138 0.485b Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

107 Table 26.1: Mean carapace length/wet weight ratios: Morfa Nefyn, February to May plus October 2009 MEAN CARAPACE LENGTH/ROSTRAL LENGTH RATIOS MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009 MONTH FEBRUARY MARCH APRIL MAY OCTOBER SEX N MEAN N MEAN N MEAN N MEAN N MEAN MALE 60 4.426a 48 4.245a 134 4.066a 46 4.612a 18 4.193a FEMALE 12 3.373b 34 3.280b 128 2.618c 47 2.689c 138 3.074b Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test of the log transformed data (P<0.05).

Summary of the analysis of carapace length/wet weight ratios: Morfa Nefyn, February to May plus October 2009 The difference in the mean log carapace length/wet weight ratios between the male and female prawns captured at Morfa Nefyn was highly significant (ANOVA, F1,655 = 766.99, P<0.001).

It is evident from Figure 84 and Table 26 that the mean log carapace length/wet weight ratios of female prawns captured in both April and May were significantly different from the log ratio values for all other months. However, no differences were found between the mean log carapace length/wet weight ratios of the females captured in April and May, or between females captured in February, March and October. No statistically significant differences were found in the mean log carapace length/wet weight ratios of male prawns between February and October.

NB: The full ANOVA and post hoc test results can be found in Appendix XII.

108 4.2.6 The number of dorsal teeth on the rostrum

MEAN NU MBER OF DORSAL TEET H +/- 95 % C I' s ︵ ︶ No. of t eet h

7. 4

7. 3

7. 2

7. 1

6. 97

6. 8

6. 7

6. 6

6. 5

6. 4 NE WQUAY ABERYST WYTH MORFA NEFYN AML WCH FEMALE MALE Loc ati on 6. 3

Figure 85: Mean number of dorsal teeth on the rostrum for all locations, February + March 2009 (error bars indicate 95% confidence intervals for the means).

Table 27: Mean numbers of dorsal teeth on the rostrum for all locations, February + March 2009

MEAN NUMBER OF DORSAL TEETH (FEBRUARY + MARCH) 2009 LOCATION NEWQUAY ABERYSTWYTH MORFA NEFYN AMLWCH SEX N MEAN N MEAN N MEAN N MEAN MALE 118 7.06abc 148 7.03abc 113 6.90ac 36 7.08abc FEMALE 84 7.13ab 233 7.13ab 48 6.75c 235 7.17ab

Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

109 Summary of the analyses of the number of dorsal teeth on the rostrum: all locations, February + March 2009 It is evident from Figure 85 that there were no significant differences in the mean number of dorsal teeth between the sexes at any of the sample locations in February and March. It was found that there was a significant variation in the mean number of dorsal teeth between locations (ANOVA, F3,999 = 6.73, P<0.001). However, post hoc tests revealed that the statistically significant differences were only between the females from Morfa Nefyn and the females from Newquay (Tukey’s adjusted P-value = 0.0398), Aberystwyth (Tukey’s adjusted P-value = 0.0213), and Amlwch (Tukey’s adjusted P- value = 0.0020). In other words, female prawns collected from Morfa Nefyn in February and March had significantly less dorsal teeth than females from the other locations.

NB: ANCOVA of the number of dorsal teeth and carapace length vs location, found that the mean number of teeth on the rostrum (and hence the results of the ANOVA) were not influenced by carapace length. The full ANOVA and post hoc test results can be found in Appendix XIIIi and the results of the ANCOVA can be found in Appendix XIIIii.

110 MEAN NU MBER OF DORSAL TEET H: NE WQUAY 2008/ 9 +/- 95 % C I' s ︵ ︶ No. of t eet h

7. 6

7. 5

7. 4

7. 3

7. 2

7. 1

6. 97

6. 8

6. 7

6. 6

6. 5

6. 4 DECEMBER JANUARY FEBRUARY MARCH FEMALE MALE Mont h 6. 3

Figure 86: Mean number of dorsal teeth on the rostrum: Newquay, December to March 2008/9 (error bars indicate 95% confidence intervals for the means).

Table 28: Mean number of dorsal teeth on the rostrum: Newquay, December to March 2008/9

MEAN NUMBER OF DORSAL TEETH NEWQUAY DECEMBER 2008 TO MARCH 2009 MONTH DECEMBER JANUARY FEBRUARY MARCH SEX N MEAN N MEAN N MEAN N MEAN MALE 29 6.79 21 7.19 18 6.89 100 7.09 FEMALE 77 7.10 16 7.19 33 7.12 51 7.14

Summary of the analyses of the number of dorsal teeth on the rostrum: Newquay, December to March 2008/9 An ANOVA of the number of dorsal teeth of the Newquay samples vs month and sex found no significant differences between any of the means (see Appendix XIIIi). These results are reflected in Figure 86 and Table 28.

111 4.2.7 The number of ventral teeth on the rostrum

MEAN NU MBER OF VENT RAL TEET H +/- 95 % C I' s ︵ ︶ No. of t eet h

5. 1

4. 95

4. 8

4. 7

4. 6

4. 5

4. 4

4. 3

4. 2 NE WQUAY ABERYST WYTH MORFA NEFYN AML WCH FEMALE MALE Loc ati on 4. 1

Figure 87: Mean number of ventral teeth on the rostrum for all locations, February + March 2009 (error bars indicate 95% confidence intervals for the means).

Table 29: Mean numbers of ventral teeth on the rostrum for all locations, February + March 2009

MEAN NUMBER OF VENTRAL TEETH (FEBRUARY + MARCH) 2009 LOCATION NEWQUAY ABERYSTWYTH MORFA NEFYN AMLWCH

SEX N MEAN N MEAN N MEAN N MEAN ab ac ac abc MALE 118 4.65 148 4.74 113 4.69 36 4.69 FEMALE 84 4.92c 233 4.74ac 48 4.38b 235 4.83ac Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

112 Summary of the analyses of the number of ventral teeth on the rostrum: all locations, February + March 2009 An ANOVA of the number of ventral teeth vs location, month and sex found a significant interaction between the location and sex means (F3,999 = 7.13, P<0.001). It is evident from Figure 87 and Table 29 that the source of the interaction was the differences in the number of ventral teeth between the sexes in the samples collected from Newquay and Morfa Nefyn. In the samples collected from Newquay the females had significantly more ventral teeth on their rostra than the males (Tukey’s adjusted P- value = 0.0433). In the samples collected from Morfa Nefyn the opposite was true; females had significantly fewer ventral teeth than males (Tukey’s adjusted P-value = 0.0479).

The ANOVA also found that there was a significant variation in the mean number of ventral teeth between locations (ANOVA, F3,999 = 4.56, P<0.001). Post hoc tests (Table 29) revealed that the statistically significant differences were only between the females from Morfa Nefyn and the females from Newquay (Tukey’s adjusted P-value = <0.0001), Aberystwyth (Tukey’s adjusted P-value = 0.0029), and Amlwch (Tukey’s adjusted P-value = <0.0001). In other words, female prawns collected from Morfa Nefyn in February and March had significantly less ventral teeth than females from the other locations.

NB: ANCOVA of the number of female ventral teeth and carapace length vs location, found that the mean number of teeth on the rostra of females (and hence the results of the ANOVA) was not influenced by carapace length. The full ANOVA and post hoc test results can be found in Appendix XIIIi and the results of the ANCOVA can be found in Appendix XIIIii.

113 MEAN NU MBER OF VENT RAL TEETH: NE WQUAY 2008/ 9 +/- 95 % C I' s ︵ ︶ No. of t eet h

5. 1

4. 95

4. 8

4. 7

4. 6

4. 5

4. 4

4. 3

4. 2

FEMALE DECEMBER JANUARY FEBRUARY MARCH MALE Mont h 4. 1

Figure 88: Mean number of ventral teeth on the rostrum: Newquay, December to March 2008/9 (error bars indicate 95% confidence intervals for the means).

Table 30: Mean number of ventral teeth on the rostrum: Newquay, December to March 2008/9

MEAN NUMBER OF VENTRAL TEETH NEWQUAY DECEMBER 2008 TO MARCH 2009 MONTH DECEMBER JANUARY FEBRUARY MARCH SEX N MEAN N MEAN N MEAN N MEAN MALE 29 4.48a 21 4.67ab 18 4.61ab 100 4.66ab FEMALE 77 4.79ab 16 4.63ab 33 4.85ab 51 4.96b (Means sharing the same superscript letter did not differ significantly from one another in Tukey’s pairwise post hoc test (P<0.05).

Summary of the analyses of the number of ventral teeth on the rostrum: Newquay, December to March 2008/9

There was a significant difference between the sex means (ANOVA, F1,337 = P<0.01). It is, however, evident from Figure 88 and Table 30 that the source of the difference found by the ANOVA was solely between the males collected in December and the females collected in March (Tukey’s adjusted P-value = 0.0104). The difference was, therefore, of little relevance. NB: The full ANOVA and post hoc test results can be found in Appendix XIIIi.

114 4.2.8 Size at sexual maturity

OVIGEROUS FEMALES: NEWQUAY FEBRUARY 2009 Proportion ovigerous (%)

100

-1.415x 90 N = 15 y = 103/(1+18.75e )

80

70

60

50 CL50 = 18.12mm

40

30

20

10

Carapace length (mm) 0 15 16 17 18 19 20 21 22 23

Figure 89: Logistic fit, ovigerous females: Newquay, February 2009.

115 OVIGEROUS FEMALES: NEWQUAY MARCH 2009 Proportion ovigerous (%)

100

-1.745x 90 N = 38 y = 99.72/(1+46.43e )

80

70

60

50 CL50 = 18.83mm

40

30

20

10

Carapace length (mm) 0 15 16 17 18 19 20 21 22 23 Figure 90: Logistic fit, ovigerous females: Newquay, March 2009.

OVIGEROUS FEMALES: ABERYSTWYTH MARCH 2009 Proportion ovigerous (%)

100

90 N = 115 y = 98.87/(1+60.91e-1.365x)

80

70

60

50 CL50 = 18.65mm

40

30

20

10

Carapace length (mm) 0 15 16 17 18 19 20 21 22 23 Figure 91: Logistic fit ovigerous females: Aberystwyth, March 2009.

116 OVIGEROUS FEMALES: ABERYSTWYTH APRIL 2009 Proportion ovigerous (%)

100

90 N = 228 y = 101.3/(1+84.6e-1.374x)

80

70

60

50 CL50 = 19.04mm

40

30

20

10

Carapace length (mm) 0 15 16 17 18 19 20 21 22 23 Figure 92: Logistic fit, ovigerous females: Aberystwyth, April 2009.

OVIGEROUS FEMALES: ABERYSTWYTH MAY 2009 Proportion ovigerous (%)

100

90 N = 66 y = 100.4/(1+32.58e-1.293x)

80

70

60

50 CL50 = 19.05mm

40

30

20

10

Carapace length (mm) 0 15 16 17 18 19 20 21 22 23 Figure 93: Logistic fit, ovigerous females: Aberystwyth, May 2009.

117 OVIGEROUS FEMALES: MORFA NEFYN MARCH 2009 Proportion ovigerous (%)

100

90 N = 13 y = 100.3/(1+26.89e-1.241x)

80

70

60

50 CL50 = 18.06mm

40

30

20

10

Carapace length (mm) 0 15 16 17 18 19 20 21 22 23 Figure 94: Logistic fit, ovigerous females: Morfa Nefyn, March 2009.

OVIGEROUS FEMALES: MORFA NEFYN APRIL 2009 Proportion ovigerous (%)

100

90 N = 166

y = 96.1/(1+15.849e-1.048x) 80

70

60

50 CL50 = 18.87mm

40

30

20

10

Carapace length (mm) 0 15 16 17 18 19 20 21 22 23 Figure 95: Logistic fit, ovigerous females: Morfa Nefyn, April 2009.

118 OVIGEROUS FEMALES: MORFA NEFYN MAY 2009 Proportion ovigerous (%)

100

90 N = 80

80 y = 97.81/(1+23.5e-0.9985x)

70

60

50 CL50 = 19.78mm

40

30

20

10

Carapace length (mm) 0 15 16 17 18 19 20 21 22 23 Figure 96: Logistic fit, ovigerous females: Morfa Nefyn, May 2009.

OVIGEROUS FEMALES: AMLWCH FEBRUARY 2009 Proportion ovigerous (%)

100

90 N = 56

y = 97.34/(1+8.144e-1.087x) 80

70

60

50 CL50 = 18.60mm

40

30

20

10

Carapace length (mm) 0 15 16 17 18 19 20 21 22 23 Figure 97: Logistic fit, ovigerous females: Amlwch, February 2009.

119 OVIGEROUS FEMALES: AMLWCH MARCH 2009 Proportion ovigerous (%)

100

90 N = 44 y = 98.48/(1+12.34e-1.27x) 80

70

60

50 CL50 = 18.53mm

40

30

20

10

Carapace length (mm) 0 15 16 17 18 19 20 21 22 23 Figure 98: Logistic fit, ovigerous females: Amlwch, March 2009. Summary of the analyses of the size at sexual maturity of the sample populations

CL50 VALUES OF OVIGEROUS FEMALES

20

19

18 Carapace length (mm)

17 FEBRUA RY MA RCH A PRIL MA Y

NEWQUA Y 18.12 18.83 ABERYSTWYTH 18.65 19.04 19.05 MORFA NEFY N 18.06 18.87 19.78 AMLWCH 18.60 18.53 Month

Figure 99: Summary of CL50 values of ovigerous females for all sample populations 2009

120 It can be seen from the individual logistic fits in Figures 89 to 98 and in the summary graph in Figure 99, that the CL50 values of the Amlwch samples decreased between February and March, whereas the opposite was true of the sample populations from

Newquay. It is also evident that there was only a slight increase in the CL50 values of the

Aberystwyth samples between March and May, but a considerable increase in the CL50 values of the samples collected from Morfa Nefyn during the same period.

121 MINIMUM CARAPACE LENGTHS OF OVIGEROUS FEMALES

17

16 Carapace length (mm)

15 FEBRUA RY MA RCH A PRIL MA Y

NEWQUA Y 16.08 16.63 ABERYSTWYTH 15.62 15.82 16.35 MORFA NEFY N 15.41 16.16 16.58 AMLWCH 16.62 16.52 Month

Figure 100: Summary of the minimum carapace lengths of ovigerous females for all sample populations 2009

It can be seen from Figure 100 that in February the minimum carapace length of ovigerous females was considerably less in the samples from Newquay than in the samples from Amlwch, but in March the minimum size of the Amlwch samples was greater. In other words the minimum carapace length of the ovigerous females in the Amlwch sample decreased between February and March, whereas the opposite was true of the sample populations from Newquay. It is also evident that the minimum carapace length of ovigerous females from Aberystwyth in April and May was less than that in the Morfa Nefyn samples. Although the opposite was true in March, there was an increase in the minimum carapace length of ovigerous females in both the Aberystwyth and Morfa Nefyn samples between March and May.

122 4.3 FECUNDITY: EGG NUMBER & EGG VOLUME

123 4.3.1 Egg number

RELATIONSHIP BETWEEN CARAPACE LENGTH & EGG NUMBER: NEWQUAY 2009 Egg number

5000

4500 N = 22

4000

3500

3000

2500

2000

1500

Carapace Length (mm) 1000 15 16 17 18 19 20 21 22

Figure 101: Relationship between carapace length and egg number: Newquay February + March 2009

The result of Spearman’s correlation test was rs = 0.49. This suggests a modest positive correlation between carapace length and egg number. The result was referred to a Table of critical values of rs and the Ho that the data were not correlated was rejected. It was concluded that the correlation was significant (P<0.05).

124 RELATIONSHIP BETWEEN CARAPACE LENGTH & EGG NUMBER: ABERYSTWYTH 2009 Egg number

7000

6500 N = 20

6000

5500

5000

4500

4000

3500

3000

2500

2000

1500

Carapace Length (mm) 1000 15 16 17 18 19 20 21 22 Figure 102: Relationship between carapace length and egg number: Aberystwyth, February + March 2009

The result of Spearman’s correlation test was rs = 0.24. At best this suggests a weak positive correlation between carapace length and egg number. The result was referred to a Table of critical values of rs and the Ho that the data were not correlated was accepted. It was concluded that the correlation was not significant.

125 RELATIONSHIP BETWEEN CARAPACE LENGTH & EGG NUMBER: MORFA NEFYN 2009 Egg number

5000

4500 N = 9

4000

3500

3000

2500

2000

1500

Carapace Length (mm) 1000 15 16 17 18 19 20 21 22 Figure 103: Relationship between carapace length and egg number: Morfa Nefyn, February + March 2009

The result of Spearman’s correlation test was rs = 0.85. This suggests a strong positive correlation between carapace length and egg number. The result was referred to a Table of critical values of rs and the Ho that the data were not correlated was rejected. It was concluded that the correlation was highly significant (P<0.01).

126 RELATIONSHIP BETWEEN CARAPACE LENGTH & EGG NUMBER: AMLWCH 2009 Egg number

5000

4500 N = 24

4000

3500

3000

2500

2000

1500

Carapace Length (mm) 1000 15 16 17 18 19 20 21 22 Figure 104: Relationship between carapace length and egg number: Amlwch, February + March 2009

The result of Spearman’s correlation test was rs = 0.86. This suggests a strong positive correlation between carapace length and egg number. The result was referred to a Table of critical values of rs and the Ho that the data were not correlated was rejected. It was concluded that the correlation was highly significant (P<0.01).

Summary of the correlation analyses of the relationship between carapace length and egg number It can be seen from Figures 101 to 104 that, although the correlation between egg number and carapace length was statistically significant in most cases, there was not a particularly strong linear relationship between carapace length and egg number in the samples from Newquay, Aberystwyth and Morfa Nefyn. In contrast, the plot for Amlwch (Figure 102) does suggest a clearer linear relationship between the variables.

127 MEAN EGG NUMBERS 2009 ADJUSTED FOR LENGTH (+/- 95% C I's) Egg number

N = 20

N = 9

3500 N = 24 3455 (3441)

3172 (3181) 3092 N = 22 (3026) 3000

2711 (2742)

2500

AMLWCH NEWQUAY ABERYSTWYTH MORFA NEFYN Location 2000

Figure 105: Mean egg numbers, all locations, February + March 2009 (adjusted for length by ANCOVA). (Error bars indicate 95% confidence intervals for the adjusted means; the original unadjusted means are shown in brackets).

Summary of the ANCOVA of the relationship between carapace length and egg number The ANCOVA found a significant difference in the mean number of eggs between locations (F3,73 = 4.703, P<0.01). No significant difference was found in the regression slopes between locations (P<0.05). It can be seen from Figures 101 to 104 that there was some variation between locations in both maximum and minimum carapace length of the ovigerous females sampled. The ANCOVA accounted for the effect of these size variations on the mean number of eggs by treating carapace length as a covariant term in the model. The lack of overlapping error bars for the Newquay and Aberystwyth means in Figure 105 indicates that the source of the significant difference in the (adjusted) mean number of eggs found by the ANCOVA was between these locations. NB: The full ANCOVA results can be found in Appendix XIV.

The mean fecundity of all sample populations combined was 3103 eggs. Female prawns from Aberystwyth were the most fecund, producing an average of 3455 eggs and those from Newquay the least fecund, producing an average of 2711 eggs.

128 4.3.2 Egg volume

RELATIONSHIP BETWEEN CARAPACE LENGTH & EGG VOLUME: NEWQUAY 2009 Egg volume (mm3)

0.17

0.16 N = 19

0.15

0.14

0.13

0.12

0.11

Carapace Length (mm) 0.1 15 16 17 18 19 20 21 22 Figure 106: Relationship between carapace length and egg volume: Newquay, February + March 2009

The result of Spearman’s correlation test was rs = 0.38. This suggests a weak positive correlation between carapace length and egg volume. The result was referred to a Table of critical values of rs and the Ho that the data were not correlated was accepted. It was concluded that the correlation was not significant.

129 RELATIONSHIP BETWEEN CARAPACE LENGTH & EGG VOLUME: ABERYSTWYTH 2009 Egg volume (mm3)

0.22

0.21 N = 17

0.2

0.19

0.18

0.17

0.16

0.15

0.14

0.13

0.12

0.11

Carapace Length (mm) 0.1 15 16 17 18 19 20 21 Figure 107: Relationship between carapace length and egg volume: Aberystwyth, February + March 2009

The result of Spearman’s correlation test was rs = 0.49. This suggests a modest positive correlation between carapace length and egg volume. The result was referred to a Table of critical values of rs and the Ho that the data were not correlated was rejected. It was concluded that the correlation was significant (P<0.05).

130 RELATIONSHIP BETWEEN CARAPACE LENGTH & EGG VOLUME: MORFA NEFYN 2009 Egg volume (mm3)

0.155

0.15 N = 9

0.145

0.14

0.135

0.13

0.125

0.12

0.115

0.11

0.105

Carapace Length (mm) 0.1 16 17 18 19 20 21 Figure 108: Relationship between carapace length and egg volume: Morfa Nefyn, February + March 2009

The result of Spearman’s correlation test was rs = 0.03. This suggests a very weak positive correlation between carapace length and egg volume. The result was referred to a Table of critical values of rs and the Ho that the data were not correlated was accepted. It was concluded that the correlation was not significant.

131 RELATIONSHIP BETWEEN CARAPACE LENGTH & EGG VOLUME: AMLWCH 2009 Egg volume (mm3)

0.2

0.19 N = 11

0.18

0.17

0.16

0.15

0.14

0.13

0.12

0.11

Carapace Length (mm) 0.1 15 16 17 18 19 20 21 22 Figure 109: Relationship between carapace length and egg volume: Amlwch, February + March 2009

The result of Spearman’s correlation test was rs = 0.66. This suggests a modest positive correlation between carapace length and egg volume. The result was referred to a Table of critical values of rs and the Ho that the data were not correlated was rejected. It was concluded that the correlation was significant (P<0.05).

Summary of the correlation analyses of the relationship between carapace length and egg volume It is evident from the spread of data in Figures 106 to 109 that there were no really clear linear relationships between egg volume and carapace length. Although Spearman’s correlation analyses of the data from Aberystwyth and Amlwch yielded significant results, the two variables appear to be poorly correlated.

132 MEAN l og EGG VOLUME +/- 95 % C I' s ︵ ︶ l og Egg v ol u me

N = 17 N = 11

-0. 8 (a)

N = 19 (ab)

N = 9

-0. 85 (ab)

(b) -0. 9

-0. 95 NEWQUAY ABERYSTWYTH MORFA NEFYN AMLWCH Loc ati on

Figure 110: Mean log egg volumes, all locations, February + March 2009 (error bars indicate 95% confidence intervals for the means: the means that did not significantly differ from one another in Tukey’s pairwise post-hoc test are indicated by the same letter in brackets).

A one way ANOVA (using log transformed data) of egg volume vs location found a significant difference in the location means. (F3,52 = 4.27, P<0.01). However, Tukey’s post hoc test revealed that the significant difference found by the ANOVA was solely between the samples from Aberystwyth and Morfa Nefyn (Tukey’s adjusted P-value = 0.0153). NB: The full ANOVA and post hoc test results can be found in Appendix XIV.

Table 31: Summary of egg volumes for all locations, February + March 2009

EGG VOLUME/PRAWN (mm3) 2009 (FEBRUARY & MARCH COMBINED) LOCATION N MINIMUM MAXIMUM MEAN S.D. NEWQUAY 19 0.120 0.163 0.140 0.013 ABERYSTWYTH 17 0.112 0.220 0.159 0.030 MORFA NEFYN 9 0.120 0.145 0.130 0.009 AMLWCH 11 0.116 0.201 0.154 0.025 ALL 56 0.112 0.220 0.147 0.024

133 4.4 THE SALEABLE PROPORTION OF THE CATCH SAMPLES

134 PROPORTION OF SALEABLE/NON-SALEABLE PRAWNS: NEWQUAY 2008/9

100

80

60

40 Percentage

20

0 DECEMBER JA NUA RY FEBRUA RY MA RCH

N 130 51 61 192 MALES <10mm CW 20.8 45.1 27.9 54.7 FEMA LES <10mm CW 5.4 0.0 0.0 2.1 MA LES ≥10mm CW 8.5 11.8 9.8 10.4 FEMA LES ≥10mm CW 65.4 43.1 62.3 32.8 Month

Figure 111: Proportion of saleable/non-saleable prawns in samples: Newquay 2008/9 (≥10mm CW = saleable, <10mm CW = non-saleable).

PROPORTION OF SALEABLE/NON-SALEABLE BIOMASS: NEWQUAY 2008/9

100

80

60

40 Percentage

20

0 DECEMBER JA NUA RY FEBRUA RY MA RCH

N 130 51 61 192 MALES <10mm CW 11.1 31.3 16.9 41.1 FEMALES <10mm CW 1.3 0.0 0.0 1.3 MA LES ≥10mm CW 6.6 10.6 8.0 10.0 FEMA LES ≥10mm CW 81.0 58.2 75.1 47.6 Month

Figure 112: Proportion of saleable/non-saleable prawn biomass in samples: Newquay 2008/9 (≥10mm CW = saleable, <10mm CW = non-saleable).

135 PROPORTION OF SALEABLE/NON-SALEABLE PRAWNS: ABERYSTWYTH 2009

100

80

60

40 Percentage

20

0 FEBRUA RY MA RCH A PRIL MA Y

N 39 445 486 111 MALES <10mm CW 17.9 32.8 31.7 19.8 FEMALES <10mm CW 2.62.20.40.9 MA LES ≥10mm CW 0.0 7.2 15.6 19.8 FEMA LES ≥10mm CW 79.5 57.8 52.3 59.5 Month

Figure 113: Proportion of saleable/non-saleable prawns in samples: Aberystwyth 2009 (≥10mm CW = saleable, <10mm CW = non-saleable).

PROPORTION OF SALEABLE/NON-SALEABLE BIOMASS: ABERYSTWYTH 2009

100

80

60

40 Percentage

20

0 FEBRUA RY MA RCH A PRIL MA Y

N 39 445 486 111 MALES <10mm CW 11.2 19.4 19.4 11.1 FEMALES <10mm CW 1.60.90.20.2 MA LES ≥10mm CW 0.0 5.7 12.5 14.3 FEMA LES ≥10mm CW 87.2 74.0 67.8 74.4 Month

Figure 114: Proportion of saleable/non-saleable prawn biomass in samples: Aberystwyth 2009 (≥10mm CW = saleable, <10mm CW = non-saleable).

136 PROPORTION OF SALEABLE/NON-SALEABLE PRAWNS: MORFA NEFYN 2009

100

80

60

40 Percentage

20

0 FEBRUA RY MA RCH A PRIL MA Y OCTOBER

N 102 121 384 164 224 MALES <10mm CW 85.3 56.2 34.4 33.5 11.6 FEMALES <10mm CW 2.0 5.8 0.5 1.2 2.2 MA LES ≥10mm CW 1.0 7.4 19.0 14.0 1.8 FEMA LES ≥10mm CW 11.8 30.6 46.1 51.2 84.4 Month

Figure 115: Proportion of saleable/non-saleable prawns in samples: Morfa Nefyn 2009 (≥10mm CW = saleable, <10mm CW = non-saleable).

PROPORTION OF SALEABLE/NON-SALEABLE BIOMASS: MORFA NEFYN 2009

100

80

60

40 Percentage

20

0 FEBRUA RY MA RCH A PRIL MA Y OCTOBER

N 102 121 384 164 224 MALES <10mm CW 78.3 43.2 20.9 17.7 7.0 FEMALES <10mm CW 1.4 4.1 0.3 0.5 1.1 MA LES ≥10mm CW 1.2 8.1 16.5 11.4 1.5 FEMA LES ≥10mm CW 19.1 44.6 62.3 70.5 90.3 Month Figure 116: Proportion of saleable/non-saleable prawn biomass in samples: Morfa Nefyn 2009 (≥10mm CW = saleable, <10mm CW = non-saleable).

137 PROPORTION OF SALEABLE/NON-SALEABLE PRAWNS: AMLWCH 2009

100

80

60

40 Percentage

20

0 FEBRUA RY MA RCH

N 184 208 MALES <10mm CW 6.5 10.6 FEMALES <10mm CW 2.2 1.0 MA LES ≥10mm CW 8.7 5.3 FEMA LES ≥10mm CW 82.6 83.2 Month

Figure 117: Proportion of saleable/non-saleable prawns in samples: Amlwch 2009 (≥10mm CW = saleable, <10mm CW = non-saleable).

PROPORTION OF SALEABLE/NON-SALEABLE BIOMASS: AMLWCH 2009

100

80

60

40 Percentage

20

0 FEBRUA RY MA RCH

N 184 208 MALES <10mm CW 3.7 5.9 FEMALES <10mm CW 0.5 0.2 MA LES ≥10mm CW 6.9 4.0 FEMA LES ≥10mm CW 88.9 89.9 Month

Figure 118: Proportion of saleable/non-saleable prawn biomass in samples: Amlwch 2009 (≥10mm CW = saleable, <10mm CW = non-saleable).

138 Summary of the seasonal variations in the proportion of saleable/non-saleable prawns in the sample populations

Newquay It is evident from Figure 111 that the proportion of saleable prawns (i.e. ≥10mm carapace width) decreased from almost 74% of the total number captured in December to fewer than 44% of the total number captured in March. However, there was considerable fluctuation between these months.

Aberystwyth It can be seen from Figure 113 that, although there was a slight decrease in March and April, the proportion of saleable prawns in the samples remained relatively even between February and May and never fell below 65%.

Morfa Nefyn It can be seen from Figure 115 that there was a considerable increase in the proportion of saleable prawns in the catch samples from fewer than 13% in February to just over 65% in May. However, there was not much of an increase between April and May. Over 86% of the total number of prawns captured in October were saleable, and most of these were female.

Amlwch It can be seen from Figure 117 that there was very little difference in the proportion of saleable prawns in the samples from Amlwch between February and March. The proportion fell from just over 91% in February to just over 88% in March (i.e. approximately 3%).

139 Summary of the regional variations in the proportion of saleable/non-saleable prawns in the sample populations Catch samples from Amlwch contained by far the greatest proportion of saleable prawns of all the samples collected; over 91% in February and almost 89% in March. Only a small proportion of the saleable prawns from Amlwch were males; just over 10% in February and just over 6% in March. The proportion of saleable prawns in the catch samples collected from Morfa Nefyn in both February and March was notably smaller than that from any of the other locations during these months, and catch samples collected from Morfa Nefyn in April and May contained proportionally fewer saleable prawns than samples from Aberystwyth during these months.

The sex ratio In all samples the overwhelming majority of saleable prawns were female, irrespective of season or location. In only one rare case (the April sample from Morfa Nefyn) the number of male prawns exceeded 34% of the total number of saleable prawns. If the two graphs for each location are compared it can be seen that the effect of the sex ratio on the proportion of saleable biomass in the samples is noticeably greater than its effect on the numerical proportion of saleable prawns.

140 4.4.1 Estimated minimum carapace length of saleable prawns Estimates of the minimum carapace length of saleable prawns were calculated using the linear regression equations describing the relationship between carapace width and carapace length for each sex shown in Figure 68, Section 4.2.3.

The linear equation describing the relationship between the carapace width and carapace length of males was: y = 1.5478x + 0.0455 (y = carapace length, x = carapace width).

The linear equation describing the relationship between the carapace width and carapace length of females was: y = 1.4642x + 0.8412 (y = carapace length, x = carapace width).

The carapace width of saleable prawns was defined as being ≥10mm (see 3.4.6).

The estimated minimum carapace length of male saleable prawns was therefore: 1.5478 × 10 + 0.0455 = 15.93mm

The estimated minimum carapace length of female saleable prawns was therefore: 1.4642 × 10 + 0.8412 = 15.48mm

141 4.5 POT MESH SIZE

142 4.5.1 Numerical differences in the catch between the 9mm and 14mm mesh pots

TOTAL NUMBER OF PRAWNS CAPTURED BY 9mm & 14mm MESH POTS

500 400 300

200 Number 100 0 914

N 508 374 ≥10mm carapace w idth 191 238 <10mm carapace w idth 317 136 Pot mesh size (mm)

Figure 119: Number of saleable and non-saleable prawns captured by the 9mm and 14mm mesh pots (≥10mm carapace width = saleable, <10mm carapace width = non-saleable).

PROPORTION OF SALEABLE/NON-SALEABLE PRAWNS CAPTURED BY 9mm & 14mm MESH POTS

100

80 60 40 Percentage 20

0 914 N 508 374 ≥10mm carapace w idth 37.6 63.6 <10mm carapace w idth 62.4 36.4 Pot mesh size (mm)

Figure 120: Relative proportion of saleable and non saleable prawns captured by the 9mm and 14mm pots (≥10mm carapace width = saleable, <10mm carapace width = non-saleable).

It is clear from Figure 119, that the number of prawns captured by the 9mm mesh pots was greater than the number captured by 14mm mesh pots, and from Figure 120, that proportionally more saleable prawns were captured by the 14mm mesh pots.

143 MEAN NU MBER OF PRA WNS/ P OT +/- 95 % CI' s ︵ ︶ Nu mber/ pot

17

16 MESH SIZE 9mm 14mm 15 SPLIT MEAN MEAN <10mm carapace width 13.2a 5.7b 14 ≥10mm carapace width 8.0b 9.9ab

13

12

11

10

<10 mm C W

>10 mm C W 9 mm 14 mm

Pot mes h si z e mm 23456789 ︵ ︶

Figure 121: Mean number of saleable and non-saleable prawns captured in 9mm and 14mm pots (error bars indicate 95% confidence intervals for the means: the means which did not differ significantly from one another in Tukey’s post hoc test (P<0.05) are labelled with same superscript letters in the Table embedded in Figure 121).

Summary of the analysis of the number of saleable and non-saleable prawns captured in 9mm and 14mm pots The ANOVA of the number of prawns captured per pot vs mesh size and the split (between prawns<10mm and ≥10mm carapace width) found that the mean number of prawns captured by the 9mm mesh pots was significantly higher than the mean number captured by the 14mm mesh pots (ANOVA, F1,92 = 4.64, P<0.05). It can be seen from Figure 121 that the mean number of saleable prawns (i.e. ≥10mm carapace width) captured by the 14mm mesh pots was higher than the mean number captured by the 9mm mesh pots. However, Tukey’s post hoc test found that this difference was not statistically significant. It can also be seen from Figure 121 that the mean number of non-saleable prawns (i.e. <10mm carapace width) captured by the 14mm mesh pots was less than the mean number captured by the 9mm mesh pots. Tukey’s post hoc test found

144 that this difference was statistically significant (Tukey’s adjusted P-value = 0.0005). The post hoc test also found that there was a significant difference between the mean number of saleable and non-saleable prawns captured by the 9mm mesh pots (Tukey’s adjusted P-value = 0.0262), and no difference between the mean number of saleable and non-saleable prawns captured by the 14mm mesh pots.

NB: The full ANOVA and post hoc test results can be found in Appendix XV.

145 4.5.2 Differences in the carapace width of prawns captured by the 9mm and 14mm mesh pots

MEAN CARAPACE WIDTHS (+/- 95% C I's) OF PRAWNS CAPTURED BY 9mm & 14mm MESH POTS

11

10

9

Carapace width (mm) 8

7 914

N 508 374 ≥10mm 10.58 10.63 <10mm 7.53 7.82 All 8.68 9.61 Pot mesh size (mm)

Figure 122: Mean carapace widths of prawns <10mm carapace width and ≥10mm carapace width captured by 9mm and 14mm pots (error bars indicate 95% confidence intervals for the means).

Summary of the analysis of the mean carapace widths of prawns <10mm carapace width and ≥10mm carapace width captured by 9mm and 14mm pots It is clear from Figure 122 that the mean carapace width of prawns captured by the 14mm mesh pots was greater than the mean carapace width of the prawns captured by the 9mm mesh pots. The ANOVA found this difference to be statistically significant

(ANOVA, F1,878 = 172.31, P<0.001). It is also clear from Figure 122 that the mean carapace width of the non-saleable prawns captured by the 14mm mesh pots was greater than the mean carapace width of the prawns captured by the 9mm mesh pots. The post hoc test found that this difference was statistically significant (Tukey’s adjusted P-value

146 = 0.0321). The post hoc test found no difference between the mean carapace width of the saleable prawns captured by the 14mm mesh pots and the mean carapace width of the saleable prawns captured by the 9mm mesh pots.

NB: All other significant differences found by the ANOVA were a consequence of including the split between prawns <10mm carapace width and ≥10mm carapace width in the model. The full ANOVA and post hoc test results can be found in Appendix XV.

147 4.5.3 Comparison between this study and the pot mesh trial of the saleable/non- saleable proportion of prawns in the catch samples

COMPARISON OF THE PROPORTION OF SALEABLE/NON- SALEABLE PRAWNS IN ALL SAMPLES CAPTURED USING 9mm MESH POTS

100

50

Percentage 0 New quay Aberystw yth Morfa Nefyn Amlw ch Mesh trial

N 454 1081 995 392 508

≥10mm carapace w idth 57.8 68.3 61.2 89.8 37.6

42.2 31.7 38.8 10.2 62.4 <10mm carapace w idth Data s our ce

Figure 123: Comparison between mesh trial and current study of the proportion of saleable/non-saleable prawns using pooled data from all samples

COMPARISON OF THE PROPORTION OF SALEABLE/NON- SALEABLE PRAWNS IN SAMPLES CAPTURED FROM FEBRUARY TO MAY USING 9mm MESH POTS

100 80 60 40

Percentage 20

0 Aberystw yth Morfa Nefyn Mesh trial

N 1081 771 508

≥10mm carapace w idth 68.3 54.0 37.6

<10mm carapace w idth 31.7 46.0 62.4

Data s our ce

Figure 124: Comparison between mesh trial and current study of the proportion of saleable/non-saleable prawns using pooled data from February to May

It is evident from Figures 123 and 124 that proportionally fewer saleable prawns were captured by the 9mm mesh pots in the pot mesh trial samples than by the 9mm pots used in this study irrespective of location or month.

148 4.5.4 Estimates of the mean and minimum carapace length of prawns captured by the 9mm and 14mm mesh pots Estimates of the mean and minimum carapace length of prawns captured by the 9mm and 14mm mesh pots were calculated using the least squares regression equation (from Section 4.2.3) describing the relationship between carapace width and carapace length of both sexes combined.

The linear equation describing the relationship between the carapace width and carapace length of both sexes was: y = 1.4738x + 0.7386 (y = carapace length, x = carapace width).

The mean carapace width of the prawns captured by the 9mm mesh pots was 8.68mm, therefore the estimated mean carapace length of the prawns captured by the 9mm mesh pots was: 1.4738 × 8.68 + 0.7386 = 13.57mm

The mean carapace width of the prawns captured by the 14mm mesh pots was 9.61mm, therefore the estimated mean carapace length of the prawns captured by the 14mm mesh pots was: 1.4738 × 9.61 + 0.7386 = 14.90mm

The minimum carapace width of the prawns captured by both 9mm and 14mm mesh pots was 4.00mm, therefore the estimated minimum carapace length of prawns captured by both 9mm and 14mm mesh pots was: 1.4738 × 4.00 + 0.7386 = 6.63mm

149 4.6 CATCH RECORDS

150 4.6.1 Quantity and value of P. serratus landed in Wales 2006 to 2009

QUANTITY OF Palaemon serratus LANDED IN WALES/MONTH: 2006 to 2009

10 9 8 7 6 5 4

Live weight (t) 3 2 1 0 JA N FEB MA R A PR MA Y JUN JUL A UG SEP OCT NOV DEC

2006 3.8 1.8 2.3 2.9 0.8 0.3 0.0 0.0 0.9 4.1 4.1 2.9 2007 4.3 4.6 9.0 2.6 1.1 0.3 0.0 0.1 1.5 3.7 3.8 2.9 2008 2.3 3.1 4.4 4.2 0.8 0.1 0.0 0.0 1.7 2.5 4.5 5.2 2009 2.6 2.1 5.2 5.1 0.8 0.3 0.0 0.1 1.3 2.8 3.4 2.1 Month

Figure 125: Quantity of P. serratus landed in Wales/month 2006 to 2009 (data source MMO, 2010)

MEAN QUANTITY OF Palaemon serratus LANDED IN WALES/MONTH: 2006 to 2009 (+/- S.D.)

10

9

8

7

6

5

4 Live weight (t) 3

2

1

0 JA N FEB MA R A PR MA Y JUN JUL A UG SEP OCT NOV DEC

Mean quantity (t) 3.2 2.9 5.2 3.7 0.9 0.2 0.0 0.1 1.3 3.3 4.0 3.3 Month

Figure 126: Mean quantity of P. serratus landed in Wales/month 2006 to 2009 (data source MMO, 2010: error bars indicate standard deviations for the means)

151 FIRST SALE VALUE OF Palaemon serratus LANDED IN WALES/MONTH: 2006 to 2009

160

140

120

100

80

Value (£k) 60

40

20

0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

2006 60.5 31.1 39.1 49.2 12.8 4.7 0.4 0.4 16.0 71.1 69.7 49.1 2007 69.7 84.0 149.4 43.9 18.4 4.4 0.4 1.7 22.4 62.0 64.9 50.0 2008 38.6 53.0 74.5 70.9 14.3 0.9 0.0 0.6 28.2 43.2 76.5 89.2 2009 42.9 34.5 90.4 81.8 15.1 5.5 0.6 1.0 25.2 52.6 61.7 41.0 Month

Figure 127: First sale value of P. serratus landed in Wales 2006 to 2009(data source MMO, 2010)

MEAN FIRST SALE VALUE OF Palaemon serratus LANDED IN WALES/MONTH: 2006 to 2009 (+/- S.D.)

160

140

120

100

80 Value (£k) 60

40

20

0 JA N FEB MA R A PR MA Y JUN JUL A UG SEP OCT NOV DEC

Mean value (£k) 52.9 50.7 88.4 61.5 15.2 3.9 0.4 0.9 22.9 57.2 68.2 57.3 Month

Figure 128: Mean first sale value of P. serratus landed in Wales/month 2006 to 2009 (data source MMO, 2010: error bars indicate standard deviations for the means)

152 Summary of the quantity and value of P. serratus landed in Wales 2006 to 2009 It can be seen from Figures 125 and 126 that most of the annual catch of P. serratus in Welsh waters from 2006 and 2009 was between the months of October and April. It is also evident from the distinct trough in the graph that there were very few or virtually no prawns landed in June, July and August. It is evident from Figures 127 and 128 that the first sale value of P. serratus broadly followed the same pattern as the quantity landed. In other words the relationship between catch quantity and value was relatively constant between 2006 and 2009.

153 4.6.2 Quantity and value of H. gammarus landed in Wales 2006 to 2009

QUANTITY OF Homarus gammarus LANDED IN WALES/MONTH: 2006 to 2009

50

45

40

35

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25

20

Live weight (t) 15 10

5 0 JA N FEB MA R A PR MA Y JUN JUL A UG SEP OCT NOV DEC

2006 3.6 3.3 3.6 10.5 16.4 29.9 43.8 36.6 19.8 12.0 6.6 4.7 2007 3.1 4.3 7.6 18.6 16.3 31.2 34.9 29.4 25.4 21.4 9.5 3.9 2008 2.0 6.1 4.7 10.6 16.8 23.4 36.5 24.7 23.7 9.2 8.2 7.6 2009 5.3 4.5 4.9 9.1 12.5 26.1 30.7 30.3 29.7 18.2 4.3 9.1 Month

Figure 129: Quantity of H. gammarus landed in Wales/month 2006 to 2009 (data source MMO, 2010)

MEAN QUANTITY OF Homarus gammarus LANDED IN WALES/MONTH: 2006 to 2009 (+/- S.D.)

50

45

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35

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20 Live weight (t) weight Live 15

10

5

0 JA N FEB MA R A PR MA Y JUN JUL A UG SEP OCT NOV DEC

Mean quantity (t) 3.5 4.6 5.2 12.2 15.5 27.7 36.5 30.2 24.6 15.2 7.2 6.3 Month

Figure 130: Mean quantity of H. gammarus landed in Wales/month 2006 to 2009 (data source MMO, 2010: error bars indicate standard deviations for the means)

154 FIRST SALE VALUE OF Homarus gammarus LANDED IN WALES/MONTH: 2006 to 2009

900

800

700

600

500

400 Value (£k) 300

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0 JA N FEB MA R A PR MA Y JUN JUL A UG SEP OCT NOV DEC

2006 63.5 59.4 65.3 189.0 295.6 535.9 781.9 645.7 346.9 210.3 116.7 83.8 2007 56.6 76.8 135.9 319.6 286.9 541.3 591.5 487.5 436.3 368.0 165.5 70.8 2008 35.3 108.9 84.4 182.9 291.7 390.6 611.0 408.6 396.5 156.1 134.3 134.2 2009 92.3 77.3 76.2 132.0 90.9 233.1 266.3 268.2 278.4 191.9 50.2 163.2 Month

Figure 131: First sale value of H. gammarus landed in Wales/month 2006 to 2009(data source MMO, 2010)

MEAN FIRST SALE VALUE OF Homarus gammarus LANDED IN WALES/MONTH: 2006 to 2009 (+/- S.D.)

900

800

700

600

500

400 Value (£k)

300

200

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0 JA N FEB MA R A PR MA Y JUN JUL A UG SEP OCT NOV DEC

Mean value (£k) 61.9 80.6 90.5 205.9 241.3 425.2 562.7 452.5 364.5 231.6 116.7 113.0 Month

Figure 132: Mean first sale value of H. gammarus landed in Wales/month 2006 to 2009 (data source MMO, 2010: error bars indicate standard deviations for the means)

155 Summary of the quantity and value of H. gammarus landed in Wales 2006 to 2009 It can be seen from Figures 129 and 130 that the landings of H. gammarus in Welsh waters from 2006 to 2009 were greatest between the months of April and October, with distinct peaks in July of each year. The average first sale values shown in Figure 132 broadly follow the same pattern as the average quantities landed between 2006 and 2009 that are shown in Figure 130. However, it can be seen from Figure 131 that there was a decline in the value of the catch during the peak season from 2006 to 2009, culminating in a slump in sales values for 2009.

156 5 DISCUSSION

157 5.1 POPULATION STRUCTURE

In any discussion of data relating to the population structure of P. serratus, it is important to note that the species migrates to deeper water during winter and returns to shallower water as spring approaches and then to the littoral zone during summer. This general migration cycle, has been observed in studies of populations from northern France (Campillo, 1979a), England (Forster, 1951) and Wales (Cole, 1958). It has also been found that the larger females migrate to the greatest depth (up to 50m) in the colder months and that the males remain in slightly shallower water during the same period (Campillo, 1979a). Given such a migratory cycle it is to be expected that the sex ratio of any particular sample population will be determined by the time of year and depth at which the sample was collected.

5.1.1 The sex ratio With respect to the sex ratio in the samples collected between February and May from Aberystwyth and Morfa Nefyn, it is highly likely that the differences in the depth of the two locations explain the different seasonal patterns evident in the samples from the two locations. The samples from Morfa Nefyn were collected at a depth of approximately 7m and those from Aberystwyth at approximately 12m. This is probably why the proportion of males in the sample populations from Morfa Nefyn was far greater than that found at Aberystwyth in February and March. It might also explain why there was an increase in the proportion of females in the sample populations from Morfa Nefyn in April and May, but not in the samples from Aberystwyth. In April and May, the females were probably leaving deeper water locations (e.g. Aberystwyth) and entering shallow water locations (e.g. Morfa Nefyn).

The high proportion of female prawns in the October sample from Morfa Nefyn is perhaps evidence that female prawns were the first to move from the littoral to slightly deeper water in the autumn prior to their movement into even deeper water in winter.

With respect to Newquay, the deepest sample location at approximately 15m, the proportion of females in the samples reduced considerably between December and March. The change in the sex ratio in the Newquay samples was perhaps due to the migration of females from the sample location. Assuming that the larger female prawns were the last to move inshore as spring approached, the very slight increase in the mean

158 size observed between December and March (see Figure 62, Section 4.2.1) may reflect a departure of smaller females for shallower water as the spring approached and perhaps an influx of larger females from even deeper water over this period.

In order to verify these possible explanations a more comprehensive data-set is required; from a series of graduated depths at a selection of locations around the coast spanning the entire annual cycle. All that can be concluded from the available data is that no seasonal or regional differences in the sex ratio were found beyond those which might be associated with variations in depth and likely migration patterns.

5.1.2 The sex ratio and biomass In all the samples collected, the amount of prawn biomass increased as the proportion of females in the sample increased, and decreased when the proportion of males increased. This indicates that female prawns were generally larger than male prawns; this was confirmed in the analyses of carapace length and log wet weight (see Section 4.2.5).

5.1.3 The proportion of ovigerous females The proportion of ovigerous females in the sample populations was low in the samples collected during winter (see Figure 12), and tended to increase with the approach of summer. This was particularly evident in the samples collected from Aberystwyth and Morfa Nefyn (see Figures 14 and 16) with the maximum proportion being reached by May.

5.1.4 Age Given the lack of any structure remaining after ecdysis, determining the number of age classes present in sample populations of crustaceans has traditionally been accomplished through the analysis of size-frequency distributions. Size-frequency analysis depends upon the identification of modes in the distribution, which can be equated with year classes or with recruitment cohorts (Hartnoll, 2001). From the most recent of the studies of the age structure and longevity of populations of P. serratus from the western Mediterranean (Guerao & Ribera, 2000), north west Spain (Figueras, 1986), and southern Ireland (Fahy & Gleeson, 1996, and Kelly et al, 2008) it was to be expected that there would most likely be no more than three year classes present in a population. The maximum number of modes detected in the sample populations by the Mixture Analyses was indeed three. If the modes are assumed to represent separate year

159 classes this would strongly suggest that, based on the limited range of data available for analysis, the longevity of the Welsh population was no more than three years.

It was expected that if the 0+ year class was present in the samples there would be far fewer of them than the 1+ or 2+ year classes. This is because the 9mm mesh size of pots used to capture the samples would theoretically allow prawns belonging to the 0+ year group to escape. Therefore, the mode representing (part of) the 0+ cohort would be expected to be correspondingly smaller than modes representing the other year classes due to the exclusion effect of the capture method. It would also be expected that the chances of detecting a smaller mode representing the 0+ year group would be greater if the number of individuals captured was higher. In many cases where a distinct group of smaller prawns was detected the mode representing them was notably smaller than the other modes detected (e.g. see Figures 24 and 32, Section 4.1.2). Furthermore, when smaller sized cohorts were detected they were frequently in samples containing a relatively large number of individuals (e.g. see Figures 33 and 42, Section 4.1.2).

Conclusions Because the data collected were irregular and truncated it was not possible to follow the progression of modes in the distributions over a sufficient period of time to discern any definite growth patterns. However, there was nothing in the available data to suggest that the age structure of the catch samples was dissimilar to that found in a recent study of the southern Irish fishery (Kelly et al, 2008). That is, dominated by female prawns from the 1+ year group with varying contributions from the 0+ and 2+ cohorts depending on the time of year.

160 5.2 MORPHOLOGY

5.2.1 Size and sex The results in Sections 4.2.1 and 4.2.2 confirm what has been found in previous studies of the species (e.g. Cole, 1958 and Campillo, 1979a), namely that females attain a greater size than males.

With respect to mean carapace length, females were universally larger than males in all sample populations, and the difference was statistically significant in all cases. The same was true with respect to the mean log wet weight of males and females from all sample populations, and the difference was also statistically significant in all but one of the samples. The one exception, the Amlwch sample for February (see Figure 64 and Table 11, Section 4.2.2), is thought to be the effect of the very low number of males present in the sample.

5.2.2 Regional and seasonal variations in size The most striking regional variation in the mean carapace length and log wet weight of samples collected in February and March was between the females from Morfa Nefyn and the females from the other locations. Bearing in mind the expected migration patterns of the species, it seems highly likely that the smaller mean size of the females from Morfa Nefyn was due to the depth and time of year at which the samples were collected rather than evidence of separate regional populations.

The notable increase in the mean size and proportion of females in the samples from Morfa Nefyn between April and May suggests that not just females, but progressively larger females, were leaving deeper water locations and entering shallow water locations during this time. This would explain the apparent difference between Aberystwyth and Morfa Nefyn in the mean size of the female samples collected between February and May. With respect to both carapace length and log wet weight there was not a great deal of change in the mean size of females from Aberystwyth between February and May, whereas there was a considerable (and statistically significant) increase in the mean size of females from Morfa Nefyn during the same period. Unsurprisingly, the same difference in seasonal patterns was also evident in the size at sexual maturity of ovigerous females from Aberystwyth and Morfa Nefyn collected between March and May (see Figure 99, Section 4.2.8).

161 5.2.3 Carapace width and carapace length Irrespective of the evident size differences between the sexes, it is clear from Figure 68 (Section 4.2.1) that there was a very strong linear relationship between the carapace width and carapace length of both sexes. However, the regression slope describing the relationship between carapace width and carapace length of male prawns was slightly steeper than that describing the relationship of females. This indicates a slight tendency for the carapace length of males to increase at a greater rate than the carapace length of females as carapace width increased. Because the two lines cross there is also a point at which there is virtually no difference between the sexes, this is where carapace width = 9.52mm and carapace length = 14.78mm; beyond this point the two lines diverge. Bearing in mind that the carapace width of saleable prawns was ≥10mm, this explains why the minimum carapace length of saleable female prawns (Section 4.4.1) was slightly less than that of their male counterparts at saleable size. It is likely that the carapace width of saleable females was slightly greater than that of their male counterparts of similar carapace length due to the development of ovaries.

With respect to the ANOVA of the mean ratio between carapace width and carapace length, it can be seen from Figure 69 (Section 4.2.3) that in February and March there were few differences between samples from Aberystwyth, Morfa Nefyn and Amlwch. However, the carapace of both males and females in samples from Newquay were significantly wider and shorter relative to those from the other locations in February. The opposite was true of the samples collected from Newquay in March when the carapaces of both males and females were narrower and longer relative to those from the other locations. Why carapace morphology varied so much between February and March in the Newquay samples, and between the Newquay samples and those from the other locations, is unclear. Nor is it clear why the mean carapace width/carapace length ratios of the Newquay samples collected between December and March fluctuated from month to month.

With respect to the mean carapace width/carapace length ratio of the samples from Aberystwyth and Morfa Nefyn, there was very little variation evident in the female samples from Morfa Nefyn between February and May. However, the mean ratio values of the female samples from Aberystwyth fluctuated considerably from month to month and from the mean ratios of female samples from Morfa Nefyn in both March and May.

162 This is perhaps a reflection of differences in the depth of the two sample locations and seasonal population movements.

There was more variation in the mean ratio values of male samples from Aberystwyth and Morfa Nefyn than in the female samples, particularly between March and May. The ratio values of males from Morfa Nefyn indicate that their carapaces were longer and narrower than the carapaces of males from Aberystwyth and that they became progressively longer and narrower than the males from Aberystwyth from March to May. Again, this is perhaps a reflection of differences in the depth of the two sample locations, seasonal population movements and/or growth patterns.

The significantly higher mean ratio values of both male and females from Morfa Nefyn in October, indicates that the carapace became shorter and wider in the autumn. The absence of a complete annual cycle of data from any of the sample locations, and no data from the other locations in October, make it difficult to discern if this was confined to Morfa Nefyn or part of a wider pattern of growth.

Conclusions Although some seasonal differences were evident in the variations in carapace morphology revealed by the analyses, few clear patterns could be seen. Sexual dimorphism was only evident in samples collected in April and May and was more pronounced in the samples from Morfa Nefyn than those from Aberystwyth. It seems unlikely that these and other regional variations, such as between Newquay and the other locations, can be accepted as evidence of separate regional populations. Such differences are more likely to be due to depth or seasonal migration and/or growth patterns, but data from different depths covering a full annual cycle would be required to confirm this conclusion.

163 5.2.4 Carapace length and rostral length Apart from the obvious size differences between the sexes, it is clear from the curvilinear trendlines fitted to the scatter plot of the data (Figure 73, Section 4.2.4) that the relationship between carapace length and rostral length was allometric. It is also clear that there was a considerable difference between the sexes with respect to the relationship; this confirms the observations made by Campillo (1979a). For any given carapace length, the rostral length of male prawns was greater than the rostral length of female prawns. The divergence of the two trendlines indicates a progressively greater increase in rostral length in males than in females as carapace length increased. However, the virtually parallel linear trend lines fitted to the log transformed data (Figure 74, Section 4.2.4) indicate that, although males and females were clearly different with respect to the relationship between carapace length and rostral length, there was little difference between the sexes in the rate at which rostral length increased in relation to carapace length.

With respect to the mean log ratio between the length of the rostrum and the length of the carapace, it is absolutely clear in all analyses that the difference between males and females in the sample populations was statistically significant without exception. The rostra of male prawns were universally longer relative to the carapace than the rostra of female prawns. The difference between males and females in the relationship between rostral length and carapace length can, as Campillo (1979a) first suggested, be considered to be a clear morphological characteristic of the species. It follows that the ratio between carapace length and rostral length can be used to determine sex with a fair degree of accuracy. Although measuring the ratio can only be done on specimens with intact rostra, it may nonetheless prove particularly useful as a supplementary technique for sexing P. serratus (and perhaps other prawn species) in the field.

There were very few seasonal and locational variations found in the log carapace length/rostral length ratio values of either sex. Having said this there were statistically significant differences in the male samples collected in March between Aberystwyth and Newquay, and between Aberystwyth and Amlwch. In these cases the rostra of the female samples from Aberystwyth were longer relative to the carapace than the rostra of female samples collected from Newquay and Amlwch. Determining why this was so requires more a comprehensive data-set and further research.

164 There was also a significant difference between the mean log ratio values of the female samples collected at Morfa Nefyn in October and the female samples collected in April and May at this location. In this case the rostra of the female samples collected in October were longer relative to the carapace than the rostra of female samples collected in April and May. As with the previous case, it is unclear why this was the case. Further research is required to determine if such variations are merely examples of natural variation or if some other cause is responsible.

Conclusions P. serratus was found to be clearly sexually dimorphic with respect to the carapace length/rostral length ratio. Although there was some seasonal variation in the ratio, there was no evidence of separate regional populations reflected in the data that were analysed.

165 5.2.5 Carapace length and wet weight Apart from the size differences between the sexes it is clear from the curvilinear trendlines fitted to the scatter plot of the data (Figure 79, Section 4.2.5) that the relationship between carapace length and wet weight was allometric. The difference between the slopes of the two linear trend lines fitted to the log transformed data (Figure 80, Section 4.2.5) indicates that the wet weight of female prawns increased at a greater rate than the wet weight of male prawns as carapace length increased. This general difference between the sexes is to be expected and can be accounted for by the fact that females develop ovaries and produce eggs whereas males do not.

With respect to the mean log ratio between carapace length and wet weight, the male values were consistently higher than the female values. This indicates that for any given carapace length the wet weight of males was less than that of females. It is clear from the ANOVA of the ratio that the difference between males and females in the sample populations was considerable and statistically significant in all but one of the samples. The exception, which relates to the sample collected at Amlwch in February, seems likely to be the effect of the exceptionally low number of males (only 7) in the sample.

Conclusions Because size seems to have been the main determinant of the ratio value it was not surprising that the differences found by the ANOVA of the mean log ratio between carapace length and wet weight were virtually the same as the differences found by the ANOVA of the mean log wet weight of the samples. The expected migration patterns of the species, together with the depth and time of year at which the samples were collected are likely to be the factors responsible for the differences found.

166 5.2.6 Rostral teeth From the data analysed in Section 4.2.6 it was clear that there were no significant variations in the mean number of dorsal teeth between the sexes at any of the sample locations in February and March, nor between December and March in the Newquay samples. It was evident however, that both male and female samples from Morfa Nefyn had noticeably fewer dorsal teeth on their rostra than samples from the other locations in February and March, but the difference was only statistically significant with respect to the females. Given that the ANCOVA found that the number of dorsal teeth was not affected by carapace length (see Appendix XIIIii), it would seem likely that the differences were related to the depth at which the samples were collected.

With respect to Section 4.2.7, statistically significant differences were found between the sexes in the mean number of ventral teeth in both the Newquay and Morfa Nefyn samples collected in February and March. The mean number of ventral teeth on the rostra of females collected from Newquay was greater than the mean number found on the rostra of males, but the opposite was true of the samples collected from Morfa Nefyn. In the Newquay samples collected in December and March there were no significant differences in the mean number of ventral teeth between the sexes. Because there was little variation in the male samples collected from the sample locations in February and March the differences between the sexes is primarily a reflection of the significant differences between locations in the female samples. The greatest difference was between the samples from Newquay and Morfa Nefyn, the deepest and shallowest of the sample locations, but the differences between the samples from Morfa Nefyn and both Aberystwyth and Amlwch were also significant. Given that the ANCOVA of the female samples found that that the number of ventral teeth was not affected by carapace length (see Appendix XIIIii), it would seem likely that the differences were related to the depth at which the samples were collected.

Conclusions The variations found in rostral dentition are probably reflections of the depth of the sample locations and the time of year at which the samples were collected rather than of separate regional populations. Why the rostral dentition of females was noticeably more variable than that of the males requires further investigation using a more comprehensive dataset based on samples collected from different depths at several locations during a full annual cycle.

167 5.2.7 Size at sexual maturity The differences found in the size at sexual maturity between locations and months were broadly in line with the general differences found in the mean carapace length of female prawns (see Section 4.2.1).

The only direct comparison with populations from elsewhere of the size at sexual maturity measured using CL50 as a measure is a study of a population in northern Portugal (Felicio et al, 2002). This particular study found that larger females were the first and the smaller prawns were the last to become ovigerous. In other words, the average size of ovigerous females (and by extension the CL50 size at sexual maturity) reduced as the season progressed. The same general pattern has been observed in other populations, including those in Wales (Cole, 1958) and was evident between February and March in the Amlwch, and in the Aberystwyth sample populations between April and May (see Figure 99, Section 4.2.8). However, the opposite seems to be true of the sample populations from Newquay and Morfa Nefyn, and in the Aberystwyth sample populations between March and April. In these cases the CL50 of the ovigerous females increased as the season progressed. It is most likely that the explanation for this apparent departure from the commonly observed pattern is connected to depth and migration. The increase in the CL50 in the samples collected from Newquay (the deepest location) in February and March may indicate the departure of the smaller females for shallower water. At Morfa Nefyn (the shallowest location) the steady increase in the

CL50 between March and May was perhaps due to the influx of progressively larger and larger females from deeper water. The initial increase in size at Aberystwyth from March to April might indicate an influx of larger females from deeper water. The only month for which data from all four locations were available was March. The main difference in the CL50 in March was between samples collected from widely varying depths; i.e. between the deeper water locations (Newquay, Aberystwyth and Amlwch) and the shallow water location (Morfa Nefyn). Obviously to substantiate these possible explanations a more comprehensive data-set is required.

The other notable difference between the CL50 values from this study and those from the

Portuguese population was that the latter values were considerably less. The CL50 values from Portugal ranged from approximately 11.85mm to 16.50mm, those from this study ranged from 18.06mm to 19.06mm. On the surface this might suggest that the Portuguese population reached sexual maturity at a smaller size than the Welsh

168 population. However, the samples for the Portuguese study were collected using a trawl net which is likely to have retained smaller prawns than the pots used to collect samples for this study. Ovigerous females as small as 10.4mm carapace length were found in samples collected using a combination of hand nets, trawls and pots for an earlier study of the Welsh population (Cole, 1958). Given that the smallest ovigerous female collected for this study had a carapace length of 15.41mm; it is possible that the differences in the CL50 between the Welsh and Portuguese populations (and indeed the Welsh population sampled by Cole) are related to different sampling methods and locations. More comprehensive sampling of the Welsh population, including estuarine and intertidal locations would be required to confirm this.

5.2.8 Additional observations The pronounced smooth ridge between the posterior pereopods of females (see Figure 5, Section 1.2.2) is not mentioned in any of the literature on the species. It does appear to be present in Cole’s (1958) drawing of the ventral surface of a typical female, but it is not shown in Campillo’s (1979a) drawing of the same. Both Cole and Campillo only refer to the presence/absence of the small protuberance found between the posterior pereopods of males as a way of distinguishing sex and make no mention of the ridge. This seems curious, when the ridge between the posterior pereopods of females is an equally distinct feature which is either present or absent depending on the sex of the specimen.

169 5.3 FECUNDITY; EGG NUMBER & EGG VOLUME

5.3.1 Egg number The poor correlation between egg number and carapace length in all but the Amlwch data was possibly due to low sample numbers. Obviously a larger dataset is required to confirm this. Although the ANCOVA found a significant difference between the mean number of eggs carried by females in the Newquay and Aberystwyth samples, the differences between both Newquay and Aberystwyth and the mean number of eggs of the sample populations combined (3130) was not statistically significant (see Figure 105, Section 4.3.1).

Conclusions On balance the analysis of the small data set does not present any evidence to suggest regional differences in the fecundity of the species around the Welsh coast. Having said this, it is interesting to note that Newquay is the most heavily fished location and the noticeably lower fecundity of the Newquay samples may be an indication that fishing pressure has impacted on fecundity. Although P. serratus is a relatively short-lived species, the effects on fecundity of constantly removing large quantities of brood-stock are not known. This is certainly a topic which requires further research.

5.3.2 Egg volume Despite the differences found in the size of eggs (i.e. log egg volume) appearing to be broadly in line with the general differences in the size of female prawns found by the ANOVAs of carapace length (Figure 60, Section 4.2.1) and log wet weight (Figure 64, Section 4.2.2) the relationship between egg volume and carapace length was not found to be related to the size of the female carrying the eggs.

Conclusions There is not really any evidence in the data analysed to suggest that differences in egg volume of the sample populations were a reflection of separate regional populations around the Welsh coast.

170 5.4 THE SALEABLE PROPORTION OF THE CATCH SAMPLES

In all samples the overwhelming majority of saleable prawns were female, irrespective of season or location. The effect of the sex ratio on the proportion of saleable biomass in the samples was noticeably greater than its effect on the mere proportion of saleable prawns because female prawns were universally larger than male prawns. It is not surprising therefore that variation in the proportion of saleable prawns/biomass in the catch samples closely followed variations in the proportion of females in the catch. This tendency was most striking in the seasonal variation of the proportion of females in the catch samples collected from Morfa Nefyn. As has been said above, the seasonal variation in the proportion of females (and hence saleable prawns) in the samples from Morfa Nefyn was likely to have been due to migration patterns and the depth at which the samples were collected.

Conclusions Because the saleable proportion of prawns in each catch sample reflects the population structure of that sample it might appear that some fishermen could be at a disadvantage because the biological population they are attempting to exploit has a different structure to biological populations elsewhere around the coast. However, this fails to account for the differences between sample populations and biological populations. The sample populations collected for this study clearly do not represent separate biological populations, merely that part of a wider biological population which is in the particular depth zone at the particular time of year the sample was collected. Furthermore, most experienced prawn fishermen fully understand the migration patterns of the species and consequently do not limit their fishing activities to particular depth zones.

171 5.5 MINIMUM POT MESH SIZE

The mesh size of a pot determines the size above which the escape of the target species is prevented. Theoretically a larger mesh size will select for larger prawns and allow individuals below a certain size to escape. As a management tool a minimum mesh size is primarily a means of regulating the size of the prawns captured by the fishery and controlling the proportion of a catch which has no real economic value. The aim of a minimum mesh size is therefore to increase the proportion of saleable prawns in the catch and to decrease discard.

5.5.1 The pot mesh trial The results in Section 4.5 of the analyses of the number and size of prawns captured by the two mesh sizes in the trial appear to show two main advantages to be gained by using 14mm mesh pots rather than 9mm mesh pots.

Firstly, and despite there being fewer prawns in total captured by the 14mm mesh pots than the 9mm mesh pots, the 14mm mesh pots still captured slightly more prawns of a saleable size than the 9mm mesh pots. Capturing marginally more saleable prawns, even if the numbers are not statistically significant, is nonetheless economically desirable from the perspective of the fishermen.

Secondly, the amount of discard (i.e. prawns <10mm carapace width) in the 14mm mesh pots was significantly less than that in the 9mm mesh pots, and its mean size was significantly greater. The reduction of discard saves time sorting the catch, and helps to minimise losses associated with damage to the catch caused by handling. Indeed fishermen that have already opted to use 14mm mesh pots report (pers. comm.) a cleaner catch which does not need further sorting for size. Reducing the quantity of non- saleable prawns and increasing their mean size is also environmentally desirable because smaller prawns which have not yet had the chance to spawn (i.e. the 0+ year group) can theoretically escape. Having said this, some very small prawns with a carapace width of 4mm, equating to a carapace length of 6.63mm, were still retained by both mesh sizes. This suggests that escape is not merely determined by mesh size, and points to the need for further research into the behaviour of prawns once they have entered pots, and in particular the effect of the presence of predators around the pots.

172 It must be added that the 14mm mesh size pots did not seem to afford any more protection to the brood-stock than the 9mm mesh pots. Naturally, neither mesh size is intended to allow the escape of any saleable prawns and the vast majority of sexually mature female prawns are likely to be of saleable size (i.e. above 15.48mm carapace length). In all but one of the many samples collected for this study the minimum carapace length of ovigerous females was considerably greater than 15.48mm (see Figure 100, Section 4.2.8). This does not mean that there were no ovigerous females in the population small enough to escape either the 9mm or 14mm mesh pots, just that none were found in the samples collected for this study.

Finally, it must be acknowledged that neither the sex, weight, nor the carapace length of the individual prawns was recorded in the pot mesh trial undertaken by the CBFA. These particular omissions made it impossible to account for the effect of the sex ratio on the relative value of the prawns captured by the two mesh sizes. It was therefore difficult to compare fully the trial data with the data collected for this study. In the comparisons that were made in Section 4.5.3 the relative proportion of saleable/non- saleable prawns captured by the 14mm mesh pots in the mesh trial (Figures 123, and 124) were closer to the relative proportion of saleable/non-saleable prawns captured by the 9mm pots used to collect samples for this study (see Section 4.4). The reasons for this are not fully understood. Ultimately, data (including the sex, weight and carapace length of the individual prawns) from locations sampled with pots fitted with the two different mesh sizes is required to fully resolve this issue.

5.5.2 Practicalities of a minimum pot mesh size The enforcement of a minimum pot mesh size would be relatively straightforward as there is no ambiguity to face; a pot mesh is either above the specified size or its not. There are however two potential stumbling blocks.

Firstly, fishermen from the Cardigan Bay fishery have expressed concerns of about the time and/or cost of changing the mesh ends in existing pots to a larger size (Huxley, 2008). This concern could perhaps be addressed by the provision of some financial assistance for a limited period to ensure compliance by a certain date.

Secondly, some fishermen (pers. comm.) were sceptical about the geographical scope of the data collected for the pot mesh trial in 2006. The doubts are rooted in the perception

173 that there are structurally distinct populations around the Welsh coast, and that the pot mesh trial was limited to just one location. While the latter is undoubtedly true, there was no evidence in the data collected for this study of structurally distinct populations of P. serratus around the Welsh coast. However, it should be added that the data collected for this study were truncated.

Conclusions Irrespective of any doubts related to the validity of the data, prohibiting the use of any pots in the fishery with a mesh size smaller than a specified minimum (i.e. 14mm) represents the most logical option for regulating the size of the prawns captured by the fishery. A 14mm mesh would help minimise discard and the byecatch of other non- commercial species and is also in keeping with the precautionary principle.

174 5.6 CLOSED SEASON

The purpose of a closed season is to limit fishing pressure on a stock during biologically critical periods. The obvious advantages to fishermen are that this can help stabilise or even increase the size of a population and thereby ensure the maximum yield per recruit for the fishery. With respect to P. serratus there are perhaps two biologically critical times; the period of maximum growth, and the period of maximum egg carriage (i.e. when most females are ovigerous and about to spawn).

The period of maximum growth of P. serratus is during the warmer summer months from May to September. With respect to samples from both Aberystwyth and Morfa Nefyn the period of maximum egg carriage was found to be from April to May (see Figures 14 and 16, Section 4.1.1). How much beyond May the majority of females remained ovigerous in the populations from these (and other) locations is uncertain as no samples were available to test. It is however, likely that the period certainly extended into June, and perhaps beyond.

It might, therefore, seem logical to close the fishery from April until September as this would maximise the potentially positive effects a closed season. This would both protect the brood-stock at a critical phase of the reproductive cycle and encompass the period of maximum growth. However, this would fail properly to acknowledge the economic basis of the fishery. Not only does the overwhelming proportion of the saleable catch consist of female prawns, but the most valuable portion consists of large females many of which are ovigerous. Prawn fishermen gain a substantial proportion of their annual income from the April catch. Over the four years for which there are data, the sales Figures for April are on average the third highest of all months (see Figures 127 and 128, Section 4.6.1); consequently, a closed season which included April is unlikely to be acceptable to fishermen. Although the average quantities of P. serratus landed in May were considerably less than April, closing the fishery in May could still prove problematic especially if some fishermen feel disadvantaged. Any attempt at imposing a closed season on the prawn fishery must therefore be seen to have a reasonable economic and practical basis behind it in addition to the logic of stock protection if it is to be acceptable to fishermen.

175 The analyses of the catch data for P. serratus and H. gammarus in Section 4.6 clearly shows the three month period from 1st June to 1st September to be a fairly uncontroversial starting point for a closed season. This is because very few (if any) prawns are landed anywhere in Wales during this period, with lobster fishing taking precedence for pot fishermen during this time and so an alternative source of income is available. There would therefore be no obvious economic grounds for opposing a closed season during this period.

5.6.1 Practicalities of a closed season Enforcing the removal of all prawn pots from the water during the closed season would be the most logical way of implementing a close season. This would be relatively easy to police and have the additional advantage of removing one of the causes of potential conflict between fishermen (i.e. unfairly holding ground). Leaving strings of prawn pots in the water during the summer can prevent other fishermen from fishing that particular ground for other species targeted by pot fishermen during the summer months such as lobsters and crabs.

It would also be prudent to legislate that all that non-commercial prawn pots were also removed from the water during the closed season. This would avoid any potential conflict between commercial and recreational prawn fishermen and greatly simplify enforcement. Existing legislation such as Byelaw 30 (see Appendix VII) which currently permits the deployment of up to 5 prawn pots per vessel for recreational fishing would have to be substantially redrafted to accommodate a closed season. Because there are no requirements to submit catch returns or records of effort under Byelaw 30 there is no information available about the impact of recreational pot fishing on the stock, especially during the summer months. All that is known is that in 2007 over 350 Byelaw 30 permit holders were registered in Wales (Owen, NWNWSFC, 2007, pers. comm.). These omissions are of great importance because much of the recreational potting is done from small vessels and takes place in the shallow inshore waters adjacent to the inter-tidal zone where the prawn population migrates to in order to spawn. The generally larger commercial vessels find it more difficult to operate in such waters and are also mostly occupied with lobster and crab fishing during the summer, which may explain why very little prawn catch was landed by commercial vessels in June, July and August.

176 Conclusions Ideally a closed season needs to be longer than three months if it is to afford greater protection to the brood stock and fully encompass the period of maximum growth. However, a reasonable compromise would be to have a closed season from 1st June to 1st September, with the inclusion of May and perhaps September at a later date being contingent on further research into the economic consequences of closing the fishery during these months.

177 5.7 GENERAL CONCLUSIONS

The size difference between the sexes was a marked feature of all samples; with respect to mean carapace length and mean wet weight, females were universally larger than males in all cases. The analysis of the saleable proportion of the samples confirmed that, being the larger of the two sexes, female prawns were the main target of the fishery, with males only generally making a small contribution to the saleable biomass in a catch sample.

With respect to the general relationship between carapace width and carapace length, there was very little difference between the sexes. The analysis of the mean ratio between carapace width and carapace length found that sexual dimorphism was only evident in the samples from Aberystwyth and Morfa Nefyn collected in April and May. During these months male carapace length was found to be slightly greater than female carapace length relative to carapace width.

Sexual dimorphism was clearly evident in the general relationship between carapace length and rostral length. With respect to the ratio between carapace length and rostral length the pronounced difference between the sexes indicated that for any given carapace length the rostra of male specimens was significantly longer than the rostra of female specimens. This confirms the findings of Campillo (1979a) that the length of the rostrum relative to the length of the carapace is a clear secondary sexual characteristic of the species. It follows from this that measuring the ratio can be used as a supplementary technique for determining the sex of specimens, particularly in the field. The only regional difference found in the ratio between carapace length and rostral length was in male specimens collected during March. Relative to the length of the carapace, the rostra of male samples from Aberystwyth were significantly longer than the rostra of males from both Newquay and Amlwch. Further investigation is required to determine why this was the case.

The number of dorsal teeth on the rostra of both male and female specimens varied between Morfa Nefyn and the other locations. Significant variations in the number of ventral teeth between locations were confined to female specimens. It was found that the differences found in rostral dentition were not affected by the size (i.e. carapace length) of the specimens. Variations in rostral dentition are therefore thought to reflect

178 the depth at which the samples were collected. Why the number of ventral teeth on the rostra of females was more variable than the number on the rostra of males requires further investigation.

Most of the seasonal and regional variations found in the morphology and structure of the sample populations, including the size of sexual maturity, egg number and egg volume, were probably reflections of the depth at which the samples were collected and the seasonal migratory patterns of the species. That is, the variations were most likely to have been largely determined by the sampling regime rather than the existence of separate populations of the species around the Welsh coast. As such, the variations found in this study are unlikely to affect the universal applicability of potential regulatory options.

The main findings of the analysis of the pot mesh trial data were that, compared to 9mm mesh pots, the 14mm mesh pots captured more prawns of a saleable size and significantly less discard. Despite the slight doubt as to the how representative the data were, pots fitted with 14mm mesh would seem to represent the most logical option for regulating the size of the prawns captured by the fishery. It seems unlikely that a 14mm mesh size could disadvantage any individual or particular group of fishermen when no evidence was found of structurally or morphologically distinct populations around the Welsh coast.

There was no evidence from the analysis of catch data to suggest that introducing a closed season from the 1st of June to the 1st of September would have any adverse affect on fishing incomes. Given that an increase in the maximum yield per recruit would be a potential advantage gained by fishermen if the stock were further protected during the periods of maximum egg carriage and maximum growth, scope also exists for the extension of the suggested closed season to include May and September. Of course this would have to be contingent on further research into the likely economic consequences.

179 5.7.1 Suggestions for further work Should further examination of the morphology of P. serratus be contemplated, then it is recommended that samples be collected on a regular basis from three different depths at a series of regional locations around the whole Welsh coastline for a continuous period of not less than one year. Sampling should also include larger enclosed estuarine environments (e.g. the Daugleddau estuary). This is so a more complete picture of the population than was possible in the present study can be gained. It is also recommended that fishermen be at the centre of any proposed sample collection due to their ownership of the means to deploy and collect the sampling equipment and their working knowledge of the species and its environment. It is essential that sufficient funding be secured to provide a reasonable financial incentive in addition to covering the costs incurred by fishermen prior to the commencement of any sampling so that a comprehensive data-set can be produced. As the current study has demonstrated, reliance on the use of purely volunteer fishermen to collect samples is likely to result in a truncated data-set that is both difficult to analyse and limited in coverage.

To support the certification of Welsh prawns under EU schemes such as the Protected Geographical Indication (PGI) and/or Protected Designation of Origin (PDO) (EU, 2011), evidence of the genetic integrity of P. serratus around the Welsh coastline may be required. Ideally, microsatellite markers need to be designed for P. serratus to detect genetic differences, as none currently exist. Microsatellite markers have been designed for the related species (Song et al., 2009), but they were found, in a recent (unpublished) pilot study at IBERS, not to be conserved in P. serratus and, therefore, of little use (pers. comm., Fish, 2011). Given the close proximity of the Irish fishery, it would be prudent to establish links with Bord Iascaigh Mhara/Irish Sea Fisheries Board (BIM) with a view to undertaking a collaborative research project. This would not only determine if there were any significant genetic differences within the Welsh stock, but also between the Welsh and Irish stocks. It may also prove possible to gain EU Community funding for such a project via, for example, the Seventh Framework Programme (EU, 2007).

180 To determine if a closed season longer than the minimum three months recommended in this study would be a viable option, research into the economic and biological consequences of closing the prawn fishery during May and September is required. Such work would have to balance the potential benefits of additional recruitment to, and growth of, the stock gained through the closure of the fishery, against the income lost by fishermen due to the closure. Much of the work could be done as a desktop exercise, utilising catch data from the MMO, supplemented by data acquired from captive aquarium based populations.

Pot fishing for P. serratus tends to target the brood-stock due to its greater size than the rest of the population. No information is available on the effects on the fecundity, size, and structure of wild populations as a result of this type of anthropogenic predation. Some insight into these effects could be gained through aquarium based experiments on captive populations.

Little is known about the behaviour of P. serratus in and around pots. How soon after being deployed do prawns enter pots, and does bait type or other factors affect this? Does the species use pots as a refuge from predators? How much movement in and out of a given pot by an individual prawn or group of prawns takes place? Do predators prevent escape? Questions such as these could be addressed by studying the behaviour of the species in the wild using remote hard drive high definition digital video cameras. This type of equipment has been used successfully used to study, for example, finfish abundance on benthic substrata in the North Sea (Polunin et al., 2009). Apart from increasing our general understanding of the species, such a project could also yield information leading to the development of more efficient fishing techniques.

As a precautionary measure, and because of the commercial importance of the species, it is recommended that an assessment be made of whether the parasites Ascophrys rodor and Bopyrus squillarum are present in the P. serratus population in Wales, and if so to what extent. As part of this work a reliable means of identifying these parasites needs to be determined and the commercial implications of infection fully explored. Canvassing the opinion of, and establishing working links with, the wholesale merchants may be particularly useful in this respect, as they are largely responsible for the quality control and distribution of the product.

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188 APPENDICES

188 Appendix I: Summary of the number of prawns captured/sample

Table I: Summary of the number of male, female and ovigerous prawns captured/sample 2008/9

NUMBER OF PRAWNS IN CATCH SAMPLES LOCATION/MONTH MALE FEMALE OVIGEROUS MALE + FEMALE NEWQUAY DECEMBER 38 92 4 130 JANUARY 29 22 2 51 FEBRUARY 23 38 15 61 MARCH 125 67 38 192 ALL MONTHS 215 219 59 434 ABERYSTWYTH FEBRUARY 7 32 3 39 MARCH 178 267 115 445 APRIL 230 256 228 486 MAY 44 67 66 111 ALL MONTHS 459 622 412 1081 MORFA NEFYN FEBRUARY 88 14 3 102

MARCH 77 44 13 121 APRIL 205 179 166 384 MAY 78 86 80 164 OCTOBER 30 194 0 224 ALL MONTHS 478 517 262 995 AMLWCH FEBRUARY 28 156 56 184 MARCH 33 175 44 208 ALL MONTHS 61 331 100 392

ALL LOCATIONS DECEMBER 38 92 4 130 JANUARY 29 22 2 51 FEBRUARY 146 240 77 386 MARCH 413 553 210 966 APRIL 435 435 394 870 MAY 122 153 146 275 OCTOBER 30 194 0 224 ALL MONTHS 1213 1689 833 2902

189 Appendix II: Summary of the number of prawns captured/pot

Table II: Summary of the number of male, female and ovigerous prawns captured/pot 2008/9

MEAN NUMBER OF PRAWNS CAPTURED/POT NO. OF LOCATION/MONTH POTS MALE FEMALE OVIGEROUS MALE + FEMALE NEWQUAY DECEMBER 10 3.8 9.2 0.4 13.0 JANUARY 10 2.9 2.2 0.2 5.1 FEBRUARY 10 2.3 3.8 1.5 6.1 MARCH 10 12.5 6.7 3.8 19.2 ALL MONTHS 40 5.4 5.5 1.5 10.9 ABERYSTWYTH FEBRUARY 20 0.4 1.6 0.2 2.0 MARCH 20 8.9 13.4 5.8 22.3 APRIL 10 23.0 25.6 22.8 48.6 MAY 10 4.4 6.7 6.6 11.1 ALL MONTHS 60 7.7 10.4 6.9 18.0 MORFA NEFYN FEBRUARY 10 8.8 1.4 0.3 10.2 MARCH 10 7.7 4.4 1.3 12.1 APRIL 20 10.3 9.0 8.3 19.2 MAY 10 7.8 8.6 8.0 16.4 OCTOBER 10 3.0 19.4 0.0 22.4 ALL MONTHS 60 8.0 8.6 4.4 16.6 AMLWCH FEBRUARY 10 2.8 15.6 5.6 18.4 MARCH 10 3.3 17.5 4.4 20.8 ALL MONTHS 20 3.1 16.6 5.0 19.6 ALL LOCATIONS DECEMBER 10 3.8 9.2 0.4 13.0 JANUARY 10 2.9 2.2 0.2 5.1 FEBRUARY 50 2.9 4.8 1.5 7.7 MARCH 50 8.3 11.1 4.2 19.3 APRIL 30 14.5 14.5 13.1 29.0 MAY 20 6.1 7.7 7.3 13.8 OCTOBER 10 3.0 19.4 0.0 22.4 TOTAL 180 6.7 9.4 4.6 16.1

190 Appendix III: Estimated prawn biomass in samples

Table III: Estimated prawn biomass in samples: Newquay 2008/9

NEWQUAY MEASURED ESTIMATED TOTAL MONTH SEX/STATE WEIGHT (g) VALUES (g) BIOMASS (g) MALE 89.508 35.440 124.948 DECEMBER FEMALE 488.365 92.973 581.338 OVIGEROUS 27.166 0 27.166 MALE+FEMALE 577.873 128.414 706.287 MALE 70.382 46.112 116.494 JANUARY FEMALE 106.912 55.133 162.045 OVIGEROUS 18.278 0 18.278 MALE+FEMALE 177.294 101.245 278.539 MALE 63.985 17.551 81.536 FEBRUARY FEMALE 216.415 30.096 246.511 OVIGEROUS 92.541 8.568 101.109 MALE+FEMALE 280.400 47.646 328.046 MALE 333.226 117.038 450.264 MARCH FEMALE 283.818 145.882 429.700 OVIGEROUS 165.092 95.175 260.267 MALE+FEMALE 617.044 262.920 879.964 MALE 557.101 216.142 773.243 ALL MONTHS FEMALE 1095.510 324.083 1419.593 OVIGEROUS 303.077 103.743 406.820 MALE+FEMALE 1652.611 540.225 2192.836

Table IV: Estimated prawn biomass in samples: Aberystwyth 2009 ABERYSTWYTH MEASURED ESTIMATED TOTAL MONTH SEX/STATE WEIGHT (g) VALUES (g) BIOMASS (g) MALE 22.431 3.832 26.263 FEBRUARY FEMALE 150.707 58.077 208.784 OVIGEROUS 16.996 8.430 25.426 MALE+FEMALE 173.138 61.910 235.048 MALE 476.764 134.907 611.671 MARCH FEMALE 1404.299 420.056 1824.355 OVIGEROUS 717.104 198.376 915.480 MALE+FEMALE 1881.063 554.963 2436.026 MALE 266.867 632.815 899.682 APRIL FEMALE 504.063 1413.899 1917.962 OVIGEROUS 456.694 1288.996 1745.690 MALE+FEMALE 770.930 2046.714 2817.644 MALE 101.506 76.873 178.379 MAY FEMALE 337.217 187.271 524.488 OVIGEROUS 335.902 187.271 523.173 MALE+FEMALE 438.723 264.144 702.867 MALE 867.568 848.428 1715.996 ALL MONTHS FEMALE 2396.286 2079.303 4475.589

OVIGEROUS 1526.696 1683.072 3209.768

MALE+FEMALE 3263.854 2927.731 6191.585

191 Appendix III cont/

Table V: Estimated prawn biomass in samples: Morfa Nefyn 2009

MORFA NEFYN MEASURED ESTIMATED TOTAL MONTH SEX/STATE WEIGHT (g) VALUES (g) BIOMASS (g) MALE 197.483 89.714 287.197 FEBRUARY FEMALE 64.493 9.521 74.014 OVIGEROUS 12.223 6.508 18.731 MALE+FEMALE 261.976 99.235 361.211 MALE 166.505 96.153 262.658 MARCH FEMALE 197.210 52.214 249.424 OVIGEROUS 67.818 21.527 89.345 MALE+FEMALE 363.715 148.367 512.082 MALE 520.266 295.317 815.583 APRIL FEMALE 972.046 391.017 1363.063 OVIGEROUS 940.427 354.436 1294.863 MALE+FEMALE 1492.312 686.335 2178.646 MALE 165.725 122.771 288.496 MAY FEMALE 370.807 333.815 704.622 OVIGEROUS 350.610 314.316 664.926 MALE+FEMALE 536.532 456.587 993.119 MALE 61.839 42.830 104.669 OCTOBER FEMALE 805.949 313.242 1119.191 OVIGEROUS 0 0 0 MALE+FEMALE 867.788 356.073 1223.861 MALE 1111.818 646.786 1758.604 ALL MONTHS FEMALE 2410.505 1099.811 3510.316 OVIGEROUS 1371.078 696.786 2067.864 MALE+FEMALE 3522.323 1746.597 5268.919

Table VI: Estimated prawn biomass in samples: Amlwch 2009 AMLWCH MEASURED ESTIMATED TOTAL MONTH SEX/STATE WEIGHT (g) VALUES (g) BIOMASS (g) MALE 34.099 95.709 129.808 FEBRUARY FEMALE 401.173 693.003 1094.176 OVIGEROUS 157.613 268.096 425.709 MALE+FEMALE 435.272 788.712 1223.984 MALE 87.698 44.865 132.563 MARCH FEMALE 875.646 323.331 1198.977 OVIGEROUS 189.914 90.365 280.279 MALE+FEMALE 963.344 368.196 1331.540 MALE 121.797 140.574 262.371 ALL MONTHS FEMALE 1276.819 1016.334 2293.153 OVIGEROUS 347.527 358.462 705.989 MALE+FEMALE 1398.616 1156.908 2555.524

192 Appendix IV: Estimated prawn biomass/pot

Table VII: Estimated prawn biomass/pot: all samples 2008/9

ESTIMATED MEAN BIOMASS/POT (g) NO. OF LOCATION/MONTH POTS MALE FEMALE OVIGEROUS MALE + FEMALE NEWQUAY DECEMBER 10 12.49 58.13 2.72 70.63 JANUARY 10 11.65 16.20 1.83 27.85 FEBRUARY 10 8.15 24.65 10.11 32.80 MARCH 10 45.03 42.97 26.03 88.00 ALL MONTHS 40 19.33 35.49 10.17 54.82 ABERYSTWYTH FEBRUARY 20 1.31 10.44 1.27 11.75 MARCH 20 30.58 91.22 45.77 121.80 APRIL 10 89.97 191.80 174.57 281.76 MAY 10 17.84 52.45 52.32 70.29 ALL MONTHS 60 28.60 74.59 53.50 103.19 MORFA NEFYN FEBRUARY 10 28.72 7.40 1.87 36.12 MARCH 10 26.27 24.94 8.93 51.21 APRIL 20 40.78 68.15 64.74 108.93 MAY 10 28.85 70.46 66.49 99.31 OCTOBER 10 10.47 111.92 0.00 122.39 ALL MONTHS 60 29.31 58.51 34.46 87.82 AMLWCH FEBRUARY 10 13.0 109.4 42.6 122.4 MARCH 10 13.3 119.9 28.0 133.2 ALL MONTHS 20 13.1 114.7 35.3 127.8 ALL LOCATIONS DECEMBER 10 12.5 58.1 2.7 70.6 JANUARY 10 11.6 16.2 1.8 27.9 FEBRUARY 50 10.5 32.5 11.4 43.0 MARCH 50 29.1 74.0 30.9 103.2 APRIL 30 57.2 109.4 101.4 166.5 MAY 20 23.3 61.5 59.4 84.8 OCTOBER 10 10.5 111.9 0.0 122.4 ALL MONTHS 180 25.1 65.0 35.5 90.0

193 Appendix V: Estimated mean weight of individual prawns captured

Table VIII: Estimated mean weight of individual male, female and ovigerous prawns captured 2008/9

ESTIMATED MEAN WEIGHT/PRAWN (g) LOCATION/MONTH MALE FEMALE OVIGEROUS MALE + FEMALE NEWQUAY DECEMBER 3.288 6.319 6.792 5.433 JANUARY 4.017 7.366 9.139 5.462 FEBRUARY 3.545 6.487 6.741 5.378 MARCH 3.602 6.413 6.849 4.583 ALL MONTHS 3.596 6.482 6.895 5.053 ABERYSTWYTH FEBRUARY 3.752 6.525 8.475 6.027 MARCH 3.436 6.833 7.961 5.474 APRIL 3.912 7.492 7.657 5.798 MAY 4.054 7.828 7.927 6.332 ALL MONTHS 3.739 7.195 7.791 5.728 MORFA NEFYN FEBRUARY 3.264 5.287 6.244 3.541 MARCH 3.411 5.669 6.873 4.232 APRIL 3.978 7.615 7.800 5.674 MAY 3.699 8.193 8.312 6.056 OCTOBER 3.489 5.769 0.000 5.464 ALL MONTHS 3.679 6.790 7.893 5.295 AMLWCH FEBRUARY 4.636 7.014 7.602 6.652 MARCH 4.017 6.851 6.370 6.402 ALL MONTHS 4.301 6.928 7.060 6.519 ALL LOCATIONS DECEMBER 3.288 6.319 6.792 5.433 JANUARY 4.017 7.366 9.139 5.462 FEBRUARY 3.595 6.765 7.415 5.566 MARCH 3.528 6.695 7.359 5.341 APRIL 3.943 7.543 7.717 5.743 MAY 3.827 8.033 8.138 6.167 OCTOBER 3.489 5.769 0.000 5.464 ALL MONTHS 3.718 6.926 7.672 5.585

194 Appendix VI: Multiple regression coefficients used to calculate biomass estimates

Table IX: Multiple regression coefficients used to calculate biomass estimates

Log y = a + log bx1 + log cx2 REGRESSION COEFFICIENTS LOCATION MONTH SEX a b c r² DECEMBER MALE -2.28866 0.76126 1.98581 0.98 NEWQUAY FEMALE -2.48630 1.10451 1.75798 0.99 JANUARY MALE -2.29374 1.42977 1.23224 0.95 FEMALE -1.89305 1.20437 1.12161 0.81

MALE -2.52987 1.76633 1.04880 0.97 FEBRUARY FEMALE -2.22623 0.55679 2.15424 0.77 MARCH MALE -2.34759 1.54415 1.10356 0.89 FEMALE -2.44705 1.23104 1.58310 0.92 FEBRUARY MALE -2.80838 0.43021 2.92448 0.97 ABERYSTWYTH FEMALE -2.50581 0.25430 2.77612 0.88 MARCH MALE -2.42544 1.06790 1.77961 0.99 FEMALE -2.47335 0.85871 2.05620 0.96

MALE -2.31854 1.47771 1.17094 0.83 APRIL FEMALE -2.23531 0.61300 2.12774 0.93 MAY MALE -2.25161 1.67468 0.85859 0.92 FEMALE -2.43422 0.44270 2.50824 0.98 FEBRUARY MALE -2.37218 0.90756 1.92066 0.98 MORFA NEFYN FEMALE -2.32746 0.80389 1.97331 0.99 MARCH MALE -2.37966 1.28062 1.47718 0.98 FEMALE -2.52235 1.08446 1.83336 0.99 APRIL MALE -2.35815 1.16119 1.59184 0.93 FEMALE -2.38327 0.87882 1.95859 0.93

MALE -2.38338 0.80795 2.01612 0.99 MAY FEMALE -2.70228 1.64053 1.33688 0.98 OCTOBER MALE -2.02113 0.47853 2.05082 0.97 FEMALE -2.07488 0.70198 1.84474 0.94 MALE -1.96670 0.18180 2.38684 0.99 AMLWCH FEBRUARY FEMALE -2.45245 1.08064 1.77282 0.99 MARCH MALE -2.48240 1.57994 1.23123 0.97 FEMALE -2.39965 0.89856 1.94403 0.98 (y = wet weight [g], x1 = carapace length [mm], x2 = carapace width [mm]).

195 Appendix VII: NWNWSFC Byelaw 30

BYELAW 30: FISHING FOR LOBSTER, CRAWFISH, CRAB, PRAWN AND WHELK 1. No person shall take or land from any fishery within the District more than the specified amount of the species listed below in a calendar day, except in accordance with paragraph 5. All such fish must be landed on the same calendar day on which they were caught and may not be stored in any keep pot or similar device at sea.

Species Maximum Daily Quantity Lobster (Homarus gammarus) 2 individuals Crawfish ( ) 1 individual Edible crabs (), Spider crabs (Maia squinado), Velvet crabs (Liocarcinus puber) Combined total of 5 individuals Prawns (Pandalidae and Palaemonidae) 1 kilogram Whelks (Buccinum undatum) 5 kilograms

2. No person, except in accordance with paragraph 5, shall fish in any part of the District, using pots or traps, except under a permit issued by the Committee.

3. Permit conditions: a) The permit shall not be transferable, and b) The person to whom the permit is issued shall not use more than 5 pots or traps, and c) All fishing gear shall be clearly marked with the number issued with the permit, and d) any boat used in accordance with the byelaw shall clearly display the number issued with the permit, shall not display more than one permit number, and shall not be used to haul any pots or traps not marked with that number, and e) the permit to fish shall be invalid if any of the above conditions are not met.

4. Applications to fish under this byelaw shall be made using the printed forms available from the Committee.

196 Appendix VIII/cont

5. This byelaw shall not apply to any person fishing from any fishing boat registered in accordance with the rule for the time being in force for the registration of a British sea fishing boat and holding a current fishing licence issued by the Government of England and Wales.

NWNWSFC, http://www.nwnwsfc.org/page/home.htm (accessed, 18/08/10).

197 Appendix VIII: Carapace length ANOVAS and Tukeys post hoc test results

Table X: ANOVA table for carapace length vs location, month and sex: all locations, February and March 2009 ANOVA TABLE FOR CARAPACE LENGTH VS LOCATION MONTH & SEX (FEBRUARY & MARCH 2009) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES LOCATION 1334.8663 3 444.95544 182.98 0.000 MONTH 9.137489 1 9.1374893 3.76 0.053 SEX 4566.7217 1 4566.7217 1878.03 0.000 LOCATION*MONTH 103.49731 3 34.499104 14.19 0.000 LOCATION*SEX 883.53174 3 294.51059 121.12 0.000 MONTH*SEX 10.967668 1 10.967668 4.51 0.034 LOCATION*MONTH*SEX 106.47231 3 35.490768 14.60 0.000 RESIDUAL 3248.6875 1336 2.4316523 (TOTAL) 8049.875 1351

Table XI: ANOVA table for carapace length vs location, month and sex: Aberystwyth and Morfa Nefyn February to May 2009 ANOVA TABLE FOR CARAPACE LENGTH VS MONTH LOCATION & SEX (ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 675.2218 3 225.07393 97.98 0.000 LOCATION 118.0437 1 118.0437 51.39 0.000 SEX 7006.9951 1 7006.9951 3050.26 0.000 MONTH*LOCATION 325.75333 3 108.58444 47.27 0.000 MONTH*SEX 101.26251 3 33.754169 14.69 0.000 LOCATION*SEX 168.99408 1 168.99408 73.57 0.000 MONTH*LOCATION*SEX 248.01602 3 82.672005 35.99 0.000 RESIDUAL 4217.625 1836 2.2971814 (TOTAL) 11814.281 1851

198 Appendix VIII cont/

Table XII: ANOVA table for carapace length vs month and sex: Newquay December to March 2008/9 ANOVA TABLE FOR CARAPACE LENGTH VS MONTH & SEX (NEWQUAY DECEMBER TO MARCH 2008/9) SUM OF DEGREES OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 16.792 3 5.5973334 2.25 0.082 SEX 1216.3163 1 1216.3163 487.85 0.000 MONTH*SEX 139.53993 3 46.513309 18.66 0.000 RESIDUAL 1062.1172 426 2.4932327 (TOTAL) 2356.7031 433

Table XIII: ANOVA table for carapace length vs month and sex: Morfa Nefyn February to May plus October 2009 ANOVA TABLE FOR CARAPACE LENGTH VS MONTH & SEX (MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009) SUM OF DEGREES OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 937.04816 4 234.26204 97.22 0.000 SEX 3050.488 1 3050.488 1266.03 0.000 MONTH*SEX 623.34296 4 155.83574 64.68 0.000 RESIDUAL 2373.3438 985 2.4094861 (TOTAL) 6031.4375 994

199 Appendix VIII cont/ Tukey’s Simultaneous Tests Response Variable CARAPACE LENGTH All Pairwise Comparisons among Levels of LOCATION*MONTH*SEX LOCATION = 1 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 1 2 3.7493 0.4120 9.1012 0.0000 1 2 1 0.8032 0.3538 2.2702 0.6462 1 2 2 4.1052 0.3768 10.8935 0.0000 2 1 1 0.4727 0.6731 0.7022 1.0000 2 1 2 4.0913 0.4263 9.5979 0.0000 2 2 1 -0.1269 0.3455 -0.3673 1.0000 2 2 2 3.9858 0.3389 11.7624 0.0000 3 1 1 -0.2679 0.3652 -0.7337 1.0000 3 1 2 2.5305 0.5286 4.7873 0.0002 3 2 1 -0.0088 0.3705 -0.0236 1.0000 3 2 2 2.9222 0.4012 7.2831 0.0000 4 1 1 1.5059 0.4388 3.4317 0.0492 4 1 2 4.1682 0.3483 11.9674 0.0000 4 2 1 0.7645 0.4236 1.8050 0.9151 4 2 2 4.0508 0.3459 11.7125 0.0000

LOCATION = 1 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 2 1 -2.946 0.2889 -10.20 0.0000 1 2 2 0.356 0.3167 1.12 0.9992 2 1 1 -3.277 0.6414 -5.11 0.0001 2 1 2 0.342 0.3741 0.91 0.9999 2 2 1 -3.876 0.2787 -13.91 0.0000 2 2 2 0.237 0.2704 0.87 1.0000 3 1 1 -4.017 0.3027 -13.27 0.0000 3 1 2 -1.219 0.4875 -2.50 0.4715 3 2 1 -3.758 0.3091 -12.16 0.0000 3 2 2 -0.827 0.3453 -2.40 0.5512 4 1 1 -2.243 0.3884 -5.78 0.0000 4 1 2 0.419 0.2821 1.48 0.9844 4 2 1 -2.985 0.3710 -8.04 0.0000 4 2 2 0.302 0.2791 1.08 0.9995

LOCATION = 1 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 2 2 3.302 0.2361 13.985 0.0000 2 1 1 -0.331 0.6057 -0.546 1.0000 2 1 2 3.288 0.3089 10.644 0.0000 2 2 1 -0.930 0.1820 -5.111 0.0001 2 2 2 3.183 0.1690 18.833 0.0000 3 1 1 -1.071 0.2170 -4.936 0.0001 3 1 2 1.727 0.4395 3.930 0.0084 3 2 1 -0.812 0.2259 -3.594 0.0287 3 2 2 2.119 0.2733 7.752 0.0000 4 1 1 0.703 0.3260 2.155 0.7287 4 1 2 3.365 0.1872 17.976 0.0000 4 2 1 -0.039 0.3052 -0.127 1.0000 4 2 2 3.248 0.1826 17.784 0.0000

Box 1 (i): Tukey’s pairwise test results for carapace length: all locations, February and March 2009 (Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 1, March = 2. Male = 1, Female = 2)

200 Appendix VIII cont/ LOCATION = 1 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 1 1 -3.632 0.6194 -5.86 0.0000 2 1 2 -0.014 0.3351 -0.04 1.0000 2 2 1 -4.232 0.2235 -18.94 0.0000 2 2 2 -0.119 0.2131 -0.56 1.0000 3 1 1 -4.373 0.2528 -17.30 0.0000 3 1 2 -1.575 0.4582 -3.44 0.0484 3 2 1 -4.114 0.2605 -15.79 0.0000 3 2 2 -1.183 0.3026 -3.91 0.0091 4 1 1 -2.599 0.3509 -7.41 0.0000 4 1 2 0.063 0.2278 0.28 1.0000 4 2 1 -3.341 0.3316 -10.07 0.0000 4 2 2 -0.054 0.2240 -0.24 1.0000

LOCATION = 2 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 1 2 3.6187 0.6507 5.562 0.0000 2 2 1 -0.5996 0.6009 -0.998 0.9998 2 2 2 3.5132 0.5971 5.884 0.0000 3 1 1 -0.7406 0.6124 -1.209 0.9982 3 1 2 2.0579 0.7218 2.851 0.2403 3 2 1 -0.4814 0.6156 -0.782 1.0000 3 2 2 2.4495 0.6345 3.860 0.0110 4 1 1 1.0332 0.6589 1.568 0.9739 4 1 2 3.6955 0.6025 6.134 0.0000 4 2 1 0.2919 0.6489 0.450 1.0000 4 2 2 3.5782 0.6011 5.953 0.0000

LOCATION = 2 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 2 1 -4.218 0.2994 -14.09 0.0000 2 2 2 -0.105 0.2917 -0.36 1.0000 3 1 1 -4.359 0.3219 -13.54 0.0000 3 1 2 -1.561 0.4997 -3.12 0.1222 3 2 1 -4.100 0.3280 -12.50 0.0000 3 2 2 -1.169 0.3623 -3.23 0.0915 4 1 1 -2.585 0.4035 -6.41 0.0000 4 1 2 0.077 0.3026 0.25 1.0000 4 2 1 -3.327 0.3869 -8.60 0.0000 4 2 2 -0.040 0.2998 -0.14 1.0000

LOCATION = 2 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 2 2 4.1128 0.1509 27.2567 0.0000 3 1 1 -0.1410 0.2032 -0.6939 1.0000 3 1 2 2.6574 0.4328 6.1396 0.0000 3 2 1 0.1182 0.2127 0.5555 1.0000 3 2 2 3.0491 0.2625 11.6141 0.0000 4 1 1 1.6328 0.3170 5.1504 0.0001 4 1 2 4.2951 0.1710 25.1146 0.0000 4 2 1 0.8915 0.2955 3.0163 0.1619 4 2 2 4.1778 0.1660 25.1675 0.0000

Box 1 (ii): Tukey’s pairwise test results for carapace length: all locations, February and March 2009 (Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 1, March = 2. Male = 1, Female = 2)

201 Appendix VIII cont/ LOCATION = 2 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 1 1 -4.254 0.1917 -22.19 0.0000 3 1 2 -1.455 0.4275 -3.40 0.0537 3 2 1 -3.995 0.2017 -19.80 0.0000 3 2 2 -1.064 0.2537 -4.19 0.0029 4 1 1 -2.480 0.3098 -8.01 0.0000 4 1 2 0.182 0.1571 1.16 0.9989 4 2 1 -3.221 0.2877 -11.20 0.0000 4 2 2 0.065 0.1517 0.43 1.0000 LOCATION = 3 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 1 2 2.7985 0.4487 6.237 0.0000 3 2 1 0.2592 0.2433 1.065 0.9996 3 2 2 3.1901 0.2879 11.080 0.0000 4 1 1 1.7738 0.3383 5.243 0.0001 4 1 2 4.4361 0.2079 21.339 0.0000 4 2 1 1.0325 0.3183 3.244 0.0872 4 2 2 4.3188 0.2038 21.193 0.0000 LOCATION = 3 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 2 1 -2.539 0.4531 -5.605 0.0000 3 2 2 0.392 0.4785 0.819 1.0000 4 1 1 -1.025 0.5104 -2.007 0.8216 4 1 2 1.638 0.4351 3.764 0.0157 4 2 1 -1.766 0.4974 -3.551 0.0333 4 2 2 1.520 0.4331 3.510 0.0381 LOCATION = 3 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 2 2 2.9309 0.2947 9.946 0.0000 4 1 1 1.5146 0.3441 4.401 0.0012 4 1 2 4.1769 0.2172 19.233 0.0000 4 2 1 0.7733 0.3244 2.383 0.5603 4 2 2 4.0596 0.2132 19.037 0.0000 LOCATION = 3 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 1 1 -1.416 0.3770 -3.757 0.0161 4 1 2 1.246 0.2662 4.681 0.0003 4 2 1 -2.158 0.3591 -6.009 0.0000 4 2 2 1.129 0.2630 4.292 0.0019 LOCATION = 4 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 1 2 2.6623 0.3200 8.318 0.0000 4 2 1 -0.7414 0.4007 -1.850 0.8979 4 2 2 2.5450 0.3174 8.018 0.0000 LOCATION = 4 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 2 1 -3.404 0.2988 -11.39 0.0000 4 2 2 -0.117 0.1717 -0.68 1.0000 LOCATION = 4 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 2 2 3.286 0.2959 11.10 0.0000 Box 1 (iii): Tukey’s pairwise test results for carapace length: all locations, February and March 2009 (Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 1, March = 2. Male = 1, Female = 2)

202 Appendix VIII cont/ Tukey’s Simultaneous Tests Response Variable CARAPACE LENGTH All Pairwise Comparisons among Levels of MONTH*LOCATION*SEX MONTH = 1 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 1 1 2 3.6187 0.6324 5.722 0.0000 1 2 1 -0.7406 0.5952 -1.244 0.9975 1 2 2 2.0579 0.7016 2.933 0.1987 2 1 1 -0.5996 0.5840 -1.027 0.9997 2 1 2 3.5132 0.5803 6.054 0.0000 2 2 1 -0.4814 0.5983 -0.805 1.0000 2 2 2 2.4495 0.6167 3.972 0.0072 3 1 1 0.4270 0.5815 0.734 1.0000 3 1 2 4.2487 0.5806 7.317 0.0000 3 2 1 0.5117 0.5826 0.878 1.0000 3 2 2 4.2225 0.5839 7.231 0.0000 4 1 1 0.7527 0.6167 1.220 0.9980 4 1 2 4.2640 0.6020 7.083 0.0000 4 2 1 0.4575 0.5980 0.765 1.0000 4 2 2 4.9192 0.5957 8.258 0.0000

MONTH = 1 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 1 2 1 -4.359 0.3129 -13.93 0.0000 1 2 2 -1.561 0.4857 -3.21 0.0951 2 1 1 -4.218 0.2910 -14.49 0.0000 2 1 2 -0.105 0.2835 -0.37 1.0000 2 2 1 -4.100 0.3188 -12.86 0.0000 2 2 2 -1.169 0.3521 -3.32 0.0695 3 1 1 -3.192 0.2860 -11.16 0.0000 3 1 2 0.630 0.2842 2.22 0.6853 3 2 1 -3.107 0.2881 -10.79 0.0000 3 2 2 0.604 0.2909 2.08 0.7809 4 1 1 -2.866 0.3521 -8.14 0.0000 4 1 2 0.645 0.3257 1.98 0.8359 4 2 1 -3.161 0.3182 -9.94 0.0000 4 2 2 1.301 0.3138 4.14 0.0036

MONTH = 1 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 1 2 2 2.7985 0.4361 6.4170 0.0000 2 1 1 0.1410 0.1975 0.7139 1.0000 2 1 2 4.2538 0.1863 22.8329 0.0000 2 2 1 0.2592 0.2365 1.0958 0.9994 2 2 2 3.1901 0.2798 11.3997 0.0000 3 1 1 1.1676 0.1900 6.1461 0.0000 3 1 2 4.9893 0.1873 26.6394 0.0000 3 2 1 1.2523 0.1932 6.4831 0.0000 3 2 2 4.9631 0.1973 25.1519 0.0000 4 1 1 1.4933 0.2798 5.3362 0.0000 4 1 2 5.0046 0.2457 20.3651 0.0000 4 2 1 1.1981 0.2357 5.0831 0.0001 4 2 2 5.6598 0.2298 24.6275 0.0000

Box 2 (i): Tukey’s pairwise test results for carapace length: Aberystwyth and Morfa Nefyn February to May 2009 (February = 1, March = 2, April = 3, May = 4. Aberystwyth = 1, Morfa Nefyn = 2. Male = 1, Female = 2)

203 Appendix VIII cont/

MONTH = 1 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 1 1 -2.657 0.4207 -6.317 0.0000 2 1 2 1.455 0.4156 3.502 0.0391 2 2 1 -2.539 0.4404 -5.766 0.0000 2 2 2 0.392 0.4651 0.842 1.0000 3 1 1 -1.631 0.4172 -3.909 0.0091 3 1 2 2.191 0.4160 5.266 0.0001 3 2 1 -1.546 0.4187 -3.693 0.0203 3 2 2 2.165 0.4206 5.146 0.0001 4 1 1 -1.305 0.4651 -2.806 0.2651 4 1 2 2.206 0.4454 4.953 0.0001 4 2 1 -1.600 0.4399 -3.638 0.0247 4 2 2 2.861 0.4368 6.551 0.0000

MONTH = 2 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 1 2 4.1128 0.1467 28.0430 0.0000 2 2 1 0.1182 0.2067 0.5716 1.0000 2 2 2 3.0491 0.2552 11.9492 0.0000 3 1 1 1.0266 0.1513 6.7851 0.0000 3 1 2 4.8483 0.1479 32.7775 0.0000 3 2 1 1.1112 0.1553 7.1565 0.0000 3 2 2 4.8221 0.1604 30.0568 0.0000 4 1 1 1.3523 0.2552 5.2995 0.0000 4 1 2 4.8636 0.2172 22.3885 0.0000 4 2 1 1.0571 0.2058 5.1363 0.0001 4 2 2 5.5188 0.1990 27.7271 0.0000

MONTH = 2 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 2 1 -3.995 0.1961 -20.38 0.0000 2 2 2 -1.064 0.2466 -4.31 0.0017 3 1 1 -3.086 0.1363 -22.63 0.0000 3 1 2 0.735 0.1326 5.55 0.0000 3 2 1 -3.002 0.1407 -21.33 0.0000 3 2 2 0.709 0.1464 4.84 0.0002 4 1 1 -2.760 0.2466 -11.19 0.0000 4 1 2 0.751 0.2071 3.63 0.0258 4 2 1 -3.056 0.1951 -15.66 0.0000 4 2 2 1.406 0.1879 7.48 0.0000

MONTH = 2 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 2 2 2.9309 0.2864 10.233 0.0000 3 1 1 0.9085 0.1996 4.552 0.0006 3 1 2 4.7301 0.1970 24.011 0.0000 3 2 1 0.9931 0.2026 4.902 0.0001 3 2 2 4.7039 0.2066 22.773 0.0000 4 1 1 1.2341 0.2864 4.309 0.0018 4 1 2 4.7454 0.2532 18.741 0.0000 4 2 1 0.9389 0.2435 3.856 0.0112 4 2 2 5.4006 0.2378 22.712 0.0000

Box 2 (ii): Tukey’s pairwise test results for carapace length: Aberystwyth and Morfa Nefyn February to May 2009 (February = 1, March = 2, April = 3, May = 4. Aberystwyth = 1, Morfa Nefyn = 2. Male = 1, Female = 2)

204 Appendix VIII cont/

MONTH = 2 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 1 1 -2.022 0.2494 -8.110 0.0000 3 1 2 1.799 0.2473 7.274 0.0000 3 2 1 -1.938 0.2518 -7.695 0.0000 3 2 2 1.773 0.2550 6.952 0.0000 4 1 1 -1.697 0.3231 -5.251 0.0001 4 1 2 1.814 0.2941 6.170 0.0000 4 2 1 -1.992 0.2858 -6.971 0.0000 4 2 2 2.470 0.2809 8.791 0.0000 MONTH = 3 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 1 2 3.82164 0.1377 27.7537 0.0000 3 2 1 0.08463 0.1456 0.5813 1.0000 3 2 2 3.79547 0.1511 25.1247 0.0000 4 1 1 0.32567 0.2494 1.3059 0.9958 4 1 2 3.83696 0.2104 18.2354 0.0000 4 2 1 0.03047 0.1986 0.1534 1.0000 4 2 2 4.49214 0.1916 23.4493 0.0000 MONTH = 3 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 2 1 -3.737 0.1421 -26.31 0.0000 3 2 2 -0.026 0.1477 -0.18 1.0000 4 1 1 -3.496 0.2473 -14.13 0.0000 4 1 2 0.015 0.2080 0.07 1.0000 4 2 1 -3.791 0.1960 -19.34 0.0000 4 2 2 0.671 0.1889 3.55 0.0334 MONTH = 3 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 2 2 3.71085 0.1550 23.9341 0.0000 4 1 1 0.24104 0.2518 0.9572 0.9999 4 1 2 3.75234 0.2133 17.5929 0.0000 4 2 1 -0.05416 0.2016 -0.2686 1.0000 4 2 2 4.40752 0.1947 22.6349 0.0000 MONTH = 3 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 1 1 -3.470 0.2550 -13.61 0.0000 4 1 2 0.041 0.2171 0.19 1.0000 4 2 1 -3.765 0.2056 -18.31 0.0000 4 2 2 0.697 0.1989 3.50 0.0390 MONTH = 4 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 1 2 3.5113 0.2941 11.939 0.0000 4 2 1 -0.2952 0.2858 -1.033 0.9997 4 2 2 4.1665 0.2809 14.831 0.0000 MONTH = 4 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 2 1 -3.806 0.2525 -15.08 0.0000 4 2 2 0.655 0.2470 2.65 0.3617 MONTH = 4 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 2 2 4.462 0.2370 18.83 0.0000

Box 2 (iii): Tukey’s pairwise test results for carapace length: Aberystwyth and Morfa Nefyn February to May 2009 (February = 1, March = 2, April = 3, May = 4. Aberystwyth = 1, Morfa Nefyn = 2. Male = 1, Female = 2)

205 Appendix VIII cont/ Tukey’s Simultaneous Tests Response Variable CARAPACE LENGTH All Pairwise Comparisons among Levels of MONTH*SEX MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 1 2 3.8820 0.3045 12.7493 0.0000 2 1 1.0588 0.3893 2.7196 0.1166 2 2 5.0122 0.4230 11.8487 0.0000 3 1 0.3957 0.4171 0.9485 0.9812 3 2 4.1450 0.3622 11.4425 0.0000 4 1 1.1989 0.2925 4.0987 0.0011 4 2 4.5008 0.3207 14.0361 0.0000

MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 1 -2.823 0.3363 -8.40 0.0000 2 2 1.130 0.3747 3.02 0.0522 3 1 -3.486 0.3681 -9.47 0.0000 3 2 0.263 0.3045 0.86 0.9891 4 1 -2.683 0.2169 -12.37 0.0000 4 2 0.619 0.2536 2.44 0.2219

MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 2 3.9533 0.4464 8.855 0.0000 3 1 -0.6632 0.4409 -1.504 0.8055 3 2 3.0862 0.3893 7.927 0.0000 4 1 0.1400 0.3255 0.430 0.9999 4 2 3.4420 0.3510 9.807 0.0000

MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 1 -4.617 0.4709 -9.80 0.0000 3 2 -0.867 0.4230 -2.05 0.4479 4 1 -3.813 0.3651 -10.45 0.0000 4 2 -0.511 0.3880 -1.32 0.8924

MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 2 3.7493 0.4171 8.988 0.0000 4 1 0.8032 0.3583 2.242 0.3265 4 2 4.1052 0.3816 10.758 0.0000

MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 1 -2.946 0.2925 -10.07 0.0000 4 2 0.356 0.3207 1.11 0.9549

MONTH = 4 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 2 3.302 0.2391 13.81 0.0000

Box 3: Tukey’s pairwise test results for carapace length: Newquay December to March 2008/9 (December = 1, January = 2, February = 3, March = 4. Male = 1, Female = 2)

206 Appendix VIII cont/ Tukey’s Simultaneous Tests Response Variable CARAPACE LENGTH All Pairwise Comparisons among Levels of MONTH*SEX MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 1 2 2.7985 0.4466 6.2656 0.0000 2 1 0.2592 0.2422 1.0700 0.9875 2 2 3.1901 0.2866 11.1308 0.0000 3 1 1.2523 0.1978 6.3302 0.0000 3 2 4.9631 0.2021 24.5586 0.0000 4 1 1.1981 0.2414 4.9632 0.0000 4 2 5.6598 0.2354 24.0466 0.0000 9 1 0.3022 0.3282 0.9209 0.9958 9 2 3.4398 0.1995 17.2420 0.0000

MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 1 -2.539 0.4510 -5.630 0.0000 2 2 0.392 0.4763 0.822 0.9983 3 1 -1.546 0.4288 -3.606 0.0116 3 2 2.165 0.4308 5.025 0.0000 4 1 -1.600 0.4506 -3.552 0.0140 4 2 2.861 0.4474 6.396 0.0000 9 1 -2.496 0.5024 -4.968 0.0000 9 2 0.641 0.4296 1.493 0.8954

MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 2 2.93094 0.2933 9.9914 0.0000 3 1 0.99308 0.2075 4.7865 0.0001 3 2 4.70393 0.2115 22.2357 0.0000 4 1 0.93892 0.2494 3.7653 0.0064 4 2 5.40060 0.2435 22.1759 0.0000 9 1 0.04305 0.3341 0.1289 1.0000 9 2 3.18061 0.2091 15.2129 0.0000

MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 1 -1.938 0.2579 -7.514 0.0000 3 2 1.773 0.2612 6.788 0.0000 4 1 -1.992 0.2927 -6.807 0.0000 4 2 2.470 0.2877 8.584 0.0000 9 1 -2.888 0.3675 -7.858 0.0000 9 2 0.250 0.2592 0.963 0.9942

Box 4 (i): Tukey’s pairwise test results for carapace length: Morfa Nefyn February to May plus October 2009 (February = 1, March = 2, April = 3, May = 4, October = 9. Male = 1, Female = 2)

207 Appendix VIII cont/ MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 2 3.7108 0.1588 23.370 0.0000 4 1 -0.0542 0.2065 -0.262 1.0000 4 2 4.4075 0.1994 22.101 0.0000 9 1 -0.9500 0.3034 -3.131 0.0552 9 2 2.1875 0.1555 14.070 0.0000

MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 1 -3.765 0.2106 -17.88 0.0000 4 2 0.697 0.2037 3.42 0.0220 9 1 -4.661 0.3062 -15.22 0.0000 9 2 -1.523 0.1609 -9.47 0.0000

MONTH = 4 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 2 4.4617 0.2427 18.383 0.0000 9 1 -0.8959 0.3335 -2.686 0.1790 9 2 2.2417 0.2081 10.772 0.0000

MONTH = 4 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 9 1 -5.358 0.3291 -16.28 0.0000 9 2 -2.220 0.2011 -11.04 0.0000

MONTH = 9 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 9 2 3.138 0.3045 10.30 0.0000

Box 4 (ii): Tukey’s pairwise test results for carapace length: Morfa Nefyn February to May plus October 2009 (February = 1, March = 2, April = 3, May = 4, October = 9. Male = 1, Female = 2)

208 Appendix IX: log Wet weight ANOVAS and Tukey’s post hoc test results

Table IV: ANOVA table for log wet weight vs location, month and sex: all locations, February and March 2009 ANOVA TABLE FOR log WET WEIGHT LENGTH VS LOCATION MONTH & SEX (FEBRUARY & MARCH 2009) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES LOCATION 4.183797 3 1.394599 81.39 0.000 MONTH 0.000008 1 8.39E-06 0.00 0.982 SEX 17.197174 1 17.197174 1003.66 0.000 LOCATION*MONTH 0.650572 3 0.2168572 12.66 0.000 LOCATION*SEX 3.038804 3 1.0129346 59.12 0.000 MONTH*SEX 0.00042 1 0.00042 0.02 0.876 LOCATION*MONTH*SEX 0.517568 3 0.1725228 10.07 0.000 RESIDUAL 15.763641 920 0.0171344 (TOTAL) 33.637634 935

Table XV: ANOVA table for log wet weight vs location, month and sex: Aberystwyth and Morfa Nefyn February to May 2009 ANOVA TABLE FOR log WET WEIGHT VS MONTH LOCATION & SEX (ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 1.390411 3 0.4634705 26.28 0.000 LOCATION 0.320172 1 0.3201719 18.16 0.000 SEX 23.101004 1 23.101004 1309.92 0.000 MONTH*LOCATION 1.074239 3 0.3580797 20.30 0.000 MONTH*SEX 0.423847 3 0.1412822 8.01 0.000 LOCATION*SEX 0.54048 1 0.5404797 30.65 0.000 MONTH*LOCATION*SEX 0.858195 3 0.2860651 16.22 0.000 RESIDUAL 18.993347 1077 0.0176354 (TOTAL) 43.58429 1092

209 Appendix IX cont/

Table XVI: ANOVA table for log wet weight vs month and sex: Newquay December to March 2008/9 ANOVA TABLE FOR log WET WEIGHT VS MONTH & SEX (NEWQUAY DECEMBER TO MARCH 2008/9) SUM OF DEGREES OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 0.521386 3 0.1737952 10.71 0.000 SEX 5.504819 1 5.5048194 339.28 0.000 MONTH*SEX 0.79892 3 0.2663067 16.41 0.000 RESIDUAL 5.127121 316 0.0162251 (TOTAL) 10.818802 323

Table XVII: ANOVA table for log wet weight vs month and sex: Morfa Nefyn February to May plus October 2009 ANOVA TABLE FOR log WET WEIGHT VS MONTH & SEX (MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009) SUM OF DEGREES OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 2.547161 4 0.6367902 45.78 0.000 SEX 11.372958 1 11.372958 817.66 0.000 MONTH*SEX 2.451594 4 0.6128986 44.06 0.000 RESIDUAL 9.110474 655 0.0139091 (TOTAL) 21.993378 664

210 Appendix IX cont/

Tukey’s Simultaneous Tests Response Variable log WET WEIGHT All Pairwise Comparisons among Levels of LOCATION*MONTH*SEX LOCATION = 1 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 1 2 0.27583 0.03836 7.1914 0.0000 1 2 1 0.00951 0.03368 0.2825 1.0000 1 2 2 0.26484 0.03662 7.2312 0.0000 2 1 1 0.03417 0.06171 0.5538 1.0000 2 1 2 0.27448 0.04119 6.6633 0.0000 2 2 1 -0.02747 0.03278 -0.8381 1.0000 2 2 2 0.27516 0.03216 8.5559 0.0000 3 1 1 -0.02901 0.03518 -0.8246 1.0000 3 1 2 0.17436 0.04878 3.5741 0.0308 3 2 1 -0.00397 0.03618 -0.1097 1.0000 3 2 2 0.19808 0.03816 5.1913 0.0001 4 1 1 0.14280 0.05831 2.4490 0.5101 4 1 2 0.27728 0.03532 7.8510 0.0000 4 2 1 0.05699 0.04160 1.3700 0.9930 4 2 2 0.27867 0.03294 8.4612 0.0000

LOCATION = 1 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 2 1 -0.2663 0.02649 -10.05 0.0000 1 2 2 -0.0110 0.03014 -0.36 1.0000 2 1 1 -0.2417 0.05809 -4.16 0.0034 2 1 2 -0.0013 0.03556 -0.04 1.0000 2 2 1 -0.3033 0.02533 -11.97 0.0000 2 2 2 -0.0007 0.02453 -0.03 1.0000 3 1 1 -0.3048 0.02837 -10.75 0.0000 3 1 2 -0.1015 0.04413 -2.30 0.6241 3 2 1 -0.2798 0.02960 -9.45 0.0000 3 2 2 -0.0777 0.03199 -2.43 0.5241 4 1 1 -0.1330 0.05447 -2.44 0.5152 4 1 2 0.0015 0.02854 0.05 1.0000 4 2 1 -0.2188 0.03603 -6.07 0.0000 4 2 2 0.0028 0.02554 0.11 1.0000

LOCATION = 1 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 2 2 0.25532 0.02391 10.678 0.0000 2 1 1 0.02466 0.05512 0.447 1.0000 2 1 2 0.26497 0.03045 8.701 0.0000 2 2 1 -0.03698 0.01745 -2.119 0.7532 2 2 2 0.26565 0.01627 16.329 0.0000 3 1 1 -0.03852 0.02163 -1.781 0.9235 3 1 2 0.16484 0.04013 4.108 0.0042 3 2 1 -0.01348 0.02322 -0.581 1.0000 3 2 2 0.18857 0.02620 7.198 0.0000 4 1 1 0.13328 0.05128 2.599 0.3992 4 1 2 0.26777 0.02186 12.251 0.0000 4 2 1 0.04748 0.03100 1.531 0.9790 4 2 2 0.26916 0.01775 15.163 0.0000

Box 5 (i): Tukey’s pairwise test results for log wet weight: all locations, February and March 2009 (Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 1, March = 2. Male =1, Female = 2)

211 Appendix IX cont/ LOCATION = 1 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 1 1 -0.2307 0.05697 -4.05 0.0053 2 1 2 0.0096 0.03368 0.29 1.0000 2 2 1 -0.2923 0.02262 -12.92 0.0000 2 2 2 0.0103 0.02172 0.48 1.0000 3 1 1 -0.2938 0.02598 -11.31 0.0000 3 1 2 -0.0905 0.04263 -2.12 0.7508 3 2 1 -0.2688 0.02732 -9.84 0.0000 3 2 2 -0.0668 0.02989 -2.23 0.6733 4 1 1 -0.1220 0.05327 -2.29 0.6305 4 1 2 0.0124 0.02617 0.48 1.0000 4 2 1 -0.2078 0.03418 -6.08 0.0000 4 2 2 0.0138 0.02285 0.61 1.0000

LOCATION = 2 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 1 2 0.24031 0.06001 4.005 0.0063 2 2 1 -0.06164 0.05457 -1.130 0.9992 2 2 2 0.24099 0.05420 4.446 0.0010 3 1 1 -0.06318 0.05605 -1.127 0.9992 3 1 2 0.14018 0.06545 2.142 0.7378 3 2 1 -0.03814 0.05668 -0.673 1.0000 3 2 2 0.16391 0.05796 2.828 0.2530 4 1 1 0.10862 0.07283 1.492 0.9837 4 1 2 0.24311 0.05614 4.331 0.0016 4 2 1 0.02282 0.06029 0.379 1.0000 4 2 2 0.24450 0.05467 4.472 0.0009

LOCATION = 2 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 2 1 -0.3020 0.02945 -10.25 0.0000 2 2 2 0.0007 0.02876 0.02 1.0000 3 1 1 -0.3035 0.03210 -9.45 0.0000 3 1 2 -0.1001 0.04661 -2.15 0.7337 3 2 1 -0.2784 0.03320 -8.39 0.0000 3 2 2 -0.0764 0.03534 -2.16 0.7241 4 1 1 -0.1317 0.05650 -2.33 0.6007 4 1 2 0.0028 0.03226 0.09 1.0000 4 2 1 -0.2175 0.03904 -5.57 0.0000 4 2 2 0.0042 0.02963 0.14 1.0000

LOCATION = 2 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 2 2 0.302632 0.01431 21.1488 0.0000 3 1 1 -0.001536 0.02020 -0.0761 1.0000 3 1 2 0.201825 0.03937 5.1259 0.0001 3 2 1 0.023502 0.02189 1.0734 0.9995 3 2 2 0.225550 0.02503 9.0123 0.0000 4 1 1 0.170266 0.05070 3.3585 0.0618 4 1 2 0.304750 0.02044 14.9092 0.0000 4 2 1 0.084463 0.03002 2.8135 0.2610 4 2 2 0.306142 0.01598 19.1633 0.0000

Box 5 (ii): Tukey’s pairwise test results for log wet weight: all locations, February and March 2009 (Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 1, March = 2. Male =1, Female = 2)

212 Appendix IX cont/

LOCATION = 2 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 1 1 -0.3042 0.01918 -15.86 0.0000 3 1 2 -0.1008 0.03886 -2.59 0.4027 3 2 1 -0.2791 0.02096 -13.32 0.0000 3 2 2 -0.0771 0.02421 -3.18 0.1036 4 1 1 -0.1324 0.05030 -2.63 0.3763 4 1 2 0.0021 0.01944 0.11 1.0000 4 2 1 -0.2182 0.02935 -7.43 0.0000 4 2 2 0.0035 0.01467 0.24 1.0000 LOCATION = 3 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 1 2 0.20336 0.04139 4.9129 0.0001 3 2 1 0.02504 0.02535 0.9878 0.9998 3 2 2 0.22709 0.02810 8.0818 0.0000 4 1 1 0.17180 0.05228 3.2861 0.0770 4 1 2 0.30629 0.02410 12.7069 0.0000 4 2 1 0.08600 0.03263 2.6360 0.3732 4 2 2 0.30768 0.02045 15.0419 0.0000 LOCATION = 3 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 2 1 -0.1783 0.04225 -4.221 0.0026 3 2 2 0.0237 0.04395 0.540 1.0000 4 1 1 -0.0316 0.06225 -0.507 1.0000 4 1 2 0.1029 0.04151 2.479 0.4870 4 2 1 -0.1174 0.04698 -2.498 0.4727 4 2 2 0.1043 0.03951 2.641 0.3700 LOCATION = 3 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 2 2 0.20205 0.02934 6.886 0.0000 4 1 1 0.14676 0.05296 2.771 0.2857 4 1 2 0.28125 0.02554 11.011 0.0000 4 2 1 0.06096 0.03370 1.809 0.9138 4 2 2 0.28264 0.02213 12.771 0.0000 LOCATION = 3 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 1 1 -0.0553 0.05433 -1.018 0.9998 4 1 2 0.0792 0.02827 2.801 0.2680 4 2 1 -0.1411 0.03582 -3.939 0.0081 4 2 2 0.0806 0.02523 3.194 0.1006 LOCATION = 4 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 1 2 0.13448 0.05238 2.568 0.4215 4 2 1 -0.08580 0.05680 -1.511 0.9816 4 2 2 0.13588 0.05080 2.675 0.3469 LOCATION = 4 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 2 1 -0.2203 0.03278 -6.721 0.0000 4 2 2 0.0014 0.02069 0.067 1.0000 LOCATION = 4 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 2 2 0.2217 0.03019 7.342 0.0000

Box 5 (iii): Tukey’s pairwise test results for log wet weight: all locations, February and March 2009(Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 1, March = 2. Male =1, Female = 2)

213 Appendix IX cont/ Tukey’s Simultaneous Tests Response Variable logWET WEIGHT All Pairwise Comparisons among Levels of MONTH*LOCATION*SEX MONTH = 1 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 1 1 2 0.24039 0.06088 3.949 0.0078 1 2 1 -0.06300 0.05686 -1.108 0.9993 1 2 2 0.14033 0.06640 2.113 0.7568 2 1 1 -0.06156 0.05536 -1.112 0.9993 2 1 2 0.24114 0.05499 4.385 0.0013 2 2 1 -0.03798 0.05750 -0.660 1.0000 2 2 2 0.16403 0.05880 2.789 0.2749 3 1 1 -0.00570 0.05649 -0.101 1.0000 3 1 2 0.29247 0.05656 5.171 0.0001 3 2 1 0.00574 0.05542 0.104 1.0000 3 2 2 0.29588 0.05547 5.334 0.0000 4 1 1 0.03340 0.06037 0.553 1.0000 4 1 2 0.29850 0.05779 5.165 0.0001 4 2 1 -0.04137 0.05764 -0.718 1.0000 4 2 2 0.30477 0.05757 5.294 0.0000

MONTH = 1 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 1 2 1 -0.3034 0.03257 -9.32 0.0000 1 2 2 -0.1001 0.04729 -2.12 0.7552 2 1 1 -0.3019 0.02988 -10.11 0.0000 2 1 2 0.0008 0.02918 0.03 1.0000 2 2 1 -0.2784 0.03368 -8.27 0.0000 2 2 2 -0.0764 0.03585 -2.13 0.7459 3 1 1 -0.2461 0.03192 -7.71 0.0000 3 1 2 0.0521 0.03203 1.63 0.9640 3 2 1 -0.2347 0.02997 -7.83 0.0000 3 2 2 0.0555 0.03008 1.85 0.9000 4 1 1 -0.2070 0.03837 -5.39 0.0000 4 1 2 0.0581 0.03417 1.70 0.9472 4 2 1 -0.2818 0.03391 -8.31 0.0000 4 2 2 0.0644 0.03379 1.90 0.8742

MONTH = 1 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 1 2 2 0.203333 0.04199 4.8419 0.0002 2 1 1 0.001443 0.02049 0.0704 1.0000 2 1 2 0.304144 0.01946 15.6288 0.0000 2 2 1 0.025021 0.02572 0.9730 0.9999 2 2 2 0.227029 0.02851 7.9642 0.0000 3 1 1 0.057300 0.02336 2.4525 0.5074 3 1 2 0.355471 0.02352 15.1125 0.0000 3 2 1 0.068739 0.02063 3.3322 0.0670 3 2 2 0.358883 0.02078 17.2727 0.0000 4 1 1 0.096400 0.03161 3.0494 0.1487 4 1 2 0.361500 0.02636 13.7151 0.0000 4 2 1 0.021630 0.02603 0.8311 1.0000 4 2 2 0.367766 0.02587 14.2171 0.0000

Box 6 (i): Tukey’s pairwise test results for log wet weight: Aberystwyth and Morfa Nefyn February to May 2009 (February = 1, March = 2, April = 3, May = 4. Aberystwyth = 1, Morfa Nefyn = 2. Male = 1, Female = 2)

214 Appendix IX cont/

MONTH = 1 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 1 1 -0.2019 0.03994 -5.054 0.0001 2 1 2 0.1008 0.03943 2.557 0.4293 2 2 1 -0.1783 0.04286 -4.160 0.0034 2 2 2 0.0237 0.04459 0.531 1.0000 3 1 1 -0.1460 0.04149 -3.520 0.0369 3 1 2 0.1521 0.04158 3.659 0.0229 3 2 1 -0.1346 0.04002 -3.364 0.0609 3 2 2 0.1555 0.04009 3.880 0.0102 4 1 1 -0.1069 0.04664 -2.293 0.6292 4 1 2 0.1582 0.04325 3.657 0.0231 4 2 1 -0.1817 0.04305 -4.221 0.0026 4 2 2 0.1644 0.04295 3.828 0.0124

MONTH = 2 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 1 2 0.30270 0.01452 20.8510 0.0000 2 2 1 0.02358 0.02221 1.0615 0.9996 2 2 2 0.22559 0.02539 8.8848 0.0000 3 1 1 0.05586 0.01944 2.8734 0.2284 3 1 2 0.35403 0.01963 18.0356 0.0000 3 2 1 0.06730 0.01605 4.1931 0.0029 3 2 2 0.35744 0.01624 22.0096 0.0000 4 1 1 0.09496 0.02883 3.2933 0.0754 4 1 2 0.36006 0.02295 15.6877 0.0000 4 2 1 0.02019 0.02257 0.8945 1.0000 4 2 2 0.36632 0.02239 16.3630 0.0000

MONTH = 2 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 2 1 -0.2791 0.02126 -13.13 0.0000 2 2 2 -0.0771 0.02457 -3.14 0.1171 3 1 1 -0.2468 0.01835 -13.45 0.0000 3 1 2 0.0513 0.01855 2.77 0.2884 3 2 1 -0.2354 0.01471 -16.00 0.0000 3 2 2 0.0547 0.01492 3.67 0.0221 4 1 1 -0.2077 0.02811 -7.39 0.0000 4 1 2 0.0574 0.02204 2.60 0.3963 4 2 1 -0.2825 0.02164 -13.06 0.0000 4 2 2 0.0636 0.02145 2.97 0.1833

MONTH = 2 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 2 2 0.202009 0.02977 6.7862 0.0000 3 1 1 0.032279 0.02489 1.2971 0.9961 3 1 2 0.330450 0.02503 13.1995 0.0000 3 2 1 0.043718 0.02234 1.9571 0.8488 3 2 2 0.333862 0.02248 14.8540 0.0000 4 1 1 0.071379 0.03275 2.1793 0.7121 4 1 2 0.336479 0.02772 12.1400 0.0000 4 2 1 -0.003390 0.02740 -0.1237 1.0000 4 2 2 0.342745 0.02725 12.5773 0.0000

Box 6 (ii): Tukey’s pairwise test results for log wet weight: Aberystwyth and Morfa Nefyn February to May 2009 (February = 1, March = 2, April = 3, May = 4. Aberystwyth = 1, Morfa Nefyn = 2. Male = 1, Female = 2)

215 Appendix IX cont/ MONTH = 2 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 1 1 -0.1697 0.02776 -6.114 0.0000 3 1 2 0.1284 0.02789 4.605 0.0005 3 2 1 -0.1583 0.02550 -6.207 0.0000 3 2 2 0.1319 0.02562 5.146 0.0001 4 1 1 -0.1306 0.03499 -3.734 0.0176 4 1 2 0.1345 0.03032 4.435 0.0010 4 2 1 -0.2054 0.03003 -6.839 0.0000 4 2 2 0.1407 0.02990 4.707 0.0003 MONTH = 3 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 1 2 0.29817 0.02261 13.187 0.0000 3 2 1 0.01144 0.01958 0.584 1.0000 3 2 2 0.30158 0.01974 15.277 0.0000 4 1 1 0.03910 0.03094 1.264 0.9970 4 1 2 0.30420 0.02555 11.907 0.0000 4 2 1 -0.03567 0.02521 -1.415 0.9903 4 2 2 0.31047 0.02504 12.397 0.0000 MONTH = 3 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 2 1 -0.2867 0.01977 -14.50 0.0000 3 2 2 0.0034 0.01993 0.17 1.0000 4 1 1 -0.2591 0.03106 -8.34 0.0000 4 1 2 0.0060 0.02569 0.23 1.0000 4 2 1 -0.3338 0.02535 -13.17 0.0000 4 2 2 0.0123 0.02519 0.49 1.0000 MONTH = 3 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 2 2 0.29014 0.01641 17.678 0.0000 4 1 1 0.02766 0.02893 0.956 0.9999 4 1 2 0.29276 0.02307 12.688 0.0000 4 2 1 -0.04711 0.02269 -2.076 0.7809 4 2 2 0.29903 0.02251 13.282 0.0000 MONTH = 3 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 1 1 -0.2625 0.02904 -9.04 0.0000 4 1 2 0.0026 0.02321 0.11 1.0000 4 2 1 -0.3373 0.02283 -14.77 0.0000 4 2 2 0.0089 0.02265 0.39 1.0000 MONTH = 4 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 1 2 0.26510 0.03326 7.971 0.0000 4 2 1 -0.07477 0.03300 -2.266 0.6493 4 2 2 0.27137 0.03287 8.255 0.0000 MONTH = 4 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 2 1 -0.3399 0.02800 -12.14 0.0000 4 2 2 0.0063 0.02786 0.22 1.0000 MONTH = 4 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 2 2 0.3461 0.02754 12.57 0.0000 Box 6 (iii): Tukey’s pairwise test results for log wet weight: Aberystwyth and Morfa Nefyn February to May 2009 (February = 1, March = 2, April = 3, May = 4. Aberystwyth = 1, Morfa Nefyn = 2. Male = 1, Female = 2)

216 Appendix IX cont/ Tukey’s Simultaneous Tests Response Variable log WET WEIGHT All Pairwise Comparisons among Levels of MONTH*SEX MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 1 2 0.29886 0.02859 10.454 0.0000 2 1 0.10322 0.03876 2.663 0.1341 2 2 0.36415 0.04102 8.877 0.0000 3 1 0.05097 0.03876 1.315 0.8935 3 2 0.32683 0.03305 9.888 0.0000 4 1 0.06050 0.02781 2.175 0.3667 4 2 0.31582 0.03114 10.142 0.0000

MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 1 -0.1956 0.03343 -5.85 0.0000 2 2 0.0653 0.03603 1.81 0.6118 3 1 -0.2479 0.03343 -7.41 0.0000 3 2 0.0280 0.02661 1.05 0.9664 4 1 -0.2384 0.01972 -12.09 0.0000 4 2 0.0170 0.02419 0.70 0.9970

MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 2 0.26093 0.04453 5.859 0.0000 3 1 -0.05225 0.04246 -1.231 0.9230 3 2 0.22361 0.03732 5.991 0.0000 4 1 -0.04272 0.03277 -1.303 0.8979 4 2 0.21260 0.03564 5.965 0.0000

MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 1 -0.3132 0.04453 -7.033 0.0000 3 2 -0.0373 0.03967 -0.941 0.9821 4 1 -0.3036 0.03542 -8.574 0.0000 4 2 -0.0483 0.03808 -1.269 0.9104

MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 2 0.275855 0.03732 7.3909 0.0000 4 1 0.009531 0.03277 0.2908 1.0000 4 2 0.264851 0.03564 7.4315 0.0000

MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 1 -0.2663 0.02577 -10.33 0.0000 4 2 -0.0110 0.02933 -0.38 1.0000

MONTH = 4 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 2 0.2553 0.02327 10.97 0.0000

Box 7: Tukey’s pairwise test results for log wet weight: Newquay December to March 2008/9 (December = 1, January = 2, February = 3, March = 4. Male = 1, Female = 2)

217 Appendix IX cont/

Tukey’s Simultaneous Tests Response Variable log WET WEIGHT All Pairwise Comparisons among Levels of MONTH*SEX MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 1 2 0.20336 0.03729 5.4528 0.0000 2 1 0.02504 0.02284 1.0962 0.9852 2 2 0.22709 0.02532 8.9699 0.0000 3 1 0.06880 0.01832 3.7555 0.0067 3 2 0.35890 0.01845 19.4500 0.0000 4 1 0.02168 0.02311 0.9379 0.9952 4 2 0.36776 0.02297 16.0084 0.0000 5 1 0.02540 0.03169 0.8013 0.9986 5 2 0.25177 0.01824 13.8048 0.0000

MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 1 -0.1783 0.03806 -4.685 0.0001 2 2 0.0237 0.03960 0.599 0.9999 3 1 -0.1346 0.03554 -3.786 0.0059 3 2 0.1555 0.03561 4.368 0.0005 4 1 -0.1817 0.03823 -4.752 0.0001 4 2 0.1644 0.03814 4.310 0.0007 5 1 -0.1780 0.04395 -4.049 0.0021 5 2 0.0484 0.03549 1.364 0.9381

MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 2 0.202049 0.02644 7.6429 0.0000 3 1 0.043764 0.01984 2.2060 0.4525 3 2 0.333860 0.01996 16.7257 0.0000 4 1 -0.003359 0.02433 -0.1380 1.0000 4 2 0.342726 0.02420 14.1613 0.0000 5 1 0.000362 0.03260 0.0111 1.0000 5 2 0.226730 0.01976 11.4726 0.0000

MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 1 -0.1583 0.02265 -6.989 0.0000 3 2 0.1318 0.02275 5.793 0.0000 4 1 -0.2054 0.02667 -7.701 0.0000 4 2 0.1407 0.02655 5.298 0.0000 5 1 -0.2017 0.03438 -5.867 0.0000 5 2 0.0247 0.02258 1.093 0.9855

Box 8 (i): Tukey’s pairwise test results for log wet weight: Morfa Nefyn February to May plus October 2009 (February = 1, March = 2, April = 3, May = 4, October = 5. Male = 1, Female = 2)

218 Appendix IX cont/

MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 2 0.29010 0.01458 19.902 0.0000 4 1 -0.04712 0.02015 -2.338 0.3641 4 2 0.29896 0.01999 14.953 0.0000 5 1 -0.04340 0.02961 -1.466 0.9056 5 2 0.18297 0.01430 12.792 0.0000

MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 1 -0.3372 0.02027 -16.63 0.0000 4 2 0.0089 0.02011 0.44 1.0000 5 1 -0.3335 0.02969 -11.23 0.0000 5 2 -0.1071 0.01447 -7.40 0.0000

MONTH = 4 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 2 0.346085 0.02446 14.1488 0.0000 5 1 0.003721 0.03279 0.1135 1.0000 5 2 0.230089 0.02008 11.4592 0.0000

MONTH = 4 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 5 1 -0.3424 0.03269 -10.47 0.0000 5 2 -0.1160 0.01992 -5.82 0.0000

MONTH = 5 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 5 2 0.2264 0.02956 7.659 0.0000

Box 8 (ii): Tukey’s pairwise test results for log wet weight: Morfa Nefyn February to May plus October 2009 (February = 1, March = 2, April = 3, May = 4, October = 5. Male = 1, Female = 2)

219 Appendix X: Carapace width/carapace length ratio ANOVAS and Tukeys post hoc test results

Table XVIII: ANOVA table for carapace width/carapace length ratio vs location, month and sex: all locations, February and March 2009 ANOVA TABLE FOR CARAPACE WIDTH/CARAPACE LENGTH RATIO VS LOCATION MONTH & SEX (FEBRUARY & MARCH 2009) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES LOCATION 0.022898 3 0.0076325 26.30 0.000 MONTH 0.01494 1 0.0149397 51.47 0.000 SEX 0.00766 1 0.0076596 26.39 0.000 LOCATION*MONTH 0.052738 3 0.0175794 60.57 0.000 LOCATION*SEX 0.006654 3 0.0022178 7.64 0.000 MONTH*SEX 0.000597 1 0.000597 2.06 0.152 LOCATION*MONTH*SEX 0.004659 3 0.0015529 5.35 0.001 RESIDUAL 0.387756 1336 0.0002902 (TOTAL) 0.483582 1351

Table XIX: ANOVA table for carapace width/carapace length ratio vs month, location and sex: Aberystwyth and Morfa Nefyn February to May 2009 ANOVA TABLE FOR CARAPACE WIDTH/CARAPACE LENGTH RATIO VS MONTH LOCATION & SEX (ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 0.022116 3 0.0073722 41.22 0.000 LOCATION 0.017632 1 0.0176317 98.58 0.000 SEX 0.018288 1 0.018288 102.25 0.000 MONTH*LOCATION 0.007936 3 0.0026453 14.79 0.000 MONTH*SEX 0.008374 3 0.0027914 15.61 0.000 LOCATION*SEX 0.001239 1 0.0012388 6.93 0.009 MONTH*LOCATION*SEX 0.001379 3 0.0004598 2.57 0.053 RESIDUAL 0.328369 1836 0.0001789 (TOTAL) 0.3927 1851

220 Appendix X cont/

Table XX: ANOVA table for carapace width/carapace length ratio vs month and sex: Newquay December to March 2008/9 ANOVA TABLE FOR CARAPACE WIDTH/CARAPACE LENGTH RATIO VS MONTH & SEX (NEWQUAY DECEMBER TO MARCH 2008/9) SUM OF DEGREES OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 0.108529 3 0.0361764 83.97 0.000 SEX 0.014461 1 0.0144607 33.56 0.000 MONTH*SEX 0.010114 3 0.0033712 7.82 0.000 RESIDUAL 0.183533 426 0.0004308 (TOTAL) 0.292664 433

Table XXI: ANOVA table for carapace width/carapace length ratio vs month and sex: Morfa Nefyn February to May plus October 2009 ANOVA TABLE FOR CARAPACE WIDTH/CARAPACE LENGTH RATIO VS MONTH & SEX (MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009) SUM OF DEGREES OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 0.05263 4 0.0131575 65.73 0.000 SEX 0.02283 1 0.0228299 114.05 0.000 MONTH*SEX 0.016115 4 0.0040288 20.13 0.000 RESIDUAL 0.197174 985 0.0002002 (TOTAL) 0.268066 994

221 Appendix X cont/

Tukey’s Simultaneous Tests Response Variable CW/CL All Pairwise Comparisons among Levels of LOCATION*MONTH*SEX LOCATION = 1 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 1 2 0.00426 0.004501 0.945 0.9999 1 2 1 -0.03644 0.003865 -9.427 0.0000 1 2 2 -0.03413 0.004117 -8.289 0.0000 2 1 1 -0.01520 0.007354 -2.067 0.7863 2 1 2 -0.01729 0.004657 -3.712 0.0190 2 2 1 -0.01551 0.003775 -4.110 0.0041 2 2 2 -0.01506 0.003702 -4.068 0.0049 3 1 1 -0.02162 0.003990 -5.419 0.0000 3 1 2 -0.01709 0.005775 -2.960 0.1861 3 2 1 -0.02135 0.004048 -5.273 0.0001 3 2 2 -0.02068 0.004383 -4.717 0.0003 4 1 1 -0.02040 0.004794 -4.256 0.0022 4 1 2 -0.01294 0.003805 -3.400 0.0543 4 2 1 -0.01691 0.004627 -3.653 0.0234 4 2 2 -0.01978 0.003778 -5.236 0.0001

LOCATION = 1 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 2 1 -0.04069 0.003156 -12.89 0.0000 1 2 2 -0.03838 0.003460 -11.09 0.0000 2 1 1 -0.01946 0.007007 -2.78 0.2824 2 1 2 -0.02154 0.004087 -5.27 0.0001 2 2 1 -0.01977 0.003044 -6.49 0.0000 2 2 2 -0.01932 0.002954 -6.54 0.0000 3 1 1 -0.02588 0.003307 -7.82 0.0000 3 1 2 -0.02135 0.005326 -4.01 0.0062 3 2 1 -0.02560 0.003377 -7.58 0.0000 3 2 2 -0.02493 0.003773 -6.61 0.0000 4 1 1 -0.02466 0.004243 -5.81 0.0000 4 1 2 -0.01719 0.003082 -5.58 0.0000 4 2 1 -0.02116 0.004054 -5.22 0.0001 4 2 2 -0.02404 0.003049 -7.88 0.0000

LOCATION = 1 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 2 2 0.002310 0.002579 0.8956 1.0000 2 1 1 0.021236 0.006617 3.2094 0.0962 2 1 2 0.019150 0.003375 5.6741 0.0000 2 2 1 0.020925 0.001988 10.5253 0.0000 2 2 2 0.021377 0.001846 11.5782 0.0000 3 1 1 0.014817 0.002371 6.2505 0.0000 3 1 2 0.019343 0.004801 4.0288 0.0057 3 2 1 0.015092 0.002468 6.1151 0.0000 3 2 2 0.015759 0.002986 5.2773 0.0001 4 1 1 0.016033 0.003562 4.5012 0.0008 4 1 2 0.023498 0.002045 11.4905 0.0000 4 2 1 0.019532 0.003334 5.8583 0.0000 4 2 2 0.016653 0.001995 8.3473 0.0000

Box 9: (i) Tukey’s pairwise test results for carapace width/carapace length ratio: all locations, February and March 2009 (Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 1, March = 2. Male = 1, Female = 2)

222 Appendix X cont/

LOCATION = 1 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 1 1 0.01893 0.006767 2.797 0.2706 2 1 2 0.01684 0.003661 4.600 0.0005 2 2 1 0.01861 0.002442 7.623 0.0000 2 2 2 0.01907 0.002328 8.191 0.0000 3 1 1 0.01251 0.002762 4.528 0.0007 3 1 2 0.01703 0.005006 3.402 0.0539 3 2 1 0.01278 0.002846 4.491 0.0008 3 2 2 0.01345 0.003306 4.069 0.0049 4 1 1 0.01372 0.003834 3.579 0.0302 4 1 2 0.02119 0.002488 8.515 0.0000 4 2 1 0.01722 0.003623 4.754 0.0003 4 2 2 0.01434 0.002447 5.860 0.0000

LOCATION = 2 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 1 2 -0.002086 0.007108 -0.2934 1.0000 2 2 1 -0.000312 0.006564 -0.0475 1.0000 2 2 2 0.000141 0.006523 0.0215 1.0000 3 1 1 -0.006419 0.006690 -0.9594 0.9999 3 1 2 -0.001893 0.007886 -0.2400 1.0000 3 2 1 -0.006144 0.006725 -0.9136 0.9999 3 2 2 -0.005477 0.006932 -0.7900 1.0000 4 1 1 -0.005204 0.007199 -0.7228 1.0000 4 1 2 0.002262 0.006582 0.3437 1.0000 4 2 1 -0.001704 0.007089 -0.2404 1.0000 4 2 2 -0.004583 0.006566 -0.6979 1.0000

LOCATION = 2 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 2 1 0.001774 0.003271 0.542 1.0000 2 2 2 0.002226 0.003187 0.699 1.0000 3 1 1 -0.004333 0.003517 -1.232 0.9978 3 1 2 0.000193 0.005459 0.035 1.0000 3 2 1 -0.004058 0.003583 -1.133 0.9991 3 2 2 -0.003391 0.003958 -0.857 1.0000 4 1 1 -0.003118 0.004408 -0.707 1.0000 4 1 2 0.004348 0.003306 1.315 0.9954 4 2 1 0.000382 0.004227 0.090 1.0000 4 2 2 -0.002497 0.003275 -0.762 1.0000

LOCATION = 2 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 2 2 0.000452 0.001648 0.274 1.0000 3 1 1 -0.006107 0.002220 -2.751 0.2980 3 1 2 -0.001581 0.004729 -0.334 1.0000 3 2 1 -0.005833 0.002324 -2.510 0.4640 3 2 2 -0.005165 0.002868 -1.801 0.9166 4 1 1 -0.004892 0.003463 -1.412 0.9905 4 1 2 0.002574 0.001868 1.378 0.9926 4 2 1 -0.001392 0.003229 -0.431 1.0000 4 2 2 -0.004271 0.001814 -2.355 0.5818

Box 9 (ii): Tukey’s pairwise test results for carapace width/carapace length ratio: all locations, February and March 2009 (Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 1, March = 2. Male = 1, Female = 2)

223 Appendix X cont/

LOCATION = 2 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 1 1 -0.006559 0.002094 -3.132 0.1193 3 1 2 -0.002033 0.004671 -0.435 1.0000 3 2 1 -0.006285 0.002204 -2.852 0.2397 3 2 2 -0.005617 0.002772 -2.027 0.8107 4 1 1 -0.005344 0.003384 -1.579 0.9722 4 1 2 0.002122 0.001717 1.236 0.9977 4 2 1 -0.001844 0.003143 -0.587 1.0000 4 2 2 -0.004723 0.001657 -2.851 0.2404 LOCATION = 3 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 1 2 0.004526 0.004902 0.9233 0.9999 3 2 1 0.000275 0.002658 0.1033 1.0000 3 2 2 0.000942 0.003145 0.2995 1.0000 4 1 1 0.001215 0.003696 0.3287 1.0000 4 1 2 0.008681 0.002271 3.8222 0.0127 4 2 1 0.004715 0.003477 1.3558 0.9937 4 2 2 0.001836 0.002226 0.8246 1.0000 LOCATION = 3 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 2 1 -0.004251 0.004950 -0.8589 1.000 3 2 2 -0.003584 0.005227 -0.6856 1.000 4 1 1 -0.003311 0.005576 -0.5937 1.000 4 1 2 0.004155 0.004753 0.8742 1.000 4 2 1 0.000189 0.005434 0.0348 1.000 4 2 2 -0.002690 0.004732 -0.5685 1.000 LOCATION = 3 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 2 2 0.000668 0.003219 0.2073 1.0000 4 1 1 0.000941 0.003760 0.2502 1.0000 4 1 2 0.008407 0.002373 3.5431 0.0342 4 2 1 0.004440 0.003545 1.2527 0.9973 4 2 2 0.001561 0.002330 0.6702 1.0000 LOCATION = 3 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 1 1 0.000273 0.004118 0.06630 1.0000 4 1 2 0.007739 0.002908 2.66129 0.3559 4 2 1 0.003773 0.003923 0.96168 0.9999 4 2 2 0.000894 0.002873 0.31109 1.0000 LOCATION = 4 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 1 2 0.007466 0.003496 2.1353 0.7423 4 2 1 0.003500 0.004377 0.7995 1.0000 4 2 2 0.000621 0.003467 0.1790 1.0000 LOCATION = 4 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 2 1 -0.003966 0.003264 -1.215 0.9981 4 2 2 -0.006845 0.001876 -3.649 0.0237 LOCATION = 4 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 2 2 -0.002879 0.003233 -0.8905 1.000

Box 9 (iii): Tukey’s pairwise test results for carapace width/carapace length ratio: all locations, February and March 2009(Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 1, March = 2. Male = 1, Female = 2)

224 Appendix X cont/ Tukey’s Simultaneous Tests Response Variable CW/CL All Pairwise Comparisons among Levels of MONTH*LOCATION*SEX MONTH = 1 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 1 1 2 -0.00208 0.005581 -0.372 1.0000 1 2 1 -0.00642 0.005252 -1.223 0.9979 1 2 2 -0.00189 0.006191 -0.305 1.0000 2 1 1 -0.00031 0.005154 -0.060 1.0000 2 1 2 0.00015 0.005121 0.029 1.0000 2 2 1 -0.00614 0.005280 -1.164 0.9988 2 2 2 -0.00547 0.005442 -1.005 0.9998 3 1 1 -0.01134 0.005131 -2.209 0.6907 3 1 2 -0.00485 0.005124 -0.947 0.9999 3 2 1 -0.01430 0.005141 -2.781 0.2796 3 2 2 -0.00705 0.005153 -1.367 0.9932 4 1 1 -0.00340 0.005442 -0.624 1.0000 4 1 2 0.00459 0.005313 0.863 1.0000 4 2 1 -0.02126 0.005277 -4.028 0.0057 4 2 2 -0.00421 0.005257 -0.801 1.0000

MONTH = 1 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 1 2 1 -0.00434 0.002761 -1.574 0.9731 1 2 2 0.00019 0.004286 0.044 1.0000 2 1 1 0.00177 0.002568 0.689 1.0000 2 1 2 0.00222 0.002502 0.888 1.0000 2 2 1 -0.00407 0.002813 -1.446 0.9879 2 2 2 -0.00339 0.003107 -1.092 0.9994 3 1 1 -0.00926 0.002523 -3.670 0.0220 3 1 2 -0.00278 0.002508 -1.107 0.9993 3 2 1 -0.01222 0.002542 -4.808 0.0002 3 2 2 -0.00497 0.002567 -1.936 0.8596 4 1 1 -0.00132 0.003107 -0.425 1.0000 4 1 2 0.00666 0.002874 2.318 0.6103 4 2 1 -0.01918 0.002808 -6.832 0.0000 4 2 2 -0.00213 0.002769 -0.770 1.0000

MONTH = 1 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 1 2 2 0.00453 0.003848 1.178 0.9987 2 1 1 0.00611 0.001743 3.507 0.0384 2 1 2 0.00657 0.001644 3.995 0.0065 2 2 1 0.00028 0.002087 0.133 1.0000 2 2 2 0.00095 0.002469 0.385 1.0000 3 1 1 -0.00492 0.001676 -2.933 0.1989 3 1 2 0.00157 0.001653 0.949 0.9999 3 2 1 -0.00788 0.001704 -4.622 0.0005 3 2 2 -0.00062 0.001741 -0.359 1.0000 4 1 1 0.00302 0.002469 1.224 0.9979 4 1 2 0.01101 0.002169 5.075 0.0001 4 2 1 -0.01484 0.002080 -7.134 0.0000 4 2 2 0.00221 0.002028 1.091 0.9995

Box 10 (i): Tukey’s pairwise test results for carapace width/carapace length ratio: Aberystwyth and Morfa Nefyn February to May 2009 (February = 1, March = 2, April = 3, May = 4. Aberystwyth = 1, Morfa Nefyn = 2. Male = 1, Female = 2)

225 Appendix X cont/

MONTH = 1 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 1 1 0.00158 0.003712 0.426 1.0000 2 1 2 0.00203 0.003667 0.555 1.0000 2 2 1 -0.00426 0.003886 -1.095 0.9994 2 2 2 -0.00358 0.004104 -0.873 1.0000 3 1 1 -0.00945 0.003682 -2.566 0.4224 3 1 2 -0.00296 0.003671 -0.807 1.0000 3 2 1 -0.01241 0.003695 -3.359 0.0617 3 2 2 -0.00516 0.003712 -1.389 0.9919 4 1 1 -0.00151 0.004104 -0.368 1.0000 4 1 2 0.00647 0.003930 1.647 0.9597 4 2 1 -0.01937 0.003882 -4.990 0.0001 4 2 2 -0.00232 0.003854 -0.602 1.0000

MONTH = 2 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 1 2 0.00045 0.001294 0.35 1.0000 2 2 1 -0.00584 0.001824 -3.20 0.0991 2 2 2 -0.00516 0.002252 -2.29 0.6295 3 1 1 -0.01103 0.001335 -8.26 0.0000 3 1 2 -0.00454 0.001305 -3.48 0.0418 3 2 1 -0.01399 0.001370 -10.21 0.0000 3 2 2 -0.00674 0.001416 -4.76 0.0003 4 1 1 -0.00309 0.002252 -1.37 0.9929 4 1 2 0.00489 0.001917 2.55 0.4326 4 2 1 -0.02095 0.001816 -11.54 0.0000 4 2 2 -0.00390 0.001756 -2.22 0.6822

MONTH = 2 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 2 1 -0.00629 0.001730 -3.64 0.0248 2 2 2 -0.00562 0.002176 -2.58 0.4119 3 1 1 -0.01148 0.001203 -9.54 0.0000 3 1 2 -0.00500 0.001170 -4.27 0.0021 3 2 1 -0.01445 0.001242 -11.63 0.0000 3 2 2 -0.00719 0.001292 -5.57 0.0000 4 1 1 -0.00354 0.002176 -1.63 0.9635 4 1 2 0.00444 0.001828 2.43 0.5255 4 2 1 -0.02141 0.001721 -12.43 0.0000 4 2 2 -0.00436 0.001658 -2.63 0.3796

MONTH = 2 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 2 2 0.00067 0.002528 0.267 1.0000 3 1 1 -0.00519 0.001761 -2.949 0.1911 3 1 2 0.00129 0.001738 0.743 1.0000 3 2 1 -0.00815 0.001788 -4.562 0.0006 3 2 2 -0.00090 0.001823 -0.495 1.0000 4 1 1 0.00275 0.002528 1.087 0.9995 4 1 2 0.01073 0.002234 4.802 0.0002 4 2 1 -0.01511 0.002149 -7.035 0.0000 4 2 2 0.00193 0.002098 0.922 0.9999 Box 10 (ii): Tukey’s pairwise test results for carapace width/carapace length ratio: Aberystwyth and Morfa Nefyn February to May 2009 (February = 1, March = 2, April = 3, May = 4. Aberystwyth = 1, Morfa Nefyn = 2. Male = 1, Female = 2)

226 Appendix X cont/

MONTH = 2 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 1 1 -0.00587 0.002201 -2.666 0.3527 3 1 2 0.00062 0.002183 0.283 1.0000 3 2 1 -0.00883 0.002222 -3.973 0.0071 3 2 2 -0.00158 0.002251 -0.700 1.0000 4 1 1 0.00207 0.002851 0.727 1.0000 4 1 2 0.01006 0.002595 3.874 0.0104 4 2 1 -0.01579 0.002522 -6.261 0.0000 4 2 2 0.00126 0.002479 0.509 1.0000 MONTH = 3 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 1 2 0.006485 0.001215 5.337 0.0000 3 2 1 -0.002961 0.001285 -2.305 0.6200 3 2 2 0.004292 0.001333 3.220 0.0935 4 1 1 0.007940 0.002201 3.608 0.0274 4 1 2 0.015922 0.001857 8.575 0.0000 4 2 1 -0.009921 0.001752 -5.661 0.0000 4 2 2 0.007128 0.001690 4.217 0.0027 MONTH = 3 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 2 1 -0.00945 0.001254 -7.536 0.0000 3 2 2 -0.00219 0.001303 -1.683 0.9516 4 1 1 0.00146 0.002183 0.667 1.0000 4 1 2 0.00944 0.001835 5.142 0.0001 4 2 1 -0.01641 0.001730 -9.485 0.0000 4 2 2 0.00064 0.001667 0.386 1.0000 MONTH = 3 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 2 2 0.007253 0.001368 5.301 0.0000 4 1 1 0.010901 0.002222 4.906 0.0001 4 1 2 0.018884 0.001882 10.033 0.0000 4 2 1 -0.006960 0.001779 -3.912 0.0090 4 2 2 0.010089 0.001718 5.872 0.0000 MONTH = 3 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 1 1 0.00365 0.002251 1.621 0.9649 4 1 2 0.01163 0.001916 6.072 0.0000 4 2 1 -0.01421 0.001815 -7.833 0.0000 4 2 2 0.00284 0.001755 1.616 0.9658 MONTH = 4 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 1 2 0.00798 0.002595 3.076 0.1389 4 2 1 -0.01786 0.002522 -7.083 0.0000 4 2 2 -0.00081 0.002479 -0.328 1.0000 MONTH = 4 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 2 1 -0.02584 0.002228 -11.60 0.0000 4 2 2 -0.00879 0.002179 -4.04 0.0056 MONTH = 4 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 2 2 0.01705 0.002091 8.153 0.0000

Box 10 (iii): Tukey’s pairwise test results for carapace width/carapace length ratio: Aberystwyth and Morfa Nefyn February to May 2009 (February = 1, March = 2, April = 3, May = 4. Aberystwyth = 1, Morfa Nefyn = 2. Male = 1, Female = 2)

227 Appendix X cont/ Tukey’s Simultaneous Tests Response Variable CW/CL All Pairwise Comparisons among Levels of MONTH*SEX MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 1 2 0.00211 0.004003 0.527 0.9995 2 1 -0.01431 0.005118 -2.796 0.0959 2 2 -0.01460 0.005561 -2.625 0.1467 3 1 0.00616 0.005484 1.122 0.9521 3 2 0.01041 0.004762 2.186 0.3601 4 1 -0.03028 0.003845 -7.875 0.0000 4 2 -0.02797 0.004215 -6.636 0.0000

MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 1 -0.01642 0.004421 -3.71 0.0050 2 2 -0.01671 0.004926 -3.39 0.0160 3 1 0.00405 0.004839 0.84 0.9910 3 2 0.00830 0.004003 2.07 0.4317 4 1 -0.03239 0.002851 -11.36 0.0000 4 2 -0.03008 0.003334 -9.02 0.0000

MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 2 -0.00029 0.005869 -0.049 1.0000 3 1 0.02047 0.005796 3.531 0.0098 3 2 0.02472 0.005118 4.830 0.0000 4 1 -0.01597 0.004278 -3.733 0.0047 4 2 -0.01366 0.004614 -2.961 0.0612

MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 1 0.02076 0.006190 3.353 0.0182 3 2 0.02501 0.005561 4.497 0.0002 4 1 -0.01568 0.004799 -3.268 0.0241 4 2 -0.01337 0.005101 -2.622 0.1480

MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 2 0.00426 0.005484 0.776 0.9943 4 1 -0.03644 0.004710 -7.737 0.0000 4 2 -0.03413 0.005016 -6.803 0.0000

MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 1 -0.04069 0.003845 -10.58 0.0000 4 2 -0.03838 0.004215 -9.11 0.0000

MONTH = 4 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 2 0.002310 0.003143 0.7350 0.9959

Box 11: Tukey’s pairwise test results for carapace width/carapace length ratio: Newquay December to March 2008/9 (December = 1, January = 2, February = 3, March = 4. Male = 1, Female = 2)

228 Appendix X cont/ Tukey’s Simultaneous Tests Response Variable CW/CL All Pairwise Comparisons among Levels of MONTH*SEX MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 1 2 0.00453 0.004072 1.113 0.9835 2 1 0.00028 0.002208 0.125 1.0000 2 2 0.00095 0.002613 0.364 1.0000 3 1 -0.00788 0.001803 -4.367 0.0005 3 2 -0.00062 0.001842 -0.337 1.0000 4 1 -0.01484 0.002201 -6.743 0.0000 4 2 0.00221 0.002146 1.031 0.9904 9 1 0.01871 0.002992 6.254 0.0000 9 2 0.01239 0.001819 6.814 0.0000

MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 1 -0.00426 0.004111 -1.035 0.9902 2 2 -0.00358 0.004342 -0.825 0.9982 3 1 -0.01241 0.003909 -3.174 0.0484 3 2 -0.00515 0.003927 -1.312 0.9512 4 1 -0.01937 0.004107 -4.716 0.0001 4 2 -0.00232 0.004078 -0.569 0.9999 9 1 0.01418 0.004580 3.095 0.0613 9 2 0.00786 0.003916 2.007 0.5938

MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 2 0.00067 0.002674 0.252 1.0000 3 1 -0.00815 0.001891 -4.310 0.0007 3 2 -0.00090 0.001928 -0.465 1.0000 4 1 -0.01511 0.002273 -6.649 0.0000 4 2 0.00193 0.002220 0.871 0.9973 9 1 0.01843 0.003045 6.052 0.0000 9 2 0.01212 0.001906 6.357 0.0000

MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 1 -0.00883 0.002351 -3.754 0.0067 3 2 -0.00157 0.002381 -0.660 0.9997 4 1 -0.01579 0.002668 -5.918 0.0000 4 2 0.00126 0.002623 0.481 1.0000 9 1 0.01776 0.003350 5.300 0.0000 9 2 0.01144 0.002363 4.843 0.0001

Box 12 (i): Tukey’s pairwise test results for carapace width/carapace length ratio: Morfa Nefyn February to May plus October 2009 (February = 1, March = 2, April = 3, May = 4, October = 9, Male = 1, Female = 2)

229 Appendix X cont/ MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 2 0.007255 0.001448 5.012 0.0000 4 1 -0.006962 0.001883 -3.698 0.0083 4 2 0.010087 0.001818 5.549 0.0000 9 1 0.026584 0.002766 9.611 0.0000 9 2 0.020268 0.001417 14.300 0.0000

MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 1 -0.01422 0.001920 -7.406 0.0000 4 2 0.00283 0.001857 1.525 0.8824 9 1 0.01933 0.002792 6.924 0.0000 9 2 0.01301 0.001467 8.873 0.0000

MONTH = 4 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 2 0.01705 0.002213 7.706 0.0000 9 1 0.03355 0.003040 11.035 0.0000 9 2 0.02723 0.001897 14.353 0.0000

MONTH = 4 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 9 1 0.01650 0.003000 5.498 0.0000 9 2 0.01018 0.001833 5.554 0.0000

MONTH = 9 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 9 2 -0.006316 0.002776 -2.275 0.4053

Box 12 (ii): Tukey’s pairwise test results for carapace width/carapace length ratio: Morfa Nefyn February to May plus October 2009 (February = 1, March = 2, April = 3, May = 4, October = 9, Male = 1, Female = 2)

230 Appendix XI: log Carapace length/rostral length ratio ANOVAS and Tukeys post hoc test results

Table XXII: ANOVA table for log carapace length/rostral length ratio vs location, month and sex: all locations, February and March 2009 ANOVA TABLE FOR log CARAPACE LENGTH/ROSTRAL LENGTH RATIO VS LOCATION MONTH & SEX (FEBRUARY & MARCH 2009) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES LOCATION 0.279645 3 0.093215 111.73 0.000 MONTH 0.001398 1 0.001398 1.68 0.196 SEX 1.606787 1 1.606787 1925.98 0.000 LOCATION*MONTH 0.052737 3 0.017579 21.07 0.000 LOCATION*SEX 0.274708 3 0.091569 109.76 0.000 MONTH*SEX 0.004424 1 0.004424 5.30 0.021 LOCATION*MONTH*SEX 0.046259 3 0.01542 18.48 0.000 RESIDUAL 0.838438 1005 0.000834 (TOTAL) 2.472097 1020

Table XXIII: ANOVA table for log carapace length/rostral length ratio vs location, month and sex: Aberystwyth and Morfa Nefyn February to May 2009 ANOVA TABLE FOR log CARAPACE LENGTH/ROSTRAL LENGTH RATIO VS MONTH LOCATION & SEX (ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY 2009) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 0.039361 3 0.0131204 16.29 0.000 LOCATION 0.011672 1 0.0116716 14.49 0.000 SEX 2.240001 1 2.2400007 2781.75 0.000 MONTH*LOCATION 0.064777 3 0.0215925 26.81 0.000 MONTH*SEX 0.032204 3 0.0107348 13.33 0.000 LOCATION*SEX 0.043426 1 0.0434257 53.93 0.000 MONTH*LOCATION*SEX 0.059672 3 0.0198907 24.70 0.000 RESIDUAL 1.081448 1343 0.0008053 (TOTAL) 3.344395 1358

231 Appendix XI cont/

Table XXIV: ANOVA table for log carapace length/rostral length ratio vs month and sex: Newquay December to March 2008/9 ANOVA TABLE FOR log CARAPACE LENGTH/ROSTRAL LENGTH RATIO VS MONTH & SEX (NEWQUAY DECEMBER TO MARCH 2008/9) SUM OF DEGREES OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 0.039639 3 0.013213 17.39 0.000 SEX 0.559217 1 0.5592166 735.84 0.000 MONTH*SEX 0.071926 3 0.0239753 31.55 0.000 RESIDUAL 0.256111 337 0.00076 (TOTAL) 0.82249 344

Table XXV: ANOVA table for log carapace length/rostral length ratio vs month and sex: Morfa Nefyn February to May plus October 2009 ANOVA TABLE FOR log CARAPACE LENGTH/ROSTRAL LENGTH RATIO VS MONTH & SEX (MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009) SUM OF DEGREES OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 0.192245 4 0.0480612 61.69 0.000 SEX 1.169154 1 1.1691536 1500.74 0.000 MONTH*SEX 0.228829 4 0.0572073 73.43 0.000 RESIDUAL 0.589744 757 0.0007791 (TOTAL) 1.773448 766

232 Appendix XI cont/

Tukey’s Simultaneous Tests Response Variable log CARAPACE LENGTH/ROSTRAL LENGTH RATIO All Pairwise Comparisons among Levels of LOCATION*MONTH*SEX LOCATION = 1 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 1 2 0.088698 0.008463 10.4802 0.0000 1 2 1 0.012186 0.007395 1.6478 0.9595 1 2 2 0.090426 0.007919 11.4193 0.0000 2 1 1 0.004550 0.013616 0.3342 1.0000 2 1 2 0.087689 0.009006 9.7367 0.0000 2 2 1 -0.002087 0.007227 -0.2887 1.0000 2 2 2 0.082898 0.007094 11.6861 0.0000 3 1 1 0.002145 0.007733 0.2773 1.0000 3 1 2 0.086091 0.010764 7.9978 0.0000 3 2 1 0.008488 0.007880 1.0772 0.9995 3 2 2 0.086653 0.008338 10.3926 0.0000 4 1 1 0.013536 0.011054 1.2245 0.9979 4 1 2 0.082422 0.007401 11.1366 0.0000 4 2 1 0.019260 0.008856 2.1747 0.7153 4 2 2 0.090082 0.007238 12.4452 0.0000

LOCATION = 1 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 2 1 -0.07651 0.005799 -13.19 0.0000 1 2 2 0.00173 0.006453 0.27 1.0000 2 1 1 -0.08415 0.012819 -6.56 0.0000 2 1 2 -0.00101 0.007749 -0.13 1.0000 2 2 1 -0.09078 0.005582 -16.26 0.0000 2 2 2 -0.00580 0.005409 -1.07 0.9996 3 1 1 -0.08655 0.006224 -13.91 0.0000 3 1 2 -0.00261 0.009737 -0.27 1.0000 3 2 1 -0.08021 0.006405 -12.52 0.0000 3 2 2 -0.00204 0.006961 -0.29 1.0000 4 1 1 -0.07516 0.010056 -7.47 0.0000 4 1 2 -0.00628 0.005806 -1.08 0.9995 4 2 1 -0.06944 0.007574 -9.17 0.0000 4 2 2 0.00138 0.005597 0.25 1.0000

LOCATION = 1 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 2 2 0.07824 0.004970 15.742 0.0000 2 1 1 -0.00764 0.012140 -0.629 1.0000 2 1 2 0.07550 0.006565 11.500 0.0000 2 2 1 -0.01427 0.003771 -3.785 0.0146 2 2 2 0.07071 0.003509 20.150 0.0000 3 1 1 -0.01004 0.004669 -2.151 0.7318 3 1 2 0.07391 0.008824 8.375 0.0000 3 2 1 -0.00370 0.004907 -0.754 1.0000 3 2 2 0.07447 0.005614 13.265 0.0000 4 1 1 0.00135 0.009175 0.147 1.0000 4 1 2 0.07024 0.004095 17.151 0.0000 4 2 1 0.00707 0.006358 1.113 0.9993 4 2 2 0.07790 0.003793 20.536 0.0000

Box 13 (i): Tukey’s pairwise test results for log carapace length/rostral length ratio: all locations, February and March 2009(Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 1, March = 2. Male = 1, Female = 2)

233 Appendix XI cont/ LOCATION = 1 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 1 1 -0.08588 0.012466 -6.89 0.0000 2 1 2 -0.00274 0.007150 -0.38 1.0000 2 2 1 -0.09251 0.004715 -19.62 0.0000 2 2 2 -0.00753 0.004509 -1.67 0.9547 3 1 1 -0.08828 0.005460 -16.17 0.0000 3 1 2 -0.00433 0.009267 -0.47 1.0000 3 2 1 -0.08194 0.005666 -14.46 0.0000 3 2 2 -0.00377 0.006287 -0.60 1.0000 4 1 1 -0.07689 0.009602 -8.01 0.0000 4 1 2 -0.00800 0.004978 -1.61 0.9674 4 2 1 -0.07117 0.006960 -10.22 0.0000 4 2 2 -0.00034 0.004733 -0.07 1.0000

LOCATION = 2 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 1 2 0.083139 0.01318 6.3062 0.0000 2 2 1 -0.006637 0.01204 -0.5513 1.0000 2 2 2 0.078347 0.01196 6.5513 0.0000 3 1 1 -0.002406 0.01235 -0.1948 1.0000 3 1 2 0.081541 0.01444 5.6462 0.0000 3 2 1 0.003938 0.01244 0.3165 1.0000 3 2 2 0.082103 0.01274 6.4463 0.0000 4 1 1 0.008985 0.01466 0.6130 1.0000 4 1 2 0.077872 0.01214 6.4125 0.0000 4 2 1 0.014710 0.01308 1.1245 0.9992 4 2 2 0.085532 0.01205 7.1008 0.0000

LOCATION = 2 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 2 1 -0.08978 0.006375 -14.08 0.0000 2 2 2 -0.00479 0.006224 -0.77 1.0000 3 1 1 -0.08554 0.006944 -12.32 0.0000 3 1 2 -0.00160 0.010212 -0.16 1.0000 3 2 1 -0.07920 0.007106 -11.14 0.0000 3 2 2 -0.00104 0.007612 -0.14 1.0000 4 1 1 -0.07415 0.010517 -7.05 0.0000 4 1 2 -0.00527 0.006572 -0.80 1.0000 4 2 1 -0.06843 0.008176 -8.37 0.0000 4 2 2 0.00239 0.006388 0.37 1.0000

LOCATION = 2 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 2 2 0.084984 0.003138 27.0813 0.0000 3 1 1 0.004231 0.004397 0.9624 0.9999 3 1 2 0.088178 0.008683 10.1550 0.0000 3 2 1 0.010575 0.004649 2.2745 0.6430 3 2 2 0.088740 0.005390 16.4647 0.0000 4 1 1 0.015622 0.009040 1.7282 0.9397 4 1 2 0.084509 0.003782 22.3462 0.0000 4 2 1 0.021347 0.006161 3.4646 0.0442 4 2 2 0.092169 0.003453 26.6954 0.0000

Box 13 (ii): Tukey’s pairwise test results for log carapace length/rostral length ratio: all locations, February and March 2009 (Newquay = 1, Aberystwyth = 2,

Morfa Nefyn = 3, Amlwch = 4. February = 1, March = 2. Male = 1, Female = 2)

234 Appendix XI cont/

LOCATION = 2 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 1 1 -0.08075 0.004175 -19.34 0.0000 3 1 2 0.00319 0.008573 0.37 1.0000 3 2 1 -0.07441 0.004440 -16.76 0.0000 3 2 2 0.00376 0.005210 0.72 1.0000 4 1 1 -0.06936 0.008934 -7.76 0.0000 4 1 2 -0.00048 0.003521 -0.14 1.0000 4 2 1 -0.06364 0.006005 -10.60 0.0000 4 2 2 0.00718 0.003165 2.27 0.6464 LOCATION = 3 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 1 2 0.083947 0.009109 9.216 0.0000 3 2 1 0.006343 0.005403 1.174 0.9987 3 2 2 0.084509 0.006052 13.963 0.0000 4 1 1 0.011391 0.009450 1.205 0.9982 4 1 2 0.080278 0.004678 17.161 0.0000 4 2 1 0.017116 0.006749 2.536 0.4446 4 2 2 0.087938 0.004416 19.913 0.0000 LOCATION = 3 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 2 1 -0.07760 0.009234 -8.404 0.0000 3 2 2 0.00056 0.009628 0.058 1.0000 4 1 1 -0.07256 0.012057 -6.018 0.0000 4 1 2 -0.00367 0.008829 -0.416 1.0000 4 2 1 -0.06683 0.010080 -6.630 0.0000 4 2 2 0.00399 0.008693 0.459 1.0000 LOCATION = 3 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 2 2 0.078165 0.006238 12.5302 0.0000 4 1 1 0.005048 0.009570 0.5275 1.0000 4 1 2 0.073934 0.004916 15.0393 0.0000 4 2 1 0.010772 0.006916 1.5576 0.9755 4 2 2 0.081594 0.004668 17.4811 0.0000 LOCATION = 3 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 1 1 -0.07312 0.009951 -7.348 0.0000 4 1 2 -0.00423 0.005621 -0.753 1.0000 4 2 1 -0.06739 0.007434 -9.066 0.0000 4 2 2 0.00343 0.005406 0.634 1.0000 LOCATION = 4 MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 1 2 0.068887 0.009180 7.5041 0.0000 4 2 1 0.005724 0.010389 0.5510 1.0000 4 2 2 0.076547 0.009049 8.4589 0.0000 LOCATION = 4 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 2 1 -0.06316 0.006365 -9.923 0.0000 4 2 2 0.00766 0.003804 2.014 0.8182 LOCATION = 4 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 2 2 0.07082 0.006175 11.47 0.0000

Box 13 (iii): Tukey’s pairwise test results for log carapace length/rostral length ratio: all locations, February and March 2009(Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 1, March = 2. Male = 1, Female = 2)

235 Appendix XI cont/

Tukey’s Simultaneous Tests Response Variable log CL/RL All Pairwise Comparisons among Levels of MONTH*LOCATION*SEX MONTH = 1 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 1 1 2 0.083139 0.01295 6.4189 0.0000 1 2 1 -0.002406 0.01213 -0.1983 1.0000 1 2 2 0.081541 0.01419 5.7470 0.0000 2 1 1 -0.006637 0.01183 -0.5612 1.0000 2 1 2 0.078347 0.01175 6.6683 0.0000 2 2 1 0.003938 0.01222 0.3221 1.0000 2 2 2 0.082103 0.01251 6.5614 0.0000 3 1 1 0.001234 0.01181 0.1044 1.0000 3 1 2 0.078377 0.01180 6.6398 0.0000 3 2 1 0.004656 0.01180 0.3946 1.0000 3 2 2 0.085543 0.01183 7.2339 0.0000 4 1 1 0.003505 0.01257 0.2789 1.0000 4 1 2 0.086099 0.01220 7.0571 0.0000 4 2 1 0.003873 0.01221 0.3172 1.0000 4 2 2 0.089451 0.01217 7.3505 0.0000

MONTH = 1 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 1 2 1 -0.08554 0.006822 -12.54 0.0000 1 2 2 -0.00160 0.010033 -0.16 1.0000 2 1 1 -0.08978 0.006263 -14.33 0.0000 2 1 2 -0.00479 0.006114 -0.78 1.0000 2 2 1 -0.07920 0.006982 -11.34 0.0000 2 2 2 -0.00104 0.007478 -0.14 1.0000 3 1 1 -0.08191 0.006230 -13.15 0.0000 3 1 2 -0.00476 0.006219 -0.77 1.0000 3 2 1 -0.07848 0.006212 -12.63 0.0000 3 2 2 0.00240 0.006260 0.38 1.0000 4 1 1 -0.07963 0.007565 -10.53 0.0000 4 1 2 0.00296 0.006942 0.43 1.0000 4 2 1 -0.07927 0.006962 -11.39 0.0000 4 2 2 0.00631 0.006887 0.92 0.9999

MONTH = 1 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 1 2 2 0.083947 0.008949 9.3801 0.0000 2 1 1 -0.004231 0.004320 -0.9795 0.9999 2 1 2 0.080753 0.004102 19.6886 0.0000 2 2 1 0.006343 0.005309 1.1949 0.9984 2 2 2 0.084509 0.005946 14.2125 0.0000 3 1 1 0.003639 0.004272 0.8519 1.0000 3 1 2 0.080782 0.004256 18.9791 0.0000 3 2 1 0.007062 0.004245 1.6635 0.9561 3 2 2 0.087949 0.004315 20.3823 0.0000 4 1 1 0.005911 0.006056 0.9761 0.9999 4 1 2 0.088505 0.005256 16.8378 0.0000 4 2 1 0.006279 0.005282 1.1888 0.9985 4 2 2 0.091857 0.005184 17.7200 0.0000

Box 14 (i): Tukey’s pairwise test results for log carapace length/rostral length ratio: Aberystwyth and Morfa Nefyn February to May 2009 (February = 1, March = 2, April = 3, May = 4. Aberystwyth = 1, Morfa Nefyn = 2. Male = 1, Female = 2)

236 Appendix XI cont/

MONTH = 1 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 1 1 -0.08818 0.008531 -10.34 0.0000 2 1 2 -0.00319 0.008423 -0.38 1.0000 2 2 1 -0.07760 0.009072 -8.55 0.0000 2 2 2 0.00056 0.009459 0.06 1.0000 3 1 1 -0.08031 0.008507 -9.44 0.0000 3 1 2 -0.00316 0.008499 -0.37 1.0000 3 2 1 -0.07689 0.008493 -9.05 0.0000 3 2 2 0.00400 0.008528 0.47 1.0000 4 1 1 -0.07804 0.009528 -8.19 0.0000 4 1 2 0.00456 0.009041 0.50 1.0000 4 2 1 -0.07767 0.009056 -8.58 0.0000 4 2 2 0.00791 0.008999 0.88 1.0000

MONTH = 2 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 1 2 0.084984 0.003083 27.565 0.0000 2 2 1 0.010575 0.004568 2.315 0.6124 2 2 2 0.088740 0.005295 16.759 0.0000 3 1 1 0.007871 0.003307 2.380 0.5627 3 1 2 0.085014 0.003286 25.869 0.0000 3 2 1 0.011293 0.003272 3.452 0.0461 3 2 2 0.092180 0.003362 27.420 0.0000 4 1 1 0.010142 0.005418 1.872 0.8889 4 1 2 0.092736 0.004507 20.577 0.0000 4 2 1 0.010510 0.004537 2.317 0.6112 4 2 2 0.096088 0.004422 21.729 0.0000

MONTH = 2 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 2 1 -0.07441 0.004362 -17.06 0.0000 2 2 2 0.00376 0.005119 0.73 1.0000 3 1 1 -0.07711 0.003016 -25.57 0.0000 3 1 2 0.00003 0.002994 0.01 1.0000 3 2 1 -0.07369 0.002978 -24.75 0.0000 3 2 2 0.00720 0.003077 2.34 0.5943 4 1 1 -0.07484 0.005246 -14.27 0.0000 4 1 2 0.00775 0.004298 1.80 0.9157 4 2 1 -0.07447 0.004330 -17.20 0.0000 4 2 2 0.01110 0.004209 2.64 0.3719

MONTH = 2 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 2 2 0.078165 0.006129 12.7539 0.0000 3 1 1 -0.002704 0.004523 -0.5979 1.0000 3 1 2 0.074439 0.004508 16.5126 0.0000 3 2 1 0.000718 0.004497 0.1597 1.0000 3 2 2 0.081606 0.004563 17.8827 0.0000 4 1 1 -0.000433 0.006235 -0.0694 1.0000 4 1 2 0.082162 0.005462 15.0422 0.0000 4 2 1 -0.000064 0.005487 -0.0117 1.0000 4 2 2 0.085513 0.005392 15.8584 0.0000

Box 14 (ii): Tukey’s pairwise test results for log carapace length/rostral length ratio: Aberystwyth and Morfa Nefyn February to May 2009 (February = 1, March = 2, April = 3, May = 4. Aberystwyth = 1, Morfa Nefyn = 2. Male = 1, Female = 2)

237 Appendix XI cont/ MONTH = 2 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 1 1 -0.08087 0.005257 -15.38 0.0000 3 1 2 -0.00373 0.005244 -0.71 1.0000 3 2 1 -0.07745 0.005235 -14.80 0.0000 3 2 2 0.00344 0.005291 0.65 1.0000 4 1 1 -0.07860 0.006786 -11.58 0.0000 4 1 2 0.00400 0.006083 0.66 1.0000 4 2 1 -0.07823 0.006106 -12.81 0.0000 4 2 2 0.00735 0.006021 1.22 0.9980 MONTH = 3 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 1 2 0.077143 0.003224 23.9303 0.0000 3 2 1 0.003422 0.003209 1.0666 0.9996 3 2 2 0.084310 0.003301 25.5436 0.0000 4 1 1 0.002272 0.005380 0.4222 1.0000 4 1 2 0.084866 0.004461 19.0223 0.0000 4 2 1 0.002640 0.004492 0.5877 1.0000 4 2 2 0.088217 0.004376 20.1608 0.0000 MONTH = 3 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 2 1 -0.07372 0.003188 -23.13 0.0000 3 2 2 0.00717 0.003280 2.18 0.7082 4 1 1 -0.07487 0.005368 -13.95 0.0000 4 1 2 0.00772 0.004446 1.74 0.9372 4 2 1 -0.07450 0.004477 -16.64 0.0000 4 2 2 0.01107 0.004360 2.54 0.4420 MONTH = 3 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 2 2 0.080888 0.003266 24.7699 0.0000 4 1 1 -0.001151 0.005359 -0.2147 1.0000 4 1 2 0.081443 0.004436 18.3617 0.0000 4 2 1 -0.000782 0.004466 -0.1752 1.0000 4 2 2 0.084795 0.004349 19.4962 0.0000 MONTH = 3 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 1 1 -0.08204 0.005414 -15.15 0.0000 4 1 2 0.00056 0.004502 0.12 1.0000 4 2 1 -0.08167 0.004532 -18.02 0.0000 4 2 2 0.00391 0.004418 0.88 1.0000 MONTH = 4 LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 1 2 0.082594 0.006191 13.3416 0.0000 4 2 1 0.000368 0.006213 0.0593 1.0000 4 2 2 0.085946 0.006129 14.0223 0.0000 MONTH = 4 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 2 1 -0.08223 0.005436 -15.13 0.0000 4 2 2 0.00335 0.005341 0.63 1.0000 MONTH = 4 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 2 2 0.08558 0.005366 15.95 0.0000

Box 14 (iii): Tukey’s pairwise test results for log carapace length/rostral length ratio: Aberystwyth and Morfa Nefyn February to May 2009 (February = 1, March = 2, April = 3, May = 4. Aberystwyth = 1, Morfa Nefyn = 2. Male = 1, Female = 2)

238 Appendix XI cont/ Tukey’s Simultaneous Tests Response Variable log CL/RL All Pairwise Comparisons among Levels of MONTH*SEX MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 1 2 0.090355 0.006006 15.0434 0.0000 2 1 0.012038 0.007899 1.5240 0.7947 2 2 0.090826 0.008585 10.5795 0.0000 3 1 0.003522 0.008272 0.4257 0.9999 3 2 0.092219 0.007017 13.1426 0.0000 4 1 0.015708 0.005814 2.7016 0.1220 4 2 0.093948 0.006412 14.6530 0.0000

MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 1 -0.07832 0.006787 -11.54 0.0000 2 2 0.00047 0.007574 0.06 1.0000 3 1 -0.08683 0.007217 -12.03 0.0000 3 2 0.00186 0.005736 0.32 1.0000 4 1 -0.07465 0.004180 -17.86 0.0000 4 2 0.00359 0.004977 0.72 0.9964

MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 2 0.078789 0.009148 8.6126 0.0000 3 1 -0.008516 0.008855 -0.9618 0.9796 3 2 0.080181 0.007695 10.4194 0.0000 4 1 0.003670 0.006617 0.5546 0.9993 4 2 0.081910 0.007148 11.4595 0.0000

MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 1 -0.08730 0.009472 -9.22 0.0000 3 2 0.00139 0.008398 0.17 1.0000 4 1 -0.07512 0.007423 -10.12 0.0000 4 2 0.00312 0.007899 0.40 0.9999

MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 2 0.08870 0.008078 10.980 0.0000 4 1 0.01219 0.007058 1.726 0.6699 4 2 0.09043 0.007558 11.964 0.0000

MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 1 -0.07651 0.005534 -13.82 0.0000 4 2 0.00173 0.006159 0.28 1.0000

MONTH = 4 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 2 0.07824 0.004744 16.49 0.0000

Box 15: Tukey’s pairwise test results for log carapace length/rostral length ratio: Newquay December to March 2008/9 (December = 1, January = 2, February = 3, March = 4. Male = 1, Female = 2)

239 Appendix XI cont/ Tukey’s Simultaneous Tests Response Variable log CL/RL All Pairwise Comparisons among Levels of MONTH*SEX MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 1 2 0.083947 0.008803 9.537 0.0000 2 1 0.006343 0.005222 1.215 0.9702 2 2 0.084509 0.005849 14.449 0.0000 3 1 0.007062 0.004175 1.691 0.8009 3 2 0.087951 0.004244 20.723 0.0000 4 1 0.006279 0.005195 1.209 0.9712 4 2 0.091857 0.005099 18.015 0.0000 9 1 0.008177 0.007047 1.160 0.9781 9 2 0.077901 0.004148 18.782 0.0000

MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 1 -0.07760 0.008923 -8.697 0.0000 2 2 0.00056 0.009304 0.060 1.0000 3 1 -0.07689 0.008354 -9.203 0.0000 3 2 0.00400 0.008389 0.477 1.0000 4 1 -0.07767 0.008908 -8.719 0.0000 4 2 0.00791 0.008852 0.894 0.9967 9 1 -0.07577 0.010100 -7.502 0.0000 9 2 -0.00605 0.008340 -0.725 0.9994

MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 2 0.078165 0.006028 12.9665 0.0000 3 1 0.000718 0.004424 0.1623 1.0000 3 2 0.081608 0.004489 18.1813 0.0000 4 1 -0.000064 0.005397 -0.0119 1.0000 4 2 0.085513 0.005304 16.1227 0.0000 9 1 0.001834 0.007197 0.2548 1.0000 9 2 0.071557 0.004397 16.2729 0.0000

MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 1 -0.07745 0.005149 -15.04 0.0000 3 2 0.00344 0.005205 0.66 0.9997 4 1 -0.07823 0.006006 -13.03 0.0000 4 2 0.00735 0.005922 1.24 0.9658 9 1 -0.07633 0.007664 -9.96 0.0000 9 2 -0.00661 0.005126 -1.29 0.9563

Box 16 (i): Tukey’s pairwise test results for log carapace length/rostral length ratio: Morfa Nefyn February to May plus October 2009 (February = 1, March = 2, April = 3, May = 4, October = 9. Male = 1, Female = 2)

240 Appendix XI cont/ MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 2 0.080890 0.003212 25.1834 0.0000 4 1 -0.000782 0.004393 -0.1781 1.0000 4 2 0.084795 0.004278 19.8213 0.0000 9 1 0.001116 0.006478 0.1722 1.0000 9 2 0.070839 0.003083 22.9756 0.0000

MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 1 -0.08167 0.004458 -18.32 0.0000 4 2 0.00391 0.004345 0.90 0.9965 9 1 -0.07977 0.006523 -12.23 0.0000 9 2 -0.01005 0.003176 -3.16 0.0498

MONTH = 4 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 2 0.085577 0.005278 16.2135 0.0000 9 1 0.001898 0.007178 0.2644 1.0000 9 2 0.071621 0.004366 16.4034 0.0000

MONTH = 4 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 9 1 -0.08368 0.007108 -11.77 0.0000 9 2 -0.01396 0.004251 -3.28 0.0346

MONTH = 9 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 9 2 0.06972 0.006460 10.79 0.0000

Box 16 (ii): Tukey’s pairwise test results for log carapace length/rostral length ratio: Morfa Nefyn February to May plus October 2009(February = 1, March = 2, April = 3, May = 4, October = 9. Male = 1, Female = 2)

241 Appendix XII: log Carapace length/wet weight ratio ANOVAS and Tukeys post hoc test results

Table XXVI: ANOVA table for log carapace length/wet weight ratio vs location, month and sex: all locations, February and March 2009 ANOVA TABLE FOR log CARAPACE LENGTH/WET WEIGHT RATIO VS LOCATION MONTH & SEX (FEBRUARY & MARCH 2009) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES LOCATION 1.814969 3 0.6049896 80.21 0.000 MONTH 0.000594 1 0.0005939 0.08 0.779 SEX 7.026066 1 7.0260658 931.55 0.000 LOCATION*MONTH 0.30672 3 0.1022401 13.56 0.000 LOCATION*SEX 1.261247 3 0.4204156 55.74 0.000 MONTH*SEX 0.002735 1 0.0027351 0.36 0.547 LOCATION*MONTH*SEX 0.206835 3 0.068945 9.14 0.000 RESIDUAL 6.938965 920 0.0075424 (TOTAL) 14.267456 935

Table XXVII: ANOVA table for log carapace length/wet weight ratio vs location, month and sex: Aberystwyth and Morfa Nefyn February to May 2009 ANOVA TABLE FOR log CARAPACE LENGTH/WET WEIGHT RATIO VS MONTH LOCATION & SEX (ABERYSTWYTH & MORFA NEFYN FEBRUARY TO MAY 2009) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 0.495085 3 0.1650285 20.89 0.000 LOCATION 0.174548 1 0.1745476 22.10 0.000 SEX 9.714823 1 9.7148228 1229.80 0.000 MONTH*LOCATION 0.439256 3 0.1464187 18.54 0.000 MONTH*SEX 0.215667 3 0.0718891 9.10 0.000 LOCATION*SEX 0.227409 1 0.2274086 28.79 0.000 MONTH*LOCATION*SEX 0.348895 3 0.1162985 14.72 0.000 RESIDUAL 8.507782 1077 0.0078995 (TOTAL) 18.829956 1092

242 Appendix XII cont/

Table XXVIII: ANOVA table for log carapace length/wet weight ratio vs month and sex: Newquay December to March 2008/9 ANOVA TABLE FOR log CARAPACE LENGTH/WET WEIGHT RATIO VS MONTH & SEX (NEWQUAY DECEMBER TO MARCH 2008/9) SUM OF DEGREES OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 0.081097 3 0.0270323 3.07 0.028 SEX 0.876517 1 0.876517 99.41 0.000 MONTH*SEX 0.143648 3 0.0478828 5.43 0.001 RESIDUAL 2.786171 316 0.008817 (TOTAL) 3.749626 323

Table XXIX: ANOVA table for log carapace length/wet weight ratio vs month and sex: Morfa Nefyn February to May plus October 2009 ANOVA TABLE FOR log CARAPACE LENGTH/WET WEIGHT RATIO VS MONTH & SEX (MORFA NEFYN FEBRUARY TO MAY PLUS OCTOBER 2009) SUM OF DEGREES OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 0.978309 4 0.2445773 39.52 0.000 SEX 4.746164 1 4.7461643 766.99 0.000 MONTH*SEX 1.090684 4 0.272671 44.06 0.000 RESIDUAL 4.053162 655 0.006188 (TOTAL) 9.470398 664

243 Appendix XII cont/ Tukey’s Simultaneous Tests Response Variable log CARAPACE LENGTH/WET WEIGHT RATIO All Pairwise Comparisons among Levels of LOCATION*MONTH*SEX LOCATION = 1 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 2 2 -0.1718 0.02545 -6.750 0.0000 1 3 1 0.0124 0.02234 0.555 1.0000 1 3 2 -0.1535 0.02430 -6.318 0.0000 2 2 1 -0.0215 0.04094 -0.526 1.0000 2 2 2 -0.1647 0.02733 -6.027 0.0000 2 3 1 0.0197 0.02175 0.907 0.9999 2 3 2 -0.1721 0.02134 -8.064 0.0000 3 2 1 0.0214 0.02334 0.916 0.9999 3 2 2 -0.1027 0.03237 -3.173 0.1068 3 3 1 0.0062 0.02400 0.257 1.0000 3 3 2 -0.1180 0.02532 -4.661 0.0004 4 2 1 -0.0952 0.03868 -2.460 0.5014 4 2 2 -0.1716 0.02343 -7.324 0.0000 4 3 1 -0.0352 0.02760 -1.275 0.9967 4 3 2 -0.1730 0.02185 -7.916 0.0000 LOCATION = 1 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 3 1 0.184168 0.01757 10.4804 0.0000 1 3 2 0.018248 0.02000 0.9124 0.9999 2 2 1 0.150226 0.03854 3.8975 0.0095 2 2 2 0.007048 0.02359 0.2988 1.0000 2 3 1 0.191480 0.01681 11.3937 0.0000 2 3 2 -0.000307 0.01627 -0.0189 1.0000 3 2 1 0.193146 0.01882 10.2618 0.0000 3 2 2 0.069076 0.02928 2.3595 0.5786 3 3 1 0.177926 0.01964 9.0598 0.0000 3 3 2 0.053759 0.02122 2.5331 0.4468 4 2 1 0.076581 0.03614 2.1190 0.7531 4 2 2 0.000144 0.01894 0.0076 1.0000 4 3 1 0.136577 0.02390 5.7136 0.0000 4 3 2 -0.001228 0.01694 -0.0725 1.0000 LOCATION = 1 MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 1 3 2 -0.1659 0.01586 -10.46 0.0000 2 2 1 -0.0339 0.03657 -0.93 0.9999 2 2 2 -0.1771 0.02020 -8.77 0.0000 2 3 1 0.0073 0.01158 0.63 1.0000 2 3 2 -0.1845 0.01079 -17.09 0.0000 3 2 1 0.0090 0.01435 0.63 1.0000 3 2 2 -0.1151 0.02662 -4.32 0.0017 3 3 1 -0.0062 0.01541 -0.41 1.0000 3 3 2 -0.1304 0.01738 -7.50 0.0000 4 2 1 -0.1076 0.03403 -3.16 0.1100 4 2 2 -0.1840 0.01450 -12.69 0.0000 4 3 1 -0.0476 0.02057 -2.31 0.6135 4 3 2 -0.1854 0.01178 -15.74 0.0000

Box 17 (i): Tukey’s pairwise test results for log carapace length/wet weight ratio: all locations, February and March 2009 (Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 2, March = 3. Male = 1, Female = 2)

244 Appendix XII cont/

LOCATION = 1 MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 2 1 0.13198 0.03780 3.492 0.0404 2 2 2 -0.01120 0.02235 -0.501 1.0000 2 3 1 0.17323 0.01501 11.541 0.0000 2 3 2 -0.01855 0.01441 -1.288 0.9964 3 2 1 0.17490 0.01724 10.146 0.0000 3 2 2 0.05083 0.02828 1.797 0.9180 3 3 1 0.15968 0.01813 8.809 0.0000 3 3 2 0.03551 0.01983 1.791 0.9201 4 2 1 0.05833 0.03534 1.651 0.9589 4 2 2 -0.01810 0.01736 -1.043 0.9997 4 3 1 0.11833 0.02268 5.218 0.0001 4 3 2 -0.01948 0.01516 -1.285 0.9965 LOCATION = 2 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 2 2 -0.1432 0.03981 -3.596 0.0285 2 3 1 0.0413 0.03621 1.139 0.9991 2 3 2 -0.1505 0.03596 -4.186 0.0030 3 2 1 0.0429 0.03719 1.154 0.9989 3 2 2 -0.0811 0.04342 -1.869 0.8902 3 3 1 0.0277 0.03761 0.737 1.0000 3 3 2 -0.0965 0.03846 -2.508 0.4652 4 2 1 -0.0736 0.04832 -1.524 0.9800 4 2 2 -0.1501 0.03724 -4.030 0.0057 4 3 1 -0.0136 0.04000 -0.341 1.0000 4 3 2 -0.1515 0.03627 -4.176 0.0031 LOCATION = 2 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 3 1 0.184432 0.01954 9.4388 0.0000 2 3 2 -0.007355 0.01908 -0.3854 1.0000 3 2 1 0.186098 0.02130 8.7375 0.0000 3 2 2 0.062028 0.03093 2.0056 0.8226 3 3 1 0.170878 0.02202 7.7586 0.0000 3 3 2 0.046711 0.02345 1.9922 0.8301 4 2 1 0.069532 0.03749 1.8547 0.8961 4 2 2 -0.006905 0.02140 -0.3226 1.0000 4 3 1 0.129529 0.02590 5.0013 0.0001 4 3 2 -0.008276 0.01966 -0.4210 1.0000 LOCATION = 2 MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 2 3 2 -0.1918 0.009494 -20.20 0.0000 3 2 1 0.0017 0.013401 0.12 1.0000 3 2 2 -0.1224 0.026123 -4.69 0.0003 3 3 1 -0.0136 0.014526 -0.93 0.9999 3 3 2 -0.1377 0.016604 -8.29 0.0000 4 2 1 -0.1149 0.033636 -3.42 0.0517 4 2 2 -0.1913 0.013562 -14.11 0.0000 4 3 1 -0.0549 0.019918 -2.76 0.2947 4 3 2 -0.1927 0.010599 -18.18 0.0000

Box 17 (ii): Tukey’s pairwise test results for log carapace length/wet weight ratio: all locations, February and March 2009 (Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 2, March = 3. Male =1, Female = 2)

245 Appendix XII cont/ LOCATION = 2 MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 2 1 0.193453 0.012727 15.2006 0.0000 3 2 2 0.069383 0.025784 2.6910 0.3362 3 3 1 0.178233 0.013907 12.8164 0.0000 3 3 2 0.054066 0.016065 3.3654 0.0606 4 2 1 0.076887 0.033373 2.3039 0.6209 4 2 2 0.000450 0.012896 0.0349 1.0000 4 3 1 0.136884 0.019470 7.0304 0.0000 4 3 2 -0.000921 0.009733 -0.0947 1.0000 LOCATION = 3 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 2 2 -0.1241 0.02746 -4.52 0.0007 3 3 1 -0.0152 0.01682 -0.90 0.9999 3 3 2 -0.1394 0.01864 -7.48 0.0000 4 2 1 -0.1166 0.03469 -3.36 0.0615 4 2 2 -0.1930 0.01599 -12.07 0.0000 4 3 1 -0.0566 0.02165 -2.61 0.3889 4 3 2 -0.1944 0.01357 -14.32 0.0000 LOCATION = 3 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 3 1 0.10885 0.02803 3.883 0.0101 3 3 2 -0.01532 0.02916 -0.525 1.0000 4 2 1 0.00750 0.04130 0.182 1.0000 4 2 2 -0.06893 0.02754 -2.503 0.4694 4 3 1 0.06750 0.03117 2.166 0.7215 4 3 2 -0.07030 0.02621 -2.682 0.3419 LOCATION = 3 MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 3 3 2 -0.1242 0.01947 -6.38 0.0000 4 2 1 -0.1013 0.03514 -2.88 0.2227 4 2 2 -0.1778 0.01695 -10.49 0.0000 4 3 1 -0.0413 0.02236 -1.85 0.8983 4 3 2 -0.1792 0.01468 -12.20 0.0000 LOCATION = 3 MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 2 1 0.02282 0.03605 0.633 1.0000 4 2 2 -0.05362 0.01876 -2.858 0.2364 4 3 1 0.08282 0.02376 3.485 0.0413 4 3 2 -0.05499 0.01674 -3.284 0.0774 LOCATION = 4 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 2 2 -0.07644 0.03475 -2.200 0.6977 4 3 1 0.06000 0.03769 1.592 0.9701 4 3 2 -0.07781 0.03370 -2.309 0.6173 LOCATION = 4 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 3 1 0.136434 0.02175 6.27404 0.0000 4 3 2 -0.001372 0.01373 -0.09991 1.0000 LOCATION = 4 MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION MONTH SEX of Means Difference T-Value P-Value 4 3 2 -0.1378 0.02003 -6.879 0.0000

Box 17 (iii): Tukey’s pairwise test results for log carapace length/wet weight ratio: all locations, February and March 2009(Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 2, March = 3. Male = 1, Female = 2)

246 Appendix XII cont/ Tukey’s Simultaneous Tests Response Variable log CARAPACE LENGTH/WET WEIGHT RATIO All Pairwise Comparisons among Levels of MONTH*LOCATION*SEX MONTH = 2 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 2 2 -0.1432 0.04074 -3.514 0.0376 2 3 1 0.0429 0.03806 1.128 0.9992 2 3 2 -0.0811 0.04444 -1.826 0.9074 3 2 1 0.0413 0.03705 1.113 0.9993 3 2 2 -0.1505 0.03680 -4.090 0.0045 3 3 1 0.0277 0.03849 0.720 1.0000 3 3 2 -0.0965 0.03936 -2.451 0.5085 4 2 1 0.0119 0.03781 0.315 1.0000 4 2 2 -0.1837 0.03785 -4.853 0.0002 4 3 1 0.0052 0.03709 0.142 1.0000 4 3 2 -0.1861 0.03713 -5.012 0.0001 5 2 1 -0.0092 0.04040 -0.228 1.0000 5 2 2 -0.1902 0.03868 -4.918 0.0001 5 3 1 0.0497 0.03858 1.289 0.9963 5 3 2 -0.1854 0.03853 -4.811 0.0002

MONTH = 2 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 3 1 0.18610 0.02180 8.538 0.0000 2 3 2 0.06203 0.03165 1.960 0.8474 3 2 1 0.18443 0.02000 9.223 0.0000 3 2 2 -0.00735 0.01953 -0.377 1.0000 3 3 1 0.17088 0.02254 7.581 0.0000 3 3 2 0.04671 0.02400 1.947 0.8541 4 2 1 0.15510 0.02136 7.261 0.0000 4 2 2 -0.04051 0.02144 -1.889 0.8813 4 3 1 0.14843 0.02006 7.399 0.0000 4 3 2 -0.04289 0.02013 -2.131 0.7454 5 2 1 0.13395 0.02568 5.216 0.0001 5 2 2 -0.04704 0.02287 -2.057 0.7926 5 3 1 0.19292 0.02270 8.499 0.0000 5 3 2 -0.04218 0.02262 -1.865 0.8918

MONTH = 2 LOCATION = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 2 3 2 -0.1241 0.02811 -4.41 0.0011 3 2 1 -0.0017 0.01371 -0.12 1.0000 3 2 2 -0.1935 0.01302 -14.85 0.0000 3 3 1 -0.0152 0.01721 -0.88 1.0000 3 3 2 -0.1394 0.01908 -7.31 0.0000 4 2 1 -0.0310 0.01564 -1.98 0.8355 4 2 2 -0.2266 0.01574 -14.39 0.0000 4 3 1 -0.0377 0.01381 -2.73 0.3119 4 3 2 -0.2290 0.01391 -16.47 0.0000 5 2 1 -0.0521 0.02116 -2.46 0.4981 5 2 2 -0.2331 0.01764 -13.22 0.0000 5 3 1 0.0068 0.01742 0.39 1.0000 5 3 2 -0.2283 0.01731 -13.19 0.0000

Box 18 (i): Tukey’s pairwise test results for log carapace length/wet weight ratio: Aberystwyth and Morfa Nefyn February to May 2009 (February = 2, March = 3, April = 4, May = 5. Aberystwyth = 2, Morfa Nefyn = 3. Male = 1, Female = 2)

247 Appendix XII cont/ MONTH = 2 LOCATION = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 2 1 0.1224 0.02673 4.579 0.0006 3 2 2 -0.0694 0.02639 -2.629 0.3777 3 3 1 0.1088 0.02869 3.795 0.0141 3 3 2 -0.0153 0.02984 -0.513 1.0000 4 2 1 0.0931 0.02777 3.352 0.0631 4 2 2 -0.1025 0.02783 -3.684 0.0210 4 3 1 0.0864 0.02678 3.226 0.0918 4 3 2 -0.1049 0.02683 -3.910 0.0091 5 2 1 0.0719 0.03121 2.304 0.6206 5 2 2 -0.1091 0.02895 -3.768 0.0155 5 3 1 0.1309 0.02881 4.543 0.0006 5 3 2 -0.1042 0.02875 -3.625 0.0258 MONTH = 3 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 2 2 -0.1918 0.009716 -19.74 0.0000 3 3 1 -0.0136 0.014866 -0.91 0.9999 3 3 2 -0.1377 0.016993 -8.10 0.0000 4 2 1 -0.0293 0.013011 -2.25 0.6579 4 2 2 -0.2249 0.013137 -17.12 0.0000 4 3 1 -0.0360 0.010741 -3.35 0.0631 4 3 2 -0.2273 0.010869 -20.91 0.0000 5 2 1 -0.0505 0.019298 -2.62 0.3871 5 2 2 -0.2315 0.015361 -15.07 0.0000 5 3 1 0.0085 0.015105 0.56 1.0000 5 3 2 -0.2266 0.014983 -15.12 0.0000 MONTH = 3 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 3 1 0.17823 0.014232 12.523 0.0000 3 3 2 0.05407 0.016441 3.288 0.0765 4 2 1 0.16246 0.012281 13.228 0.0000 4 2 2 -0.03315 0.012416 -2.670 0.3500 4 3 1 0.15578 0.009845 15.823 0.0000 4 3 2 -0.03553 0.009985 -3.559 0.0324 5 2 1 0.14130 0.018814 7.511 0.0000 5 2 2 -0.03968 0.014748 -2.691 0.3363 5 3 1 0.20027 0.014481 13.830 0.0000 5 3 2 -0.03482 0.014355 -2.426 0.5276 MONTH = 3 LOCATION = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 3 3 2 -0.1242 0.01992 -6.23 0.0000 4 2 1 -0.0158 0.01666 -0.95 0.9999 4 2 2 -0.2114 0.01676 -12.62 0.0000 4 3 1 -0.0225 0.01495 -1.50 0.9826 4 3 2 -0.2138 0.01504 -14.21 0.0000 5 2 1 -0.0369 0.02192 -1.68 0.9512 5 2 2 -0.2179 0.01855 -11.75 0.0000 5 3 1 0.0220 0.01834 1.20 0.9983 5 3 2 -0.2131 0.01824 -11.68 0.0000

Box 18 (ii): Tukey’s pairwise test results for log carapace length/wet weight ratio: Aberystwyth and Morfa Nefyn February to May 2009 (February = 2, March = 3, April = 4, May = 5. Aberystwyth = 2, Morfa Nefyn = 3. Male = 1, Female = 2)

248 Appendix XII cont/ MONTH = 3 LOCATION = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 2 1 0.10839 0.01858 5.834 0.0000 4 2 2 -0.08722 0.01867 -4.672 0.0004 4 3 1 0.10171 0.01707 5.960 0.0000 4 3 2 -0.08960 0.01715 -5.225 0.0001 5 2 1 0.08724 0.02342 3.726 0.0181 5 2 2 -0.09375 0.02029 -4.619 0.0005 5 3 1 0.14620 0.02010 7.273 0.0000 5 3 2 -0.08889 0.02001 -4.442 0.0010 MONTH = 4 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 2 2 -0.1956 0.01513 -12.93 0.0000 4 3 1 -0.0067 0.01311 -0.51 1.0000 4 3 2 -0.1980 0.01321 -14.99 0.0000 5 2 1 -0.0212 0.02071 -1.02 0.9998 5 2 2 -0.2021 0.01710 -11.82 0.0000 5 3 1 0.0378 0.01687 2.24 0.6673 5 3 2 -0.1973 0.01676 -11.77 0.0000 MONTH = 4 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 3 1 0.188931 0.01323 14.2769 0.0000 4 3 2 -0.002382 0.01334 -0.1786 1.0000 5 2 1 0.174454 0.02079 8.3920 0.0000 5 2 2 -0.006534 0.01720 -0.3800 1.0000 5 3 1 0.233421 0.01697 13.7569 0.0000 5 3 2 -0.001674 0.01686 -0.0993 1.0000 MONTH = 4 LOCATION = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 4 3 2 -0.1913 0.01098 -17.42 0.0000 5 2 1 -0.0145 0.01936 -0.75 1.0000 5 2 2 -0.1955 0.01544 -12.66 0.0000 5 3 1 0.0445 0.01519 2.93 0.2005 5 3 2 -0.1906 0.01507 -12.65 0.0000 MONTH = 4 LOCATION = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 5 2 1 0.176836 0.01943 9.0992 0.0000 5 2 2 -0.004152 0.01553 -0.2673 1.0000 5 3 1 0.235803 0.01528 15.4333 0.0000 5 3 2 0.000708 0.01516 0.0467 1.0000 MONTH = 5 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 5 2 2 -0.1810 0.02226 -8.131 0.0000 5 3 1 0.0590 0.02208 2.670 0.3500 5 3 2 -0.1761 0.02200 -8.005 0.0000 MONTH = 5 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 5 3 1 0.239954 0.01874 12.8030 0.0000 5 3 2 0.004860 0.01864 0.2606 1.0000 MONTH = 5 LOCATION = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH LOCATION SEX of Means Difference T-Value P-Value 5 3 2 -0.2351 0.01843 -12.75 0.0000

Box 18 (iii): Tukey’s pairwise test results for log carapace length/wet weight ratio: Aberystwyth and Morfa Nefyn February to May 2009 (February = 2, March = 3, April = 4, May = 5. Aberystwyth = 2, Morfa Nefyn = 3. Male = 1, Female = 2)

249 Appendix XII cont/

Tukey’s Simultaneous Tests Response Variable log CARAPACE LENGTH/WET WEIGHT RATIO All Pairwise Comparisons among Levels of MONTH*SEX MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 1 2 -0.1301 0.02107 -6.175 0.0000 2 1 -0.0656 0.02857 -2.297 0.2949 2 2 -0.1759 0.03024 -5.818 0.0000 3 1 -0.0253 0.02857 -0.885 0.9875 3 2 -0.1498 0.02437 -6.148 0.0000 4 1 -0.0423 0.02050 -2.062 0.4401 4 2 -0.1365 0.02296 -5.946 0.0000 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 1 0.06449 0.02465 2.617 0.1498 2 2 -0.04579 0.02656 -1.724 0.6715 3 1 0.10484 0.02465 4.254 0.0006 3 2 -0.01969 0.01961 -1.004 0.9740 4 1 0.08786 0.01454 6.043 0.0000 4 2 -0.00636 0.01783 -0.357 1.0000 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 2 -0.1103 0.03283 -3.359 0.0178 3 1 0.0404 0.03130 1.289 0.9031 3 2 -0.0842 0.02751 -3.059 0.0460 4 1 0.0234 0.02416 0.967 0.9789 4 2 -0.0708 0.02627 -2.697 0.1235 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 1 0.15063 0.03283 4.5886 0.0001 3 2 0.02610 0.02924 0.8927 0.9868 4 1 0.13365 0.02611 5.1192 0.0000 4 2 0.03943 0.02807 1.4045 0.8556 MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 2 -0.1245 0.02751 -4.526 0.0002 4 1 -0.0170 0.02416 -0.703 0.9969 4 2 -0.1112 0.02627 -4.233 0.0006 MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 1 0.10755 0.01900 5.6605 0.0000 4 2 0.01333 0.02162 0.6164 0.9987 MONTH = 4 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 2 -0.09422 0.01715 -5.493 0.0000

Box 19: Tukey’s pairwise test results for log carapace length/wet weight ratio: Newquay December to March 2008/9 (December = 1, January = 2, February = 3, March = 4. Male = 1, Female = 2)

250 Appendix XII cont/ Tukey’s Simultaneous Tests Response Variable log CARAPACE LENGTH/WET WEIGHT RATIO All Pairwise Comparisons among Levels of MONTH*SEX MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 2 -0.1241 0.02488 -4.99 0.0000 3 1 -0.0152 0.01523 -1.00 0.9924 3 2 -0.1394 0.01689 -8.25 0.0000 4 1 -0.0377 0.01222 -3.08 0.0635 4 2 -0.2290 0.01231 -18.61 0.0000 5 1 0.0068 0.01542 0.44 1.0000 5 2 -0.2283 0.01532 -14.90 0.0000 10 1 -0.0183 0.02114 -0.87 0.9974 10 2 -0.1549 0.01216 -12.74 0.0000 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 1 0.1089 0.02539 4.287 0.0008 3 2 -0.0153 0.02641 -0.580 0.9999 4 1 0.0864 0.02370 3.645 0.0101 4 2 -0.1049 0.02375 -4.418 0.0004 5 1 0.1309 0.02550 5.133 0.0000 5 2 -0.1042 0.02544 -4.096 0.0017 10 1 0.1057 0.02932 3.607 0.0115 10 2 -0.0309 0.02368 -1.304 0.9530 MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 2 -0.1242 0.01763 -7.04 0.0000 4 1 -0.0225 0.01323 -1.70 0.7977 4 2 -0.2138 0.01331 -16.06 0.0000 5 1 0.0220 0.01623 1.36 0.9398 5 2 -0.2131 0.01614 -13.20 0.0000 10 1 -0.0031 0.02174 -0.14 1.0000 10 2 -0.1397 0.01318 -10.60 0.0000 MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 1 0.10171 0.01511 6.734 0.0000 4 2 -0.08960 0.01518 -5.904 0.0000 5 1 0.14620 0.01779 8.218 0.0000 5 2 -0.08889 0.01771 -5.019 0.0000 10 1 0.12106 0.02293 5.280 0.0000 10 2 -0.01556 0.01506 -1.033 0.9903 MONTH = 4 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 2 -0.1913 0.009722 -19.68 0.0000 5 1 0.0445 0.013442 3.31 0.0318 5 2 -0.1906 0.013336 -14.29 0.0000 10 1 0.0193 0.019747 0.98 0.9934 10 2 -0.1173 0.009540 -12.29 0.0000

Box 20 (i): Tukey’s pairwise test results for log carapace length/wet weight ratio: Morfa Nefyn February to May plus October 2009 (February = 2, March = 3, April = 4, May = 5, October = 10. Male = 1, Female = 2)

251 Appendix XII cont/

MONTH = 4 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 5 1 0.235803 0.013523 17.4375 0.0000 5 2 0.000708 0.013417 0.0528 1.0000 10 1 0.210660 0.019802 10.6383 0.0000 10 2 0.074039 0.009653 7.6699 0.0000

MONTH = 5 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 5 2 -0.2351 0.01632 -14.41 0.0000 10 1 -0.0251 0.02187 -1.15 0.9794 10 2 -0.1618 0.01339 -12.08 0.0000

MONTH = 5 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 10 1 0.20995 0.02180 9.629 0.0000 10 2 0.07333 0.01329 5.520 0.0000

MONTH = 10 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 10 2 -0.1366 0.01971 -6.930 0.0000

Box 20 (ii): Tukey’s pairwise test results for log carapace length/wet weight ratio: Morfa Nefyn February to May plus October 2009 (February = 2, March = 3, April = 4, May = 5, October = 10. Male = 1, Female = 2)

252 Appendix XIIIi: ANOVA of the number of teeth on the rostrum and Tukeys post hoc test results

Table XXX: ANOVA table for the number of dorsal teeth vs location, month and sex: all locations, February and March 2009. ANOVA TABLE FOR THE NUMBER OF DORSAL TEETH VS LOCATION MONTH & SEX (ALL LOCATIONS FEBRUARY & MARCH) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES LOCATION 9.853732 3 3.28457737 6.73 0.000 MONTH 1.181723 1 1.18172336 2.42 0.120 SEX 2.810142 1 2.81014156 5.76 0.017 LOCATION*MONTH 0.509933 3 0.16997753 0.35 0.790 LOCATION*SEX 2.822131 3 0.94071048 1.93 0.123 MONTH*SEX 0.17023 1 0.17023036 0.35 0.555 LOCATION*MONTH*SEX 1.860502 3 0.62016737 1.27 0.283 RESIDUAL 487.582031 999 0.4880701 (TOTAL) 502.605469 1014

Table XXXI: ANOVA table for the number of ventral teeth vs location, month and sex: all locations, February and March 2009.

ANOVA TABLE FOR THE NUMBER OF VENTRAL TEETH VS LOCATION MONTH & SEX (ALL LOCATIONS FEBRUARY & MARCH) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES LOCATION 4.966334 3 1.65544474 4.56 0.003 MONTH 0.000708 1 0.00070781 0.00 0.965 SEX 1.362986 1 1.36298621 3.76 0.053 LOCATION*MONTH 0.599385 3 0.19979514 0.55 0.648 LOCATION*SEX 7.754798 3 2.58493257 7.13 0.000 MONTH*SEX 0.469528 1 0.46952799 1.29 0.256 LOCATION*MONTH*SEX 0.784722 3 0.26157412 0.72 0.540 RESIDUAL 362.431641 999 0.36279443 (TOTAL) 375.884766 1014

253 Appendix XIIIi cont/ Tukey’s Simultaneous Tests Response Variable DORSAL TEETH All Pairwise Comparisons among Levels of LOCATION*SEX LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 1 2 0.0917 0.10043 0.913 0.9849 2 1 -0.0349 0.08630 -0.405 0.9999 2 2 0.0653 0.07886 0.828 0.9916 3 1 -0.1243 0.09420 -1.319 0.8919 3 2 -0.3012 0.11953 -2.520 0.1870 4 1 0.0368 0.13307 0.277 1.0000 4 2 0.1373 0.08001 1.716 0.6769

LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 2 1 -0.1267 0.09720 -1.303 0.8981 2 2 -0.0265 0.09016 -0.293 1.0000 3 1 -0.2160 0.10081 -2.143 0.3873 3 2 -0.3929 0.12645 -3.107 0.0398 4 1 -0.0549 0.13904 -0.395 0.9999 4 2 0.0455 0.08868 0.513 0.9996

LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 2 2 0.1002 0.07340 1.365 0.8731 3 1 -0.0893 0.09128 -0.979 0.9775 3 2 -0.2663 0.11642 -2.287 0.3007 4 1 0.0717 0.13043 0.550 0.9994 4 2 0.1722 0.07601 2.265 0.3129

LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 3 1 -0.1895 0.08342 -2.272 0.3090 3 2 -0.3665 0.11086 -3.306 0.0213 4 1 -0.0285 0.12540 -0.227 1.0000 4 2 0.0720 0.06671 1.079 0.9612

LOCATION = 3 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 3 2 -0.1769 0.12121 -1.460 0.8289 4 1 0.1611 0.13410 1.201 0.9319 4 2 0.2615 0.08013 3.264 0.0244 LOCATION = 3 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 4 1 0.3380 0.1538 2.197 0.3533 4 2 0.4384 0.1109 3.955 0.0020 LOCATION = 4 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 4 2 0.1005 0.1250 0.8037 0.9930

Box 21: Tukey’s pairwise test results for dorsal teeth: all locations, February and March 2009(Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 2, March = 3. Male = 1, Female = 2)

254 Appendix XIIIi cont/

Tukey’s Simultaneous Tests Response Variable VENTRAL TEETH All Pairwise Comparisons among Levels of LOCATION*SEX LOCATION = 1 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 1 2 0.2641 0.08577 3.079 0.0433 2 1 0.0907 0.07415 1.223 0.9253 2 2 0.0899 0.06789 1.325 0.8896 3 1 0.0377 0.07908 0.477 0.9998 3 2 -0.2775 0.10286 -2.698 0.1230 4 1 0.0419 0.11440 0.366 1.0000 4 2 0.1815 0.06779 2.677 0.1295 LOCATION = 1 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 2 1 -0.1734 0.08208 -2.113 0.4064 2 2 -0.1742 0.07647 -2.278 0.3058 3 1 -0.2264 0.08656 -2.616 0.1502 3 2 -0.5417 0.10871 -4.982 0.0000 4 1 -0.2222 0.11969 -1.857 0.5810 4 2 -0.0826 0.07638 -1.082 0.9607 LOCATION = 2 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 2 2 -0.0008 0.06316 -0.012 1.0000 3 1 -0.0530 0.07506 -0.706 0.9969 3 2 -0.3682 0.09980 -3.690 0.0055 4 1 -0.0488 0.11166 -0.437 0.9999 4 2 0.0908 0.06305 1.440 0.8386 LOCATION = 2 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 3 1 -0.0522 0.06888 -0.758 0.9951 3 2 -0.3675 0.09524 -3.859 0.0029 4 1 -0.0480 0.10760 -0.447 0.9998 4 2 0.0916 0.05555 1.648 0.7207 LOCATION = 3 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 3 2 -0.3153 0.10352 -3.046 0.0479 4 1 0.0042 0.11499 0.036 1.0000 4 2 0.1438 0.06878 2.090 0.4211 LOCATION = 3 SEX = 2 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 4 1 0.3194 0.13247 2.411 0.2356 4 2 0.4590 0.09517 4.823 0.0000 LOCATION = 4 SEX = 1 subtracted from: Difference SE of Adjusted LOCATION SEX of Means Difference T-Value P-Value 4 2 0.1396 0.1075 1.298 0.8999 Box 22: Tukey’s pairwise test results for ventral teeth: all locations, February and March 2009(Newquay = 1, Aberystwyth = 2, Morfa Nefyn = 3, Amlwch = 4. February = 2, March = 3. Male = 1, Female = 2)

255 Appendix XIIIi cont/

Table XXXII: ANOVA table for number of dorsal teeth vs month and sex: Newquay, December 2008 to March 2009 ANOVA TABLE FOR THE NUMBER OF DORSAL TEETH (NEWQUAY) VS MONTH & SEX

SUM OF DEGREES OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 1.022811 3 0.34093711 0.89 0.447 SEX 0.770231 1 0.77023149 2.01 0.157 MONTH*SEX 1.463127 3 0.48770896 1.27 0.284 RESIDUAL 129.126953 337 0.38316604 (TOTAL) 132.886719 344

Table XXXIII: ANOVA table for number of ventral teeth vs month and sex: Newquay, December 2008 to March 2009 ANOVA TABLE FOR THE NUMBER OF VENTRAL TEETH (NEWQUAY) VS MONTH & SEX

SUM OF DEGREES OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MONTH 0.506582 3 0.16886084 0.49 0.687 SEX 3.843082 1 3.84308219 11.24 0.001 MONTH*SEX 1.536923 3 0.51230782 1.50 0.215 RESIDUAL 115.214844 337 0.34188381 (TOTAL) 121.466797 344

256 Appendix XIIIi cont/

Tukey’s Simultaneous Tests Response Variable VENTRAL TEETH All Pairwise Comparisons among Levels of MONTH*SEX MONTH = 1 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 1 2 0.3094 0.1274 2.4291 0.2271 2 1 0.1839 0.1675 1.0977 0.9575 2 2 0.1422 0.1821 0.7812 0.9941 3 1 0.1284 0.1755 0.7316 0.9961 3 2 0.3657 0.1488 2.4574 0.2140 4 1 0.1772 0.1233 1.4372 0.8400 4 2 0.4780 0.1360 3.5152 0.0104 MONTH = 1 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 1 -0.1255 0.14395 -0.872 0.9885 2 2 -0.1672 0.16065 -1.041 0.9682 3 1 -0.1811 0.15308 -1.183 0.9370 3 2 0.0563 0.12166 0.463 0.9998 4 1 -0.1322 0.08865 -1.491 0.8124 4 2 0.1686 0.10556 1.597 0.7524 MONTH = 2 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 2 2 -0.04167 0.1940 -0.2147 1.0000 3 1 -0.05556 0.1878 -0.2958 1.0000 3 2 0.18182 0.1632 1.1140 0.9540 4 1 -0.00667 0.1404 -0.0475 1.0000 4 2 0.29412 0.1516 1.9400 0.5231 MONTH = 2 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 1 -0.01389 0.2009 -0.06913 1.0000 3 2 0.22348 0.1781 1.25466 0.9152 4 1 0.03500 0.1574 0.22231 1.0000 4 2 0.33578 0.1675 2.00414 0.4789 MONTH = 3 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 3 2 0.23737 0.1713 1.3855 0.8642 4 1 0.04889 0.1497 0.3266 1.0000 4 2 0.34967 0.1603 2.1813 0.3630 MONTH = 3 SEX = 2 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 1 -0.1885 0.1174 -1.606 0.7471 4 2 0.1123 0.1306 0.860 0.9894 MONTH = 4 SEX = 1 subtracted from: Difference SE of Adjusted MONTH SEX of Means Difference T-Value P-Value 4 2 0.3008 0.1006 2.990 0.0564 Box 23: Tukey’s pairwise test results for ventral teeth: Newquay, December 2008 to March 2009 (December = 1, January = 2, February = 3, March = 4. Male = 1, Female = 2)

257 Appendix XIIIii: ANCOVA of the number of rostral teeth and carapace length vs location

Table XXXIV: ANCOVA table for the number of female dorsal teeth and carapace length vs location

ANCOVA TABLE FOR NUMBER OF FEMALE DORSAL TEETH & CARAPACE LENGTH VS LOCATION SS df MS F p(same) Adj. means 6.3915 3 2.1305 4.256 0.005476 Adj. error 297.86 595 0.50061 Adj. total 304.25 598 Homogeneity of slopes F: 1.286 P(equal): 0.2783

Table XXXV: Supplementary results from ANCOVA of number of female dorsal teeth and carapace length vs location

LOCATION Mean Adj. mean Slope N NEWQUAY 7.13 7.13-0.01964 84 ABERYSTWYTH 7.13 7.13 0.060811 233 MORFA NEFYN 6.75 6.77 -0.01407 48

AMLWCH 7.17 7.17-0.00077 235

Table XXXVI: ANCOVA table for the number of male dorsal teeth and carapace length vs location

ANCOVA TABLE FOR NUMBER OF MALE DORSAL TEETH & CARAPACE LENGTH VS LOCATION SS df MS F p(same) Adj. means 1.6454 3 0.54846 1.171 0.3204 Adj. error 192 410 0.46829 Adj. total 193.65 413 Homogeneity of slopes F: 0.952 p(equal): 0.4154

Table XXXVII: Supplementary results from ANCOVA of number of male dorsal teeth and carapace length vs location

LOCATION Mean Adj. mean Slope N NEWQUAY 7.06 7.050.092993 118 ABERYSTWYTH 7.03 7.04 0.01464 148 MORFA NEFYN 6.90 6.91 -0.02654 113 AMLWCH 7.08 7.07-0.07961 36

258 Appendix XIIIii cont/

Table XXXVIII: ANCOVA table for the number of female ventral teeth and carapace length vs location

ANCOVA TABLE FOR NUMBER OF FEMALE VENTRAL TEETH & CARAPACE LENGTH VS LOCATION SS df MS F p(same) Adj. means 10.42 3 3.4734 9.281 5.26E-06 Adj. error 222.68 595 0.37426 Adj. total 233.1 598 Homogeneity of slopes F: 0.8056 p(equal): 0.491

Table XXXIX: Supplementary results from ANCOVA of number of female ventral teeth and carapace length vs location

LOCATION Mean Adj. mean Slope N NEWQUAY 4.92 4.920.032062 84 ABERYSTWYTH 4.74 4.74 -0.02292 233 MORFA NEFYN 4.38 4.37 -0.04305 48 AMLWCH 4.83 4.830.011356 235

259 Appendix XIV: Egg number and egg volume

Table XL: Results of error check of egg counts

Sample Actual Count Estimate% Error M163 2530 26565.0 M187 1963 1928-1.8 M208 3352 33800.8 A17 2266 23162.2 A18 2957 30603.5 Sum/mean 13068 13340 2.1

Table XLI: ANCOVA table for egg number and carapace length vs location

ANCOVA TABLE FOR EGG NUMBER & CARAPACE LENGTH VS LOCATION SS df MS F p(same) Adj. means 5.96E+06 3 1.99E+06 4.703 0.00476 Adj. error 2.96E+07 70 4.23E+05 Adj. total 3.56E+07 73 Homogeneity of slopes F: 0.9114 p(equal): 0.4403

Table XLII: Supplementary results from ANCOVA of egg number and carapace length vs location

LOCATION Mean Adj. mean Slope N SE t 95%CI NEWQUAY 2741.5 2711.3243.86 22 138.6116 2.079614 288.2586 ABERYSTWYTH 3441.3 3455.0 476.42 20 145.3771 2.093024 304.2778 MORFA NEFYN 3025.8 3092.1 358.99 9 216.7154 2.306004 499.7466 AMLWCH 3180.7 3172.2459.92 24 132.7105 2.068658 274.5326

260 Appendix XIV cont/

Analysis of Variance for log EGG VOLUME, using Sequential SS for Tests

Source DF Seq SS Adj SS Seq MS F P LOCATION 3 0.049867 0.049867 0.016622 4.27 0.009 Error 52 0.202505 0.202505 0.003894 Total 55 0.252373

Box 24: ANOVA table for log egg volume vs location

Tukey’s Simultaneous Tests Response Variable log EGG VOLUME All Pairwise Comparisons among Levels of LOCATION LOCATION = 1 subtracted from: Difference SE of Adjusted LOCATION of Means Difference T-Value P-Value 2 0.06193 0.02475 2.502 0.0723 3 -0.03868 0.02911 -1.328 0.5497 4 0.01729 0.02857 0.605 0.9300

LOCATION = 2 subtracted from: Difference SE of Adjusted LOCATION of Means Difference T-Value P-Value 3 -0.1006 0.03216 -3.129 0.0153 4 -0.0446 0.03166 -1.410 0.4995

LOCATION = 3 subtracted from: Difference SE of Adjusted LOCATION of Means Difference T-Value P-Value 4 0.05596 0.03518 1.591 0.3935

Box 25: Results of Tukey’s pairwise post hoc test of location log egg volume means (1 = Newquay, 2 = Aberystwyth, 3 = Morfa Nefyn, 4 = Amlwch)

261 Appendix XV: ANOVAS of the number of prawns and carapace width vs pot mesh size, and Tukeys post hoc test results

Table XLIII: ANOVA table for the number of prawns captured/pot vs mesh size and the split between saleable and non-saleable portions of the catch

ANOVA TABLE FOR NUMBER OF PRAWNS CAPTURED VS MESH SIZE & SPLIT (between saleable and non-saleable portions of the catch) DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MESH SIZE 187.0416 1 187.0416 4.64 0.034 SPLIT 6 1 6 0.15 0.701 MESH*SPLIT 541.5 1 541.5 13.43 0.000 RESIDUAL 3710.084 92 40.327 (TOTAL) 4444.625 95

Tukey’s Simultaneous Tests Response Variable NUMBER/POT All Pairwise Comparisons among Levels of MESH SIZE*SPLITMESH SIZE = 1 SPLIT = 1 subtracted from: MESH Difference SE of Adjusted SIZE SPLIT of Means Difference T-Value P-Value 1 2 -5.250 1.833 -2.864 0.0262 2 1 -7.542 1.833 -4.114 0.0005 2 2 -3.292 1.833 -1.796 0.2821

MESH SIZE = 1 SPLIT = 2 subtracted from: MESH Difference SE of Adjusted SIZE SPLIT of Means Difference T-Value P-Value 2 1 -2.292 1.833 -1.250 0.5968 2 2 1.958 1.833 1.068 0.7096

MESH SIZE = 2 SPLIT = 1 subtracted from: MESH Difference SE of Adjusted SIZE SPLIT of Means Difference T-Value P-Value 2 2 4.250 1.833 2.318 0.1013

Box 26: Results of Tukey’s pairwise post hoc test of mean number of prawns/pot vs mesh size and the split between saleable and non-saleable portions of the catch (9mm mesh =1, 14mm mesh =2, <10mm carapace width =1, ≥10mm carapace width =2)

262 Appendix XV cont/

Table XLIV: ANOVA table for carapace width vs mesh size and the split between saleable and non-saleable portions of the catch

ANOVA TABLE FOR CARAPACE WIDTH VS MESH SIZE & SPLIT DEGREES SUM OF OF MEAN F-STAT P-VALUE SQUARES FREEDOM SQUARES MESH SIZE 185.4354 1 185.4354 172.31 0.000 SPLIT 1964.239 1 1964.239 1825.22 0.000 MESH*SPLIT 133.5611 1 133.5611 124.11 0.000 RESIDUAL 944.875 878 1.076167 (TOTAL) 2917.359 881

Tukey Simultaneous Tests Response Variable CARAPACE WIDTH All Pairwise Comparisons among Levels of MESH SIZE*SPLIT MESH SIZE = 1 SPLIT = 1 subtracted from: MESH Difference SE of Adjusted SIZE SPLIT of Means Difference T-Value P-Value 1 2 3.0480 0.09502 32.077 0.0000 2 1 0.2904 0.10634 2.731 0.0321 2 2 3.0929 0.08898 34.762 0.0000

MESH SIZE = 1 SPLIT = 2 subtracted from: MESH Difference SE of Adjusted SIZE SPLIT of Means Difference T-Value P-Value 2 1 -2.758 0.1164 -23.69 0.0000 2 2 0.045 0.1008 0.45 0.9705

MESH SIZE = 2 SPLIT = 1 subtracted from: MESH Difference SE of Adjusted SIZE SPLIT of Means Difference T-Value P-Value 2 2 2.803 0.1115 25.13 0.0000

Box 27: Results of Tukey’s pairwise post hoc test of mean carapace width of prawns/pot vs mesh size and the split between saleable and non-saleable portions of the catch (9mm mesh =1, 14mm mesh =2, <10mm carapace width =1, ≥10mm carapace width =2).

263