The reproductive biology of the surf clams Triangle Shell (Spisula aequilatera), Ringed dosinia (Dosinia anus) and Deep water Tuatua (Paphies donacina) from the North- East of South Island, New Zealand Nuha Al jadani A thesis submitted to Auckland University of Technology In partial fulfilment of the requirement for the degree of Master of Science (MSc) 2013 School of Applied Science Table of Content List of figures …………………………………………………………………………..…..………..iv List of tables………………………………………………………………………...….……...….…..v Attestation of authorship……………………………………………………………....………....….vii Acknowledgement…………………………………………………………………….………....….viii Abstract………………………………………………………………………………....….…...……ix 1 Introduction .................................................................................................................................. 1 1.1 Background/significance of the problem ............................................................................... 1 1.2 Aim and objectives ................................................................................................................ 3 1.3 Scope and limitation .............................................................................................................. 4 1.4 Organization of the thesis ...................................................................................................... 4 2 Literature review .......................................................................................................................... 6 2.1 Biological characteristics of surf clams ................................................................................. 6 2.2 Life history ............................................................................................................................ 7 2.2.1 Reproductive cycle of surf clams ................................................................................... 8 2.3 Development of surf clams .................................................................................................. 10 2.4 Distribution of surf clams throughout the world ................................................................. 13 2.5 Commercial fishery of surf clams ....................................................................................... 14 2.6 Surf clams in NZ.................................................................................................................. 15 2.6.1 Distribution of surf clams in NZ .................................................................................. 15 2.6.2 Growth rates of surf clams in NZ and influencing factors ........................................... 19 2.7 Harvesting of surf clams in NZ ........................................................................................... 21 2.7.1 Management of surf clams in NZ ................................................................................. 22 2.7.2 Significance of gametogenesis and gonadal development researches ......................... 24 2.8 Conclusion ........................................................................................................................... 26 Triangle shell (Spisula aequilatera) ................................................................................................... 27 3 Triangle shell (Spisula aequilatera) ........................................................................................... 28 i 3.1 Introduction ......................................................................................................................... 28 3.2 Materials and methods ......................................................................................................... 29 3.2.1 Study sites .................................................................................................................... 29 3.2.2 Sampling method .......................................................................................................... 30 3.2.3 Environmental parameters used ................................................................................... 30 3.2.4 Size and growth ............................................................................................................ 30 3.2.5 Techniques to investigate the reproductive biology ..................................................... 31 3.2.6 Statistics ....................................................................................................................... 36 3.3 Data, results and interpretations .......................................................................................... 37 3.3.1 Environmental parameters ............................................................................................ 37 3.3.2 Size and growth ............................................................................................................ 38 3.3.3 Sex ratio ........................................................................................................................ 44 3.3.4 Sexual cycle .................................................................................................................. 47 3.3.5 Condition index for Spisula aequailatera in Cloudy Bay ............................................ 60 3.4 Discussion ............................................................................................................................ 64 Ringed dosinia (Dosinia anus) ........................................................................................................... 75 4 Ringed dosinia (Dosinia anus) ................................................................................................... 76 4.1 Introduction ......................................................................................................................... 76 4.2 Materials and methods ......................................................................................................... 77 4.3 Data, results and interpretations .......................................................................................... 77 4.3.1 Environmental parameters ............................................................................................ 77 4.3.2 Size and growth ............................................................................................................ 77 4.3.3 Sex ratio ........................................................................................................................ 83 4.3.4 Sexual cycle .................................................................................................................. 85 4.3.5 Condition index for Dosinia anus in Cloudy Bay ........................................................ 99 4.4 Discussion .......................................................................................................................... 102 Deep water Tuatua (Paphies donacina) ........................................................................................... 108 ii 5 Deep water Tuatua (Paphies donacina) ................................................................................... 109 5.1 Introduction ....................................................................................................................... 109 5.2 Materials and methods ....................................................................................................... 110 5.3 Data, results and interpretations ........................................................................................ 110 5.3.1 Environmental parameters .......................................................................................... 111 5.3.2 Size and growth .......................................................................................................... 111 5.3.3 Sex ratio ...................................................................................................................... 116 5.3.4 Sexual cycle ................................................................................................................ 118 5.3.5 Condition index for Paphies donacina in Cloudy Bay .............................................. 131 5.4 Discussion .......................................................................................................................... 135 6 Conclusion ................................................................................................................................ 142 References iii List of figures Figure 1-1: 16 sites where biomasses of surf clams are estimated for 450 m wide strips (Cranfield & Michael, 2001b) ................................................................................................................................... 18 Figure 3-1: male and female reproductive cycle .................................................................................. 35 Figure 3-2: Directions of length and width measured .......................................................................... 37 Figure 3-3 :Length versus width: Spisula aequailatera ....................................................................... 40 Figure 3-4 :Length versus total weight: Spisula aequailatera ............................................................. 41 Figure 3-5 :Length versus shell weight: Spisula aequailatera ............................................................. 41 Figure 3-6 :Length versus flesh weight: Spisula aequailatera ............................................................ 42 Figure 3-7 : presence of hermaphrodite: Spisula