lssN 0113-2504 New Zealand Freshwater Fisheries Report No.94 Fisheries investigations of the Ashers - Waituna, Benhãr, and Hawkdun lignite deposit areas Y:iäffina{i¡i't¡t:'f¡:ffi i r.!,!.rr..^.rri¡r.r¡.r ì¡ ¡.r ''r',;:fflli MAFFish New Zealand freshwater fisheries report no. 94 (1988) New Zealand Freshwater F'isheries Report No. 94 Fisheries investigations of the Ashers-l.laìtuna, Benhar, and Hawkdun 'l'ignì te deposì t areas Report to: Liqu'id Fuels Trust Board Freshwater Fisheries Centre MAFFi sh Chrì stchurch New Zealand freshwater fisheries report no. 94 (1988) NEI,J ZEALAND FRESHI,IATER FISHERIES RTPORTS Thìs report is one of a series'issued by the Freshwater Fjsheries Cäni..,'t'tnf f i sft, on j ssues rel ated to New Zeal and ' s freshwater iiirr.rÍ.r. Théy are i ssued under the fol ì owì ng crìteri a: (1) They are for limited circulation, s9--that persons and o.õánltãtions normaì'lv receivins.MAFFi :h qf!]lçations ifróul d not expect to iecei ve copi es automat i caì I y. (Ð copies will be jssued free only to organisatjons to which the rePort 'is directlY reì evant' (3) copies wi'l'l Þe i ssued to other organi sations on request. A schedule of charges js included at the back of each report. Prices iñclude GST, packagìng, and postage.' (4)Organ.isationsmayapPlytothelibrariantobeputonthe raíl i ng-i i it to iecäì vä al ì reports as thev are publ i shed' An invõjce will be sent with each new pub'ljcation. rsBN 0-477-08063-4 MAFFish 'is the f isheries business group of .the New lealan¿ Minìstry of Ag¡iculture and F1sheries. It was ãiiuolished on i ApriÍ tgAZ and comb'ines the functions ãi if,. old Fìsheriäs Research Division and Fisheries úunãgã.ãnt Division, and the fisheries functions of the ol d Economics D'ivision. The New Zealand Freshwater Fjsheries Report series .ôñtiñr.i the F'ishe¡ies Environmental Report se¡ies. Enquiries to: The Li brari an Freshwater Fi sheries Centre P0 Box 8324 Chri stchurch Ner,¡ Zeal and. New Zealand freshwater fisheries report no. 94 (1988) CONTENTS Page Summary I4 1. Introducti on 15 1.1 Background 15 I.2 Study Areas 16 1.3 0bjectì ves 16 2. Hab'itat Descripti on 2L 2.1. Ashers-!,la'ituna 2L 2.I.I StudY Area 21, 2.1.2 Aquati c Habi tats 23 2.1..2.I Smal I Streams 23 2.I.2.2 Waì tuna Lagoon 26 2.t.2.3 Lower Mataura Ri ver 28 2.J-2.4 Bog Ponds 29 2.2 Benhar 29 2.2.I Study Area 29 2.2.2 Aquatic Hab'itats 32 2.2.2.1 Smal I Streams 33 2.2.2.2 Lake Tuak'itoto 35 2.2.2.3 Lower Clutha River 37 2.3 Hawkdun 38 2.3.I Study Area 38 2.3.2 Aquatìc Habjtats 42 2.3.2.L UPPer Manuherikì a River Mai nstem 42 2.3.2.2 Trì butarY Streams 43 2.3.2.3 Falls Dam Reservoìr 48 2.3.2.4 Lower Manuheri k'ia Ri ver Mai nstem 48 3. Sampl i ng Methods 49 3.1 Electric Fish'ing 49 3.1.1 Ashers-LJaituna 49 3,I.2 Benhar 49 3.1.3 Hawkdun 50 New Zealand freshwater fisheries report no. 94 (1988) Page 3.2 Netting 52 3.2.I Seì ne Nettì ng 52 3 .2.2 FYk e Nett ì n g 53 3. 3 TraPP'i ng 53 3.4 Benthic Invertebrates 54 3.4.1 Surber SamPl i ng 54 3.4.2 Dredge SamPl i ng 55 3.5 Aquati c Pl ants 55 3.6 ZooPl ankton 55 3.7 SPawnìng SurveYs 55 3.8 Creel SurveYs 56 3.9 Expert Interviews 56 4. Fi sh Stocks 57 4.I Ashers-Wa'ituna 57 4.1.1 Background 57 j 4.I.2 Speci es Compos ì ti on , Dì stri but on , L'if e 58 Hi stori es, and Habj tat Requi rements 4.I.2.t Brown Trout 59 4.7.2.2 Perch 68 4.L.2.3 Long-fi nned Eel 68 4.I.2.4 Short-fi nned Eel 69 4.r.2.5 Lamprey 69 4 .r.2.6 Common Bul ìy 69 4 .1.2.7 Up1 and Buì 1y 7T 4.I.2.8 Red-fj nned Bul lY 7T 4.I.2.9 Gi ant Kokopu 7L 4.r.2.r0 Banded Kokopu 72 4.r .2.rL Inanga 73 4.1.2.12 Common Smelt 74 4.r.2.r3 Bl ack Fl ounder 74 4.L.2.r4 Yel I owbel 1y Fl ounder 75 4.L.2.I5 Sand Flounder 75 4.r.2.16 Cockabul 1y 75 4.r.2.t7 Yellow-eyed Mullet 76 4.r.2.r8 Stargazer 76 4.I.2.I9 Parrotfi sh 76 4.1.2.20 Kah awai 76 76 4 .L2.2I Freshwater CraYfi sh 4.1.3 Spawning 77 4.1.3.1 Native Fish 77 4.L.3.2 Introduced Fish 78 New Zealand freshwater fisheries report no. 94 (1988) Page 4.I.4 Recreational Fisheries 86 4.I .4. L l'la j tuna Lagoon 86 4.L.4.2 Lower Mataura River 89 4.2 Benhar 90 4.2.1 Background 90 4.2.2 Specíes Composition, Distrìbution, Life 92 Histories, and Habitat Requirements 4.2.2.1 Brown Trout 95 4.2.2.2 Perch 95 4.2.2.3 Qui nnat Salmon 96 4.2.2.4 Long-f i nned Eel 96 4.2.2.5 Short-f i nned Eel 97 4.2.2.6 LampreY 98 4.2.2.7 Common Bul ìY 98 j 'lY 4.2.2.8 G ant Bu'l 98 4.2.2.9 G'iant KokoPu 98 4 .2.2. 10 I nanga 99 4.2.2.11 Koaro 99 4.2.2.12 Common Smelt 100 4.2.2.13 Black Flounder 100 4 .2.2. 14 Yel I ow-eYed Mu I I et 101 4.2.2. 15 Kah awa j 101 4.2.2. L6 Freshwater CraYf ì sh 101 4.2.3 Spawn i ng 101 4.2.3.I Natì ve Fi sh 101 4.2.3.2 Introduced Fish I02 4.2.4 Recreational Fisheries t02 4.2.4.I Lower Clutha River 104 4.2.4.2 Lake Tuakitoto 10s 4.2.4.3 Lovells Stream 106 4.2.5 Commercial Fisheries 106 4.2.6 Traditional Fisheries 106 4.3 Hawkdun I07 4.3.1 Background L07 4.3.2 Spec'i es Compos j ti on , Dì stri but'ion , Li f e 109 Histories, and Habitat Requ'irements 4 .3.2.I Brown Trout 109 4.3.2.2 Brook Char 113 4.3.2.3 Common Ri ver Gal ax'i as 116 4.3.2.4 Upl and Buì 1Y 116 4.3. 3 Spawn ì ng lr7 4.3.3.1 Native Fish II7 4.3.3.2 Introduced F'ish tI7 New Zealand freshwater fisheries report no. 94 (1988) Page 4.3.4 Recreatìonal Fisheries 119 4.3.4.1 Manuherikia River below Fal I s Dam 120 4 .3.4.2 F a1l s Dam Reservo'i r 1.2r 4.3.4.3 Manuherikia River above Fal I s Dam r22 Reservoi r 5. Benthic Invertebrates and Zooplankton L25 5. 1 Ecoì og'i ca1 Importance of Benthos 125 5.2 Ashers-t,Jaituna 126 5.2.L I,'lai tuna Lagoon L26 5.2.2 Waituna Streams I29 5.3 Benhar 131 5.3.1 Lake Tuakitoto 13i 5.3.2 TributarY Streams 134 5.4 Hawkdun 134 5.4.1 Fal I s Dam Reservo'ir L37 5.4.2 TributarY Streams 138 5.5 Zoopì ankton 140 5.5.1 Ecol og'ical ImPortance 140 5.5.2 Sampl i ng Resul ts 141 5.6 Surmary 143 6. Aquatic Plants and Margìnaì Vegetation 143 6.1 Eco'logi cal Importance 143 6.1.1 Aquatic Plants 143 6.I.2 Marg'i nal Vegetati on I44 6.2 Ashers-Waituna 144 6.3 Benhar 148 6.4 Hawkdun I49 7. Relative Importance of Study Areas 151 7.L Existjng Habitat and Fìshery Features 151 7 .L,L Ashers-Wa'ituna 151 New Zealand freshwater fisheries report no. 94 (1988) Page 7.I.2 Benhar 154 7.1.3 Hawkdun 155 7.2 Relative Rank'ing of Study Areas 156 7 .2.1 Cri teri a 156 7.2.2 Features of Fish Stocks 156 7 .2.2.I Di vers i tY 156 7.2.2.2 Rarity (natìve) 158 7.2.2.3 RarìtY ('introduced) 160 7.2.3 Ecosystem TYPe 160 7.2.3.t Lakes, Estuarìes, and Reservojrs 160 7.2.3.2 Streams 161 7 .2.3 .3 R'i vers 161 7 .2.4 Val ue of Habi tat to F'ish 161 7.2.4.L SPawning r62 7 .2.4.2 Reari ng I62 7.2.4.3 Adult Habitat 163 7 .2.4.4 M'igrat'ion I64 7 .2.5 Fi shery Val ue 164 7 .2.5.L Recreat'ional 164 7 .2.5.2 Commerci al 165 7.2.5.3 Traditional 165 7.3 Biological/Scientific Conservation Values 166 7 .4 Overal I B'iologi cal Ranki ng of Study Areas I67 8.