Fisheries Research Bulletin No. 19 î6 The Life History of Neochanna apoda Günther (Pisces: Galaxiidae) by G. A. Eldon Fisheries Research Division New Zealand Ministry of Agriculture and Fisheries The Life History of Neochanna apoda Günther (Pisces: Galaxiidae) Frontispiece: Natu¡al habitat of the broul nudfish, Fisheries Research Bulletin Nt¡. tg The Life History of l,{eochanno apoda Günther (Pisces: Galaxiidae) by c. A. Bldon Fisheries Research Division, Ministry of Agriculture and Fisheries, Christchurch, New Zealand Fisheries Research Division New Zealand Ministry of Agriculture and Fisheries t978 Published by the New Zealand Ministry of Agriculture and Fisheries Wcllington 1978 ISSN 0110-1749 FOREWORD MANY of New Zealand's native freshwater fishes are small and inconspicuous and until recently little was known of their detailed distribution, biology, and behaviour. In recent years our knowledge of thern has steadily increased as a result of the work and interest of various memtrers of staff of Fisheries Research Division. Tony Eldon has ably contributed to our understanding of the biology arid envirohmental requirements of the brown mudfish. This species, though still common, is seldom seen because it inhabits swamps and drainage ditches in rvhich it can survive, even during dry seasons, provided it can hide in a damp atmosphere in holes or under forest debris. One point to stress is that species such as this, which are seldom seen and little known, can easily be eliminated from an area by thoughtless environ- mental changes such as swamp reclamation. G. DUNCAN WAUGH, Director, Fisheries Research Division DESCRIPTION OF THE STUDY AREAS .. GENERAL BEHAVIOUR 34 4r ACKNO\,VLEDGMEN'TS 4T IN ^''HÈ-C*-OWTHAPPENDIX: SOMB COMMEF'I-TS ON THE O-UANTITATIVE I\'{ETHODS LISED STUDTES I. 11. West 42 FIGURNS Page 1. Adult -^f, aþoda .. 1l , wairarapa, with locations of the study ar€as, and lower lrinau Valle¡ showing places where N, øþoda was found r2 t4 Hinau 18 4. where the ditch breaks down into an area of wet turf 15 5. Forest 24, showing boundary between forest and pasture l5 6. Forest 28, showiug shallower area ofwinte¡ pondage l6 7. Dalefield 3D, the hard-bottomed watercourse which regul¿.rly dries up . I6 B. Hyaline zones in otoliths 1B 9. Holes under trees where aþoda aestivates "iìy', and breeds 2l Tank used [0. in some aestivation experiments 22 I l. Loss ofweight ancl length during aestivation and subsequent recovery ancl growth of fish kept rn captrvrty .: :. 2g 12. Fecundity of stage 3 females 24 13. Proportions ofadult fish at various stages ofmaturity at different times ofthe year 24 14. Tins used to determine the location of spawning of N. aþoda 24 15. Growth Forest of fry during first few weeks of liê and continued recruitment over 2 months 25 16. Months during which newly hatched fry have been found in the study areas 26 17, The pool in which N. aþoda eggs were found ar Dalefield 26 lB. Juvenile development of N. aþoda .. 2g l9A. Growth curve of Forest fish and calculated growth curve of marked Hinau fish 30 l9B. Month of capture and age in years plotted again5t total length 30 20, Monthly grÕwth plotted against length fì¡om marked fish dara g2 21. Length-frequency distriþutions oftwo samples offish from Forest 2A g2 22. Trough used in experiment to demonstrate overland movement gz 23, Food items found in fry and adults from the three study areas g6 24. Food items eaten at Fo¡est 2A immediately after the breaking of the drought g7 TABLES 3. Shrinkage,weightloss,andlossofcondition'tnN,aþodaduringlaboratoryaestivation 4. Condition factors of fish at various reprqductive stages and pelrentãge of weight contributed by ovaries and testes . ' 22 5. Marked ñsh retu¡¡rs from Hinau 29 Number of fish recorded in different age groups fì'om otolith readings 32 Food composition in Hinau fish other than immediately after aestivation 34 Food composition in Forest fish other than immediateþ afær aestivation 35 Food composition iri Dalefreld fish J5 Food composition in Harihari fish 35 INTRODUCTION The brown mudfish (Neochanna aþoCa) is one of three Ranges and is largely drained by one main river species of Neochanna (Galaxiidae), all of which are system-the Ruamahanga (Fig. 2) . indigenous to New Zealand. Each species has its own Much of the Wairarapa was swampy, but the distinct range of distribution, that of N. aþoda being swamps have been drained after the felling of the the greatest (Skrzynski 1968). Neochanna aþoda was forest. This swamp drainage has hacl an unknown first described in 1867 by Günthel from a single fish effect on the distribution and abundance of N. aþoda, found at Kaniere, near Hokitika on the west coast of but judging frorn the number of small remnant the South Island, and sent to him by Sir James habitats in isolated places, and from the large numbers Hector at the request of Sir George Grey. Since then of individuals within some of these habitats, the N. apoda has been recorded from much of the west extent and overall numbers of the fish in the Wairarapa coast north of the Whataroa Rìver in the South may once have been large. It seems likely that their Island and from Wellington, Wairarapa, Manawatu, potential habitat in the Wairarapa was spread over and, rarely, Taranaki in the North Island. aÍr area exceeding 2000 km 2. carried Neochanna aþoda does not usually exceed 150 mm in This study was mostly a spare-time pursuit length, but occasional specimens of about 200 mm are out from 1969 to 1973 and directed at learning some- recorded (Phillipps 1923; present study see Table 6). thing of the life history and ecology of N. aþoda. It was The fish has a brown, cylindrical, cigar-shaped body followed as opportunity permitted. Few data were the (Fig. l). It has no pelvic fins and the dorsal and anal collected at regular intervals and much of fins are fleshy. It has adapted to swamp habitats information is lragmentary. The study began unsuitable for other species offish except short-finned spontaneously with the bogging of a vehicle in a eels (Anguilla australis Richardson) (Eldon l968). The ditch close to a field station being used on another adult mudfish is nocturnal and secretive in its habits project. Mudfish were found when the vehicle was and therefore is difficult to observe. being dug out. The habitats in this area were frequently disrupted or even destroyed by lärm The populations used for this study were located improvement and ditch-clearing operations, and so in the Wairarapa, a once heavily forested region, a further study area in a remnant patch of forest was which lies to the east of the Rimutaka and Tararoa used to try to complete the work. Fig. 1: Adult N. aþoda (R. M. McDowall). DESCRIPTION OF THE STUDY AREAS There were three study areas within a few kilo- AREÄ I- metres of each other (Fig. 2), and each included a This area. referred to as FIinau, is part of the lower number of different habitat types. Two areas were Hinau Valley (Fig. 2). The valley is formed by one used extensively, the third being used mainly for main semi-permanent stream, but is criss-crossed by a comparison of feeding habits. network of drains, ditches, and natural watercourses, ll Hinau Valley, -.fÌo*itrg-iù-"Fig. 2: Map of the Wairarapa, with the locations.of .the thlee study.a.reas malked b.y crosses. Jnset: Lower ptu..r *fré"" ;iI ipoii *Ã found. A: An imperrnanent rápid stream in a pine plantation. B: A ditch alongside the road (Ëie. 3)] C: e very short'ditch which connects subterranean pipès to a rapicl w'atercourse confined to a regime channel' D: Site rih"i. firh we.e þresent before the watercourse was piped and filled in (see pages 2l and39)' T2 some of which are now confined to subterranean from the others by a stock water race which bisects drainage pipes. Many of these watercourses have a the reserve. This population was used only for the permanent flow of water, but those fèatured in Fig. 2, collection of a few aestivating fish. with the exception of the Hinaki Stream, normally dry up from late January or early February to late AII the Forest waters begin to dry up in summer. April. The original forest cover has gone and, with the The period of total drought (no surface water at exception of habitat A, which is a stream runriing all) is usually from mid February to mid April, through an exotic pine (Pinus radiata) plantation, the but the effective drought (insuficient water to watercourses are open. They run through fields or allow free movement of adult mudfish) is longer alongside roads, but with one or both sicles protected and may extend from late January to late April. by banks I m or more high. Habitat A is a shallow tror.rgh up to 0.5 m deep, Habitat A, "Cretney's Creek", is a stony-bcclded r,r,ith a low wet area around it which extends front impermanent creek less than I m wide which falls the trees into an open pasture and which gradually down a hillside at the rate of 6.7 m per 100 m of narrows down to an artificially confined clrainage stream course. It contains pools of up to 0.4m2 in channel. The demarcation between the wet area area and 0.2 m in depth formed by pine tree roots and (about 450-500 m 2) among the trees and the boggy fallen branches, where mud and pine needles collect part (350-400 m2) of the pasture is abrupt (fìig.