Fisheries Research Bulletin No. 23

Fish Eggr and Larvae of the ,

by J. Crossland

Fisheries Research Division I.[ew Zealand Ministry of Agriculrure and Fisheries Fish Eggr and Larvae of the Hauraki Gulf, I.{ew Zealand $r'- ¡- -j Fisheries Research Bulletin No. 23

Fish Eggr and Larvae of rhe Hauraki Gulf, New Zealand

by J. Crosslan{

Fisheries Research Division, Ministry of Agriculture and Fisheries, Wellington, New Zealand

Fisheries Research Division It{ew Zea\and Ministry of Agriculture and Fisheries 19Br Published by the New Zealand Ministry of Agriculture and Fisheries Wellington l98r ISSN 0l l0-1749

R¿c¿iu¿d 28 February 1978; reuisíon receiu¿d 4 June 1980 FOREWORI) Jnvrs CRossI-AND has already used the distribution and abundance of the eggs and larvae of snapper to assess the standing stocks of this most valuable species in New Zealand's most important cornmercial fishery. llowever, despite the rapid expansion of fishing effort over the past few years, our knowledge of the available resources, even in the Hauraki Gulf, has remained meagre. The data in this bulletin not only add to our undeistanding of the other species in the Hauraki Gulf, but are an important prerequisite to our appreciation oÍ its significance as a spawning or nursery ground {or fisheries elsewhere. At the same time, this type of information will be of value as a background for integrated management of the total resources of the area in the future. G. DUNcAN Weucn, Director, Fisheries Research Division CONTENTS Pog, INTRODUCTION il

MATERIALAND METHODS 1l Sampling and Sorting 1l Identific¿tion of Eggs and Lawae ll Descriptions of Eggs and Laruae t2 Daø Presentation l2

RESULTS l3 Family Engraulidae 13 Family Clupeidae t4 Family Muraenidae t7 Family Congridae 20 Family Moridae. .. 20 Family Exocoetidae oq Family Trachichthyidae 22 Family Zeidae ... 23 Family Syngnathidae 23 Family Triglidae 23 Family Acanthoclinidae 2+ Famiiy Carangidae 26

Family Sparidae.. . 31 Family Mugilidae 34 Family Labridae 34 Family Uranoscopidae 35 Families Blenniidae, Clinidae, and Tripterygiidae 5t) Family Eleotridae 38 Family Gempylidae 38 Family Scombridae 38 Family +0 Family 4l Family Balistidae 49 Family Diodontidae 5+

DISCUSSION 56 Sampling Period 56

Effect of Temperature on Spawning.. . 56 Effect of Water Movements on Distribution of Larvae . .. 57

SUMMARY 58

REFERENCES 59

ACKNOWLEDGMENTS ... 59 FIGIJRES

Page l. The Hauraki Gulf, showing places mentioned in the text l0

2. Survey stations and study area t2

3. Distribution of anchovy eggs by cruises, 197 4-7 5 and I 975-76 t.t- I 5

4. Numbers of ancÌíovy eggs within the study area, lg74-75 and 1975-76 l5

5. Distribution of anchorry laruae by cruises, I 974-75 and I 975-76 . . . l6

6 Distribution of pilchard eggs,4-8 November 1974 t7

7. Distribution of pilchard larvae by cruises, 1974-75 and 1975-76 ... l8

8. Numbers of pilchard larvae taken by cruises, 197 4-7 5 and I 975-76 t9

9. Cumulative distribution of sprat eggs, 1974-75 and 1975-76 l9

10. Moray eel eggs l9

I I . Cumulative distribution of moray eel eggs, 197 4-7 5 20

12. Morayeellarva ... 20

I 3. Distribution of ahuru eggs by cruises, 197 +-7 5 and I 975-76 21

14. Numbers of ahuru eggs taken by cruises, 1974-75 and 1975-76 22

15. Ahu¡u larvae .. 22

16. Numbers of ahuru larvae taken by cruises, 1974-75 and 1975-76

I 7. Distribution of ahuru lawae by cruises, 1974-75 and 1975-76 23-24

18. Garfish larva 2+

19. Roughylarva 2+

20. Cumulative distribution of red gurnard eggs,197+-75 and 1975-76

21. Numbers of red gurnard eggs within the study area,1974-75 and 1975-76 2s

22. Cumulative distribution of red gurnard law¿e, 197 4-7 5 and I 975-76 25

23. Rockfish larva 26

24. Cumulative distribution of rockfish larvae, 1974-75 and 1975-76... 26

25. Jack mackerel Trachuns noaae4landiae eggs 27

26. Distributionof jackmackerelT.noue¿elandiaøeggsbycruises, 1974-75and 1975-76 ... 28

27. Numbers of jack mackerel T. noaaezelandia¿ eggs within the study area, 1974-75 and 1975-76 29

28. Jack mackerel T. noaa¿zelandia¿lawae 29

29. Distributionof jackmackerelT.nooaez¿lundiaelaruaebycruises, 1974-75 and 1975-76 30

30. Numbers of jack mackerel T. noaaezelandia¿lawae taken by cruises , I97 4-7 5 and I 975-76 3t

3 I Eggs of jack mackerel Trachutas decliuis 3l

32. Cumulative distribution of jack mackerel T. declitis eggs,1974-75 and 1975-76 J1

33. Snapper lawae 32

34. Distribution of snapper larvae by cruises, 197 4-7 5 and 197 5-7 6 .. JJ

35. Numbers of snapper laruae taken by cruises, Ì97,[-75 and 1975-76 5+

36. Yellow-eyed egg 34

37. Cumulative distribution o{ yellow-eyed mullet eggs, 1974-75 anð 1975-76 5f, 35 38. Yellow-eyed mullet larva .. . Page

39. Spotty lawa 35

,10. Spotted stargazer eggs 36

41. Cumulative distribution of spotted stargazer eggs, 197,1-75 and 1975-76 36

42. Spotted stargazer larvae JI

43. Cumulative distribution of spotted stargazer larvae, 197 4-7 5 and I 975-76 ...

.14. Graham's gudgeon larvae

45. Cumulative distribution of Graham's gudgeon laruae,.1974-75 and 1975-76 39

46. Blue mackerel egg 39

47. Numbe¡s of blue mackerel eggs taken by cruises, 1974-75 39

48. Distribution of blue macke¡el eggs by cruises, I97,t-75 and t97 5-76 +0 49. Blue mackerel laruae 4l

50. Numbers of blue mackerel larvae taken by cruises, 1974-75 and 1975-76 +1

51. Distribution of blue macke rel laruae by cruises, 1974-75 and 1975-76 42

52. Crested flounder eggs +3

53. Cumulative distriburion of crested flounder eggs, 1974-75 +3

54. Crested flounder larvae ++

55. Distribution of crested flounder laruae by cruises, lg7+-75 and 1975-76 +5

56. Distribution of pleuronectid eggs by cruises, 197+-75 and 1975-76 +G-47

57. Numbers of pleuronectid eggs taken by cruises, lg7+-75 and 19?5-76 +8

58 Flounder lawa +8

59. Cumulative distribution ol flounder laruae, 1974-75 znd 197:_76... 48

60. Numbers of flounder larvae raken by cruises, 1974-75 and 1975-76 49

6l . Speckled sole larvae 49

62. Cumulative distribution of speckled soìe larvae, lg74-75 and lg75-76 50

63. Numbers of speckled sole laruae taken by cruises, 1974-75 and 1975-76 50

64. Leather jacket eggs 50

65. Numbers o{ leather jacket eggs within the study area, lg74-75 and 1975-76 50

66 Distribution of leather jacket eggs by cruises, 1974-75 and 1975-76 5 r-52

67. Leather jacket larvae 53

68. Cumulative distribution of leatherjacket lawae,1974-75 and 1975-76 )+

69. Unidentified egg I 54

70. Unidentified egg 2 55

71. Unidentified egg 3 55

72. Numbers of eggs of all species taken by cruises, 1974-75 and 197i:-16 57

73. Monthly cumulative wind speed from obseruations at 58 TABLES Page

I . I(nds of eggs and larvae collected in the Hauraki Gulf . .. .

2. Spawning season and remperarures for the principal species in the Hauraki Gulf 56

3. Comparative eggproduction for 1974-75and 1975-76 ... 57

Inset I 175"E 3ó"S

Little

Greot Borrier I

Omoho Boy

Colvílle chonn-l

I .#--th*"wouärr( Cope Colville / 30

Tiririri \Motongi^ I

Rokino ,0 " .',

Firth of

Thomes

Fig. l:The Hauraki Gull, showing places mentioned in the text' INTRODUCTION

The Hauraki Gulf, New Zealand's richest fishing There are few published accounts of ichthyoplank- ground, is a large, relatively shallow embayment with ton surveys from New Zealand. In the Hauraki Gulf many islands and harbours (Fig. l). It is an Cassie (t956a) studied the distribution of snapper important spawning ground for many fish species, eggs, and Colman (1973) studied the spawning of two including snapper (Chrysophrys auratus), which domi- species of flounder. Baker (1972) surveyed pilchard nates the commercial landings. During the spring- eggs and larvae in Tasman Bay, Robertson (ì980) summer periods (October to January) oÍ 1974-75 and recorded the distribution of the eggs of 17 species off 1975-76,2-weekly plankton surveys were carried out the Otago coast, and Colman (1979) studied the with the aim of estimating the stock size of snapper spawning of the sprat around the South Island. based on egg counts (Crossland 1980). These surveys Additional information on the eggs and larvae of were specifically designed for sampling snapper eggs; species mentioned in this bulletin is given in Elder however, many types of fish eggs and larvae were (1966), Robertson and Raj (1971), Baker (1973), collected, identified, and counted. These data are Robertson (1973), Castle and RÒbertson (1974), and presented in this bulletin. James (1976). Robertson's (1975) key describes the planktonic eggs of 56 species of New Zealand fishes.

MATERIAL AND METHODS

SAMPLING AND SORTING and larvae and sorted them according to type. When the sorters were sufficiently experienced to identify the Plankton samples were taken by oblique tows of a different kinds accurately, the common ones were cylinder-cone net at the stations shown in Fig. 2. counted in situ in the samples. Regular checks were Details of the net were: mouth area0.25 m2; cylinder made on the accuracy of identifications and sample 56 cm diameter by 150 cm long; cone slope length counts. Large samples were divided with a Folsom 185 cm; gauze 0.425-mm aperture with a porosity of splitter until a manageable fraction was obtained. In 47"/.. Ttie total filtering area was 2.225 m2 and the samples where eggs were abundant but larvae were filtering'area/mouth area ratio was 8.9, made up of not, eggs were subsampled, and the whole sample was 5.35 in the cylinder a¡rd 3.55 in the cone. The volume sorted for larvae. Details of the dates of sampling, of water sampled (range 50-300 m3) was recorded numbers of stations, ancl sea temperature data and with a digital flow meter, type 2030 by General further information on the sampling technique can be Oceanics, Inc., which was mounted at a distance of a found in Crossland (1980). quarter the diameter from the rim of the net. Tows were made at a boat speed of 2 to 2.5 knots, with the net usually descending to within 2 to 4 m of the IDENTIFICATION OF EGGS AND LARVAE bottom. Robertson's (1975) key was useful in identifying Samples were preserved in 5y" neutralised many of the eggs. Other eggs and larvae were formalin. During sorting all fish eggs and larvae were identified by building up a series of developmental counted. Initially plankton sorters removed all eggs stages from egg to larva to recognisable juvenile. ll .40 ll. 42.

33. 34. 35. 36. 37. 38. 39. 28. 26. 25.

aa i'frãJ iot ''. 21. zlA!

ì5. 14. 13.

Fig 2: Suruey stations and study area. Left: 1974-75. Right: 1975-76.

Larvae of some species were identified by their DATA PRESENTATION similarity to those of related species which had been This study was made on a more intensive scale described from other parts of the world. Electrophor- (that is, at shorter time intervals and with stations etic tissue analysis aided in identifying snapper larvae closer together) than is common with ichthyoplankton (Smith and Crossland 1977) and larvae of the spotted surveys. The complete data, which are held in stargazer. The distribution and abundance of species Fisheries Research Division library, give the counts occurring locally as adults were also considered. recorded for each type of egg and larva for every sample taken; these were calculated as numbers per DESCRIPTIONS OF EGGS AND LARVAE 100 m3 (eggs) and numbers per 500 m3 (larvae). This bu-letin describes and illustrates eggs and !'or some of the more common egg types the Iarvae taken or refers to published accounts. densities were integrated over the study area to give The descriptions of larvae are intended to highlight estimates of the total numbers present at one time on features which will allow recognition of the individual that cruise. This was done by multiplying each species; they are not meant to be detailed, stage-by- individual station volume (station area by mean stage descriptions of larval growth and morphology. depth) by its egg density and then summing over the Most species can readily be distinguished. Exceptions whole study area. The calculations were adjusted for are the two species of. Rhombosole¿ and the two species the slight variation in area between the 2 years. The of. Trachurus, all of which may be present in the method of integration is explained fully in Crossland sampling area. (1980) . The embryonic period was not known for any total egg A1l descriptions and measurements apFly to of the eggs; so it was not possible to calculate material which was preserved in 5"/" neutralised production. formalin. Measurements were made under a stereo Distribution maps were plotted for the more microscope at a magnification of 62 x. The length common tyPes of eggs and larvae as numbers below recorded {or larvae was total length. The figures o{ l0 m2. Cruises not shown in the map series recorded eggs and larvae were also made by use of a stereo fewer eggs and larvae than the minimum contour level microscope and a drawing tube. for that species. t2 RESULTS

Both fish eggs and larvae were very abundant in the immediately recognisable, as the only other species Hauraki Gulf. In 1974-75 the 330 samples contained known from New Zealand to have an elliptical egg, 583 000 eggs and 55 000 larvae. In 1975-76, 589 000 the carapid Echiodon sp., cloes not occur in the Hauraki eggs and 79 000 larvae were collected in 426 samples. Gulf. The maximum number of eggs taken in one haul was 89 000, and that of larvae was 6000. For both years combined, only 2 samples contained no eggs, and 2l The distribution of anchovy eggs for the 2 years contained no larvae. The kinds of cggs and larvae (Fig. 3) showed a spawrring centre within the study recognised are shown in Table l. Details of the area. Anchovy eggs were common and occurred on all distribution, seasonality, and abundance for eggs and cruises in both years. During October spawning was larvae of each species are given below. The species light and took place in the southern part of the gulf have been placed in phylogenetic sequence according near and the northern part of the to Nelson (1976). . The main burst of spawning observed was during November in 1974, and December in 1975. The centre of spawning moved The relationship between spawning and tempera- north to the central gulf- area as the ture was also considered. For demersal species (for season progressed, a similar pattern to that observed example, flounder or gurnard) the sea bottom for snapper (Crossland 1980). Spawning was still temperature was used; for pelagic species (for taking place at the end o{ the sampling period in each example, anchovy or pilchard) the sea surface year. temperature; and for species occurring throughout the water column (for example, jack mackerel or ahuru) the mean of bottom and surface temperatures. The relationship betw,een temperature and - ing (Fig. 4) showed that spawning began when rhe sea surface temperature was about l6"c and was most intense at l9o-20"c. The number of eggs produced in Family Engraulidae the 1975-76 study period was about three times that of the previous year (Fig. 4). These figures have been Anchory Engraulis australis (White, I790) integrated over the stucly area, but not over time, Eggs. The anchor,y egg is described and {igured in because the embryonic period of the anchovy is not Robertson (1975). Its elliptical shape makes it known. Crude egg counts do not consider the effect of

TABLE l: Kinds of eggs and larvae collected in the Hauraki Gulf, October to January in 197Ç75 and 1975-76 Species Egg. Lawae Species Egg. Lawae Anchorry (Engrailis australi) I + Snapper (Chrysoþhrys auratus) + + Pilchard (Sardinops neopilchardus) + + Yellow-eyed mullet (Aldrichetta forster) + + Sprat (Sprattus ant;þodum) + -l Grey mullet (Mugil cephalus) - + Moray eel Family Muraenidae + + Spotty (Pseudolabrus celidotus) - + Sand eel Gtathophis sp. + Spotted stargazer (Gcnyagnu monoþterygius) + + Alauru (Auchmoccros þanctatus) + Blennies: Family Blenniidae, Family Clinidae, Garfi ihr) l + Family Tripterygiidae + Roug chthyidae + Graham's gudgeon (Grahamíihthys radiatus) + John as) + Bar¡acouta (Tþrsítes atun) + Seaho¡se (Hippocampus abdominalis) + Blue mackerel (Scomber australasicus) + + Long-snouted pipefish (Stigmatoþhora longiros tns) + Crested flounde¡ (Lophonectes gallus) + + Red gurnard (Chelídonichthys kunu) + Flounder Rhombosolea þIebcía &. R. leporina + + Rockfish Acanthoclinus quadridacllus I + Speckled sole (Peltorhamþhus latw) + + Rockfish A. trilin¿atus + Leather jac*.et (Nooodon coruexirostris) + + jaatlifents Jack mackerel Trachurus noaa¿z¿landiae + + Porcupine Tts}:, Allomycterus + Jack nackerel T. decliais + Three unidentified species +

+ Present. t Absent.

IJ îÅffi 4-8 Nov 1974

î,tffi ó-'l0 Jon 1975

5000- >t0 000 r0 000

No. below l0 m2 Fig. 3 (above and right): Distribution of anchovy eggs by cruises, 1974-75 and 1975-76.

temperature on development. The egg production larvae were in the central and outer gulf, further north shown in Fig. 4 has been adjusted on the basis that the than the eggs. Large numbers of larvae occurred on development period is halved for a l0oç rise in the November cruises in 1974, when the numbers of temperature. This effect was found experimentally for eggs were low. This probably resulted from bursts of snapper eggs {rom the Hauraki Gulf (Cassie 1956b). spawning which took place between sampling cruiscs and were thus not sampled, and it showed that even Larvae. The anchovy larva is described and figured sampling at 2-weekly intervals may be insufficient to in Baker (t972). It may readily be distinguished from measure the egg production of the mobile, shoaling larvae of the other lttrew Zealand clupeoids pilchard ancholy. (Sardinoþs neoþilchardus) and sprat (Spratns antipodum) by its underslung jaw and the relative positions of its anal and dorsal fins, which overlap. The latter feature is particularly useful for identification, even in small larvae. Family Clupeidae Pilchard Sardinoþs neoþilchardus (Steindachner, IB79)

The distribution of anchovy larvae (Fig.'5) differed Eggs. The development of the pilchard egg is from that of the eggs. The main concentrations of described and Iigured in Baker (1972). These eggs I4 I Z-21 Nov 1975 I -5 Dec 1975 15 -]9 Dec ]975

î,tffi *ffi îtffi 29 -31 Dec 1975 12-16 )on197ó 27 -3Q Jon 1976

rvere present from the beginning of sampling in each 24 year (October) until mid November in 1974 and mid I)ecember in 1975. They were seldom abundant, and 22 on only one cruise (,1.-B November 1974) was there a large spawning within the study area (Fig. 6). 20^ (J

The is l8 c¡ Larvae. pilchard larva described and figured f in Baker (1972). Small pilchard larvae are difficult to lóbo distinguish from larvae of the sprat Sþrattus antiþodum. o- E Larvae longer than about 25 mm can be identified by o the differences noted by Baker. Pilchard larvae have a Ic o o melanophore below the eye and one at the base of the ,( l o) , and the last ray in the anal fin is elongated. o) CJ o These features are absent in sprat larvae. During this o 203 study all clupeid larvae large enough to be identified c) -o were pilchard; smaller larvae of the same type were, E f therefore, assumed to be pilchard also. Some error z may be introduced by this, but since pilchard is very common in the Hauraki Gulf and sprat uncommon, the error will be small. 1529 122ó1024721 4 Nov Dec Jon Feb

Fig.4: Number ancholy eggs within the area at the The distribution of larvae in both years (Fig. 7) of study time of sampling for each cruise, 197 Ç-7 5 and 1975-76. Mean showed that the main spawning areas of the pilchard sea surface temperatu¡es for each cruise are also shown. t5 2- ó Dec 1974

0 r-. i) â A\/ d ^ l__r">^L L,E-,.1-J cv"nä;t \uu4 0 //\l(\ r^\^ .lV (

6 -9 Oct 1975 lZ-20 Nov ì975 l-4 Dec 1975

â. h-l / ¿¡ r !:u _-ì ./ | -- / t I \Wl' ! \ s----:-- \-?' - - - s - 'fiQ l-//-t

!'>L il rsJ t--'l\ J çz-¿r,t¿) \J'Þ^\/ ^ r,4lJ,4 ov"Ëfd^L ^L auy4 *j. /\.c> ! /\¡^..- ü As>"'"q¡"J¿ ! ló - 19 Dec 1975

rLiii ll|illiill 50-200 200-500 500- >looo 1000

No. below ìO m'

Fig. 5: Distribution of anchory larvae by cruises, 197'l-75 and 1975-76. 27 -3O Jon1976 took place outside the study area; however, the sea surface temperatures at the outer stations were in the range 16.lo-17.8"c at the peak occurrence of larvae.

Sprat Sþrattus antipodum (Hector, 1872) Eggs. The sprat egg is described and figured in Baker (1973). These eggs were taken in only small numbers and occurred sporadically in time and space. Their cumulative distributions for the 2 years are shown in Fig. 9. The largest patch of eggs was found in late October 1975, off Kauri Point, Waiheke Island.

Larvae. Sprat larvae were not recognised in any sample, but they may have been confused with small (less than 25 mm) pilchard larvae.

Adult sprat are occasionally taken by bottom trawl 4- 8 Nov 1924 in the Hauraki Gulf if a cod-end liner is fitted, but they do not appear to be abundant. Baker (1973) recorded sprat spawning in the Marlborough Sounds from July to January. Robertson (I980), sampling off the Otago coast, found that spawning lasted from May to November and peaked in June-August. In the 500- 2000- 5000- >10 000 Hauraki Gulf the sampling period was outside the 2000 5000 r0 000 main spawning season found by these workers. However, it is unlikely that major spawning took No. below lO m2 place in the winters oÍ 1974 and 1975, because sprar larvae or juveniles would have been recognised in the Fig. 6: Distribution of pilchard eggs, 4-B Novembe¡ 1974. samples. were north of the study area, probably in the Jellicoe and Cradock Channels. The numbers of larvae taken in each cruise are shown in Fig. 8. A similar pattern was apparent in both years, but the peak lagged by 2 Family Muraenidae weeks in 1975-76, when temperatures were lower. Larval numbers reached a maximum in the first week Morayeel (unidentified) of November in 1974, and in the third week in 1975. Eel eggs and larvae of a previously undescribed Peak spawning would therefore have taken place type were occasionally taken in the outer stations of earlier, possibly in late October or early November. the study area. Because of their close similarity to the eggs and larvae of moray eels from European waters (see Sparta 1939), they were identified as one of the These results can be compared with those of Baker species of morays found in New Zealand. The most (1972), who studied a population in Tasman Bay and commonly observed species locally is the yellow found the breeding season to be lrTovember to moray (Llcodontis þrasinus (Richardson, 1847)). February, with a peak in December-January; that is, some 6 weeks to 2 months later than in the Hauraki Gulf . The difference in latitude between Tasman Bay Eggs. These eggs hadi a diameter of 3.9-4.5 mm; a (41" S) and the Hauraki Gulf (36' 30' S) is the wide perivitelline space (especially in early stages); probable reason for this. Baker found that most and a finely segmented yolk with 6 to 40 oil droplets, pilchard eggs were spawned when the sea surface 0.07-0.15 mm in diameler (Fig. l0). Eggs were first temperature was between 16.0' and l6.4oc It was observed in mid December and were still present at difficult to make a direct comparison with tempera- the end of the sampling period in late January. The ture data from this study, because most spawning cumulative egg distribution for 1974-75 is shown in

T7 â\\, -*_ _/--\\ sÈ{il!, õJ ._--_-r 'r._____

*ffi0 21 -25 Oct 197Á. l8 - 22 Nov 1974

al .-'-/'-l (_---- i.

13'4l')Ä> ,y 16 - 20 Dec 1974

2\ql \\ i \\lr ',/..' z-: ,/ ? \.r'

0 )\ a /\l¡-J-J ^L f-'>\.l r,'-'t?) t)v> l,â.2_. \ \J"> t¡ê,.i -1N *!yrÌ" xuy4 o ](\ ¡ ( //\ r\^ \l /lÄ> ,v ó -9 Oct ì975 20 - 23 Oct 1975 3-7Nov1975

't''l q"rn ,;

0

/-\ ^L/ d .rJ \JVÞ 1,¡¿7e,-,.1 \uy4 o \l\ ) I /À¡\Þ"v2\ ñ \) îÅs lZ- 20 Novì ló - 19 Dec 1975 ,iffiffiffi 50-200 200-500 500- >1000 1000 No below lO m'

Fig. 7: Distribution of pilchard larvae by cruises,1974-75 and 1975-76. Fig. ll. Spawning appeared to be located mainly outside the study area, probably over the rocky bottom around Great and Little Barrier: Islands, a habitat favoured by morays. Fewer eggs were taken in o 1975-76 because the outer part of the Hauraki Gulf was not sampled. x 0) o Larvae. Five larvae were taken in 1974-75 and two o in 1975-76; they were found close to the eggs. They o were immediately recognisable by their long, slender o shape and fearsome array of íorward-pointing teeth ¡ 1975-76 E (Fig. I2). zl

lrs29 1226 1024721 4 Fig.8: Numbers of pilchard la¡vae taken by cruises, I974-75 Ocl Nov Dec Jon Feb and 1975-76

5-20 20-50 50 - 100 No. below l0 m2

Fig. 9: Cumulative distribution of sprat eggs. Left: 1974-75 Right: 1975-76.

,{

Fig. l0: Moray eel eggs

t9 Family Moridae Ahuru Auchenoceros punctatus (Hutton, 1873) Eggs. The ahuru egg is described and figured in Robertson (1975). The distribution of ahuru eggs for the 2 years is shown in Fig. 13. The centre of spawning was in the northern part of the Firth of Thames. Figure 14 shows seasonal changes in egg numbers for the 2 years and the mean sea temperatures in the spawning area. Few eggs were observed in 1974, but they were common during October and November 1975, when sea temperatures were lower than in the previous year. These findings are consistent with those of Robertson (1980), who found that in Otago waters ahuru were winter-spring spawners, preferring cool, Iow-salinity, in-shore waters.

Larvae. The. main distinguishing features of the larvae are the large numbers of rays in the dorsal and anal fins, and in older larvae the single hair-like ray in front of the dorsal fin (Fig. 15). Small larvae have no particularly distinctive features and were recognised after building up a developmental series.

..'..''.'''..'..''.''.': Ahuru larvae were common in the study area and ...... Jir¡¡¡; were more abundant than the eggs, particularly in the r -5 5-20 first year. In 1974-75,6800 were recorded, and in 1975-76, 9700. They were most numerous during No. below lO m2 October and Nlovember (Fig. l6), with a marked peak in November 1975, weeks after the peak in egg Fig. ll: Cumulative dist¡ibution of moray eel eggs, Ig?4-75 2 numbers. The relatively high numbers of larvae and low numbers of eggs in 197+-75 indicated that spawning either took place mainly outside the study area (to the south) or before sampling began. Family Congridae Sand eel Gnathophis incognitus Castle, 1963 or G. The distribution of larvae (Fig. l7) shows distinct habenatus (Richardson, I848) and puzzling differences from that of the eggs. In both Eggs. The egg of Gnathoþhis sp. is described and years few larvae were found in the immediate vicinity {igured in Castle and Robertson (1974) . Five eggs of of spawning. In 1974-75 larvae were commonest in this type were taken in one sample on 22 January the eastern gulf, off the . In 1975; two were at the early blastodisc stage and three 1975-76 they were found both there and more widely had well-developed embryos. spread over the central gulf.

Fig. 12: Moray eel Larva (9.6 mnr).

20 4-8 Nov 1974

ó - l0 Oct 1975 20 -24 Oct 1975 3 -7 lNov 1975

50-200 200-500 500- > r000 1000 No. below lO m'

,l975 l7-21 Nov 1 -5 Dec 1975

Fig. 13: Distribution of ahuru eggs by cruises, 197'[-75 and 1975-76

A possible expianation for the disjunctive egg and ' and the smallest larvae taken were about 4 mm long. larval distributions is that the larvae were carried by Flowever, ahuru juveniles, some up to 45 mm long, water movements from the spawning area and were were sometimes tallen and were the largest not sampled until they reached a size large enough to ichthyoplankton caught during this survey. Adults be retaiñed by the plankton net. The newly hatched seldom exceed 120 mm and are susPected to live off larva from the small ahuru egg (0.525-O.600 mm the bottom. Graham (1956) found that ahuru fed diameter) is unlikely to exceed 1.5 mm total length principally on a surface-living copepod.

2t Family Exocoetidae Garfish Hyþorhamþhus zår Phillips , Ig32 The early development of the garfish is described p and figured in Graham (1956). This species has I róã adhesive, demersal eggs. : r; 9 Larvae. Two larvae (measuring 10.6 and I 1.0 mm) þo x o_ were taken in 1975, and one (meâsuring ll.3 mm) in E 1976. $r 20P In both years they were taken in the northern o o central gulf in late c, January. The heaviiy pigmenred o2 18. garfish larva is distinctive (Fig. IB), with a prominent o o ! o double row of rouncl pigment spots along its back. 5r ló= The lower jaw projects beyond the upper. z

0 14 I 1529122610247214 Family Trachichthyidae Oct Nov Dec Jon Feb

Roughy (unidentified) Fig. 14: Numbers of ahuru eggs taken by cruises, 1974-75 and 1975-76. Mean sea temperatures in the spawning area are Larvae. During December and January, larvae also shown. (Fig. I9) identified to this farnily were taken occasionally at the outer stations of the study area.

Fig. 15: Ahuru (Auchnoceros þunctatus) larvae (5.6, 12.8 mm).

22 single juvenile ll.9 mmL lÒng was taken in the outer gulf on 16 January 1976.

Family Syngnathidae 'o Small juveniles of the seahorse (Hippocampus x abdominalis Lesson, l8l8) and the long-snouted (¡) (Stigmatoþhora longirostris I 8 72) were o pipefish llutton, 5 197s-76 occasionally recorded. _9 o 4

(¡) -o E Family Triglidae l z Red gurnard Chelidonichthys kumu (Lesson and Garnot, l826) Eggs. The red gurnard egg is described and figured in Mito (1963) and Robertson (1975). Red gurnard eggs were taken on every cruise during both years, but were never abundant. The cumulative egg distribu- 12 26 721 1 l15 years (Fig. 20) Oct Nov Dec Jú Feb tion was remarkably similar in both and showed the main spawning centre to be at the Fig. 16: Numbers of ahuru larvae taken by cruises, 1974-75 and northern edge of the study area or still further to the 1975-76. north. The seasonal variation in egg numbers for 197+-75 indicated a spring spawning peak in They may have been larvae of the slender roughy October, but in 1975-76 peak egg numbers occurred (Optiaus elongatus, (Günther, 1859)), the most common in December (Fig. 2t). However, in both years the sea species of roughy observed by divers along rocky bottom temperatures in the spawning area were coastlines in northern New Zealand (Doak 1972). similar at peak spawning (15.6'c in 1974-75 and Most larvae were small (3.5-4.5 mm long). The 15.7'c in 1975-76). Ekler (1976) considered that the Iargest was 8.3 mm and the skin on the dorsal surface time of peak spawning was influenced by temPera- of its head and body was covered with tiny spines. ture, through its effect on the maturation rate of the gonads.

Family Zeidae John Dory Zeas japonicas (Richardson, IB45) Larvae. Early stages of the red gurnard larva are The eggs of this species have'been described figured in Mito (1963) . The cumulative distrit¡utions (Robertson 1975), but were not taken in this study. A of larvae (Fig. 22) showed a pattern of dispersal

*ffi 2t-25 æ 1971 l8 -22 Nov 1974

Fig. 17: Distribution of ahuru lawae by cruises, 1974-75 (see key on following page).

23 {t z-ì / li

\ I -----** )r-s.-- \ z

)\ lL z---r\ / cr,-a r:J al\/^/L ¡r^^.-.t"!vìqt\rJ ^--"-" > o Y^""qnJ¿ \t\ -J I /J\ * t'\ //\ r^r^ V l/ ì.\ Y "w 6-9 Oct1975 20 - 23 Oct 1975 3 -Z Nov 1975

20-s0 s0-200 200-500 No. below l0 m2

l7 -20 Nov 1975 1 -4 Dec 1975

Fig l7 (continued): Distribution of ahuru larvae by cruises, 1975-76.

southwards from the spawning area; this was more marked ín 1974-75, perhaps because spawning began earlier that year (see Fig. 2l). These findings concur with those of Elder (1976), who postulated that larvae drifted south a{ter â northward, contranatant migration of adult red gurnard from the inner Hauraki Gulf to a spawning ground in the Cradock Fig. 18: GarÍish (Hyþorhamþhus ih) larua (1t.3 mm). and Colville Channels.

Family Acanthoclinidae Rockfish Acanthoclinus quadridactylus (Bloch and Schneider, l80l) and A. trilineatus (Griffin, 1933) Jillett (1968) described the early life history of A. quadridactylus, a small littoral fish which lays demersal eggs. The adults of both A. quadridactylus and A. trilineatus are described and figured in Griffin (1933).

Fig. 19: Roughy (Family Trachichthyidae) larva (5.3 mm).

2+ r-5 5-20 >20 below l0 m2

î,1 ffi

Fig' 20: cumulative disrriburion or red gurnard eggs Lefr: rg74-75. Righr: 1975-76

l8 o) o) o ló U o o f o t4 E o l o- z r50 E 1975-76 o Ê 100 r8 o o tó o rn Fig. 2.1: of red ^Numbers gurnard eggs taken by cruises, lg74-75 and 1975-76. Mean sea bottom temperaturés 14 in the Ápawning rt5 1226t024721 4 area are also shown. Oct Nov Dec Jon Feb

r-5 5 -r0 r0-20 >20 No. below lO m2

\ '\ sï?/!-/-{-\,

Fig.22: Cumulative distribution of red gurnard larvae. Left: 1,974-75. Right: 1975-76

25

Inset 3 Larvae. Small larvae oÍ A. quadridacQlus up to Family Carangidae 5.5 mm long are figured in Jillett (1968) . Lawae of the There are two species oÍ Trachurus (jack mackerel) two species were not recorded separately during this found in New Zealand waters (Stephenson and study. The illustrated specimen (Fig. 23) is A' Robertson 1977). Trachurus nouaezelandiae is abundant trilineatus, which has more dorsal and anal fin rays in in-shore waters in northern New Zealand. Trachurus than A. quadridactllus and a more slender body. The decliuis usually lives further off shore and is found larvae are heavily pigmented with dark brown sPots' throughout New Zealand. The eggs of both species are described in Robertson (1975), but this study and recent findings of Robertson (pers. comm.) have 'l'he cumulative distribution for the 2 years shown these descriptions to be inaccurate. (Fig. 2a) showed the larvae to be well dispersed' but largest numbers usually recorded close to with the (Richardson, land. Larvae were collected on all cruises in both Jack mackerel Trachurus noaaezelandiae years, except the làst cruise in 1974-75. Their rB43) numbers declined steadily as the sea temPerature Eggs. The eggs of T. nouaezelandiae (: T. mccullochl increased. More larvae were collected in 1975-76 than are described in Robertson (1975) as having a in the previous year, which was warmer. These results diameter of 0.720-0.820 mm, a segmented yolk, and a are consistent with Jillett's findings that A. single oil droplet. During this study eggs conforming quadridacQlus is a winter spawner, with peak spawning to this description were not taken, but an egg slightly in September and October. (Jillett considered Sep- Iarger than this was regularly caught and was very tember and October as winter.) abundant. The likely causes of this size discrepancy

Fig. 23: Rockfish Acanlhoclinus trilin¿alus Iarva (10.0 mm).

3-4 â\* -- - n( ------._,t 10 m2 -'.f-Ð---''. \*-' \ \-v1. 1 \i ,'

Fig 24: Cumularive distribution of rockfish laruae LeÍv 1974-75. Right: 1975-76.

26 are that Robertson's measurements were of unfertil- The egg distribution (Fig. 26) showed the Hauraki ised eggs which were probably not fully mature, and Gulf to be an important spawning area Íor T. that a slight increase in size normally occurs at nouae4landiae. Most sparvning occurred in the western fertilisation. side of the gulf, a few rniles off shore, and in depths greater than 30 m. Spawning extended from Rakino The eggs shown in Fig. 25 had a diameter of 0.78- Island in the south to Cape Rodney in the north, with 0.88 mm; a narrow perivitelline space; a segmented the densest patches of eggs east of Tiritiri Matangi yolk (segmentation irregular and not always distinct, and Kawau Islands, the areas in which snapper eggs in the early stages more noticeable just below the were also most abundant (Crossland 1980). In 1974- blastodisc) (see Fig. 25 top); and a single, yellowish 75 there was another important spawning area off the oil droplet, 0.204.27 rnrn in diameter, situated south-west shore of ; this part of anteriorly in late stage eggs. The embryo was stout the gulf was not sampled in t975-76. bodied with numerous prominent melanophores along the dorsal surface. The seasonal changes in egg production are shown These eggs were considered be those T. to of in Fig. 27. TÌr'e figures have been adjusted for nouae4landiae for the following reasons: temperature effect (as described for anchovy eggs) and the numbers in the .t974-75 season are for a;trarea 1. They had the typical carangid egg features of equivalent to that sampled in 1975-76. The observed segmented yolk; single, anterior oil droplet; and egg production was similar in both years. peak relatively undeveloped embryo at hatching. spawning occurred in nrid November in 1g74, when the 2. An embryological series was built up and the late mean sea temperature was 17.3"c, and in mid December in 1975 a stage embryos were indistinguishable from yolk-sac at mean sea temperature of l7.9oc. larvae of T. nouaelelandiae.

3; Measurements of 100 unfertilised eggs from a ripe Larvae. The larvae of. T. nouae¿elandiae (Fig. 28) are specimen of T. nouaezelandiae gave the following similar to those of. T. symmetreczs (Ahlstrom and Ball results:.diameter 0.775-0.865 mm (mean 0.825 mm); 1954) from the north-eastern Pacific. They show the oil droplet 0.191-0.250 mm diameter (mean distinctive carangid feature of three rows of 0.226 mm) (Robertson pers. comm.). melanophores on each side, one each along the dorsal and ventral margins of the body and one along the lateral 4. The eggs are not those of trevally (Caranx georgianus line. They can readily be distinguished lrom (Cuvier, 1833)), another carangid known to occur in the larvae of trevally because the latter are more the Hauraki Gulf. Although of a similar size, the dlkly pigmented and have a deeper body (James r s76). trevally egg has an unpigmented embryo (James r e76).

The distribution of larvae (Fig. 29) was similar for both years. Larvae were found close to the eggs for the corresponding period, but were displaced a few miles to the north-east, further into the central gulf. Larval numbers (FiS. 30) showed a distinct peak in November of each year. In 1974 this coincided with the peak in egg numbers, but in 1975 it occurred a month before the egg peak. This could be the result of a large spawning inside the study area between sampling periods, or it could have resulted from a spawning to the north of the study area, with the larvae carried south lty currents (compare with pilchard and gurnard).

Jack mackerel Trachurus decliais (Jenyns, 1841) Eggs. Robertson's (1975) description gives the egg diameter as l.l-1.3 mm. This was based on a poorly preserved sample and is inaccurate. A more recent Fig. 25: Jack macke¡el Trachurus nouac¿clandiae eggs. sample of 100 artificially fertilised eggs had a diameter

27 4-8 Nov 1974

20-23 Jo¡1975

gK4;^L l\ r^.,^ tl

20-24 Oc¡ 1975 3 -Z Nov 1975

I -5 Dec l9Z5 l5 -19 Dec 1975 29 - 31 De< 1975

500- 2000- 5000- >t0000 2000 5000 10000 No. below l0 m'

Fie. 26: Distribution of jack - mackerel T. noaaez¿Iandia¿ eggs bY cruises, 1974-75 and 1975-76. 27 -3O )on 1976 range of 0.970-1.030 mm (mean 0.998 mm) and a segmented yolk with an oil droplet of 0.238-0.302 mm (mean 0.266 mm) diameter (Robertson pers. comm.). Eggs conforming to this description were occasionally l8 recorded in the Hauraki Gulf. They ranged in size from 0.95 to 1.02 mm diameter and had an oil droplet I of 0.23-0.29 mm diameter. The late stage embryo was =,o lói c) more slender and muc.h more lightly pigmented than x o that of T. nouae4landiae (Fig. 3l). Cumulative egg q) o o) distributions for the 2 years are shown in Fig. 32. o E CJ o o {J Larvae. The larvae oÍ T. decliuis are probably so -o c )E similar to those of. T. nouaelelandiae that separation of z 'rg the two species may only be possible by biochemical means. Stephenson and Robertson (t977) could not distinguish juveniles of the two species if they were shorter than 35 mm standard length. Because the eggs oL T. decliuis were only rarely recorded, and nearly all adult jack mackerel observed in the Hauraki Gulf are 11529 4 1226 1024721 T. nouae4landiae, all Trachurus lar.'ae were assumed to Oct Nov Dec Jon Feb be T. nooaelelandiae.

Fig. 27: Number of jack mackerel T. noraezelandiaø eggs within the study area at the tirre of sampling for each cruise, 197.f- 75 and 1975-76. Mean sea tempe¡atu¡es for each cruise a¡e also shown.

Fig. 28: Jack mackerel Trachums noaa¿- zelandiae larvae (4.4, 7.6, 8.9 mm).

29 I U\l \¿ f-.r\/^ tz'-.-¡") :. o u4-4t.9

21 - 25 Oct 1974 18 -22 Nov 1974

93"4//\ r^\^ V

ll;:t:iitiiilli:tlrill

ii::rliiiiii:i:l:ri:ii 50-200 200-500 500- >t000 \t t000 r'------/ No. below lO m'1

0 i,Effi Fig. 29: Distribution of jack mackerel T. noaae4landiaelarvaeby 2Q-23 Jon1975 cruises, 197,S-75 and 1975-76.

/\ L /-\/ d -J !)v* l,rÞ--ê^41ì/'¿ \ . \t\ ) I /ìÀÞ,v/)\.a\\

aJi I <-__i

I

\--\- /!

0

29 -3ì Dec 1975 'o x o o o o o E zl Fig. 3l: Eggs of jack mackerel Trachwas decliuis.

Larvae. The early stage larva uP to a length of 3.2 mm is described and figured in Cassie (1956b) . The patches of yellow pigment he observed in living 1226 1024721 4 11529 specimens were not aPParent in preserved samples, Oct Nov Dec Jon Feb and the absence of distinctive features in small Fig. 30: Numbers of jack mackerel T. nooaezelandiae larvae taken snapper larvae made initial identification difficult. by cruises, 197+-75 and 1975-76. Gradually a series was built up and it showed that the most useful identifying character, before the develop- ment of the fin ray pattern, was the Presence of two Family Sparidae pigment spots on the ventral su¡face of the gut (Fig. Snapper Chrysoþhrys auratus (Forster, l80l) 33 top). These larvae '*'ere confirmed to be snapper by Eggs. The snapper egg is described and figured in electrophoretic analysis of their enzyme patterns and Cassiè (1956b) and Crossland (1980). The distribu- comparison with those of the adult (Smith and tion and abundance of snapper eggs in the Hauraki Crossland 1977). Lawae large enough to be identified Gulf have been described previously (Crossland by their fin ray count (that is, Iarvae more than 1980). They were the most abundant of all egg tyPes. l0 mm long) were rarely taken.

::.:. .: ':,: ':r'''': 5 -20 20-50 No. below l0 m2

Fig.32: Cumulative distribution of jack mackerel T. decliais eggs. Left: 1974-75' fught: 1975-76'

3l ' i.i'l'::;ïi;j; ¡,rí" . .'" '- I '. ', ç' -¿" /.'rr'1.1{ù^..''i

_ a :e

Fig. 33: Snapper (Chrysoþhrys auratus) la*ae (5.6, 9.7, 13.5 mm).

The distribution of snapper larvae was patchy in 2 years indicated that it was lower in 1975-76 than in 197+-75 (Fig. 34), aqd they were not abundant (Fig. the year before and that about the same number of 35). In I975-76 they were much more common, and eggs survived to hatch in each year. more evenly distributed, mainly over the central gulf (Fig. 3a). Consideration of these facts alone would How can the five times greater number of larvae in l97l-70 be explainedl The relative scalci 0f

I I heavier in I975-76 th'an 1974-75, yet the opposite was snapper larvae (even in 1975-76) compared with the true (Crossland 1980) . A study of egg mortality in the larvae of other species whose eggs were much less

32 t2!t L,' L^lâ\

/\ L

î54Ë//\ -r^\- V

18 -22 Nov 1974

17- 20 Nov ì975 1-4 Dec 1975 ló - l9 Dec 1975

20-50 50-200 200-500 >500 No. below ]O m2

Fig. 34: Distribution of snapper laruae by cruises, 197.[-75 and 197Í176. o 'o x 0) o ! o

ot _o E zl

11529 1226 l0 247 21 4 Oct Nov Dec Jon Feb ,\i Fig. 35: Numbers of snapper lawae taken by cruises, t974-7 5 and 1975-76.

abundant (such as jack mackerel) indicates that the snapper larva has a short pelagic phase. Cassie (I956b) observed that newly hatched snapper larvae Fig. 36: Yellow-eyed mullet (Aldrichan forsten) egg. preferred the bottom of their container. If the demersal habit is quickly adopted, the larvae collected in the plankton may be mainly those displaced by small juveniles the pigmentation merges to form a currents or tidal movements. Thus the chances of uniform, dark grey background. sampling them will depend not only on their actual abundance, but also on the effects of the prevailing Larvae, and juveniles up to 33 mm iong, were weather or the state of the tide. One sample in recorded throughout the study area, but were taken November 1975 taken off the south shore of Kawau only occasionally. The occurrence of juveniles during Island, where tidal movements are.rnore pronounced the early part of the study period indicated that than in open water, contained more laryae than the spawning also occurred during late winter and that total for the whole of the previous year. This is also the yellow-eyed mullet has an extended breeding the only locality in which Cassie (1956b) recorded season. snapper larvae in any numbers. Grey mullet Mugil æphaløs Linnaeus, 1758 A single juvenile I1.5 mm long was recorded in mid Family Mugilidae January 1976. It was very similar to juvenile yellow- eyed mullet, but could be distinguished by its having Yellow-eyed mullet Aldrichetta forsteri (Valenciennes, 1836) only 8 anal soft rays (compared with 12 in the yellow- eyed mullet); both species have 3 spinous rays. Eggt. The egg of the yellow-eyed mullet is described in Cassie (1956b). Eggs of this species were taken in the inner gulf throughout the study period, but never in large numbers. They ranged in size from 0.84 to 0.93 mm diameter. The number of oil droplets Family Labridae varied from 3 to 13. Late stage eggs were never Spotty Pseudolabrus celidotus (Forster, l80l) recorded; most eggs were at the stage shown in Fig. 36. The cumulative egg distributions for the 2 years Eggs of this common littoral fish, which are (Fig. 37) showed a spawning centre east of Tiritiri described in Robertson (1975), were not recorded Matangi Island. Eggs were more abundant in 1974- during this study. 75 than in the following year. Larvae. Larvae (Fig. 39) were recorded in small numbers between October and the beginning of in 1975- Lônae, Lawae 0i this sPecies ate very dark' December and were three times as abundant

I because of rnany small melanophores over the whole of the body and head (Fig. 3B). In older larvae and

34 5-20 20 -50 No. below l0 m2

Fig. 37: Cumulative distribution of yellow-eyed mullet eggs. Left: 1974-75. I{ight: 1975-76.

Fig. 38: Yellow-eyed mullet (Aldrichettø forstcn) Iawa (10.5 mm).

Fig. 39: Spotty (Pseudolabrus celídotus) larua (13.2 mm).

Family lJranoscopidae droplets, and in the late stages only a single, Spotted stargazer Genyagnus monoþterygius (Bloch and posteriorly placed droplet remained (Fig. a0 bottom). Schneider, l80l) The late stage embry¡o was spotted with numerous melanophores; there were also some on the surface of Eggs. The spotted egg described in stargazer is the yolk. The dorsal median fin fold was strongly Robertson (1975) (diameter 1.800-2.000 non- mm; developed and began at the front of the head. segmented yolk; three to nine oil droplets). Eggs with a size range of 1.79-1.96 mm and multiple oil droplets Spotted stargazer eggs were recorded consistently were recorded in both years (Fig. 40 top). During during Octobe¡ and lrTovember of each year, but in sorting a developmental series of these eggs was built only small numbers; from December onwards they up and it showed that as the egg matured the oil were rare. Their distribution (Fig. 4l ) was patchy and droplets coalesced, so that by the middle stages (Fig. widespread, consistent with the occurrence of this 40 centre) there were only two or three larger species.

35 Larvae. These were identified by building up a developmental series (Fig. a2). The smallest larva (top) was consistent with the most advanced embryo (Fig. a0 bottom). The adult fish has a small barbel on the chin, and this was observed in the largest larva taken (Fig. 42 bottom), which also showed the characteristic forward placement of the pelvic fins. Although no specimen was developed far enough to allow comparison of fin ray counts, biochemical tests confirmed the identification. Electrophoretic tissue analysis by *y colleague P. J. Smith on one of these Iarvae and on adult spotted stargazer detected a glucosephosphate isomerase (GPI) Iocus of similar mobility in both. These loci are good species markers because of electrophoretic variability of phenotypes (Avise and Kitto 1973, Dando 1974).

The cumulative distribution of larvae is shown in Fig. 43. They were less scattered than the eggs, commonest in the central gulf during both years, and taken at all times during the study period.

Families Blenniidae, Clinidae, and Triptery- giidae Blennies Larvae of these ubiquitous families of fishes (the adults of which lay demersal eggs) were a common component of the ichthyoplankton. Most were small (less than 8 mm), and no attempt was made to identify them to species level.

Fig. 40: Spotted sta¡gazer (Genyagnus monoþtcrygius) eggs.

iiii: t ::::: äi!ii::::t!tl

r -5 5-20 No. below l0 m2

Fig. 4l: Cumulative distribution of spotted stargazer eggs' Left: 1974-75. Right: 1975-76.

36 Fig.42: Spotted stargazer (Gnlagnus monoþterygius) larvae (5.6, 7.2, 13.8,20.0 mm).

3t 1-2 2- 5 No. below l0 m2

Fig. 43: Cumulative distribution of sported stargazer larvae. Left: 197+-75. Right: 1975-76.

Family Eleotridae Family Scombridae Graham's gudgeon Grahamichthys radiatus (Quoy and Blue mackerel Scomber australasicus Cuvier and Gaimard, IB37) Valenciennes, 1831 Larvae. Larvae of this species (another which lays The eggs and larvae of this species were identified demersal eggs) are shown in Fig. 44.Tlne young larva from their close similarity to those of the Pacific (top) is transparent and has a conspicuous swim (Japanese) mackerel Scomber japonicus (: bladder which becomes less prominent as the larva Pneumatoþhorus diego) (Kramer 1960). matures (bottom). These larvae-were common and were taken throughout the sampling period, being Eggs. These eggs (Fig. 46) had a diameter of I.05- most abundant from late November onwards in 1974 1.20 mm; a narrow perivitelline space; a non- and from early December in 1975. Their distribution segmented yolk; and a single oil droplet of 0.26- was similar in both years (Fig. 45) and extended in a 0.33 mm diameter, situated posteriorly in late stage broad band across the northern half of the studv area. eggs. The advanced embryo is moderately pigmented dorsally and laterally, from the head almost to the tip Family Gempylidae of the tail. A few melanophores also occur on the Barracouta Thyrsites atun Euphrasen, l79l surface of the yolk near the embryo. Ten specimens of larvae and pre-juveniles were taken in the outer stations on the first cruise in 1974. BIue mackerel eggs were taken throughout the They ranged in length from 7.5 to 25 mm. study period in 1974-75. Their abundance varied

Fig. .14: Graham's gudgeon (Gralary- lchtþs radiatu) larvae (4.9, 12.2 mm),

38 r-.5 5-t0 10-20

No. below l0 m'?

Fig. 45: cumulative dis¡¡ibution of G¡aham's gudgeon larvae. Lelt: lg74-75. -Right: 1975-76.

greatly from cruise to cruise (Fig. 47), which is to be top of the head and derLse pigmentation on rhe sides of expected with this highly mobile schooling {ish. The the visceral cavity. These leatures distinguish them spatial distribution (FiS. 48) showed the main from snapper larva€:, which they s.uperficially spawning area to be outside the study a¡ea or on irs resemble in the early stages. Details of pigmentation northern periphery. In 1975-76 this part of the gulf are remarkably similar ro rhose of the Pacific mackerel was not sampled and blue mackerel eggs were less described by Kramer (1960). However, larvae of S. common, being taken in large numbers only during australasicus are more slender and have less developed one cruise. fin rays than S. jaþonints larvae of comparable length. The largest larva recorded was 19 mm long. Larvae. Blue mackerel larvae (FiS. 49) are characterised by a patch of round meianophores on Blue mackerel were among the most abuñdant Iarvae in plankton from the outer stations; on several occasions over 1000 were taken in one sample, and a maximum of 2704 tvas recorded. The seasonal variation in larval numbers (Fig. 50) showed two marked peaks in both seasons. I was not able to determine whether these were caused by chance during sampling or were a significant feature of the spawning of this species. The distribution of larvae (Fig. 5l) was similar in both years and was centred close to the observed spawning areas, but dispersed further south into the central gulf.

,o x o) o) (¡) o o _o E zl l'r529 1226 1024721 4 Oct Nov Dec Jon Feb

Fig.47: N_umbers of blue mackerel eggs taken by cruises, Fig. 46: Blue macke¡el (Scomber australasims) egg. r974-7 5.

39 îÅffi l8 - 22 Nov 1974

lrrr:rl:l:i:r.: ::r ¡::!:i*i:i::.¡i:i:i 50-200 200-500 500- >1000 1000 No. below l0 m'

16 - 20 Dec 1974 20-23 Jon1975

mackerel eggs cruises, 1974-75 and 1975-76 lZ-21 Nov 197 Fig. 48: Distribution of blue by

Family Bothidae (Arnoglossus scapha (BIoch and Schneider, 1B0l)) (see Robertson 1975 for eggs and Robertson 1973 for Crested flounder Loþhonectes gallus Gunther, 1880 larvae). The eggs of this species have not previously been described from New Zealand, and the larvae have been described only in an unpublished account Eggs. These eggs (Fig. 52) had a diameter of 0.81- (Robertson 1973). Eggs and larvae were identilied by 0.88 mm; a non-segmented yolk; and a single oil mm diameter. Crested flounder and raryar series' rh1 droolet of 0.I2-0.16 fllllülllf l¡ ft[ IlllfIÎt'¡nut lll crulse In closely resemble those of the related species witch eggs were taken at the outer stations on every

40 Fig. 49: Blue mackerel (Seomber australasicus) larvae (9 4, I4.4 mm).

or 1974-75 bothid larvae taken in this study were positively identified as those oÍ L. gallus by their fin ray counts. 8-l Loþhonectes gallushas 87 to 93 dorsal rays and 7l to 77 anal rays; A. scaþha has ltl to 126 and 87 to 99 respectively (Norman 1934). The largest lal.va 'o recorded was 14 mm long, at which size metamor- )( phosis had not begun. (¡) o IJnlike the eggs, Iarvae crested o of flounder were at times abundant, particularly in 1975-76, when as o many as 152 were recorded in a sample. The larval (¡) -o distribution (Fig. 55) shows dispersion south into the E z) central gulf from the northern spawning centre. This was more marked in 1975-76, when larvae were common as far south as Tiritiri Matangi Island. Although larvae were taken on all cruises in both years, their numbers varied greatly, and periods of abundance did not correspond in the 2 years. In 1974-75larvae were common on the first three cruises 11529 1226r0 24721 4 (October and November); in 1975-76 they were rare Oct Nov Dec Jon Feb on the first three cruises, suddenly became abundant Fig. 50: Numbers of blue mackerel larvae taken by cruises, on the fourth cruise (mid November), and continued 1974-75 and 1975-76. to be so until the end of December.

The thin, Ieaf-life form of the crested flounder larva 1974-75, but were never common excePt at one indicates that it is a weak swimmer and is probably station off the south-west shore of Great Barrier more truly planktonic than many other fish larvae and Island (Fig. 53). The spawning area aPPears to be thus more affected by water movements. This, with its north of the study area. Iong larval period, means that it can occur in samples taken a considerable distance from the spawning site. Larvae. The ybung larva (Fig. 54 top) is quickly recognisable by a prominent band of black pigment near the tail and by the bifid whisker on top of the head. (Sometimes only a single ray was present, Family Pleuronectidae possibly as a result of damage.) Larger larvae are Three members of this family are commonly found transparent and every detail of the viscera and in the Hauraki Gulf: the sand flounder (Rhombosolea structure of the gills is visible. They also have the bifid þlebeia Richardson, 1843), the yellow-belly flounder whisker. These features also apply to the larvae of the (R. leporina Günther, lB73), and the speckled sole more southerly distributed A. scaþha. ÉIowever, the (Peltorhamþhus latus James, 1972). The development of

+t 1y"4 //\ -r\,- \l *ffi 16 - 20 Dec1974

*ffi

lil,iffi ffi ffi 2000- 5000- >10000 5000 l0 000 No. below l0 m2

29 -31 Dec 1975 Fig.5l:Distributionofbluemackerellarvaebycruises,IgT+-75and1975-76.

+2 Fig.52: Crested flounde¡ (Loþhoncctcs gallas) eggs.

the sand flounder egg is described and figured in Robertson and Raj (1971); the egg of the yellow-belly flounder is very similar (Robertson 1975). Eggs of these two species could not be distinguished in plankton samples by Colman (1973) who studied their spawning in the Hauraki Gulf. The eggs of P. latus have not been described, but are probably similar to the eggs of the other two species of given in Robertson (1975); these are 50-200 200-5100 500- similar both to each other and to flounder eggs. The eggs of the three pleuronectid species from the 1000 together. Hauraki Gulf were therefore classed No. below l0 m2

Fig.-53: C_umulative dist¡ibutioir of c¡ested flounder eggs, Eggs. The distribution of pleuronectid eggs (Fig. t974=7 5. 56) showed (hat spawning was concentrated in the northern part of the Firth of Thames; this confirmed the findings of Colman (1973). Ilowever, particularly sea bottom temperaturce in the spawning area was in 1974-75, there were additional spawning areas l5.5oc at peak spawning in 1974 and l5.9oc in 1975. north of Waiheke Island and between Motutapu Colman found that egg numbers were low from Island and Tiritiri Matangi Island. In 1975-76 December to April. Eggs were also less abundant patches of eggs were encountered in or to the east of during December for thLe 2 years in this study, but the Omaha Bay. If the distributions of flounder and sole numbers were still appreciable, especially since the larvae (Figs. 59 and 62) are studied in conjunction data in Fig. 57 were not adjusted for the effect of with the egg distribution, it aPPears that those eggs temperature on the embryological period. found north and east of Waiheke Island are a mixture of flounder and sole; eggs from between and Tiritiri Matangi Island, mainly flounder; Rhombosole¿ larvar:. Larvae of the two flounder and eggs from Omaha Bay, sole. species could not be distinguished from each other; but their dark bro'wn appearance, caused by numerous round mellanophores (Fig. 58), easily Pleuronectid eggs were taken throughout the distinguished them from the relatively unpigmented sampling period (Fig. 57). They were most abundant sole larva (see Fig. 61). Flounder larvae over 6 mm during October and November and their numbers long were seldom taken; most were 3 to 4 mm. then were greater than those recorded at arry time by Colman (1973); however, differences in sampling methods may have influenced the results. The peaks The distribution of larvae (Fig. 59) showed them to in egg numbers occuried during the first week of be most abundant at the northern end of the Firth of November in 1974 and the third wcek in 1975. The Thames and north of Waiheke Island. In 1974-75

+3 Fig. 54: Crested flounder (Lophonectes gallus) larvae (5.0, 14.0 mm).

4+ *M 21 -25 Oct 1974 4-8 Nov 1974 18 -22 Jon 1975

,/--\ / øÅ *) ^ I/'F=.J/ Y:" /\Ä'\? )j l7 -20 Nov 1975

'' ':::::::l::::::¡:::::

20-50 50-200 200-500 No. below l0 mt

29 -31 Dec'1975 Fig. 55: Distribution of crested flounder laruae by cruises, I974-75 and 1975-76

+5 21 -25 Oct 1974 4-8 Nov 1974

2 -6 Dec 1974 16 -2O Dec 1974 ffiffi 500- > 1000 t000 Fig. 56: (above and right): Distributiou of pleuronectid eggs by cruises, 1974-75 and No. below l0 m2 l 975-76.

they were also comrnon around and recorded from this area. In addition, larvae with Motutapu Island. Larvae were most abundant during developed median fins gave ray counts in agreement November in each year (Fig. 60) and this abundance with those lor P. latus recorded by James (1972). The corresponded to the peaks in egg numbers. Since the specimen in Fig. 6l (bottom) had 87 dorsal rays and presence of larvae is an indicator of past spawning, 56 anal rays. Small larvae (Fig. 6l top), which did not the smaller numbers observed during October, have any obvious features, were recognisable particularly in 1975, perhaps signify that peak by an area of small spots on the belly. spawning for flounders occurred during the study period, not at some time before sampling began. The distribution of speckled sole larvae (Fig. 62) was similar in both years, but differed from that of Peltorhamþhuslaxvae. All sole larvae taken during flounder larvae. Most sole larvae were recorded in the this study were identified as those of Peltorhamþhus eastern gulf, with the main centre of abundance to the /¿/us. Adults of this small species are abundant in the west of the Motukawao Group; larvae were rare in the Hauraki Gulf, but P. nouaezeelandiae is only rarely Firth of Thames. The larval distribution pattern observed, and the third species, the southerly indicates a spawning centre to the north oI that for distributed P. tenuis James, 1972, has not been flounders. However, since sole larvae were taken up to

+6 ó -10 Oct 1975 20-24 Oct 197s 3-7 Nlov 1975

17-21 Nov 1975 l5 -19 Dec l9Z5

29 -31 Dec 1975 12 -16 Jon 1976 27 -3O Jon 1976

+7 a length of I I mm, they have a longer planktonic stage than flor¡nders and thus may be recorded further o from their spawning site. 'o o) f The longer planktonic stage may also be the reason x s o why sole larvae were more numerous than flounder o) o- o) E larvae; over the 2 years almost four times as many sole o o larvae were recorded. Larvae were most abundant in o E o o I.{ovember l97a (Fig. 63), when there was a distinct -o o E _o peak. In 1975 they were less abundant and their f occurrence spread over the study z c) was mofe evenly tt', period.

Oct Feb

Fig. 57: Numbers ofpleuronectid eggs taken by cruises, 1974-75 and 1975-76. Sea bottom temperatuÌes for the spawning area are also shown.

Fig. 58: Flounder Rhombosolea plebeia or R. Ieþorina larva (5.3 mm).

1-2 2- 5 5 -r0 No. below l0 m'

Fig. 59: Cumulative distribution of flounder larvae. Left: 197+-75. Right: 1975-76.

+8 Family Balistidae r50 1974-75 Leather jacket Nouodon conuexirostris (Bloch and r00 Schneider, l80l) Egg.. The leather jacket egg is described in o Robertson (1975) . (The egg has a diameter of 0.650- -g 0.725 mm; a non-segmented yolk; and a single oil o droplet of 0.150 mm diameter.) Eggs with a size range (¡) _o oÍ. 0.644.74 mm and a single oil droplet of 0.13- E 0.18 mm diameter were commonly taken during this zf study and were assumed to be those of the leather jacket. These eggs (Fig. 6a) had a remarkably clear yolk, surrounded by a perivitelline space which was 0.06-0.08 mm in the early stages, but much less in 11529 1226 1024721 4 Iater stages. In the advanced egg the oil droplet was Ocl Nov Dec Jon Feb placed posteriorly. The embryo was transparent, the only pigmentation being two lines of inconspicuous Fig.60: Numbe¡s of flounde¡ laNae taken by cruises, 1974-75 dorsal melanophores. and 1975-76.

Fig. 61: Speckled sole (Peltorþamphus latus) larvae (4.2, 10.0 mm).

Leather jacket eggs were one of the commonest steady decline in spaLwning intensity as the sea types and were taken on every cruise in both years. temperature rose. The egg distribution in 197+-75 The seasonal variation in egg production (Fig. 65) has showed spawning to b,e centred in the central and been adjusted Íor the effect of temperature and is for northern parts of the strrdy area, with eggs rare in the an equivalent area in both years, so that production in south of the gulf, particularly later in the season. This the 2 years can be directly compared. Leather jacket is consistent with the ilistribution of adults observed was a spring spawner in the Hauraki Gulf, with a from trawling in the area. In 1975-76 spawning was peak in egg numbers during October, and thereafter a again heaviest in the northern half of the study area,

49 i::::::::::i:l::::::: ii:!:iii¡iii::iii:i:i: ffiN 2-5 s ió ro-20 20-50 No. below '10 m'

Fig. 62: Cumulative distribution of speck- led sole larvae. Left: 1974-75. Right: t975-76.

but there was another centre near the entrance of the Firth of Thames (Fig. 66) . The numbers of leather jacket eggs were much greater than was expected from the quantity of this species which is taken during fishing in the Hauraki Gulf. The species is known to be common close in shore, particularly among weed- 0) o covered rocks (Graham 1956, page376). Possibly this is much the year, and only moves _9 its habitat for of it o off shore for spawning.

0) _o Larvae. The leather jacket larva is recognisable E zf from an early stage by the prominent dorsal spine and the band of pigment near the tail (Fig. 67 top). Older Iarvae (Fig. 67 bottom) are unmistakably junior versions of the adult.

The number of larvae taken in both years was low, particularly compared with the abundance of the r1529 1226 1024721 4 ãggs. A *ide tange of sizes, up to juveniles 25 mm Oct Nov Dec Jon Feb long, was taken. The cumulative distributions for the 2 years are shown in Fig. 68. In both years the larvae Fig. 63: Numbers of speckled sole larvae taken by cruises, 1974-75 and 1975-76. were commonest close to the spawning centres.

20

o -o ID l8- c, x f o, ló o d) (, t¡) Â E o 14 o o -o E E o l o z -o o r¡, a/,

15 29 12 26 l0 24

t.l l]tu ilu lll Fig. 65: Number of ieathe¡ jacket eggs within the study area at Fi¡¡.64: Leather iacket (Nooodon convexitostris) eggq. the time of sampling for each cruise, 197'[-75 and 1975-76'

50 21 -25 Oct 1974 18 -22 Nov l9Z4

1þ4/\ -r.\- V 16-2O Dec1974 6 -1O Jon1975

s00 - >1000 r000

No. below l0 m2 *ffi 20-23 )o¡ 1975 Fig. 66: Distribution of leather jacket eggs by cruises, 197+-75

5l ':::::::::::

:i::rli::::i:

,l975 6 -10 Ocl' 1975 20 - 24 oct 1975 3-7 Nov

I 7 - 2l Nov 1925 15-19 Dec 1975

29-31 Dec1975 12 -16 Jon 1976 27-3O Jon 1976

Fig. 66 (continued): Distribution of leather jacket eggs by cruises, 1975-76 (see key on previous page).

52 Fig. 67: Leather jacket (Notlodon conrexirostrk) larvae (4.5, 6.7 mm).

53 t-2 2- 5 5 -10 No. below l0 m2

Fig.68: Cumulative distribution of leather jacket larvae. Leh: 1974-75. Right: 1975-76.

Family Diodontidae a moderately segmented yolk (James 1976). Another Porcupine lish Allomycterus jaculiferus (Cuvier, l8l8) possibility is that they are the eggs of the koheru Lawae and juveniles of this species were (Decaþterus koheru (Hector, 1875)), a carangid whose occasionally recorded. eggs have not been described, and which occurs in this region.

Unidentified egg I (Fig. 69) This egg had a diameter of 0.80-0.89 mm; a narrow perivitelline space; a segmented yolk; and a single, pale yellow oil droplet, 0.20{.25 mm in diameter. During the early stages of development this egg was very conspicuous because of the large, strongly marked segmentation of its yolk; as the egg developed the segmentation became smaller and less prominent. Later stages were difficult to distinguish from those of the jack mackerel Trachurus nouae¿elandiae.

Eggs of this type were taken on every cruise during both years except the first October cruise in 1975. They occurred irregularly, but occasionally were very abundant, with a maximum ol. 8972 being taken in Fig. 69: Unidentified egg I one sample during January 1976. They frequently occurred with large hauls of jack mackerel eggs and were found mainly in the central gulf. The spawning pattern indicates that these eggs are from a schooling species not very com.mon in the study area. The egg Unidentified egg 2 (Fig. 70) characteristics are those of a carangid fish. One This egg had a diameter of 1.12-1,22 mm, a very

,.,.1ilT1,, l. ,1,., ,1,., t. ,1,... ,ï,. ,..""T[, narrow ,.',",L11,". spâce, a ..**.'l.lr"ll, ,'i whose eggs have a diameter''", range of"l 0.76-{.86 mm oil droplet. The advanced embryo is darkly". and an oil droplet of 0.20-0.25 mm diameter, but only pigmented.

54 Fig. 7l: Unidentified egg 3.

Unidentified egg 3 (Fig. 71) This egg had a diameter of l 02-1 .12 mm; a narrow perivitelline space (0.08 mm); a non-segmented yolk; Fig. 70: Unidentified egg 2, and two to eight oil droplets, with a maximum diameter of 0.05 mm. This egg was taken regularly at the outer stations, but never in large numbers. It was most abundant in This egg was very rare and was taken only at the November and December. It may be the egg of a outer stations. It is similar to, but slightly smaller roughy, the larvae of which were occasionally taken than, the egg of the latrid Mendosoma lineatum (see page 22). Guicheirot, lB49 described in Robertson (1975).

55 DISCUSSION

SAMPLING PERIOD The effect of temperature on the number of eggs The October-January sampling period was spawned was not so easy to determine. The number of designed to cover the spawning season of snapper, but stations and volume of water sampled on correspond- it also effectively included the main spawnings of most ing cruises of each year were approximately the same. other species in the Hauraki Gulf. The only Figure 72 shows the crude egg numbers to be similar commonly occurring species whose eggs were not for the 2 years. However, this may not reflect the taken were: John Dory, parore ( tricusþidata actual situation. Apart from the direct effect of (Q,roy and Gaimard, 1824)), spotty, and blue temperature on embryonic period, there may also be maomao (Scorþio aiolaceus (Hutton, 1873) ). John Dory differences in egg mortality between the 2 years. For is known to spawn at this time of year (Robertson snapper, egg mortality over the embryonic period was 1975); it must do so elsewhere. Parore probably 640/o in 1974-75 and 26lo in 1975-?6 (Crossland spawns outside the sampling grid, in muddy, 1980) . Egg mortality probably results mainly from estuarine areas, its favoured habitat. Spotty and blue predation and unfavourable environmental condi- maomao are thought to be winter spawners. tions. It is therefore likely to be similar for different species. If it is assumed that rates observed for snapper apply for other species, it appears that lower EFFECT OF TEMPERATURE ON SPAWNING temperatures reduced ,egg production (Table 3) for Temperature was probably the most important snapper, jack mackerel, and leather jacket (the figures environmental factor affecting spawning in the are derived from egg numbers integrated over the Hauraki Gulf during this study. Table 2 gives a study atea as described previously). Anchovy, summary of the spawning se?sons and preferred however, showed higher production in the colder temperatures for the principal species. The effect of year. This is a short-lived species, and egg production temperature on spawning became apparent only is more likely to be affected by changes in population because there was a noticeable difference in size between years than it is in the other three species, temperature between the 2 years. The effect of lower whose populations are more stable. temperatures in 1975-76 was to delay spawning by During this study all sampling was done in a period some 2 to 4 weeks. This was observable both over all of rising temperature. Consequently, spawning was (Fig. 72) and for individual species, where this could first observed in the south and west of the gulf, those be determined (Table 2) . The sea temperatures at areas quick to warm up early in the spring. An peak spawning were closely similar for the two exception was the spawning of the leather jacket, but seasons, with a mean differeäce of 0.4oc for six species. this was because the species was not so abundant in

TABLE 2: Spawning season and temperatures.for the principal-specie_s in the Hauraki Gulf. Brackets indicate that spawning may begin earlier, or continue later, than the months shown Dates of spawning peaks and Spawning Prefe¡¡edspawning temperatures (oc) Species season temperature ("C) 197+-75 197s-76

Anchovy (Engraulis australis) Nov-(Jan) 18.5-20.5 SS+ 2-6 Dec 20.2 l5-19 Dec 19.4 (Oct)-Nov 16.0-18.0 SS _+ L (Oct)-Nov 14.0-17.0 MST 3-7 Nov 16.2 (Oct)-(Jan) 1s.0-16.5 SBg 2I-25 Oct 15.4 1-5 Dec 15.6 Nov-Jan 16.5-18.5 MS 18-22 Nov 17.3 I5-19 Dec 18.0 Oct-Jan 15.0-17.0 SB 18-22 Nov 16.3 1-5 Dec 16.2 (Oct)-Nov 15.0-16.5 SB Nov-(Jan) (Oct)-Dec 14.0-17.0 SBì Oct-Dec 14.0-17.0 SBf 4-8 Nov I5.5 I7-21 Nov I5.9 (Oct)-Dec 14.0-17.0 SB 2l-25 Oct I5.4 20-24 Oct 15.5 * Sea su¡face.

1 illillillililìlffitflr ] Mean sea. $ Sea bottom.

56 EFFECT OF WAT]ER MOVEMENTS ON DISTRIBUTIION OF LARVAE In the enclosed, inner Hauraki Gulf, tidal movements are more important than long-shore currents. The tidal sitreams run in reciprocal directions on flood and ebb, with the general set of the flood tide being to the south-south-west, but modified in places by the shape of the land. Tidal streams run most strongly off , through the channels between the many islands of the gulf, and, to a smaller extent, in and out of the Firth of Thames. ,o In the outer gulf, on the northern periphery of the x study area, water movements are more aflected by o) o o :- oceanic influences, particularly the East q) Current (Paul 1968). This current, which sets in a o 14€ c) south-easterly direction across the northern part of o E o. the gulf, enters through Jellicoe and Cradock l E z o Channels and passes out through the . There is a gen.eral tendency for currents to 20 7, tJ1 set inwards near large bays, and this probably occurs in the Hauraki Gulf.

Water movements are also affected by the wind, if it blows strongly and fronn the same direction for any Iength of time. To study the possible effect of wind- induced water movements, twice-daily wind data from Tiritiri Matangi Island were analysed. During the two study periods of October to January, the total amount of wind was similar, but there were differences in the proportion from each quarter r1529 1226 1024721 4 (Fig. 73). In 1974-75 the cumulative total of wind Oct Nov Dec Jon Feb speed from rhe two southerly quadrants was 1818 Fig. 72: Numbers of eggs of all species taken by cruises, l97tt-75 knots; in 1975-76 it was 2807, an increase of 607o. For and 1975-76. Mean sea bottom and sea surface temperatures are also shown. the October to December period, those months when larvae were most abundant, the difference was more marked: 1241 knots in 1974, and 2240 in 1975, an Despite these di{ferences, there was the south. During the season, as the northern and increase of B0%. apparent effect on the distribution of larvae. central gulf became warmer, the centres of spawning no true for snapper (Crossland moved there. This was It is difficult to predict the individual effects on jack During the study 1980), ancho\.y, and mackerel. Iarvae of tides, winds, and currents, because of their coincided with the period, the area of coolest water complexity and the lack of detailed knowledge, fish eggs. This cool water area- of. Ieast abundance of particularly about subsurface drift. Flowever, empiri- extended, tongue-like, Iay on the eastern side and cal observations showed there r,r'e¡e three distinct of south from Cape Colville towards the Firth patterns of larval movement in the study area. Thames. The first pattern of leLrval drift showed a north or north-west movement of larvae of those sPecies whose spawning was centred in the Fìrth of Thames. The TABLE 3: Comparative egg production for 197¿L75 anð centre of larval occurrence was about 5 nautical miles t975-76 to the north of the eggs for flounder, l0 to the north- 1975-76 production as 7o west for speckled sole, and l0 to 20 north and north- oî. 1974-75 production Adjusted for west for ahuru. Species Obsened egg mortality Snapper 62 +6 The second pattern was a north or north-east Jack mackerel 100 72 dispersal for those sPecies whose spawning was Leather jacket 67 48 gulf, Anchory 300 218 concentrated in the western Part of the central

57 along the arc from Waiheke to Tiritiri Matangi to Kawau Islands. The centre of larval occurrence was l0 nautical miles to the north of the eggs for snapper, l0 to 15 north and north-east for jack mackerel, and 7 north-east for anchovy. The third pattern was a southward movement of o Iarvae from spawning centres near the northern c periphery crested of the study area. Pilchard and ! o flounder larvae were centred about 20 nautical miles o c from their supposed spawning grounds (to the north ! of the study area), gurnard larvae l0 to the south, and .sÌ blue mackerel 15 to the south or south-west. With o blue mackerel the situation was more complex o f because, though the main egg concentrations were in E the Cradock and Colville Channels, the larvae were u centred in the north-west corner of the study area. llowever, these larvae probably dispersed from an unlocated spawning ground in the Jellicoe Channel to the north. Larvae from the known spawning centre may disperse eastwards through the Colville Channel. The larval movements deduced from these NE sr observations are consistent with a clockwise circula- November Jonuory tion of water in the Hauraki Gulf, presumably under Fig. 73: Monthly cumulative wind speed by quadrant from the impetus of the East Auckland Current after it twice-daily observations at Tiritiri Matangi Island, Hauraki Gulf. Number of occur¡ences shown in italics; seven calm strikes the western side of the Coromandel Peninsula observations in each 4-month period. (Source: New Zealand and is deflected southwards. Meteorological Service.)

SUMMARY

The results of 2-weekly plankton cruises in the Iarvae on 9 cruises in 1975-76. Nineteen kinds of eggs Hauraki Gulf from October to January lor 1974-75 and27 of larvae were recognised. Figures are given of and 1975-76 are presented. About 50 stations were all eggs and larvae not previously illustrated in the sampled on each cruise by oblique tows of a cyli-.der- published literature. The distribution, abundance, coné plankton net with a mouth area of 0.25 m2. AII and seasonality of each species are discussed fish eggs and larvae were sorted and counted. Totals separately. The effects of temperature on spawning, of 583 000 eggs and 55 000 larvae were collected on and water movements on the distribution of larvae, 7 cruises \n 1974-75, and 589 000 eggs and 79 000 are also considered.

58 RH.FERENCES

AHLSTRoM, E. H., and B,ALL, O. P" 1954: I-ìescription of eggs and Jauns, G. D. 1972: Revisicn of the Nex. Zealand fiarfish lan¿ae of jack mackercl (Trachurus symmetricus) and Peltarhamphur u.irh descriptions of tw'o new specíes. Copeia distribution and abunrlance of larvae in l9li0 and i951. 1972 (2): 345-55. Fishery tsulletin, U.S. Fish and Wildlife Senice 56 (97):2A9.--ó,5. ..-...... _1976' Eggs and lzwae oÍ. the trevally Caranx georgianus Aviso, J. C", and Krrlo, G. B. 1973: Phosphogluccse isome¡ase (Teleostei: Carangidae). N.Z. Joumal of N4arine a¡d Freshuater gene duplication in the bony fishes: an evolutionaw historl- Research l0 (l: 3AI-IA. Biochanical Genetits I (2): 113-32. JTLLETT, J. B. 1968: The biology ol AcantlzocLinus quadridactllus B¡Ji.tR., A. N. 1972: Reproduction, early lilc histo4,, and age- (Bloch and Schneider) (Teleostei-Blennioidez). II Breed- growth ¡elationships of the Nev¡ Zealand pilcharcì, Sarriinoþs ing and deveiopment. Au.stralien taumø! oJ Marine and neoþilchardus (Steindachner). Fi: h¿ries Res ¿srch Bull¿tàn, N. Z. Freshwat¿r Research 19 (I): 9-18. Marine Deþartment, Na. 5. 64 pp. KR{MDR, Ð. 1960: Devetropment of eggs and la,ruae o{ Pacific ----1973' Spawning and development of the |ie*'Zealand sprat, mackerel and dist¡i'outi,>n and abundance oi laruae 1952-56. Sþrattus anlíþodum (Hector). Zoalogy Fublications from Victoria Fishery Bulleti;t, Lr.,S. .Fiså anti Wíldlit'c Saúæ 60 (171):393- UniaersiÍy of Wellington, Nc. 62. 12 pp- +JÚ. CAssIE, R. I\4. 1956a: Spaming of the snapper, Chryscþhrys aurotus MITo, 5. i963: Peiagrc fish eggs fron Japanese waters-Vlll Forster, in the Hau¡aki Gulf. Trartsaúiore o.f the R.oyal Sociery af Cottina. Japanese Journt:l cf lchtlryoíog, XÌ; 65-79. N.z. 84 (2):3a9-2a. l{ELSoN, J. S. i976: "Fishes o{ the Wo¡ld." -\r'r¡iley-Inrerscience Early develooment of the snapoer, Chryrsop¡rt ourt* Publ ley and Sons, Ne'r' York. 416 pp. Forster. ].-ransactions af íhe Roya! Socittl' of N.Z. 83 (4):705-13. NoRMAN, J stematic Monograph o{ the CASTI-E, P. H.J., and R.osnt'rsoN. D. A. 1974: lìa¡1)¡ lifc history of (Het I Psettodidae, Bóthi.dae, Pieuronec- -1956b'the eels Gnathophis habenalus and G. incognilus in New ddae." British Museura, London. 459 pp. congrid -1. Zealand waters- N.Z. fotmal of Maine and Fresht¡.taler Research PAUL, L. Ì968: So¡ne seasor¡al watei temperature patterns in the 5 (lJ: 9s-110. Hauraki Gulf, New Zealand. N.Z. lournal of Marine and CoLMAN, J. A. 1973: Spa'oning and fecuncliry of tn'o flounder Fr¿shuater R¿seardt 2 (3:): 535-58, species in the Hauraki GulÍ, New Zealand. N.Z. jownai af R.oenx.'rsoN, D. A. 1973; Pianktonic eggs and larvae of some New lluine and Freshuai¿r Research 7 (] &. 2): 2143. Zealand marine teieostri. (Ph.D. thesis, lodged in University Spawning of the sprat, Sþrùttus antiþodtm (F{ector), of Otago li'orary.) --1979'round the Soi¡.th Island of Nern' Zealand. ¡'¡.¿. .loti.nal oj A key to the plânltonic eggs of some Nerv Zealand Marine and Fr¿shwatcr Rcsearch l.t (2): 263-7?-. marine teleosts . Fí.çhei¿s Res¿arch f)iaision Occasionel Publica- CRossLAr.rD, j. 1980: Tb.e number oÍ snapper. Chrysaþhrys auratus -.-1915'tion, N.Z. ì,Íinisiry of Aginlturc and Fisheies, tVo. 9. 19 pp. (Forsier), in the Hauraki Guii, Ne-w Zealand, based on egg Hydroiogy ani the quantitative distribution of su:veys in 1974-75 an¿l 1975-76. Fishen¿¡ ]ì.esearch Bul.letin, pianktoni.c eggs of sonte r.arine fishes of the Otago coalt, N.Z. IvÍinistry o! Agrinlture and Fishtries, No. 22. 38 pp" south-eastern New Zealand- Fí.¡heies Res¿arch Bull¿tin. N.Z. Demct, P. R.. 1974: Distribution of muitiple giucosephosphate -1980'NIinistry af Agia;lk*e and Fisheries, No. 2J. 69 pp. isornerases in teieostean lishes. Çomþarutiue Eioclztmistry ane Roannlsom, D. 4., and R¡J, L. l97I: Egg and yolk sac stages of the Fh¡siolagy 478: 663-79. sand Ilounder (Telcostei: Pieuronectid.ae) . N.Z. Joumal of Donr, W. 1972: "Fishes of the Nerv Zealand R'egion." Hodde¡ anC Marine and Fr¿shu¡st¿r lTesearch 5 (3 & 4): +04-l+. Stoughton, Auckland. 132 pn. SMITH, P. J., and Cnossr.rtrr, J. i977: Ider,tification of larvae of ELDER, R.. D. 1966: Lârva1 teleosts in rhe plan-ktcn oi Weìiington snapper Chrysaþiir7s auratu.r Forster b;r eìectrophoretic Ilarbour. (I\{.Sc. thesis, Ioclged in Victoria I]niversitv of sepaiation of tissue en:rymes (note). -N-..Z. lounal af Marine Wellington library.) and Freshuater Res¿arch 11 (4): 795-A. Studies on age anci gtowth, reproduction, and Sr.ttre, A. i939: Contribj:ro alla conoscenza dello sviluppo popuiation dynamics of red. gurnard, Chelidonichthys kumu embrionale e post-emb,rionale nei Mu¡enoidi YI Oplzinrus --1976'(Lesson and Garnot), in the Hauraki Gulf, Nerv Zaalztd. serþms L. R. Comihtta Talassografico Iîaliano Mmaia Fisheries Re¡¿arch Bull¿tin, N.Z. Ministry of Agrialture anl CCLXVII" 12 pp. [ìn ltalian.] Fisheix, No. 12. 77 pp. SrnrnrssoN, .4. B., and Rctrnrsox, Ð. A. 1-077: The New Gnanen, D. H" 1956: "A Treasury of New Zealand Fishes", 2nci Zealand species of Trachunts (Pisces: Carangidze). Journal of editicn. A. II. and A. W. Reed, Wellington. 42+ pp. ihe Royal SocixT o.f N.Z. 7 (2): 2+3-53. Gnrrnrt, L. T. 1933: Studies in New Zeaiand fishes. Transactíans and Praeeedings of thc N.Z. Institut¿ 63 (3): 330-3"

ACKNOWLEDGMENTS

I thank D. A. Robertson for help in identiliying eggs contour maps; A. I" Tornlinson of the New Zealand and larvae and, with J. A. Coiman, for helpful reviews Meteorological Service for weather data; and all those oÍ the manuscript; J. Carruthers for Figs. I and 73 who helped in the sorting of the plankton samples. and the histograms; J. D. Hadfield for Fig. 2 and the

59 INDEX

Abundance, 12, 13-36, 3843, 45-52, Embryo, 20,27,29,35, 36, 38, 49, 54' Larval distribution, effect of weather on, 54-55, 57. Embryonic period, 12, 13, 43, 56. 34. Acanthoclinidae, 24-26. on, 57. Engraulidae, 13-14. Larval dist¡ibution, effect of wind Acanthoclinus quadridactylus, 13, 24-26. Larval Engraulis australis, 13-14, 56. drift, 2+, 57-58. A. trilineatus, 13, 24-26. Europearl waters, 17. Latrid, 55. Adult, 12, 17,21,2+,29, 31, 36, 46, 49, 50. Exocoetidae, 22. Leather jacket, 13, +9-5+, 56, 57. Ahuru, 13, 20-21,22,23,24, 56,57. , 10, 19. Aldrichetta forsterí, 13, 34, 35. Long-snouted pipefish, 13, 23. Firth of Thames, 1 0, I 3, 20, 43, +6, 50, 57 . Allomyctcrus jactliferus, 13, 54. Lophonectcs gallus, 13, 4HI, 43, 44. Flounder, ll, Ì3, 4l-48, +9, 56,57. Anchovy, 13-14, 15, 16, 27, 56, 57, 58. Lycodontis prasinus, 1,7. Amoglossus scapha, 40, 41. Flounder, crested, 13, +o-4.I, +3, 44, +5, 58. Auchenoceros þunctatus, 13, 20-21, 22, 56. Flounder, sand, 4l-43. Mackerel, blue, 13, 3840, +1,42,56,58. Flounder, yellow-belly, 41-43. Mackerel, jack, 13, 26-31, 3+, 54, 56, 57, Balistidae, 49-54. Folsom splitter, 11. 58. Barracouta, 13, 38. Mackerel, Japanese, 38. Blennies, 13, 36. Mackerel, Pacific, 38, 39. 13, 2+. 13, Garfish, 22, Blenniidae, 36. Maomao, blue, 56. Gempylidae, 38. mackerel, 13, Blue 38-40, +1,42,56,58. Marlborough Sounds, 17. Gmyagnus monoþtcrygius,13, 35-36, 37, 56. Blue maomao, 56. lineatum, 55. Girella tricuspidata, 56. Mendosoma Bothidae, 40-4]. Moray eel, 13, 17-20. Gnathophis, 13. Breeding season, 17, 34. Moridae,20-21. G. habcnatus, 20. Mortality, egg, 32, 56, 57. G. incognitus, 20. Cape Colville, 10, 57. Motukawao Group, 10, 46. Grahamichthys radiatus, 13, 38. Cape Rodney, 10, 27. Motutapu Island, 10, 43, 46. Graham's gudgeon, 13, 38, 39. Carangidae, 26-31, 54. MugíI cephalus, 13, 34. Great Barrier Island, 10, 19,27, +1.. Caranx georgianus, 27. Mugilidae, 34. Grey mullet, 13, 34. Carapid, 13. grey, 13, 34. Gudgeon, Graham's, 13, 38, 39. Mullet, Chelidonichthys kumu, 13, 23-2+, 56. yellow-eyed, 13, 34, 35. Gurnard, 13, 27, 58. Mullet, Chrysoþhrys auratus, 11,13, 31-34, 56. 17-20. Gurnard, red, 13, 23-2+,25, 56. Muraenidae, 13, Clinidae, 13, 36. Clupeidae, l4-17. Nooodon conacxirostris, 13, 49-54, 56. Colville Channel, 10, 2+, 57, 58. Hiþþocampus abdominalü, 13, 23. Congridae, 20. Hyþorhamþhus ihi, 13, 22, 24. Omaha Bay, 10, 43. Copepod,21. Optiaus clongatus, 23. Co¡omandel Peninsula, 10, 20, 58. 12, Ichthyoplanlton, 11, 21, 36. Otago coast, 11, 17. Cradock Channel, 10, 17,24,57,58. Otago waters, 20. Crested flounder, 13, 4041, +3, 44, +5, 58. Jack mackerel, 13,26-31,34, 54, 56, 57, Currents, effect on lawal distribution, 27, 58. 34, 57-58. Pacific mackerel, 38, 39. Japanese mackerel, 38. Pacific, north-eastern, 27. Jellicoe Channel, 10, 17, 57, 58. Parore, 56. D¿caþterus koheru, 54. John Dory, 13, 23, 56. Diodontidae, 54. Peltorhamþhus, 43, +648. Juvenile, 11, 17, 21, 23, 29, 3+, 38, 50, 54. Iatus, 13, 56. Distribution, I 1, 12, 13-36, 3843, +5-52, P. 4143, +648,49, 5,t-55, 57. P. nouae4elandiae, 46. Kauri Point, 10, 17. P. tenuis, 46. East Auckland Current, 57, 58. Kawau Island, 10, 13,27,34, 58. Pilchard, Ì1, 13, 14-17, 18, 19, 27, 56, 58. Echiodon sp., 13. Koheru, 54. Pipefish, long-snouted, 13, 23. Eel, moray, 13, 17-20. Plankton, ll, 34, 39, 41, +3, +8. Eel, sand, 13, 20. Plankton net, 11, 21. Labridae, 34. Egg counts, 11, 13. Plankton suweys, 11. Lawal dispersal,23,26, +1, 57, 58. Egg mortality, 32, 56, 57. Pleuronectidae, 4l-48. lr Larval distribution, effect of currents on) lrrl l* o.oJ,,",lo', 1t, 1â, l¿, t?, 4ô, t¿, lt. 27,94,57-58. Porcupine fish, 13, 54. Eggs, unidentified, 5,t-55. Larval distribution, effect of tide on, 34, Electrophoretic analysis, 12, 31, 36. 57. Production, egg, 12, 13, 1+,27,49, 56, 57. Larual distribution, effect of water move- Pseudolabnts c¿lidotus, t3, 34, 35. Eleotridae, 38. ments on, 21, 4I, 57-58. 60 Rakino Isiand, 10, 27 Spawning, 13, 14, 15, 17,19,23,24,26,27, Tiritiri Matangi Island, 10, 27, 34, +1, +3, +9, 56. 57, 58. Rangitoto Island, 10, 46. 32, 3+, 39, +3, 46, 54, Trachichthyidae, 13, 22-23, 24. Red gurnard, 13, 23-2+, 25, 26. Spawning area, 11, 13, 15, 20, 21, 22, 23, 24,25,27,34, 39, 41, +3,46, +8, +9,50, Trac,hurus, 12, 26-31. Rhombosolea, 12, +346. 56, 57, 58. T. decliais, 13, 26, 27-29, 31. R. Ieporina, 13, 4l-43, 48, 56. Spawning, effect of tempe¡atu¡e on, 56-57. T. mcallochi,26. R. plebeia, 13, 4l-43, 48, 56. Speckled sole, 13, +143, +648,49, 50, 56, T. nouae¿elandiae, Rockfish, 13,2+-26. 13, 26-27 , 28, 29, 30, 31, s4, 56. Roughy, 13, 22-23, 2+, 55. Spotted stargazer, 12, 13, 35-36, 37, 38, 56. T. rymmetriczs, 27. Spotty, 13, 34, 35, 56. Trevally, 27, 54 Sampling technique, 11. Trig.lidae, Sprat, 11, 13, 14, 15, 17, 19. 23-24. Sand eel, 13, 20. Sprattus antþodun, 13, 14, 15, \7. Tripterygiidae, 13, 36. Sand flounder, 4l-43. Stargazer, spotted, 12, 13, 35-36, 37, 38, Sardinops neoþilchardus, 13, l4-17, 56. 56. Unidentified eggs, 54-55. Scomber auslralasiats, 13,38-40, 41, 56. Stigmatlphlra longirostris, 13, 23. IJranoscopidae, 35-36. Scomber japoniats, 38, 39. Stock size, 11. Scombridae, 38-40. Study area, 12, 13, 15, 17, 19,20,22,23, Waiheke Island, 10, 13, I7, +3, 58. Scorpio uiolacets, 56. 27,29,3+,38, 39, 41, 49, 50, 54, 56, 57, Water movements, effect on larval dis- 58. tribution, 21, +I, 57-58. Seahorse, 13, 23. Survey stations Il, 12, 17 22, 38, 39, +0, Weather, effect on larval distribution, 34. Seasonality, l3-36, 38-43, +5-52, 54-55, , , 41, 55, 56. 56,57. Wind, effect on lawal distribution, 57. Syngnathidae, 23 Slender roughy, 23. Witch, 40. Snapper, It, 12, 13, 1+, 27, 3I-34, 39, 56' 57, 58. Tasman Bay, 11, 17. Yellow-belly flounder, 4l-43. Sole, 43, 46. Temperature, 1 l, 13, 14, 15, 17, 20,22, 23, Yellow-eyed mullet, 13, 34, 35. 29, +3, 48, 49, 57. Sole, speckled, 13, +143, +648, +9, 50, 25, 27, Yellow moray eel, 17. 56, 57. Temperature, effect on spawning, 56-57. South Island, 1 I Thyrsites atun, 13, 38. Zetdae, 23. Sparidae, 3l-34. Tide, effect on larual distribution, 34, 57. Zeus japonins, 13, 23.

6l Bulletins of the Fisheries Research Division No. 1. The New Zealand . By D. E. Gaskin. Published in 1968. 92 pp. 2.Galaxias maculatus (Jenyns), the New Zealanò whitebait. By R. M. McDowall. Published in 1968. 84 pp. 3. Phytoplankton productivity in Tomahawk Lagoon, Lake Waipori, and Lake Mahinerangi. By S. F. Mitchell. Published in 1971. 87 pp. 4. Some aspects of the bionomics of fish in a brown trout nursery stream. By C. L. Hopkins. Published in 1970. 38 pp. 5. Reproduction, early life history, and age-growth relationships of the New Zealand pilchard, Sardinoþs neoþilchardus (Steindachner). By AIan N. Baker. Published in I972. 64 pp. 6. The biology oI the New Zealand tarakihi, Cheilodactylus macroþterus (Bloch and Schneider). By L. J. Tong and C. M. Vooren. Published in 1972. 60 pp. 7. An analysis of the statistics on the fishery for tarakihi, Cheilodactylus maøoþterus (Bloch and Schneider), in New Zealand waters from 1936 to 1969, with notes on the trawl fishery in general. By C. M. Vooren. Published in 1974. 44 pp. 8. Lakes Rotorua and Rotoiti, I{orth Island, New Zealand: Their trophic status and studies for a nutrient budget. By G. R. Fish. Published in 1975. 72 pp. 9. A survey of the taraki}ni, Cheilodactylus mauoþterus (Bloch and Schneider), in the East Cape area, New Zealand,26-30 March 1971. By C. M. Vooren and L. J. Tong. Published in 1973. 28 pp. 10. The relation between primary productivity, nutrients, and the trout environment in some New Zealand lakes. By A. M. R. Burnet and Denise A. Wallace. Published in 1973. 28 pp. ll. Biology and distribution of the toheroa, Paþhies (Mesodesma) uentricosa (Gray). By P. Redfearn. Published ín 1974. 51 pp. 12. Studies on age and growth, reproduction, and population dynamics of red gurnard, Chelidonichthys kumu (Lesson and Garnot), in the Hauraki Gulf, New ZeaIand. By R. D. Elder. Published in 1976. 77 pp. 13. A study on age, grpwth, and population structure of the snapper, Chrysoþhrys auratus (Forster), in the Hauraki Gulf, New Zealand. By L. J. Paul. Published in 1976. 62 pp. 14. Variations in growth, mortality, and population density of snapper, Chrysophrys auratus (Forster), in the Hauraki Gulf, New Zealand. By C. M. Vooren and R. F. Coombs. Published in 1977. 32 pp. 15. The commercial fishery for snapper, Chrysoþhrys auratus (Forster), in the , \Tew Zealand, from 1900 to 1971. By L. J. Paul. Published in 1977 .84 pp. 16. A bibliography of the literature about New Zealand's marine and freshwater commercial fisheries, 1840-1975. By L. J. Paul. Published in 1979. 43 pp. 17. Age, growth, and condition of the common river galaxias, Galaxias uulgarisStokell, in the Glentui River, Canterbury, New Zealand. By P. L. Cadwallader. Published in t978. 35 pp. 18. Tagging experiments on the sand flounder, Rhombosolea þlebeia (Richardson), in Canterbury, New Zealand, 1964 to 1966. By J. A. Colman. Published in 1978. 42 pp. 19. Thèlife history oÍ Neochanna aþoda Gid,nther (Pisces: Galaxiidae). By G. A. Eldon. Published in 1978. 44pp. 20.The ecolog'y of whitebait migrations (Galaxiidae: Galaxias spp.). By R. M. McDowall and G. A. Eldon. Published in 1980. l7l pp. 2I. Hydrology and the quantitative distribution of planktonic eggs of some marine fishes of the Otago coast, south-eastern New Zealand. By D. A. Robertson. Published in 1980. 69 pp. 22. The number of snappei, Chrysoþhrys auratus (Forster), in the Hauraki Gulf, New Zealand, based on ègg surveys in 1974-75 and 1975-76. By J. Crossland. Published in 1980. 38 pp. 23. Fish eggs and larvae òÎ the Hauraki GuIf, New Zealand. By J. Crossland. Pubtistred in 1981. 61 PP.

P. D HASSELBERG, COWRNMENT PRINTER, WELLINGTON, NEW ZEAL.AND_Ig8I 50336C- 1200,/7,/80PT