Sharks caught in the protective gill nets off Natal,South Africa. 3. The shortfin mako shark Isurus oxyrinchus (Rafinesque)

Between 1966 and 1989,255 shortfin mako sharks Isurus oxyrinchus were caught in the gill nets which protect the tourist beaches of Natal. The catch rate showed no trend, fluctuating about a mean of 0,34 sharks·km-net^?1·year^?1. Catches were highest between May and November, when the water tends to be cooler. The sex ratio was 1,4 males to 1 female. Specimens ranged in size from 84 to 276 cm precaudal length, with a mode of 191–195 cm for males and 251–255 cm for females. Males matured at 160-170 cm and females at approximately 220 cm. Catches included two recently fertilized females and two with well-developed embryos. External injuries were found on 14 per cent of males examined and 41 per cent of females. Elasmobranchs were the most common prey category, occurring in 60 per cent of stomachs containing food, followed by teleosts at 40 per cent. Most of the elasmobranch prey were sharks shorter than 1 m.     

Two new species of hatschekia (copepoda,dichelesthiidae) from New Zealand waters

Two new species of Hatschekia Poche, 1901 are described from New Zealand specimens of Allomycterus jaculiferus (Cuvier, 1818) and Lepidopus caudatus (Euthrasen, 1878) respectively. Comment is made on the need for revision within the genus Hatschekia.     

Distribution,seasonality, lengths,and feeding behaviour of whale sharks (Rhincodon typus) observed in New Zealand waters

Data from 36 whale shark (Rhincodon typus Smith, 1828) sightings off north‐east North Island, New Zealand are summarised. Sightings were concentrated over the outer shelf and shelf break in areas influenced by the East Auckland Current at sea surface temperatures (SST) of 21–24°C. Sightings occurred from late spring to early autumn (November‐April) but were most frequent in midsummer (February) when upwelling along the north‐east shelf is weakest. The data indicate whale sharks occur off north‐east New Zealand most summers, including those when SST is colder than usual. A cluster of sightings and three observations of whale sharks feeding on schools of anchovy (Engraulis australis) near Whale Island, Bay of Plenty, suggest whale sharks may aggregate seasonally in this area. Estimated total lengths (TL) of 26 whale sharks ranged from 3.5 to 15 m, with 73% between 6 and 9 m TL.     

Effect of size grading on the growth performance of shortfin eel (Anguilla australis) during its yellow stage

It is generally believed that size grading in a fish farm improves the total biomass output, because it will minimise the stress imposed by larger individuals over small individuals, resulting in higher feed intake and growth rate. The objective of this study was to evaluate the effect of size grading on individual growth performance of yellow New Zealand shortfin eel (Anguilla australis). A 109 day trial was conducted in a recirculation aquaculture system (RAS) with 103 eels of similar initial weight (101 ± 12 g). All eels were individually marked by PIT (passive integrated transponder) tags. On day 42, eels were graded to establish the following groups: only small eels (S-graded ≤ 135 g), only large eels (L-graded > 135 g), and small and large eels together (S-ungraded and L-ungraded). The large eels showed better specific growth rate (SGR), feed intake (FI) and feed conversion ratio (FCR) than the small eels. Nevertheless, no significant differences were found either between L-graded and L-ungraded or between S-graded and S-ungraded. The age of eels was not significantly different between groups. These findings suggest that the individual growth rate performance of the eels is not primarily a consequence of social interaction among tank-mates.     

New Notodelphyidae (Copepoda: Cyclopoida) from New Zealand solitary ascidians

The male of Doropygus platylhorax Jones, 1974 and two new species of Doropygus (D. louisae and D. spinosus) are described and illustrated. The specimens of Doropygus described by Schellenberg (1922) as D. pulex are assigned to the new species D. louisae. Specimens of Ophioseides (Scolecimorpha) joubini described by Schellenberg (1922) have been re‐examined together with fresh material, and have been described as a new species, Ophioseides schellen‐bergi.     

First record of Lepidocybium flavobrunneum (Pisces: Gempylidae) from New Zealand

Lepidocybium flavobrunneum (Smith, 1849) is widespread in warmer oceanic waters and has recently been recorded in the catches of tuna longline vessels in the New Zealand region. Twenty‐five specimens were caught at 31°46′‐32°03′S, 170°49′‐171°11′ E on 23–27 June 1979, thus extending the known range of the species to northern New Zealand.     

A new echiuran species Thalassema malakhovi (echiura) from New Zealand

A new echiuran Thalassema malakhovi, collected at 20 m depth off the Bay of Plenty, New Zealand, is described. The possibility of using the structure of the nephrostome for subgrouping Thalassema species is discussed. The generic diagnosis of Thalassema Pallas is given.     

First record of the crocodile shark,Pseudocarcharias kamoharai (Chondrichthyes: Lamniformes), from New Zealand waters

Commercial tuna longline fishing targeting bigeye tuna, Thunnus obesus (Lowe 1839), on the Three Kings Rise, northern New Zealand, resulted in the bycatch of a single specimen of a mature male crocodile shark, Pseudocarcharias kamoharai (Matsubara 1936). This is the first record for the New Zealand Exclusive Economic Zone, and a major southern range extension of the species in the Indo‐Pacific.     

The two species of sprat in New Zealand waters (Sprattus antipodum and S. muelleri)

Two broadly sympatric species of sprat are shown to inhabit New Zealand waters, the more slender Sprattus antipodum (Hector, 1872) and the more common and deeper‐bodied S. muelleri (Klunzinger, 1872). Overlap in most morphometric and meristic characters had earlier led to their synonymy, but recent protein analysis suggested otherwise. This is now confirmed by distinct differences in shape and dentition of the basihyal plate, vertebral numbers, scale sculpture, and fresh colour. The five known species of Sprattus are keyed and the genus diagnosed and discussed.     

Genetic and morphological evidence for a single species of pink ling (Genypterus blacodes) in New Zealand waters

Two species of ling, Genypterus blacodes (Forster in Bloch & Schneider, 1801) and G. microstomus (Regan, 1903) have been recorded from New Zealand and Australian waters; a third species, G. tigerinus (Klunzinger, 1872) has been recorded from Australia. Specimens of ling collected from northern, central, and southern localities in the New Zealand Exclusive Economic Zone (EEZ), and specimens of G. blacodes from Australia were shown to be similar with respect to partial sequences of mitochondrial (mt)DNA, and morphometric and meristic characters. DNA sequences of part of the cytochrome b and control region showed that G. blacodes from Tasmania and New Zealand differed by 1/291 and 4/284 nucleotides respectively, but there was much greater genetic differentiation between G. blacodes and G. tigerinus (14/291 and 14/284 nucleotides), and between G. blacodes and G. capensis (23/291 and 8/284 nucleotides). MtDNA haplotypes within New Zealand show that G. blacodes is subdivided into northern and southern stocks. It is concluded that ling in New Zealand represent a single species referable to G. blacodes, and that G. microstomus Regan is a junior synonym.     

From Vagrant to Resident: occurrence,residency and births of leopard seals (Hydrurga leptonyx) in New Zealand waters

ABSTRACT

In contrast to previous reports that leopard seals (Hydrurga leptonyx) are rare vagrants to New Zealand, we show that this species is a regular member of the marine fauna of this region. We present a first analysis from the New Zealand Leopard Seal Database – an extensive collation of 2,711 records of leopard seals within New Zealand between 1200 and 2018. Of these records, 51.2% (n?=?1,408) were photographic. Leopard seal sightings have increased over time and been reported in all seasons and regions of New Zealand. Sightings are predominantly of adult individuals of good or excellent body condition, which differs to previous hypotheses suggesting that leopard seals visiting New Zealand shores are primarily juvenile animals in poor health condition. A total of 176 unique individuals have been identified in the New Zealand Leopard Seal Catalogue between 2014 and 2018 and preliminary results indicate that numbers per annum have continued to increase over time. Three leopard seal births and a number of juvenile animals (34% of the NZ records) have been documented. Considering the information presented here and the current definitions in the New Zealand Threat Classification System, the threat status of leopard seals within New Zealand waters should be reclassified from Vagrant to Resident.     

Ocean acidification in New Zealand waters: trends and impacts

The threat posed by ocean acidification (OA) to the diversity and productivity of New Zealand marine ecosystems is assessed in a synthesis of published trends and impacts. A 20-year time series in Subantarctic water, and a national coastal monitoring programme, provide insight into pH variability, and context for experimental design, modelling and projections. A review of the potential impact of changes in the carbonate system on the major phyla in New Zealand waters confirms international observations that calcifying organisms, and particularly their early life-history stages, are vulnerable. The synthesis considers ecosystem and socio-economic impacts, and identifies current knowledge gaps and future research directions, including mechanistic studies of OA sensitivity. Advanced ecosystem models of OA, that incorporate the indirect effects of OA and interactions with other climate stressors, are required for robust projection of the future status of New Zealand marine ecosystems.     

Marine invertebrate hosts of New Zealand Anisakidae (Nematoda)

Possible invertebrate intermediate hosts of Anisakis simplex (Rudolphi, 1809, det. Krabbe, 1878), Thynnascaris adunca (Rudolphi, 1802), and Pseudoterranova (= Phocanema) decipiens (Krabbe, 1878) were determined from examination of stomach contents of teleosts which are regularly infected by these parasites. The euphausiid, Nyctiphanes australis, and the galatheid crab, Munida gregaria, are possible sources of A. simplex larvae. M. gregaria is a definite source of T. adunca larvae (and adults). Smaller zooplankton (e.g., copepods and decapod larvae) could also be sources of T. adunca larvae. No potential hosts of P. decipiens larvae were apparent. Naturally occurring invertebrate hosts of anisakids were found in plankton samples. A. simplex larvae were found in N. australis. T. adunca larvae occurred in chaetognaths (Sagitta spp.), a medusa, and a decapod larva. These anisakid larvae are all morphologically similar to Stage III larvae from teleosts. Experimental infection of N. australis and M. gregaria with Stage II larvae of A. simplex and T. adunca was unsuccessful. Infection rates, host specificity, and larval morphology are discussed.     

Records of subantarctic fur seals in New Zealand (Note)

Subantarctic fur seals (Arctocephalus tropicalis) appear as stragglers on New Zealand coasts. Four records are noted, the most recent at Antipodes Island in December 1989.     

Neophrynichthys heterospilos,a new species of fathead sculpin (Scorpaeniformes: Psych rol utidae) from New Zealand

A second species of Neophrynichthys is described from 20 specimens collected from the Campbell Plateau, south of South Island, New Zealand. It differs from its sole congener, N. latus, in having 25–26 pectoral rays (versus 22–24), cirri on head more than twice as large, half as few (c. 50 versus >100), and generally absent from the mid‐region behind the eyes (versus being relatively dense), and in spotted colour pattern covering much less than 50% of the dorsal surface of the head (versus >50%). This new species is the sixth psychrolutid known from New Zealand. The genus Neophrynichthys is formally diagnosed by two synapomorphic characters unique among psychrolutids: having light spots on a dark ground colour and having an open fourth and fifth infraorbital, fifth and sixth cranial arch, medial extrascapular, and posterior tabular of the pterotic.     

Propeller scars on and known home range of two orca (Orcinus orca) in New Zealand waters

Two orca (Orcinus orca, Linnaeus, 1758), photo‐identified as part of an ongoing study in New Zealand waters, have a series of deep scars in their dorsal lumbar‐caudal regions which suggests they were caused by propellers. One of the animals, first noted to have the scars in 1982, is considerably smaller than an adult of similar age. The known home range of these orca are presented. A third orca hit by a boat is presumed dead.     

Cyanobacteria in New Zealand inland waters: Experimental studies

A small volume of experimental work with cyanobacteria in New Zealand has been produced through the last two decades. Except for some studies with geothermal organisms biased to New Zealand conditions, most work has followed the world‐wide trends in cyanobacterial research. There has been some emphasis on N₂‐fixing species, but symbiotic relationships, metabolic kinetics, nutrient and other environmental factors promoting ecological dominance, and toxicity have been investigated.     

The fauna and chemical composition of some athalassic saline waters in New Zealand

The fauna and chemical composition of two athalassic saline waters located near central Otago are discussed, and available rainfall and evaporation data for the region summarised. One water (dominated by Na and C1) had a salinity of 15‰ and contained the rotifer Brachionus plicatilis, the copepod Microcyclops monacanthus, the ostracod Diacypris, and larvae of the dipteran Ephydrella The second water (dominated by Na and HCO₃) had a salinity of 6‰ and contained larvae of Ephydrella (adults of E. novaezealandiae occurred on the shore), and the hemipterans Sigara arguta, Anisops wakefieldi and Anisops assimilis The relationship between Microcyclops monacanthus and M. arnaudi (an Australian species), and the basis of their current taxonomic separation is discussed in some detail.

At a minimum, the faunas of Australian and New Zealand athalassic saline waters have in common the following distinctive (non‐cosmopolitan) forms: Ephydrella, Diacypris, and two closely related halobiont species of Microcyclops     

Prey spectrum of breeding sooty shearwaters (Puffinus griseus) in New Zealand

Prey remains from sooty shearwater (Puffinus griseus Gmelin, 1792) regurgitates, stomachs, and gizzards, were collected from four breeding colonies in southern New Zealand. We found a wide range of prey species (minimum 39 species of 35 genera), the most important of which were crustaceans (particularly euphausiid krill and hyperiid amphipods), cephalopods (notably arrow squid), fishes, and salps. Malacostracans (krill, amphipods, and decapods) were the predominant taxa of prey in both diversity and frequency of occurrence. Regurgitates were easily obtained from harvested chicks and provided the greatest range of prey remains (36 of the 39 species identified). However, these regurgitates comprised only 29% of the total number of samples collected. Fish, malacostracan, and salp prey ranged from 4 to 170 mm in size, whereas total lengths of squid ranged from 50 to 535 mm. Based on size and mass, the largest squid were undoubtedly scavenged, possibly in association with commercial fishers. The geographical distribution of prey species indicate that most sooty shearwaters breeding near Stewart Island forage in waters lying between the Subtropical and Polar Fronts. Our results suggest that the abundance of krill, the impact of fisheries and the influence of climate perturbations on prey species may play important roles in sooty shearwater breeding and survival.