Zealand Fish Research Articles

Genomics reveals repeated landlocking of diadromous fish on an isolated island.

Landlocking of diadromous fish in freshwater systems can have significant genomic consequences. For instance, the loss of the migratory life stage can dramatically reduce gene flow across populations, leading to increased genetic structuring and stronger effects of local adaptation. These genomic consequences have been well-studied in some mainland systems, but the evolutionary impacts of landlocking in island ecosystems are largely unknown. In this study, we used a genotyping-by-sequencing (GBS) approach to examine the evolutionary history of landlocking in common smelt (Retropinna retropinna) on Chatham Island, a small isolated oceanic island 800 kilometres east of mainland New Zealand. We examined the relationship between Chatham Island and mainland smelt and used coalescent analyses to test the number and timing of landlocking events on Chatham Island. Our genomic analysis, based on 21,135 SNPs across 169 individuals, revealed that the Chatham Island smelt was genomically distinct from the mainland New Zealand fish, consistent with a single ancestral colonisation event of Chatham Island in the Pleistocene. Significant genetic structure was also evident within the Chatham Island smelt, with a diadromous Chatham Island smelt group, along with three geographically structured landlocked groups. Coalescent demographic analysis supported three independent landlocking events, with this loss of diadromy significantly pre-dating human colonisation. Our results illustrate how landlocking of diadromous fish can occur repeatedly across a narrow spatial scale, and highlight a unique system to study the genomic basis of repeated adaptation.

Laboratory-based comparison of screening materials for excluding juvenile freshwater fishes from New Zealand water intakes

ABSTRACT Growing demand for water requires resource managers to be innovative to minimise impacts on aquatic ecosystems. There are increasing concerns about fish damage and losses at water intakes, but few studies have examined the effectiveness of different screening material for excluding New Zealand fishes. We experimentally tested six screens (50–100 and 100–200 mm rock bunds, 3 mm woven mesh, 1.5, 2 and 3 mm wedge-wire), on two introduced and five native fish species. Bluegill bully (> 32 mm), common bully (> 30 mm), Canterbury galaxias (> 47 mm) and rainbow trout (> 40 mm) were screened effectively by 3 mm woven mesh and wedge-wire. Chinook salmon (> 43 mm) and īnanga whitebait (> 46 mm) were excluded by 2 mm wedge-wire, but shortfin elvers (< 80 mm) penetrated 3 and 2 mm wedge-wire, and glass eels (< 63 mm) penetrated 1.5 mm wedge-wire. Rock bunds were effective barriers for rainbow trout but were ineffective, and acted as habitat, for bluegill bully, Canterbury galaxias and shortfin eels. We recommend that 1.5 mm wedge-wire screens are used in the tidal zone of New Zealand rivers, 2 mm screens are used beyond this zone with an upstream transition to 3 mm screens dependent on catchment-specific fisheries values.

Functional beta diversity of New Zealand fishes: Characterising morphological turnover along depth and latitude gradients, with derivation of functional bioregions

AbstractChanges in the functional structures of communities are rarely examined along multiple large‐scale environmental gradients. Here, we describe patterns in functional beta diversity for New Zealand marine fishes versus depth and latitude, including broad‐scale delineation of functional bioregions. We derived eight functional traits related to food acquisition and locomotion and calculated complementary indices of functional beta diversity for 144 species of marine ray‐finned fishes occurring along large‐scale depth (50–1200 m) and latitudinal gradients (29°–51°S) in the New Zealand Exclusive Economic Zone. We focused on a suite of morphological traits calculated directly from in situ Baited Remote Underwater Stereo‐Video (stereo‐BRUV) footage and museum specimens. We found that functional changes were primarily structured by depth followed by latitude, and that latitudinal functional turnover decreased with increasing depth. Functional turnover among cells increased with increasing depth distance, but this relationship plateaued for greater depth distances (&gt;750 m). In contrast, functional turnover did not change significantly with increasing latitudinal distance at 700–1200 m depths. Shallow functional bioregions (50–100 m) were distinct at different latitudes, whereas deeper bioregions extended across broad latitudinal ranges. Fishes in shallow depths had a body shape conducive to efficient propulsion, while fishes in deeper depths were more elongated, enabling slow, energy‐efficient locomotion, and had large eyes to enhance vision. Environmental filtering may be a primary driver of broad‐scale patterns of functional beta diversity in the deep sea. Greater environmental homogeneity may lead to greater functional homogeneity across latitudinal gradients at deeper depths (700–1200 m). We suggest that communities living at depth may follow a ‘functional village hypothesis’, whereby similar key functional niches in fish communities may be maintained over large spatial scales.

Spoiler baffle patch design for improved upstream passage of small-bodied fish

The cumulative effect of culverts in impeding upstream fish passage is similar to that of large-scale high-head instream structures. The common solution to overcome this impediment is to add ancillary elements, with the goal to lower water velocities and to create discrete low velocity zones (LVZs) for fish to rest. The addition of spoiler baffles is one example of retrofitting structures with ancillary elements, with their efficacy having been proven in various field studies. The scope of the present work is to conduct a detailed laboratory study to evaluate the arrangement of spoiler baffles of different sizes and spatial density. Chosen baffle arrangements are consistent with the present size and spacing recommendations of the New Zealand Fish Passage Guidelines. Flow fields for two different flow rates within different baffle arrangements were obtained with acoustic Doppler velocimeter (ADV) technology. We show that for the standard design, as recommended in the New Zealand Fish Passage Guidelines, the maximum value of mean streamwise velocity and turbulence parameters (turbulent kinetic energy (TKE) and Reynolds stresses) is less than for two other designs we tested. However, the distribution of flow parameters within the plane is significantly different for all tested designs. In general, a shorter size baffle arranged at medium spatial density exhibits highly heterogeneous flow, with numerous LVZs, as well as providing wider pathways compared to the standard design. Wider pathways can also accommodate various fish species, which generally prefer different water velocity and turbulence, with the generated flow field allowing a lower energy cost of fish swimming whilst resting or station holding. Thus, this study shows the viability of using shorter baffles as an alternative fish passage solution for culverts, which can subsequently be validated with different fish species.

Effect of anticoagulants on farmed giant kokopu, Galaxias argenteus (Gmelin 1789) haematological parameters and erythrocyte fragility.

We sought to determine a compatible anticoagulant for routine haematological and physiological assessments with giant kokopu (Galaxias argenteus), an endemic New Zealand fish. We observed that blood treated with lithium heparin (LH) rapidly coagulated and haemolysed, making it unsuitable for G. argenteus. Dipotassium ethylenediaminetetraacetic acid (K2 EDTA) and trisodium citrate (citrate) effectively prevented blood coagulation. K2 EDTA-treated erythrocytes exhibited the least mean haemolysis and mean corpuscular fragility. Further studies into prolonged storage effects of citrate and K2 EDTA are recommended to find a compatible anticoagulant for use with G. argenteus blood.

Overview of Australian and New Zealand harmful algal species occurrences and their societal impacts in the period 1985 to 2018, including a compilation of historic records

Similarities and differences between Australia and New Zealand in Harmful Algal species occurrences and Harmful Algal Events impacting on human society (HAEDAT) are reported and factors that explain their differences explored. Weekly monitoring of harmful phytoplankton and biotoxins commenced in Australia in 1986 and in New Zealand in 1993. Anecdotal historic HAB records in both countries are also catalogued. In Australia, unprecedented highly toxic Paralytic Shellfish Toxin (PST)-producing blooms of Alexandrium catenella have impacted the seafood industry along the 200 km east coast of Tasmania from 2012 to present. Toxic blooms in 1986-1993 by Gymnodinium catenatum in Tasmania were effectively mitigated by closing the affected area for shellfish farming, while a bloom by this same species in 2000 in New Zealand caused significant economic damage from restrictions on the movement of greenshell mussel spat. The biggest biotoxin event in New Zealand was an unexpected outbreak of Neurotoxic Shellfish Poisoning (NSP) in 1993 in Hauraki Gulf (putatively due to Karenia cf. mikimotoi) with 180 reported cases of human poisonings as well as reports of respiratory irritation north of Auckland. Strikingly, NSP never recurred in New Zealand since and no NSP events have ever been reported in Australia. In New Zealand, Paralytic Shellfish Poisoning (PSP) was the predominant seafood toxin syndrome, while in Australia Ciguatera Fish Poisoning (CFP) was the major reported seafood toxin syndrome, while no CFP has been recorded from consumption of New Zealand fish. In Australia, Diarrhetic Shellfish Poisoning (DSP) illnesses were recorded from two related outbreaks in 1997/98 following consumption of beach harvested clams (pipis) from a previously non-monitored area, whereas in New Zealand limited DSP illnesses are known. No human illnesses from Amnesic Shellfish Poisoning (ASP) have been reported in either Australia or New Zealand. Selected examples of HABs appearing and disappearing (NSP in New Zealand, Alexandrium catenella in Tasmania), species expanding their ranges (Noctiluca, Gambierdiscus), and reputed ballast water introductions (Gymnodinium catenatum) are discussed. Eutrophication has rarely been invoked as a cause except for confined estuaries and fish ponds and estuarine cyanobacterial blooms. No trend in the number of HAEDAT events from 1985 to 2018 was discernible.

Carryover effects of larval environment on individual variation in a facultatively diadromous fish.

Intraspecific trait variation may result from “carryover effects” of variability of environments experienced at an earlier life stage. This phenomenon is particularly relevant in partially migrating populations composed of individuals with divergent early life histories. While many studies have addressed the causes of partial migration, few have investigated the consequences for between‐individual variability later in life.We studied carryover effects of larval environment in a facultatively diadromous New Zealand fish, Gobiomorphus cotidianus, along an estuarine salinity gradient. We investigated the implications of varying environmental conditions during this critical stage of ontogeny for adult phenotype.We inferred past environmental history of wild‐caught adult fish using otolith microchemistry (Sr/Ca) as a proxy for salinity. We tested for main and interactive effects of larval and adult environment on a suite of traits, including growth rates, behavior (exploration and activity), parasite load, and diet (stable isotopes and gut contents).We found a Sr/Ca consistent with a continuum from freshwater to brackish environments, and with different trajectories from juvenile to adult habitat. Fish with Sr/Ca indicating upstream migration were more vulnerable to trematode infection, suggesting a mismatch to freshwater habitat. Diet analysis suggested an interactive effect of larval and adult environments on trophic position and diet preference, while behavioral traits were unrelated to environment at any life stage. Growth rates did not seem to be affected by past environment.Overall, we show that early life environment can have multiple effects on adult performance and ecology, with the potential for lifetime fitness trade‐offs associated with life history. Our study highlights that even relatively minor variation in rearing conditions may be enough to generate individual variation in natural populations.

Detection and identification of furan fatty acids from fish lipids by high-performance liquid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry

Using high-performance liquid chromatography coupled to high-resolution electrospray ionization quadrupole time-of-flight mass spectrometry (HPLC/ESI-Q-TOF-MS), we have developed a new method for detection and identification of furan fatty acids (F-acids), which are widely distributed in living organisms and foods as minor lipid components and are known to have antioxidant and anti-inflammatory effects. For this purpose, total fatty acids prepared from the testis lipids of Japanese chum salmon (Oncorhynchus keta) were examined without any concentration or isolation of F-acids. In negative ESI mode, F-acids gave a prominent [M−H]− ion, by which individual F-acids could be detected and identified. High-resolution extracted ion chromatograms clearly showed the occurrence of five major F-acid homologs as already reported by GC/MS. The method was successfully applied to several fish samples and revealed the occurrence of F-acids for the first time in the two New Zealand fish, hoki (Macruronus novaezelandiae) and school shark (Galeorhinus galeus).

Assessing sperm membrane viability using flow cytometry in farmed New Zealand giant kokopu Galaxias argenteus

ABSTRACTWe employed flow cytometry to assess plasma membrane viability of sperm cells in farmed giant kokopu Galaxias argenteus, an endemic amphidromous New Zealand fish. Specifically, the variables of fish size (TL mm) and weight (grams) were assessed against sperm viability. We found no significant difference (P < .05) in sperm viability when compared across size and weight distribution of G. argenteus. This study shows that flow cytometry is an effective, accurate and rapid method for analysing sperm viability in G. argenteus.

The Varying Role of Vertebrae in Pacific Fishbone Analysis: Comparing Tropical Versus Temperate Midden Assemblages

AbstractArchaeologists working in the tropical Pacific have demonstrated the feasibility and value of including fish vertebrae in midden analyses, and recent New Zealand studies draw similar conclusions. This work provides an illustrated guide to the identification of vertebrae from key New Zealand fish taxa and shows the effects of including vertebrae on a large fishbone assemblage from southern New Zealand. We note major differences between New Zealand and tropical Pacific assemblages resulting from the inclusion of vertebrae. Unlike the Indo‐Pacific taxa of the tropical Pacific, no New Zealand species have been shown to be sensitive to the inclusion of vertebrae. In both places, including vertebrae results in changes in relative abundance and rank order; but in New Zealand, this is a function of processing practices, not fishing behaviours. This work serves to highlight changes in the Polynesian fishing adaption following the colonisation of New Zealand. Copyright © 2017 John Wiley &amp; Sons, Ltd.

Effects of latitude and depth on the beta diversity of New Zealand fish communities

Marine ecosystems are difficult to sample quantitatively at increasing depth. Hence, few studies attempt to measure patterns of beta diversity for ecological communities in the deep sea. Here we (i) present and quantify large-scale gradients in fish community structure along depth and latitude gradients of the New Zealand EEZ, (ii) obtain rigorous quantitative estimates of these depth (50–1200 m) and latitudinal effects (29.15–50.91°S) and their interaction, and (iii) explicitly model how latitudinal beta diversity of fishes varies with depth. The sampling design was highly structured, replicated and stratified for latitude and depth, using data obtained from 345 standardised baited remote underwater stereo-video deployments. Results showed that gradients in fish community structure along depth and latitude were strong and interactive in New Zealand waters; latitudinal variation in fish communities progressively decreased with depth following an exponential decay (r2 = 0.96), revealing increasingly similar fish communities with increasing depth. In contrast, variation in fish community structure along the depth gradient was of a similar magnitude across all of the latitudes investigated here. We conclude that an exponential decay in beta diversity vs depth exists for fish communities present in areas shallower than the New Zealand upper continental slope.

Hiding in the swamp: new capillariid nematode parasitizing New Zealand brown mudfish.

The extent of New Zealand's freshwater fish-parasite diversity has yet to be fully revealed, with host-parasite relationships still to be described from nearly half the known fish community. While advances in the number of fish species examined and parasite taxa described are being made, some parasite groups, such as nematodes, remain poorly understood. In the present study we combined morphological and molecular analyses to characterize a capillariid nematode found infecting the swim bladder of the brown mudfish Neochanna apoda, an endemic New Zealand fish from peat-swamp-forests. Morphologically, the studied nematodes are distinct from other Capillariinae taxa by the features of the male posterior end, namely the shape of the bursa lobes, and shape of spicule distal end. Male specimens were classified into three different types according to differences in the shape of the bursa lobes at the posterior end, but only one was successfully characterized molecularly. Molecular analysis indicated that the studied capillariid is distinct from other genera. However, inferences about the phylogenetic position of the capillariid reported here will remain uncertain, due to the limited number of Capillariinae taxa characterized molecularly. The discovery of this new capillariid, which atypically infects the swim bladder of its host, which itself inhabits a very unique ecosystem, underlines the very interesting evolutionary history of this parasite, which for now will remain unresolved.

Gaining insights into the ecological role of the New Zealand sole (Peltorhamphus novaezeelandiae) through parasites.

Despite the fact that tapeworms comprise the bulk of parasite communities of sharks in marine ecosystems, little is known about their life cycles and, more specifically, about the potential intermediate hosts they utilize as transmission routes. In the absence of morphological features required for specific identification of larval tapeworms from potential intermediate hosts, recent molecular advances have contributed to linking larval and adult parasites and, in some instances, uncovering unknown trophic links. Host-parasite checklists are often the first source of information consulted to assess the diversity and host specificity of parasites, and provide insights into parasite identification. However, these host-parasite checklists are only useful if they encompass the full spectrum of associations between hosts and parasites. A checklist of New Zealand fishes and their parasites has been published, but recent parasitological examinations of commercial fish species reveal that the checklist appears to be far from complete. We focused our current study on a comprehensive survey of macroparasites of a commercial species, the New Zealand sole (Peltorhamphus novaezeelandiae) off the coast of Otago, New Zealand. Specifically, we were expecting to recover marine tapeworms using sharks as their definitive hosts that are generally underreported in parasite surveys. The parasites recovered included tapeworms, flukes, round worms and thorny-headed worms. Surprisingly, a large proportion of the non-tapeworm parasites we recovered were not previously reported from this fish species. A discussion on the potential ecological roles played by this fish species in the transmission of parasites is included.

Concerns with the Study on Australian and New Zealand Fish Oil Products by Nichols et al. (Nutrients 2016, 8, 703).

n/a.

Australian and New Zealand Fish Oil Products in 2016 Meet Label Omega-3 Claims and Are Not Oxidized.

We provide new fish oil product results to assist industry in Australia and New Zealand and, ultimately, consumers in understanding the high product quality assurance protocols in place, together with the high product quality that has been determined by both industry and independent laboratories. Fish oil capsule products common to Australia and New Zealand were purchased in May 2016 in Richmond, Victoria, Australia. Products were from two groups; five standard fish oil products and five fish oil concentrates. Noting Therapeutic Goods Administration (TGA) requirement for use of standard methods, for all analyses undertaken a laboratory was selected that met the TGA criteria, including with accreditation. Total n-3 content exceeded the label-claimed content for all 10 products, with supplements containing on average 124% of the claimed content (range 115%–136%); eicosapentaenoic acid and docosahexaenoic acid (EPA + DHA) content averaged 109% of the label claim (range 99%–119%). All 10 products (100%) similarly met the international recommended peroxide value (PV) level. Anisidine value (pAV) met the international recommended level for eight of the 10 products, with two products known to contain flavorings that interfere with the pAV test. When accredited laboratories and standard protocols are used, Australian and New Zealand fish oil products have been shown to clearly meet their label claims for EPA + DHA content, and are not oxidized.

Do freshwater aquaculture facilities provide an invasion risk for zooplankton hitchhikers?

While numerous examples exist of freshwater species from aquaculture facilities establishing non-indigenous populations following intentional release, and unintentional escape, clear links between invasions of non-target ‘hitchhiker’ species and this vector are to date are far less convincing. We examined zooplankton from nine New Zealand fish farms, including those with traditional outdoor pond systems, modern Recirculating Aquaculture Systems (RAS), and of zooplankton cultured as food for fish, to determine the prevalence of non-indigenous species among these facilities. Several non-indigenous species were found during our surveys, from all three sources, indicating that freshwater aquaculture provides invasion risks for non-native zooplankton in a variety of ways. Significantly, the North American calanoid copepod Skistodiaptomus pallidus was recorded at five farms with pond operations, greatly strengthening the link between the establishment of this species in New Zealand lakes with the release of grass carp for aquatic weed control. Traditional pond systems were commonly found to contain large populations of non-indigenous species, with risk seemingly greatest where fish are released from these operations. RAS operations contained relatively low numbers of individuals overall, suggesting a movement to this form of aquaculture from pond systems will greatly reduce the invasion risk from the freshwater aquaculture industry. We recommend a tightening of regulations regarding fish release from aquaculture ponds, following the determination of best practice methods to reduce the potential movement of hitchhiking taxa.

Variable survival across low pH gradients in freshwater fish species.

A series of 14 day experiments was conducted on five common New Zealand fish species (redfin bully Gobiomorphus huttoni, inanga Galaxias maculatus, brown trout Salmo trutta, longfin eel Anguilla dieffenbachii and koaro Galaxias brevipinnis) to assess the effect of pH on survival and changes in body mass. No species survived in water of pH <4 although there was 100% survival of all adults at pH 4.5, G. maculatus larvae were also tested and had high mortality at this pH. Results suggest that adults are tolerant of low-pH waters; however, successful remediation of anthropogenically acidified streams will require an understanding of the susceptibility to low pH on different life cycle stages.

KNOW YOUR NEW ZEALAND FISHES - By J. Enderby and T.Enderby

KNOW YOUR NEW ZEALAND FISHES - By J. Enderby and T.Enderby

Do mitochondria limit hot fish hearts? Understanding the role of mitochondrial function with heat stress in Notolabrus celidotus.

Hearts are the first organs to fail in animals exposed to heat stress. Predictions of climate change mediated increases in ocean temperatures suggest that the ectothermic heart may place tight constraints on the diversity and distribution of marine species with cardiovascular systems. For many such species, their upper temperature limits (Tmax) and respective heart failure (HF) temperature (THF) are only a few degrees from current environmental temperatures. While the ectothermic cardiovascular system acts as an “ecological thermometer,” the exact mechanism that mediates HF remains unresolved. We propose that heat-stressed cardiac mitochondria drive HF. Using a common New Zealand fish, Notolabrus celidotus, we determined the THF (27.5°C). Haemoglobin oxygen saturation appeared to be unaltered in the blood surrounding and within heat stressed hearts. Using high resolution respirometry coupled to fluorimeters, we explored temperature-mediated changes in respiration, ROS and ATP production, and overlaid these changes with THF. Even at saturating oxygen levels several mitochondrial components were compromised before THF. Importantly, the capacity to efficiently produce ATP in the heart is limited at 25°C, and this is prior to the acute THF for N. celidotus. Membrane leakiness increased significantly at 25°C, as did cytochrome c release and permeability to NADH. Maximal flux rates and the capacity for the electron transport system to uncouple were also altered at 25°C. These data indicate that mitochondrial membrane integrity is lost, depressing ATP synthesis capacity and promoting cytochrome c release, prior to THF. Mitochondria can mediate HF in heat stressed hearts in fish and play a significant role in thermal stress tolerance, and perhaps limit species distributions by contributing to HF.

GANNET'S GAZE STAYS FOCUSED UNDERWATER

Plunging birds' eyes are keen enough to detect fishy prey, even through the erratic shimmer of the ocean's surface, before the birds dive rapidly into the water. For some of these birds, however, merely seeing prey from the sky is insufficient for catching a meal. They must also have exceptional vision while submerged, which is no easy feat. While flying in air, the eye's ability to focus is provided by the refractive power of the cornea. However, while submerged, the refractive index of the cornea is about the same as that of the surrounding water – so there has to be some other mechanism for focusing an image on the retina.Gabriel Machovsky-Capuska of Massey University, New Zealand, and colleagues from around the world wanted to know whether Australasian gannets, birds that plunge dive and swim to catch prey, have found a solution to this visual tradeoff. Gannets are unique in being one of the few species of bird that both plunge dive and ‘wing flap’ underwater. This suggested to the researchers that the gannets could be visually tracking fish even while submerged.To determine whether gannets caught fish during the plunge section of their dive or after a visually guided underwater chase, Machovsky-Capuska and colleagues filmed diving gannets both above and below water in the field, noting when, and how many, successful prey captures resulted from each dive. The vast majority of successes occurred during the wing-flap stage of a dive – when the birds must be tracking the fish underwater.Encouraged by these findings, the researchers photographed the eyes of several gannets both above and below the water. From the photographs, they used the reflection of light off the gannet's eyes to measure the curvature of the cornea, a proxy for its refractive power. They also used infrared photorefraction to determine how well focused an eye is from the position of light reflected off the retina.The gannet's eyes were usually hyperopic, or far-sighted, in air and underwater. However, the birds were capable of achieving myopia, or near-sightedness, within about a tenth of a second of submergence. This ability to focus differently represented the birds' capacity to adapt to underwater vision even without the refractive power of their cornea.Machovsky-Capuska and colleagues suggest that gannets may change the shape of their eye lens, instead of the retina, to retain the ability to focus. Many aquatic animals, including fish, amphibians, whales and penguins have evolved spherical lenses to cope with the challenges of underwater vision. Specialized lens morphology may permit the gannet's remarkable ability to switch from aerial to aquatic vision quickly and compensate for the cornea's ineffectual refractive power in water. More research will undoubtedly reveal the mechanism of the gannet's remarkably flexible visual system. In the interim, New Zealand fish might consider camouflage.