Lepidorhynchus Denticulatus Research Articles

Integrating survey and observer data improves the predictions of New Zealand spatio-temporal models

AbstractIn many situations, species distribution models need to make use of multiple data sources to address their objectives. We developed a spatio-temporal modelling framework that integrates research survey data and data collected by observers onboard fishing vessels while accounting for physical barriers (islands, convoluted coastlines). We demonstrated our framework for two bycatch species in New Zealand deepwater fisheries: spiny dogfish (Squalus acanthias) and javelinfish (Lepidorhynchus denticulatus). Results indicated that employing observer-only data or integrated data is necessary to map fish biomass at the scale of the New Zealand exclusive economic zone, and to interpolate local biomass indices (e.g., for the east coast of the South Island) in years with no survey but available observer data. Results also showed that, if enough survey data are available, fisheries analysts should: (1) develop both an integrated model and a model relying on survey-only data; and (2) for a given geographic area, ultimately choose the index produced with integrated data or the index produced with survey-only data based on the reliability of the interannual variability of the index. We also conducted a simulation experiment, which indicated that the predictions of our spatio-temporal models are virtually insensitive to the consideration of physical barriers.

Origin of Ciguateric Fish: Quantitative Modelling of the Flow of Ciguatoxin through a Marine Food Chain

To begin to understand the impact of food chain dynamics on ciguatera risk, we used published data to model the transfer of ciguatoxins across four trophic levels of a marine food chain in Platypus Bay, Australia. The data to support this first attempt to conceptualize the scale of each trophic transfer step was limited, resulting in broad estimates. The hypothetical scenario we explored generated a low-toxicity 10 kg Spanish mackerel (Scomberomorus commerson) with a flesh concentration of 0.1 µg/kg of Pacific-ciguatoxin-1 (P-CTX-1, also known as CTX1B) from 19.5–78.1 µg of P-CTX-1 equivalents (eq.) that enter the marine food chain from a population of 12–49 million benthic dinoflagellates (Gambierdiscus sp.) producing 1.6 × 10−12 g/cell of the P-CTX-1 precursor, P-CTX-4B. This number of Gambierdiscus could be epiphytic on 22–88 kg of the benthic macroalgae (Cladophora) that carpets the bottom of much of Platypus Bay, with the toxin transferred to an estimated 40,000–160,000 alpheid shrimps in the second trophic level. This large number of shrimps appears unrealistic, but toxic shrimps would likely be consumed by a school of small, blotched javelin fish (Pomadasys maculatus) at the third trophic level, reducing the number of shrimps consumed by each fish. The Spanish mackerel would accumulate a flesh concentration of 0.1 µg/kg P-CTX-1 eq. by preying upon the school of blotched javelin and consuming 3.6–14.4 µg of P-CTX-1 eq. However, published data indicate this burden of toxin could be accumulated by a 10 kg Spanish mackerel from as few as one to three blotched javelin fish, suggesting that much greater amounts of toxin than modelled here must at certain times be produced and transferred through Platypus Bay food chains. This modelling highlights the need for better quantitative estimates of ciguatoxin production, biotransformation, and depuration through marine food chains to improve our understanding and management of ciguatera risk.

Diet and Feeding Habits of the Javelin Grunt Pomadasys kaakan (Cuvier, 1830) in Pabean Bay West Java

The Pabean Bay is an estuary area that inhabited by many fish species such as javelin grunt (Pomadasys kaakan Cuvier, 1830). The purposes of this study were to identify food item and determine the feeding habit of the javelin grunt in The Pabean Bay, West Java. Fishes were collected monthly from June to December 2016 using gill nets and trap nets. Observation food is in vitro by conducting an examination of the stomach and the intestines of an example and refer on the books of the identification by Carpenter and Niem. Analysis of fish diet includes index of relative importance, niche breadth, and niche overlap. Fishes were grouped into three groups based on the size length. The result showed that the javelin grunt was crustacivore. Generally, the diet of javelin grunt consists of Acetes sp., Penaeus sp., Portunus sp., Clupeid, Ambassid, Sciaenid, Gobiid, Sillaginid, and unidentified organisms. Penaeus sp. was the main food and could be found on each size of group in monthly observation. The proportion of index of relative importance value was changed in regard of length size groups of A (41-85 mm: 12.105), B (86-130 mm: 13.804), and C (131-175 mm: 7.561). The niche breadth of javelin fish was higher in the larger ones and a high diet overlap among size groups was found. According to prey item and feeding habit, the javelin grunt can be classified as benthic crustacean feeder.

Hector's dolphin diet: The species, sizes and relative importance of prey eaten by Cephalorhynchus hectori, investigated using stomach content analysis

AbstractStomach contents of 63 Hector's dolphins (Cephalorhynchus hectori) were collected between 1984 and 2006 from throughout New Zealand to provide the first quantitative assessment of prey composition. Twenty‐nine taxa were identified. Those most commonly consumed were red cod (Pseudophycis bachus), ahuru (Auchenoceros punctatus), arrow squid (Nototodarus sp.), sprat (Sprattus sp.), sole (Peltorhamphus sp.), and stargazer (Crapatalus sp.). By mass, these six species contributed 77% of total diet. Red cod contributed the most in terms of mass (37%), while ahuru and Hector's lanternfish (Lampanyctodes hectoris) were consumed in large numbers. Prey ranged from <1 cm to >60 cm in total length, but the majority of prey items were <10 cm long, indicating that for some species, juveniles were targeted. Diets of dolphins from South Island east and west coasts were significantly different, due largely to javelinfish (Lepidorhynchus denticulatus) being of greater importance in west coast stomachs, and a greater consumption of demersal prey species in the east. The feeding ecology of Hector's dolphin is broadly similar to that of other Cephalorhynchus species. Hector's dolphin is shown to feed on species from throughout the water column, and differences in diet between populations are thought to reflect prey availability.

Different food preferences in four sympatric deep-sea Macrourid fishes

Feeding habits of the four most abundant deep-sea demersal trawl-caught macrourids on Chatham Rise, New Zealand, were examined from stomach contents. Two species were predominantly benthic foragers: Coelorinchus bollonsi on infaunal and epifaunal polychaetes, and C. aspercephalus on epifaunal crustaceans; and two species were predominantly mesopelagic foragers; C. oliverianus on calanoid copepods, and Lepidorhynchus denticulatus on mesopelagic crustaceans. The most important predictors of diet variability were identified using distance-based linear models and included areal predictors in all four species, fish size in C. aspercephalus, C. bollonsi and L. denticulatus, and sample year in C. bollonsi. Cluster analyses showed that the diets of C. aspercephalus and C. bollonsi were most distinct. There was a greater interspecific similarity in diet in the spatial and fish size subgroups of C. oliverianus and L. denticulatus, than at the species level. Failing to account for areal, temporal, and ontogenetic variability in diets may bias evaluations of resource competition.

Proximate composition, energy content, and fatty acid composition of marine species from Campbell Plateau, New Zealand

Campbell Plateau is an important fishing ground for the main commercial New Zealand species. Yet, studies on trophic interactions between species and their nutritional values are limited. The objectives of this study were to determine the proximate composition and energy contents of selected commercial and non‐commercial marine species from Campbell Plateau and their fatty acid (FA) composition, and to evaluate the degree to which species can be differentiated by their FA compositions. We analysed 43 fish specimens from 5 different species (Macruronus novaezelandiae, Lepidorhynchus denticulatus, Pseudophycis backus, Hemerocoetes spp. and Squalus acanthias), 17 cephalopod specimens from 2 species (Nototodarus sloani and Enteroctopus zealandicus), and 6 Metanephrops challengeri (crustacean). The variation of energy contents between fish species was not significant, but their lipid and protein contents varied significantly. FA signatures distinguished the species analysed and, at a broader scale, the type of habitat. Within‐specie s variability was important for benthic species. In general, the diet inference from FA trophic markers was consistent with reported diets from stomach contents.

Feeding ecology of two high-order predators from south-eastern Australia: the coastal broadnose and the deepwater sharpnose sevengill sharks

Quantifying the feeding ecology of marine predators is essential for understanding their trophic interactions and their potential regulatory effects in marine ecosystems. I quantified the feed- ing ecology of 2 related predators that overlap only in part in spatial distribution: the coastal broad- nose Notorynchus cepedianus and the deepwater sharpnose Heptranchias perlo sevengill sharks. I found the following: These 2 shark species have different diet specialisation patterns, but show sim- ilarities in their prey handling mode. N. cepedianus has a generalised diet, whereas H. perlo shows high specialisation and lower prey diversity. For both shark species, small, medium and large individ- uals use different strategies for handling different prey groups. H. perlo preys largely on deepwater teleosts, mainly Lepidorhynchus denticulatus, with larger individuals (901 to 1365 mm total length, TL) also consuming high proportions of large predatory teleosts of the families Gempylidae and Trichiuridae. N. cepedianus has a diverse diet. Small individuals (≤900 mm TL) prey largely on teleosts and secondarily on chondrichthyans. Medium individuals (901 to 1520 mm TL) prey primar- ily on chondrichthyans and secondarily on teleosts. Chondrichthyans (mainly Mustelus antarcticus) are also the main prey of large N. cepedianus (>1700 mm TL), but this group also shows a greater preference (than small and medium individuals) for fur seals. Despite the overall differences in dietary composition and the minimal overlap in spatial distribution, the 2 shark species consume prey that migrate from deep to coastal waters (ommastrephid squid and gempylid fish).

New Zealand Demersal Fish Assemblages

Demersal fish assemblages in the New Zealand Exclusive Economic Zone were identified using presence–absence data from 19 215 bottom trawl tows made over a 37-year period. The dataset spanned latitudes 34–54°S and depths of 4–1500 m. A total of 123 taxa occurred in more than 1% of the tows (121 fish and 2 squid). Multivariate ordination and classification (correspondence analysis and Ward's cluster analysis) identified four primary species assemblages that were associated with the inner continental shelf, mid–outer continental shelf and shelf edge, upper continental slope and mid continental slope. The most frequently occurring species (> 40% of tows) in each assemblage were (in descending order): inshore – Chelidonichthys kumu, Pagrus auratus and Zeus faber; shelf – Nototodarus spp., Squalus acanthias and Thyrsites atun; upper slope – Macruronus novaezelandiae, Lepidorhynchus denticulatus, Genypterus blacodes and Hydrolagus sp.; mid slope – Hoplostethus atlanticus, Etmopterus baxteri, Halargyreus johnsonii, Coryphaenoides subserrulatus, Deania calcea, Coryphaenoides serrulatus, Pseudocyttus maculatus, Mora moro, Diastobranchus capensis and Centroscymnus crepidater. Further species associations were also identified within each primary assemblage. Canonical correspondence analysis revealed that most of the explainable variation in species composition was associated with depth and latitude; longitude and season explained little extra variance. The usefulness of our results is limited by the use of presence–absence rather than abundance data, and by the uneven spatial distribution of trawl tows. However, the present study provides a large-scale framework within which to interpret the results of studies using abundance data over smaller spatial and temporal scales.

Demersal fish assemblages off southern New Zealand in relation to depth and temperature

We examined the relationship between demersal fish assemblage and depth, temperature, latitude and longitude off southern New Zealand (46–54°S and 165–180°E) in water depths of 80–787 m. Catch weight data were analysed by two-way indicator analysis (TWIA), groupaverage agglomerative clustering (UPGMA) and Detrended Correspondence Analysis (DCA). The spatial pattern of demersal fish off southern New Zealand conforms to the concept of species groups or fish assemblages related to environmental gradients. Shallow-water assemblages were dominated by species from the families Gempylidae, Squalidae, Triakidae and Moridae, mainly represented by Thyrsites atun, Squalus acanthias, Galeorhinus australis, and Pseudophycis bachus. Deep water assemblages were dominated by Chimaeridae, Argentinidae, Merlucciidae and Macrouridae, mainly represented by Hydrolagus novaezelandiae, Argentina elongata, Macruronus novaezelandiae, and Lepidorhynchus denticulatus. Total catch weight was often dominated by Merlucciidae, Macrouridae and Gempylidae. Fish assemblages were related to discrete ranges of depth (< and >300 m) and temperature (< and >9.5°C), but the range of sediment types was too narrow to show any correlation.

Benthic and pelagic fish biomass of the upper continental slope off eastern Tasmania

Benthic and pelagic fishes were sampled east of Maria Island, Tasmania, at two-monthly intervals from April 1984 to June 1985, from the surface to the bottom (500 m depth), using commercial-sized trawls. Biomass was calculated by the “area swept/volume filtered” method and divided by estimated catchability coefficients so that catches from the two sampling gears could be combined. Of the 54 families caught, three (Myctophidae, Squalidae, Sternoptychidae) contributed 25% of the 115 species. Most benthic and dispersed species were caught regularly, whereas most pelagic species occurred only occasionally and in low numbers, although a core group was always present. Total fish biomass was high (range=77 to 532 g m-2; x= 390 g m-2), due almost entirely to the myctophid Lampanyctodes hectoris (over 90% of the biomass). Benthic biomass was relatively low and stable, but derived from many species. Pelagic biomass was high, fluctuated widely and was composed of a few species. Biomass was highest in summer: Maurolicus muelleri increased by a factor of 200, Diaphus danae by 50, and L. hectoris, Macruronus novaezelandiae and Lepidorhynchus denticulatus by almost 10. Peaks in biomass may correlate with the interactions of the subtropical convergence and the East Australian Current and the resultant marked seasonal cycle in water temperature, nutrients and primary productivity.

Diets of fishes of the upper continental slope of eastern Tasmania: content, calorific values, dietary overlap and trophic relationships

Diets of 15 species of demersal and pelagic fishes on the upper continental slope (420 to 550 m) were determined, based on samples taken every two months over 13 mo (April 1984 to April 1985) off eastern Tasmania. The calorific contribution of each prey item to the diets was determined. The fish could be divided into four trophic categories: pelagic piscivores, epibenthic piscivores, epibenthic invertebrate feeders and benthopelagic omnivores. Dietary overlap between the groups was low. The pelagic piscivores Apogonops anomalus, Trachurus declivis, Brama brama, Lepidopus caudatus and Macruronus novaezelandiae primarily consume the shelf-break myctophid Lampanyctodes hectoris; their diet is narrow, with a large overlap between species. The epibenthic piscivores Deania calcea and Genypterus blacodes both take a greater variety of prey, but have little dietary overlap. The fish feeding on epibenthic invertebrates, Coelorinchus sp. 2 and Centriscops humerosus, obtain most of their energy from benthic Crustacea and Ophiuroidea, supplemented with Lampanyctodes hectoris; the diet is broad, with little overlap. Among the benthopelagic omnivores (Cyttus traversi, Coelorinchus sp. 4, Lepidorhynchus denticulatus, Neocyttus rhomboidalis, Helicolenus percoides, Epigonus denticulatus and E. lenimen), most diets are broad and show slight overlap. All but E. denticulatus consume significant quantities of Lampanyctodes hectoris as well as Crustacea, particularly Polychaeta, Euphausiacea and Pyrosoma atlanticum. Seasonal changes in diet occurred in G. blacodes, T. declivis, Lepidopus caudatus, Coelorinchus sp. 4, Lepidorhynchus denticulatus, H. percoides, E. denticulatus and E. lenimen; these were related to changes in abundance of particular prey species, not to alterations in feeding habits. Only three species, Lepidopus caudatus, Coelorinchus sp. 2 and H. percoides, showed significant diel feeding periodicity. Ontogenetic dietary changes were evident in Cyttus traversi, Coelorinchus sp. 2, Lepidorhynchus denticulatus and H. percoides. Cyttus traversi and H. percoides progressively changed from crustaceans to fish as their size increased. The diets of size classes within species showed little overlap, except for Lepidorhynchus denticulatus, which eats chiefly euphausiids and Lampanyctodes hectoris at all sizes. In addition to describing the diets and trophic relationships of 90% of the fish biomass, the results emphasize the importance to the entire fish community of mesopelagic food resources, particularly Lampanyctodes hectoris. Many benthopelagic species undertake extensive vertical migrations in search of prey, thus playing a major role in the transport of energy from midwater regions to the benthos of the continental slope.

The food and feeding of seven fish species from the Campbell Plateau, New Zealand

Abstract The food and feeding habits of hoki (Macruronus novaezelandiae), southern blue whiting (Micromesistius australis), javelin fish (Lepi‐dorhynchus denticulatus), ling (Genypterus blacodes), smooth rattail (Coelorinchus aspercephalus), silverside (Argentina elongata), and small‐scaled notothenid (Notothenia microlepidota) sampled from the Campbell Plateau in 1979 were examined. The importance of prey items in the diet has been assessed by an ‘index of relative importance’, which combines measurements of frequency of occurrence, number, and weight of prey. Hoki, southern blue whiting, and javelin fish are pelagic feeders. Hoki preyed largely on natant decapod crustaceans, amphipods, and myctophid and photichthyid fishes. The main prey of southern blue whiting were amphipods, natant decapods, and euphausiids. Javelin fish fed on natant decapods, amphipods, and small squid. Seasonal and regional differences in feeding, and dietary changes with length of fish were evident. Ling, smooth rattail, silverside, and small‐scaled notothenid are predominantly benthic feeders. Ling preyed on natant decapods, macrourid fishes, and small hoki. The diet of rattail comprised natant decapod crustaceans, opal fishes (Hemerocoetes spp.), and poly‐chaetes. Silverside fed almost solely on salps. Salps, amphipods, brachyuran crustaceans, and opal fishes were the main prey of small‐scaled notothenid.

Feeding relationships of seven fish species from the Campbell Plateau, New Zealand

Abstract Aspects of feeding relationships between hoki (Macruronus novaezelandiae), southern blue whiting (Micromesistius australis), javelin fish (Lepidorhynchus denticulatus), ling (Genypterus blacodes), smooth rattail (Coelorinchus aspercephalus), silverside (Argentina elongata), and small‐scaled notothenid (Notothenia microlepidota) were examined. These included dietary overlap, predator‐prey size selection, feeding diversity, and similarity of prey composition of fishes caught in the same trawl. ‘Pelagic’ and ‘benthic’ feeding guilds are described and the extent of food resource partitioning among the fishes is discussed. Spatial and temporal feeding differences, and variations in prey type and prey size were evident for most of the fishes.

The nature and fatty acid composition of the oils from deep-sea fish species from New Zealand waters.

AbstractThe oils from the edible flesh, frame, head, skin and viscera of seven deep‐sea fish namely, alfonsino (Beryx splendens), cardinal fish (Epigonus sp.) javelin fish (Lepidorphynchus denticulatus), lookdown dory (Cyttus traversi), rattail (Coelorynchus sp.), ribaldo (Mora pacifica) and sea perch (Helicolenus papillosus) were examined. The fatty acids analysed are present as glycerol‐based lipids and no marine wax esters were detected. The distribution of the major fatty acid moieties, i.e. 16:0, 18:1 and 22:6 resembled the pattern common to established commercial fish oils.

Observations on some Tasmanian fishes : Part XXV

Five species are for the first time recorded from Tasmania; in each case some observations are made on the material, the chief points commented on here noted in parentheses. CHAULIODIDAE - Chauliodus sloani (dentition, general features): IDIACANTHIDAE - Idiacanthus fasciola (specimen from gut of Hyperoglyphe antarctica); I. niger (type locality of synonymic I. aurora, Macquarie Island, part of a Tasmanian municipality): EMBIOTOCIDAE - Diretmus argenteus (juvenile characters): CARANGIDAE - Trachurus mccullochi (key to Tasmanian carangids): ANTHIIDAE - Hypoplectrodes nigrorubrum (additions to, revision of, published accounts, key to Tasmanian anthiids). Observations are made also on the following species:- MACROURIDAE - Coelorinchus mortoni (new material of little-known species); Lepidorhynchus denticulatus (food of Rexea solandri, abnormal spinous structure); Macruronus novaezelandiae (fluviatile example): SYNGNATHIDAE - Solegnathus fasciatus (sex dimorphism, relative growth, table of dimensions); Stigmatophora argus (comparison with published data). Syngnathus phillipi (proportions): SPHYRAENIDAE- Austroluzza novaehollandiae (food of seal, proportions): SCOMBRIDAE - Gasterochisma melampus (additional Tasmanian record): ANTHIIDAE - Anthias pulchellus (second Tasmanian record, extension of extant accounts). Caesioperca rasor (examination of 11 examples, table of dimensions); Caesioperca lepidoptera (additions to published accounts); Callanthias allporti (additions to, revision of, published descriptions): ECHENEIDAE- Remora remora (comparison with larger examples reported on earlier). In the case of several species the existence of one or both of two interesting form patterns has been examined: (a) length of head, length to vent, standard length are found to be collinear in a loglog plot on integral numbers, (b) the lengths of spines and rays, in one or more sets, are found to yield a linear graph when plotted on a loglog grid against their serial (or reverse serial) numbers.