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Macaulay, G. J., Kloser, R. J., and Ryan, T. E. 2013. In situ target strength estimates of visually verified orange roughy. – ICES Journal of Marine Science, 70:215–222.The first estimates of orange roughy (Hoplostethus atlanticus) target strength at 38 and 120 kHz with visual verification were obtained from a self-contained echosounder and video camera system affixed to a demersal trawl towed through dense aggregations of spawning orange roughy. Mean target strength estimates were obtained from 24 tracks of orange roughy containing 83 echoes. The mean target strength at 38 kHz was –52.0 dB with a 95% confidence interval of –53.3 to –50.9 dB for fish with a mean length of 33.9 cm. At 120 kHz the mean target strength was –47.9 dB (confidence interval of –48.8 to –46.4 dB). This work makes two significant advances: in situ TS measurements have been made that can be confidently attributed to orange roughy, and using a trawl to herd orange roughy past the system resolved the previously intractable problem of fish avoidance. [ABSTRACT FROM PUBLISHER]

Hoplostethus gigas McCulloch, 1914 and two previously unnamed species of the genus that reach a similarly 'giant' size are described. The redescription of H. gigas, which is confined in distribution to the southern coast of Australia, is based on specimens identified as comprising at least part of McCulloch's type series (one herein designated lectotype), together with subsequently collected material. The very similar H. melanopeza sp. nov., occurring in northern New Zealand and southeastern Australian waters, as well as seamounts in the intervening Tasman Sea, is distinguished by the distinctly black outer margins of fins in large adults and count of predorsal scales. The New Caledonian H. grandperrini sp. nov., known only from the two types, differs from previously described species in having the combination of 17 or 18 pectoral-fin rays, 13 or 14 abdominal scutes, 19 or 20 total gill rakers and a buccal cavity that is mostly pale, the only black pigmentation occurring posterior to the gill arches. [ABSTRACT FROM AUTHOR]

O'Driscoll, R. L., de Joux, P., Nelson, R., Macaulay, G. J., Dunford, A. J., Marriott, P. M., Stewart, C., and Miller, B. S. 2012. Species identification in seamount fish aggregations using moored underwater video. – ICES Journal of Marine Science, 69: 648–659.Acoustic surveys of New Zealand deep-water seamounts often show fish aggregations up to 150 m high on the summit. Although bottom trawls on the seamount slopes catch predominantly orange roughy (Hoplostethus atlanticus), species composition in the midwater plumes is extremely uncertain. In June 2010, moored underwater video cameras were deployed on the summit of the Morgue seamount (summit depth 890 m), a feature that has been closed to fishing since 2001. Cameras and lights were timed to come on for 2 min every 2 h. Fish response to the mooring was monitored using vessel-mounted echosounders. Moored cameras confirmed that orange roughy were present up to 70 m above the seamount summit. Orange roughy made up 97% of the fish identified from the video. Other species observed included smooth oreo (Pseudocyttus maculatus), spiky oreo (Neocyttus rhomboidalis), deep-water dogfish, cardinalfish (Epigonus spp.), and squid. Total along-track backscatter from the plume varied by a factor of 25 over a period of hours. Peak acoustic densities in the plume (equivalent to 20 orange roughy m−3) were an order of magnitude higher than peak visual estimates (0.64 orange roughy m−3), but relative densities between paired video and acoustic observations were generally consistent. [ABSTRACT FROM PUBLISHER]

Orange roughy Hoplostethus atlanticus juveniles <24 cm fork length ( LF) (10–17 years old) were recorded for the first time in Chile, when 10 specimens were collected on the continental slope and seamount JF2 in Juan Fernandez Archipelago. The LF, total mass, anatomical and parasitological information are reported. Relevance to current life-cycle hypotheses is discussed. [ABSTRACT FROM AUTHOR]

We examined site differences in the elemental composition of the primordium and ontogenetic variability of Sr in otoliths of fish from Australia and New Zealand and, as an out-group, the North Atlantic. Differences among sites in primordium composition are slight, but significant for all five elements assayed (Sr, Pb, Cu, Zn and Hg), but principally reflect differences between the North Atlantic and SW Pacific specimens, do not replicate for independent samples in the SW Pacific and constitute a poor “natural tag” in roughy, with <25% of fish successfully assigned to source location. However, mean Sr weight-fractions at the primordium showed similar latitudinal variation across sites in Australia, New Zealand and the Tasman Sea, indicating both spatially structured populations and a common structuring process across the region. Comparisons of ontogenetic variability of Sr in otoliths from juveniles and young adults within and between sites in the SW Pacific strongly support the hypothesis that variability in this element is site-specific and environmentally sensitive, although the environmental factors involved are not obvious. The otolith analysis confirms previous suggestions that juvenile and adult Hoplostethus atlanticus are relatively sedentary, but also indicates that the population sub-structuring by age within sites is more complex and there are likely to be more spawning areas in Australian waters than previously thought. More broadly, although single point analysis of otolith composition at the primordium resolves a population structure in roughy, alone it is not precise enough to test hypotheses about the processes causing this structure. Ontogenetic variability in Sr provides better resolution of spatial structure, even in a relatively homogenous marine environment like the deep ocean, and also provides insight into behavioural and ecological factors. Ontogenetic analyses of Sr in otoliths are expensive to obtain, require more effort in specimen preparation than single point analyses, and are difficult to compare statistically, but the increased information they yield warrants their broader consideration in marine species. [ABSTRACT FROM AUTHOR]

The history of orange roughy (Hoplostethus atlanticus) stocks, primarily in New Zealand and Australia, is commonly used as an example of the inability to manage fisheries resources. We review the history and status of the New Zealand orange roughy fishery and show that the total loss of potential biological yield from overfishing is no more than 8.3% (1260 tonnes (t)·year–1) of the potential yield. The losses from underfishing are estimated to be 810 t·year–1. We consider the biological and economic consequences of alternative management approaches to the New Zealand orange roughy fishery. We suggest that given the uncertainty in stock abundance and productivity and market and processing capacity limits, the management of New Zealand orange roughy stocks has been close to economically optimal and has produced near maximum sustainable yield from the resource. [ABSTRACT FROM AUTHOR]

Data on the diet, feeding habits and daily rations ofHoplostethus mediterraneusCuvier, 1829 in the bathyal eastern Ionian Sea (Mediterranean Sea) are presented. A total of 430 specimens collected by bottom trawls at depths ranging from 473 to 603 m during four 24-h day-night sampling cycles covering the four annual seasons was examined.H.mediterraneusdiet consisted of pelagic and vagile epibenthic prey, mainly crustaceans, and was dominated by benthopelagic natantian decapods (83.35% IRI, index of relative importance). Seasonal changes in diet were apparent and related to seasonal fluctuations in suprabenthic and zooplanktonic prey in the environment. Diel patterns in stomach fullness and trends in diel feeding cycles are discussed in relation to the vertical migratory movements of available prey (i.e. suprabenthos and zooplankton). Daily-ration estimates were determined by evacuation-rate models and ranged from 0.143% to 0.397% WW/WW. Overall, daily-ration estimates were within the range of the daily consumption of other deep-sea fish. Deduced from diet contents, we found a constant gross energy intake (305-316 kcal g-1) during all seasons. As a possible response to the reproductive peak of mature females observed in summer,H.mediterraneusincreases its food consumption, which, in turn, is coupled with an increase in food availability. [ABSTRACT FROM AUTHOR]

“Stars” are an alternative design for acoustically acoustically surveying isolated fish aggregations in which transects cross at a centre point over an aggregation to form a star or wheel-spoke pattern. The method was devised particularly for aggregations of orange roughy (Hoplostethus altanticus Collett) to cope with the practical difficulties of manoeuvring a vessel towing a transducer over a small, dense school of fish. Several methods of analysing star patterns were considered including kriging and a method that ignored the spatial arrangement of the transects. However, simulations of roughy aggregations showed that the best approach was to transform from Cartesian to polar coordinates and then use standard statistical methods (polar method). The polar method was robust to shifts in the transect centre off the aggregation centre and aggregation movement in a random way. Variance estimation was best with a polar version of transitive kriging. Stars using the polar method were also better than the usual parallel transect design when transect numbers were low but the results were similar when six or more transects were used. However, in all the cases considered parallel transects consistently overestimated the variance. We conclude that star transects offer a robust and effective way of estimating the biomass of small, localized aggregations of fish that minimizes vessel time, and yields good precision. Copyright 2003 Published by Elsevier Science Ltd on behalf of International Council for the Exploration of the sea. [Copyright &y& Elsevier]

Presents information on a study which estimated the mean age and length at onset maturity for orange roughly (Hoplostethus atlanticus) populations off New Zealand, Namibia and Great Britain. Methodology of the study; Results and discussion on the study.

Fillets of deep-skinned orange roughy (Hoplostethus atlanticus) were found to contain 5.46% total lipids consisting of as much as 93% non-digestible wax esters. The fillets therefore act as a mild laxative, which probably contributes to their popularity on the American and Japanese markets. In addition, the fillets had remarkably low levels of cholesterol and phospholipids (seemingly irreplaceable constituents of cell membranes) of 0.033% and 0.17%, respectively. These concentrations are much lower than those of pelagic fish and it is not clear what replaces them in the membranes of this long-lived, deep-water fish. The phospholipid composition was, however, similar to that of other fish species, consisting of 51% phosphatidylcholine, 22% phosphatidylethanolamine, 10% sphingomyelin, 7% cardiolipins, 5% phosphatidylinositol, 3% phosphatidylserine and 2% lyso phosphatidylcholine. The non-phosphorylated lipids consisted of 96.3% wax esters, 1% cholesterol esters, 0.6% free fatty acids, 2% triacylglycerols and 0.1% free cholesterol. The fatty acid compositions of the phospholipids and the non-phosphorylated lipids were different, the phospholipids having a high level of docosahexaenoic acid (C22:6 n-3) of 40.4%, whereas the non-phosphorylated lipids had a high level of oleic acid (C18:1 n-9) of 58.3%. Almost two thirds of the alcohols of the wax esters from the non-phosphorylated lipids consisted of mono-unsaturated fatty alcohols (C14:1 to C24:1), whereas the remaining one third were saturated alcohols (C16:0 to C24:0). [ABSTRACT FROM AUTHOR]

The article offers information on the first records documented for Mediterranean slimehead, hoplostethus mediterraneus in Adriatic Sea on April 2010. It says that the slimehead commonly occurs in the northeastern Atlantic, Mediterranean, and Indian oceans at depths of 100 and 1175 meters (m). It says that the slimehead may have arrived through active migration and the effect of Adriatic ingressions and oceanographic changes in Adriatic Sea.

A specimen of the Slimy head Hoplostethus mento was collected at a depth of 650–700 m from off the Pacific coast of Costa Rica. This specimen constitutes the first record of the species in Costa Rican waters and a north-west range extension of about 600 km on known distribution. A brief description of the specimen as well as comparative morphometric data and distributional information are provided. [ABSTRACT FROM PUBLISHER]