Reproductive biology of the red throat emperor Lethrinus miniatus (Pisces : Lethrinidae) from the southern Great Barrier Reef, Australia

The reproductive biology of the red throat emperor, Lethrinus miniatus (Schneider, 1801) was examined in the southern Great Barrier Reef (GBR), Australia. The species was found to display the characteristics of an incomplete metagynous hermaphrodite based on histological evidence and size frequency information. Over 95% of functional males possessed a remnant lumen, but there was no evidence of oocytes in the testes of males. A single transitional fish was sampled which had both ovarian and testicular tissue present in its gonad. Size frequency data showed that females dominated the smaller size classes with the majority of fish < 40 cm being females. Lethrinus miniatus had an extended spawning season from July-November, although spawning was more pronounced during the spring. Spawning was initiated earlier at lower latitudes. There was no particular size or age when sex change occurred since females older than 20 and males as young as 2-yrs old were sampled.

Jukka Ruohomäen sävellystuotanto ja tyylipiirteet 1970-luvulla : Esimerkkianalyysi teoksesta Pisces

Tutkimuksessani olen keskittynyt tarkastelemaan säveltäjä Jukka Ruohomäen (s.1947) 1970-luvun sävellystuotantoa ja teosten tyylipiirteitä sekä Ruohomäen toimintaa elektroakustisen musiikin parissa. Ruohomäen 1970-luvun teokset kuuluvat elektroakustisen nauhamusiikin lajiin. Aiempaa tutkimusta hänen musiikistaan ei ole tehty. Tutkimuksen kohteen tarkastelua varten työssä luodaan kuva elektroakustisen musiikin historian, kulttuurin ja analyysin kehitykseen sekä elektroakustisen musiikin terminologiaan ja työtapoihin. Elektroakustisen musiikin historiallista kehitystä seurataan 1800-luvulta 1960- ja 1970-lukujen taitteeseen asti, jotta voidaan ymmärtää, mihin kulttuurihistorialliseen kontekstiin Ruohomäen ensimmäisen sävellyskauden (1970–1978) tuotanto on syntynyt. Historiallisesta näkökulmasta tutkimus on kartoittavaa perustutkimusta. Elektroakustisen musiikin analyysimenetelmiä esittelevässä osassa esitellään ne keskeiset menetelmät, joita tässä työssä käytetään Ruohomäen tuotannon analysointiin. Analyysin pääpaino on teosten äänimateriaalien ja rakenteen tarkastelussa. Tähän tarkasteluun valittuja analyysimenetelmiä ovat Simon Emmersonin elektroakustisten teosten jaottelu äänimateriaalien narratiivisuuden ja syntaktisten piirteiden suhteen, Denis Smalleyn spektromorfologia ja Robert Coganin musiikin kuvaamiseen esittelemä sonogrammikuvaaja. Ruohomäen 1970-luvun teosten esittelyn lisäksi tarkemman analyysin kohteeksi on valittu sävellys Pisces (1975–76). Teosesittelyjen pohjalta muodostetaan kuva Ruohomäen ensimmäisen sävellyskauden vaikutteista ja sävellystyylin muuttumisesta. Ruohomäki painottaa sävellysprosessissa kuuntelun merkitystä ja hänen teoksensa syntyvät pikemminkin vuorovaikutuksessa äänimateriaalin ja sävellysteknologian kanssa kuin tarkan etukäteissuunnitelman ohjaamina. Varhaisten teosten populaarimusiikkivaikutteista Ruohomäen musiikki kehittyi 1970-luvulla kohti puhtaampaa konkreettisen musiikin traditiota. Minimalistiset ja stokastisen musiikin ideat ovat kuultavissa kaikissa ensimmäisen sävellyskauden teoksissa. Analyysi teoksesta Pisces tarkentaa kuvaa Ruohomäen sävellysten tyylipiirteistä. Teosanalyysissä luodaan pohjaa myös Ruohomäen kahden sävellyskauden vertailuun. Jatkotutkimuksen kannalta mielenkiintoiseksi kysymykseksi nousee Ruohomäen kahden sävellyskauden vertailu sekä sävellysteknologian kehityksen ja elektroakustisen musiikin estetiikan suhteen tarkastelu tämän vertailun avulla.

Stock structure of Grey Mackerel, Scomberomorus semifasciatus (Pisces: Scombridae) across northern Australia, based on otolith stable isotope chemistry

The stable isotopes of delta O-18 and delta C-13 in sagittal otolith carbonates were used to determine the stock structure of Grey Mackerel, Scomberomorus semifasciatus. Otoliths were collected from Grey Mackerel at ten locations representing much of their distributional and fisheries range across northern Australia from 2005 to 2007. Across this broad range (similar to 6500 km), fish from four broad locations-Western Australia (S1), Northern Territory and Gulf of Carpentaria (S2, S3, S4, S5, S6, S7), Queensland east coast mid and north sites (S8, S9) and Queensland east coast south site (S10)-had stable isotope values that were significantly different indicating stock separation. Otolith stable isotopes differed more between locations than among years within a location, indicating temporal stability across years. The spatial separation of these populations indicates a complex stock structure across northern Australia. Stocks of S. semifasciatus appear to be associated with large coastal embayments. These results indicate that optimal fisheries management may require a review of the current spatial arrangements, particularly in relation to the evidence of shared stocks in the Gulf of Carpentaria. Furthermore, as the population of S. semifasciatus in Western Australia exhibited high spatial separation from those at all the other locations examined, further research activities should focus on investigating additional locations within Western Australia for an enhanced determination of stock delineation. From the issue entitled "Proceedings of the 4th International Otolith Symposium, 24-28 August 2009, Monterey, California"

Spatial subdivision among assemblages of Spanish mackerel, Scomberomorus commerson (Pisces: Scombridae) across northern Australia: implications for fisheries management

Aim: This study investigated the use of stable δ13C and δ18O isotopes in the sagittal otolith carbonate of narrow-barred Spanish mackerel, Scomberomorus commerson, as indicators of population structure across Australia. Location: Samples were collected from 25 locations extending from the lower west coast of Western Australia (30°), across northern Australian waters, and to the east coast of Australia (18°) covering a coastline length of approximately 9500 km, including samples from Indonesia. Methods: The stable δ13C and δ18O isotopes in the sagittal otolith carbonate of S. commerson were analysed using standard mass spectrometric techniques. The isotope ratios across northern Australian subregions were subjected to an agglomerative hierarchical cluster analysis to define subregions. Isotope ratios within each of the subregions were compared to assess population structure across Australia. Results: Cluster analysis separated samples into four subregions: central Western Australia, north Western Australia, northern Australia and the Gulf of Carpentaria and eastern Australia. Isotope signatures for fish from a number of sampling sites from across Australia and Indonesia were significantly different, indicating population separation. No significant differences were found in otolith isotope ratios between sampling times (no temporal variation). Main conclusions: Significant differences in the isotopic signatures of S. commerson demonstrate that there is unlikely to be any substantial movement of fish among these spatially discrete adult assemblages. The lack of temporal variation among otolith isotope ratios indicates that S. commerson populations do not undergo longshore spatial shifts in distribution during their life history. The temporal persistence of spatially explicit stable isotopic signatures indicates that, at these spatial scales, the population units sampled comprise functionally distinct management units or separate ‘stocks’ for many of the purposes of fisheries management. The spatial subdivision evident among populations of S. commerson across northern and western Australia indicates that it may be advantageous to consider S. commerson population dynamics and fisheries management from a metapopulation perspective (at least at the regional level).

A review of the biology, ecology, distribution and control of Mozambique tilapia, Oreochromis mossambicus (Peters 1852) (Pisces: Cichlidae) with particular emphasis on invasive Australian populations

Oreochromis mossambicus (Peters 1852) are native to the eastward flowing rivers of central and southern Africa but from the early 1930s they have been widely distributed around the world for aquaculture and for biological control of weeds and insects. While O. mossambicus are now not commonly used as an aquaculture species, the biological traits that made them a popular culture species including tolerance to wide ranging ecological conditions, generalist dietary requirements and rapid reproduction with maternal care have also made them a 'model' invader. Self-sustaining populations now exist in almost every region to which they have been imported. In Australia, since their introduction in the 1970s, O. mossambicus have become established in catchments along the east and west coasts and have the potential to colonise other adjacent drainages. It is thought that intentional translocations are likely to be the most significant factor in their spread in Australia. The ecological and physical tolerances and preferences, reproductive behaviour, hybridization and the high degree of plasticity in the life history traits of O. mossambicus are reviewed. Impacts of O. mossambicus on natural ecosystems including competitive displacement of native species, habitat alteration, predation and as a vector in the spread of diseases are discussed. Potential methods for eradicating or controlling invasive populations of O. mossambicus including physical removal, piscicides, screens, environmental management and genetic technologies are outlined.

Nota sobre Cyrtocharax squamosus (Eigenmann y Kennedy) (Pisces: Characoidei).

Trabajo de contribución a la sistemática de peces carácidos, subfamilia Characinae. Género Cyrtocharax; su descripción.

Nota sobre Auchenipterus nuchalis (Spix) (pisces: Siluroidei).

Al estudiar la ictiofauna de agua dulce, especialmente la correspondiente al Paraná inferior, he encontrado en las colecciones del Museo de La Plata un lote de 20 ejemplares de la localidad de San Pedro (provincia de Buenos Aires)pertenecientes a la especie Auchenipterus nuchalis (Spix). Su descripción e ilustración. (PDF tiene 9 paginas.)

Porotergus ellisi. Una nueva subespecie de gimnótido de la Argentina (Pisces: Gymnotoidei).

Debido a una revisión de la colección del Museo de La Plata he encontrado cuatro gimnótidos que a mi juicio corresponden a una nueva especie del género Porotergus Ellis. (PDF tiene 10 paginas.)

Los Hypostominae (Pisces: Loricariidae) de Argentina.

This is part of Fauna de agua dulce de la República Argentina. (PDF is 64 pages.)

La familia Stromateidae en la Argentina (Pisces, Stromateidae).

A brief synthesis of the systematics of argentine Stromateidae is given together with a general key and morphological and statistical data based on numerous specimens. The southern limit of the range of Perilus parus is discussed. (PDF tiene 12 paginas)

Bibliografía Argentina del género Prochilodus (Pisces: Curimatidae).

This compilation groups the bibliographic references up to the year 1992 of the species of the genus Prochilodus present in Argentina. A list of the species of the genus inhabiting del Plata basin is presented.