Galaxias truttaceus

Spotted Galaxias Galaxias truttaceus has most recently been assessed for The IUCN Red List of Threatened Species in 2019. Galaxias truttaceus is listed as Least Concer

Spawning, egg development and recruitment of diadromous galaxiids in Taranaki, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Ecology at Massey University

Spawning biology of Galaxias postvectis Clarke (shortjaw kokopu) was investigated in streams in northwest Taranaki, New Zealand. Most G. postvectis were found to spawn near their adult habitat on the river bank during spate flows between May 9 and 17, 2001. Other galaxiids captured appeared to begin spawning earlier in late April. Sixteen galaxiid nests were discovered amongst flooded areas, lying on or amongst the substrate, vegetation and debris on the banks of the Katikara Stream. Mitochondrial (mt) DNA sequences were used to identify these morphologically similar eggs, with 12 being identified as G. postvectis and four as G. fasciatus Gray (banded kokopu). Galaxias fasciatus nest sites had more vegetation and debris than G. postvectis nests. The presence of a backwater or pool, cover and gravel were found to be important characteristics associated with both species nests. Egg development took around three to four weeks on the Katikara Stream margins. Under experimental conditions, most G. postvectis and G. fasciatus eggs were found to hatch within the first hour of re-immersion in water, and more hatching occurred in moving than still water at warmer temperatures. In the Katikara Stream, eggs hatched and moved downstream only at times of increased water levels. MtDNA sequences were used to identify G. fasciatus, G. postvectis and G. brevipinnis Günther (koaro) larvae caught drifting downstream in May and June, 2001. From reproductive assessment of adults captured, developmental stage of eggs in nests found, and timing of emigrating larvae, G. fasciatus appeared to spawn earlier than G. brevipinnis, and both species spawned earlier than G. postvectis. Whitebait migrations were examined within the tidal influence and c. 40 km inland in two rivers in south Taranaki, one with a dam and one without. Whitebait catches were dominated by G. maculatus (Jenyns) (inanga) and catches appeared to be similar in both rivers. Large schools of whitebait were however seen below the Patea Dam from October onwards in the Patea River. No whitebait were found to surmount the dam using the elver pass. So the presence of a dam does not appear to affect whitebait recruitment within the tidal influence, however it does block whitebait migrating further upstream to adult habitat

International workshop: Basis for the whitebait Galaxias spp. Fish culture

Proyecto FONDEF D96I1071 "Investigación y desarrollo de la tecnología para el cultivo comercial del puye Galaxias maculatus"Galaxias maculatus es una especie circumantártica de importancia comercial que se encuentra en Chile, Argentina, Islas Malvinas, Nueva Zelandia, Tasmania y Australia. El estado juvenil cristalino que se consume se le conoce comúnmente como puye, angula o whitebait. Esta delicatessen es un símil de la angula del género Anguilla, que corresponde a la larva cristalina leptocephala. El puye o whitebait es tradicionalmente consumido en Chile y Nueva Zelanda alcanzando altos precios. El estudio de mercado muestra interesantes posibilidades en los países donde ya se consume, en los países donde se consume la angula, tales como México, Perú, sur hispano de USA, España o en los países de oriente donde consumen larvas de peces cristalinos, como Japón y China. Las pesquerías de puyes en Chile se encuentran sobrexplotadas, motivo por el cual las capturas anuales son bajas y fluctúan entre 10 a 20 toneladas. En Nueva Zelanda, extraoficialmente se menciona una captura de 300 toneladas anuales, que son insuficientes para la demanda interna y deben importar un símil de origen chino. El desarrollo de la tecnología de cultivo del puye Galavias maculatus es fundamental para una producción masiva que permita sustentar la exportación. Así mismo, el cultivo del puye es una valiosa herramienta para el manejo y recuperación de las pesquerías a través de la repoblación. Teniendo en consideración estos fundamentos, CONICYT aprobó el Proyecto FONDEF DI96-1071 Investigación y Desarrollo de la tecnología de cultivo del puye Galaxias maculatus, cuyos resultados se presentan en este Seminario.1. La pesquería del puye (Galaxias spp.) en Chile. 2. The state of the whitebait fishery for Galaxias species (Teleostei: Galaxiidae) in New Zealand. 3. Mercado y comercialización del puye, símiles y sucedáneos 4. Estado del conocimiento de la biología y ecología de Galaxias maculatus en Chile. 5. The ecology of the inanga, Galaxius maculatus (Teleostei: Galaxiidae), in New Zealand. 6. Parámetros fisiológicos para la estimación de capacidad de carga para cultivo de "puye" (Galaxias macuIatus). 7. Principales enfermedades encontradas en reproductores adultos de la especie Puye (Galaxias maculatus, Jenyns, 1842) mantenidos en cautiverio. 8. Manejo de reproductores de Galaxias macukztus. 9. Manejo reproductivo del puye (Galaxias maculatus) en condiciones de cultivo. 10. Incubación de Galaxius maculatus en hatchery. 11. Larvicultura de Galaxias maculatus en un sistema intensivo de producción. 12. Estudio base para el desarrollo del proyecto piloto de cultivo de puyes "Galaxias maculatus" en la XI región. 13. Introducción de nuevas tecnologías para el cultivo comercial del puye (Galaxias maculatus) en la XI región Chile. 14. Cosecha y procesamiento del recurso puye (Galaxias spp.)

Shortjaw kokopu (Galaxias postvectis Clarke) distribution, habitat selection and seasonal activity in the northern Tararua Ranges : a thesis presented in partial fulfillment of the requirements for the degree of a Masters of Science in Ecology at Massey University, Palmerston North, New Zealand

Freshwater fish communities were surveyed at 59 sites in the Mangatainoka, Makakahi and Ruamahanga catchments of the northeastern Tararua Ranges during 2000/01. At each site, habitat characteristics were recorded and fish identified by spotlighting over a 100 m reach. Benthic invertebrate samples were also collected from 50 of these sites. Shortjaw kokopu (Galaxias postvectis Clarke) occurred at 16 sites, located in the Mangatainoka and Makakahi catchments only. Ninty-five shortjaw kokopu were caught in total, ranging from juveniles (120 mm), with adults comprising approximately 75% of the population. Six other fish species were also recorded. Koaro (G. brevipinnis GÜnther), longfin eel (Anguilla dieffenbachii Gray), Cran's bully (Gobiomorphus basalis Gray), torrentfish (Cheimarrichthys fosteri Haast) and brown trout (Salrmo trutta Linnaeus) all co-occurred with shortjaw kokopu; and a single banded kokopu (G. fasciatus Gray) was found in the Ruamahanga catchment. Discriminant analysis found six habitat factors defined shortjaw kokopu presence. These were low percentages of debris jams, pasture and backwaters; high percentages of shrubs and riffles; and high conductivity. The invertebrate community also proved effective at predicting shortjaw kokopu presence. However, it appears that shortjaw kokopu are limited in distribution by recruitment rather than habitat. Different age classes of shortjaw kokopu were also found to use distinct microhabitats. Sand substrate, pool length, width at the top of the pool, velocity, gradient below the pool, and cobble in the habitat above the pool were found to discriminate between the age class microhabitats. At three sites in the Mangatainoka River, surveys were undertaken monthly, for 16 months. Number of shortjaw kokopu observed was greatly reduced at all three sites during winter and at a maximum in autumn. This showed that shortjaw kokopu exhibited reduced activity rather than seasonal movements within the catchment. Three methods for surveying fish communities were tested on shortjaw kokopu. Gee-minnow traps failed to catch any shortjaw kokopu, but electrofishing and spotlighting both proved effective. While spotlighting caught more shortjaw kokopu at more sites, no significant difference in performance was found between the two methods

Pathology associated with larval Eustrongylides sp. (Nematoda: Dioctophymatoidea) infection in Galaxias maculatus (Actinopterygii: Galaxiidae) from Patagonia, Argentina

Helminth infections within tissues tend to be subjected to a host response that can include encapsulation and melanization to isolate the parasite. The effectiveness of this response depends on the host species. During a survey of parasites of the native fish, Galaxias maculatus, we found conspicuous, strongly melanized exterior cysts located in the caudal peduncle of the fish. Dissection of these cysts exposed larval nematodes whose morphometrical features allowed their identification as Eustrongylides sp. Species of this genus are distributed worldwide. Galaxias maculatus was previously reported as second intermediate host to Eustrongylides sp. larvae, and the aquatic bird Podiceps major was cited as definitive host of Eustrongylides tubifex in Andean Patagonian lakes. The site of infection in the fish, and the host´s response are unique among infections by larvae of Eustrongylides sp. in fishes, so the objective of this study was to describe the histological injury caused by larvae of the genus Eustrongylides parasitizing G. maculatus. Samples of fish were taken near the shore of Gutiérrez lake, in northwestern Patagonia. Some larval morphometric features were described to confirm the identity of larvae to generic level. Histopathological analysis (tissues sectioned at 5?7 μm, stained with Hematoxylin and Eosin, and Masson´s Trichrome) of the caudal peduncle revealed almost complete disappearance of the epaxial musculature due to compressive atrophy and a chronic inflammatory response, associated mainly with a dense fibrotic capsule and an intense melanic deposit. This is the first description of the histopathology of an external cyst caused by Eustrongylides sp. larvae in fishes.Fil: Guagliardo, Silvia Elizabeth. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Viozzi, Gustavo Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Brugni, Norma Leonor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

Haemoglobin and size dependent constraints on swimbladder inflation in fish larvae

In developmental studies of fish species (especially physostomians) it could be demonstrated, that the lack of haemoglobin during larval and juvenile stages is a relatively common phenomenon. Generally it is linked with body translucency. In representatives of the families Galaxiidae, Osmeridae and Clupeidae, partly reared, partly observed immediately after being caught in the wild, it turned out, that this condition coincides with a considerable delay in swimbladder inflation. To determine the moment of its first inflation, larvae placed in a hermetic chamber were observed under a dissecting microscope. While lowering the pressure, the expanding swimbladder showed whether or not its content is really gaseous. The reason postulated to be responsible for the delayed inflation is that larvae lacking haemoglobin do not have the possibility of oxygen transport to their buoyancy organ by means of the blood. Apart of this, capillarity force calculations and body force estimations show that with decreasing size the constraints linked with surface tension increase overproportionally. While in larger sized larvae like trout we could demonstrate inflation by swallowing air, in species with small larvae this was not the case. Below a certain size, even in physostomians, the ductus pneumaticus is no alternative to the blood pathway for swimbladder inflation

Influence of open and closed river systems on the migrations of two northern New Zealand populations of banded kokopu (Galaxias fasciatus)

Otolith microchemical analysis by laser ablation inductively coupled mass spectrometry (ICP-MS) was used to investigate the migratory life histories of banded kokopu (Galaxias fasciatus) in two streams on the North Island of New Zealand. Known differences in marine and freshwater chemistry were used as a premise to document the migratory life strategies of banded kokopu between these environments. More specifically, temporal trends in high and low strontium/calcium ratios (Sr/Ca) identified in fish otoliths were used to determine evidence of migration between fresh and saltwater environments. Trace element analysis of fish captured above the Whau Valley Reservoir reflected non-migratory life histories and exhibited consistently low Sr/Ca ratios across the entire otolith. However, one fish from above the reservoir indicated unusually high Sr/Ca ratios in early adulthood. These high Sr levels were attributed to localised inputs from mineral-rich seepages associated with past mining practices in the region and low calcium availability within the Pukenui Stream. Otoliths from banded kokopu collected from Komiti Stream were shown to be migratory with a marine larval stage (high Sr/Ca ratio levels at the otolith nucleus), followed by a freshwater adult phase (low Sr/Ca ratio levels towards the edge) indicating their amphidromous origins. The study provides further evidence of non-diadromous recruitment for banded kokopu as a consequence of a large in-stream barrier and will add to the known distribution of landlocked species in New Zealand

Estimating the abundance of banded kokopu (galaxias fasciatus gray) in small streams by nocturnal counts under spotlight illumination

The abundance of banded kokopu (Galaxias fasciatus Gray) in small streams has usually been determined by the labour intensive and invasive method of electric fishing. Recently, nocturnal counts under spotlight illumination have been used to determine presence or absence and relative abundance of banded kokopu, but the proportion of the population seen was unknown. We compared 20 spotlight counts of banded kokopu in approximately 20 m reaches in streams in the North Island, New Zealand, to population estimates determined by removal electric fishing in the same reaches. Spotlight counts were related to population estimates over a range of densities, and on average, spotlight counts were 64% of the population estimates. Though we tried to separate age-0 fish from older fish visually in the spotlight counts, the size frequency distribution of the fish caught by electric fishing showed that the visual separation was not reliable. In addition, visual counts were generally inefficient for age-0 fish (40-70 mm total length), as only about 40% were observed. Banded kokopu were also recorded in streams using time-lapse video recordings with a camera sensitive to low light levels. Diel activity showed two major peaks, one in the early morning from 0400 h to 0900 h, and the other in the afternoon and evening from 1300 h to 1900 h. Fish were less disturbed by the observer.s approach after dark than during the day, so we suggest that from dusk to about 2200 h is the best time for visual counts of banded kokopu by spotlight in summer months