1,720,996 research outputs found
Macroscopic and histological analyses of gonads durinG the spawning season of Chionodraco hamatus (Pisces, Channichthyidae) off Terra Nova Bay, Ross Sea, Southern Ocean.
No full textGametogenesis and reproductive strategies in some species of the Antarctic fish genus Trematomus (Nototheniidae) from Terra Nova Bay, Ross Sea.
No full textGametogenesis in the dragonfishes Akarotaxis nudiceps and Bathydraco marri (Pisces, Notothenioidei: Bathydraconidae) from the Ross Sea.
No full textLife style and genetic variation in teleosts: the case of pelagic (Aphia minuta) and benthic (Gobius niger) gobies (Perciformes: Gobiidae).
No full textFeeding ecology of two nototheniid fishes, Trematomus hansoni and Trematomus loennbergii, from Terra Nova Bay, Ross Sea
No full textSpecies composition and distribution of the Antarctic plunderfishes (Pisces, Artedidraconidae) from the Ross Sea.
Full text linkThe reproductive biology of two epibenthic species of Antarctic nototheniid fish of the genus Trematomus.
No full textPattern of gonad maturation and the question of semelparity in the paedomorphic goby Aphia minuta (Risso, 1810) (Teleostei: Gobiidae)
No full textLife history traits of Notothenia rossii and N. coriiceps along the southern Scotia Arc
No full textNotothenia coriiceps and Notothenia rossii are two widespread nototheniid fishes, that live sympatrically along the southern Scotia Arc from South Georgia to the South Shetland Islands. In this sector of the Southern Ocean, they experienced different exploitation rates in the past and exhibit different habitat and food preferences as adult. Aiming to evaluate the influence of these factors in shaping life history traits of these species, we compare the reproductive investment and the age structure between the species and in N. rossii, between populations inhabiting different areas. Based on histological analyses, the two species share the same pattern of gamete development in both sexes. The potential fecundity was similar and was positively related to fish size in both species, being relatively high with respect to other notothenioids and in terms of egg size at deposition. Based on sagittal otolith readings, the growth rate and maximum age recorded differed significantly between the two species. Notothenia rossii exhibited a higher growth rate and a comparatively lower maximum age than N. coriiceps. Similarly, N. rossii attained sexual maturity at the same age but at a larger size than N. coriiceps. At the intraspecific level, no differences in life history traits were observed between the populations of N. rossii collected from different areas. Consistent with the different levels of fishing pressure exerted on these species and their low resilience, a recent significant decrease over time in the maximum fish size and related reproductive potential has been observed only in the overexploited populations of N. rossii
Some reproductive traits of the Tristan klipfish, Bovichtus diacanthus (Carmichael 1819) (Notothenioidei: Bovichtidae) from Tristan da Cunha (South Atlantic)
No full textThe reproductive biology of the Tristan klipfish, Bovichtus diacanthus, was investigated by macroscopic and histological analyses of the gonads. Fish samples were collected in tide pools at Tristan da Cunha in July 2004. Most specimens of both sexes were developing, or sexually mature, with a gonadosomatic index (GSI) of 7.0-9.2% in females and 0.2-0.6% in males. Histologically, testes showed a random distribution of spermatogonia along the lobules, a condition defined as the unrestricted spermatogonial type. Ripe males exhibited lobules with all spermatogenic stages of development from spermatogonia to spermatozoa. In mature females, the ovarian follicles consisted of three main cohorts of oocytes of different sizes; the smaller one represented by previtellogenic oocytes of 15-150 mu m and the other two by yolked oocytes measuring, respectively, 300-1000 and 800-1500 mu m. The overlap between the stock of advanced yolked oocytes and the early yolked oocytes was low, decreasing progressively with final maturation. As a result, B. diacanthus was considered a batch spawner, with a spawning season extending from July to August onward. Batch fecundity, based on the most advanced yolked oocytes, was 2,047-8,317 mature oocytes/female, whereas the relative fecundity was 77-141 mature oocytes/g. In the light of the phyletically basal position of bovichtids in the suborder, the reproductive traits of B. diacanthus were compared with those previously described in other Antarctic and non-Antarctic notothenioids
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