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Aspects of embryonic development in two southwest Atlantic gadi-form fish: tadpole codling, Salilota australis [Moridae], and southern blue whiting, Micromesistius australis [Gadidae]

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Laptikhovsky V., Brickle P.

Acta Ichthyologica et Piscatoria

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2009

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tom 39

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nr 2

127-130

Background. Tadpole codling, Salilota australis (Günther, 1878), (known also as red cod) and southern blue whiting, Micromesistius australis Norman, 1937, are two commercially important species, which spawning grounds are situated in the Falkland waters. Nothing is known about duration of the embryonic development in these fish, whereas these data are necessary to study life cycle strategies as well as for stock management. Because of this, experiments with artificial egg fertilisation were carried out onboard a research boat that was the only way to obtain such an information. Materials and Methods. Eggs from each species were taken from running females captured on their spawning grounds and then fertilised. Egg samples were collected every 6 hours and stage of embryonic development was assigned using a dissecting microscope. Results. Tadpole codling eggs are of 1.20–1.55 mm, with an oil globule of 0.29–0.33 mm, incubation takes between 140–150 h at 6–8.5ºC, 40–45 degree-days. Larval size at hatching is ca 2.9 mm TL. Blue whiting eggs are of 1.40–1.55 mm with no oil globule. Development takes from 150 h at a mean temperature of 7.15ºC to 200 h at between 5.5 and 6ºC, 45–50 degree-days. Larval size at hatching is 2.8–3.0 mm. Conclusion. Duration of embryonic development for commercial southwest Atlantic gadiform fish, tadpole codling, Salilota australis, and southern blue whiting, Micromesistius australis, is documented for the first time. It allows to draw some conclusions about possible mortality during this ontogenetic stage (assuming that daily rates are similar to those in other similar species) and to hypothesise about possible egg transport by currents and interannual spawning grounds’ variability.

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Occurrence od cestodes in fishes from the Weddell Sea

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Rocka A.

Wiadomości Parazytologiczne

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1998

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tom 44

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nr 3

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Cestodes in fishes of the Weddell Sea

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Rocka A., Zdzitowiecki K.

Acta Parasitologica

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1998

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tom 43

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nr 2

In total, 404 fishes of 34 species caught in the Weddell Sea were examined, including four specimens of skates, Bathyraja maccaini and Bathyraja sp., and 23 specimens of the gadiform fish, Macrounis whitsoni (the only three species infected with adult Cestoda). Skates were infected with four representatives of the order Tetraphyllidea, Marsupiobothrium awii sp. n., Anthocephalum siedlecka (syn. Phyllobothrium siedleckii), Anthocephalum arctowskii (syn. Phyllobothrium arctowskii), Oncobothrium antarcticum. The three last species were first described in the South Shetland Islands area. Phyllobothrium siedleckii from B. maccaini (new host) and P. arctowskii from Bathyraja sp. are transferred to the genus Anthocephalum and their descriptions are emended. Marsupiobothrium awii sp. n. from B. maccaini is characterised by: apolytic strobila; scolex with four sessile, jar-like bothridia, each with opening provided with a ring of muscles and submarginal sucker; 120-150 testes; vagina with dilatation in proximal part and sphincter present distally; eggs 0.016 x 0.017 mm. Differential diagnosis with remaining species of the Marsupiobothrium is given. Oncobothrium antarcticum was found in B. maccaini (new host). M. whitsoni was infected with one pseudophyllidean species, Parabothriocephalus johnstoni, previously known as only from the same host in the Indian sector of the Antarctic Ocean.

Ograniczanie wyników

1 Acta Ichthyologica et Piscatoria

1 Acta Parasitologica

1 Wiadomości Parazytologiczne

2 Rocka A.

1 Brickle P.

1 Laptikhovsky V.

1 Zdzitowiecki K.

1 2009

2 1998

Aspects of embryonic development in two southwest Atlantic gadi-form fish: tadpole codling, Salilota australis [Moridae], and southern blue whiting, Micromesistius australis [Gadidae]

Occurrence od cestodes in fishes from the Weddell Sea

Cestodes in fishes of the Weddell Sea