Nutritional condition and vertical distribution of Baltic cod larvae
Newly hatched Baltic cod Gadus morhua larvae are typically found at depths >60 m. This is a region of low light and prey availability, hence generating the hypothesis that larvae have to migrate from hatching depth to the surface layer to avoid starvation and improve their nutritional condition....
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Wiley-Blackwell
1997
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Online Access: | https://oceanrep.geomar.de/id/eprint/6479/ https://oceanrep.geomar.de/id/eprint/6479/1/Clemmesen.pdf https://doi.org/10.1111/j.1095-8649.1997.tb06108.x |
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ftoceanrep:oai:oceanrep.geomar.de:6479 2023-05-15T16:19:19+02:00 Nutritional condition and vertical distribution of Baltic cod larvae Gronkjaer, P. Clemmesen, Catriona St. John, M. 1997 text https://oceanrep.geomar.de/id/eprint/6479/ https://oceanrep.geomar.de/id/eprint/6479/1/Clemmesen.pdf https://doi.org/10.1111/j.1095-8649.1997.tb06108.x en eng Wiley-Blackwell https://oceanrep.geomar.de/id/eprint/6479/1/Clemmesen.pdf Gronkjaer, P., Clemmesen, C. and St. John, M. (1997) Nutritional condition and vertical distribution of Baltic cod larvae. Journal of Fish Biology, 51 (Suppl. A.). pp. 352-369. DOI 10.1111/j.1095-8649.1997.tb06108.x <https://doi.org/10.1111/j.1095-8649.1997.tb06108.x>. doi:10.1111/j.1095-8649.1997.tb06108.x info:eu-repo/semantics/restrictedAccess Article PeerReviewed 1997 ftoceanrep https://doi.org/10.1111/j.1095-8649.1997.tb06108.x 2023-04-07T14:53:01Z Newly hatched Baltic cod Gadus morhua larvae are typically found at depths >60 m. This is a region of low light and prey availability, hence generating the hypothesis that larvae have to migrate from hatching depth to the surface layer to avoid starvation and improve their nutritional condition. To test this hypothesis, Baltic cod larvae were sampled during the spawning seasons of 1994 and 1995 with depth-resolving multiple opening/closing nets. Each larva was aged by otolith readings and its RNA/DNA ratio was determined as a measure of nutritional condition. The RNA/DNA ratios of these larvae aged 2-25 days (median 10 days) ranged from 0.4 to 6.2, corresponding to levels exhibited by starving and fast-growing larvae in laboratory calibration studies (starvation, protein growth rate, Gpi= -12.2% day−1; fastgrowing larvae, Gpi=14.1%day−1) respectively. Seventy per cent of the field caught larvae had RNA/DNA ratios between the mean values found for starving and fed laboratory larvae. Only larvae aged 8-11 days had higher mean RNA/DNA ratios above 45 m than below (t-test, P<0.05). However, the instantaneous protein growth rates were significantly higher for all larval age groups in the surface layers (t-test, P<0.05). Starving larvae were found in all depths sampled (10-85 m), whereas growing larvae (positive Gpi) were restricted to samples taken shallower than 45 m. These superior growth rates above 45 m corroborate the hypothesis and imply that migration to the shallow water layers is a prerequisite for good nutritional condition, growth and survival of Baltic cod larvae. The frequent occurrence of cod larvae older than 8 days in the deep water in poor condition suggests that a proportion of the larvae will die from Starvation in the deep layers of the Baltic Sea. Article in Journal/Newspaper Gadus morhua OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Journal of Fish Biology 51 sa 352 369 |
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Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
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ftoceanrep |
language |
English |
description |
Newly hatched Baltic cod Gadus morhua larvae are typically found at depths >60 m. This is a region of low light and prey availability, hence generating the hypothesis that larvae have to migrate from hatching depth to the surface layer to avoid starvation and improve their nutritional condition. To test this hypothesis, Baltic cod larvae were sampled during the spawning seasons of 1994 and 1995 with depth-resolving multiple opening/closing nets. Each larva was aged by otolith readings and its RNA/DNA ratio was determined as a measure of nutritional condition. The RNA/DNA ratios of these larvae aged 2-25 days (median 10 days) ranged from 0.4 to 6.2, corresponding to levels exhibited by starving and fast-growing larvae in laboratory calibration studies (starvation, protein growth rate, Gpi= -12.2% day−1; fastgrowing larvae, Gpi=14.1%day−1) respectively. Seventy per cent of the field caught larvae had RNA/DNA ratios between the mean values found for starving and fed laboratory larvae. Only larvae aged 8-11 days had higher mean RNA/DNA ratios above 45 m than below (t-test, P<0.05). However, the instantaneous protein growth rates were significantly higher for all larval age groups in the surface layers (t-test, P<0.05). Starving larvae were found in all depths sampled (10-85 m), whereas growing larvae (positive Gpi) were restricted to samples taken shallower than 45 m. These superior growth rates above 45 m corroborate the hypothesis and imply that migration to the shallow water layers is a prerequisite for good nutritional condition, growth and survival of Baltic cod larvae. The frequent occurrence of cod larvae older than 8 days in the deep water in poor condition suggests that a proportion of the larvae will die from Starvation in the deep layers of the Baltic Sea. |
format |
Article in Journal/Newspaper |
author |
Gronkjaer, P. Clemmesen, Catriona St. John, M. |
spellingShingle |
Gronkjaer, P. Clemmesen, Catriona St. John, M. Nutritional condition and vertical distribution of Baltic cod larvae |
author_facet |
Gronkjaer, P. Clemmesen, Catriona St. John, M. |
author_sort |
Gronkjaer, P. |
title |
Nutritional condition and vertical distribution of Baltic cod larvae |
title_short |
Nutritional condition and vertical distribution of Baltic cod larvae |
title_full |
Nutritional condition and vertical distribution of Baltic cod larvae |
title_fullStr |
Nutritional condition and vertical distribution of Baltic cod larvae |
title_full_unstemmed |
Nutritional condition and vertical distribution of Baltic cod larvae |
title_sort |
nutritional condition and vertical distribution of baltic cod larvae |
publisher |
Wiley-Blackwell |
publishDate |
1997 |
url |
https://oceanrep.geomar.de/id/eprint/6479/ https://oceanrep.geomar.de/id/eprint/6479/1/Clemmesen.pdf https://doi.org/10.1111/j.1095-8649.1997.tb06108.x |
genre |
Gadus morhua |
genre_facet |
Gadus morhua |
op_relation |
https://oceanrep.geomar.de/id/eprint/6479/1/Clemmesen.pdf Gronkjaer, P., Clemmesen, C. and St. John, M. (1997) Nutritional condition and vertical distribution of Baltic cod larvae. Journal of Fish Biology, 51 (Suppl. A.). pp. 352-369. DOI 10.1111/j.1095-8649.1997.tb06108.x <https://doi.org/10.1111/j.1095-8649.1997.tb06108.x>. doi:10.1111/j.1095-8649.1997.tb06108.x |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1111/j.1095-8649.1997.tb06108.x |
container_title |
Journal of Fish Biology |
container_volume |
51 |
container_issue |
sa |
container_start_page |
352 |
op_container_end_page |
369 |
_version_ |
1766005701069504512 |