Abstract
Successful spawning of Baltic cod (Gadus morhua L.) is restricted to the deep basins of the Baltic Sea and is dependent on abiotic conditions such as salinity and water oxygen content. Due to irregular inflows of saline water from the North Sea, the conditions for spawning fluctuate and consequently so does the cod stock. In May and June 1990 eggs were obtained from spawning cod caught off northern Gotland, Sweden. Our investigation revealed neutral egg buoyancy for Baltic cod at a salinity of 14.4±1.1 ppt, with a slight decrease some days before hatching. Today salinities of this magnitude occur only in the Bornholm basin, whereas in the Gdansk and Gotland basins the eggs sink toward the bottom and are exposed to lethal oxygen conditions.
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Coombs, S. H. (1981). A density-gradient column for determining the specific gravity of fish eggs, with particular reference to eggs of the mackerelScomber scombrus. Mar. Biol. 63: 101–106
Craik, J. C. A., Harvey, S. M. (1984). Biochemical changes occurring during final maturation of eggs of some marine and freshwater teleosts. J. Fish Biol. 24: 599–610
Davenport, J., Lønning, S., Kjørsvik, E. (1981). Osmotic and structural changes during early development of eggs and larvae of the codGadus morhua. J. Fish Biol. 19: 317–331
Grauman, G. B. (1964). The importance of the size of the eggs of the Baltic cod for survival of foetuses. Int. Counc. Explor. Sea Comm. Meet. (Gadoid Fish Committee) 85: 1–5
Grauman, G. B. (1973). Investigations of factors influencing fluctuations in abundance of Baltic cod. Rapp. P.-v. Reun. Cons. int. Explor. Mer. 164: 73–76
Grauman, G. B. (1974). Investigations on the spawning of Baltic cod in 1968 to 1970. Rapp. P.-v. Réun. Cons. int. Explor. Mer. 166: 7–9
Hansson, S., Rudstam, L. G. (1990). Eutrophication and Baltic fish community. Ambio 19: 123–125
Hohendorf, K. (1968). Zur Schwebfähigkeit pelagischer Fischeier in der Ostsee. Ber. dt. wiss. Kommn. Meeresforsch. 19: 181–193
Kändler, R. (1944). Untersuchungen über den Ostseedorsch während der Forschungsfahrten mit dem R.F.D. „Poseidon“ in den Jahren 1925–1938. Ber. dt. wiss. Kommn. Meeresforsch. (neue Folge) 11(2): 137–245
Kändler, R., Tan, E. O. (1965). Investigations on the osmoregulation in pelagic eggs of gadoid and flatfishes in the Baltic. Part 1: Changes in volume and spec. gravity at different salinities. Int. Counc. Explor. Sea Comm. Meet. (Baltic-Belt Seas Comm.) 43: 1–5
Lebedek, W. (1978). Occurrence and distribution of sprat and cod eggs and larvae in the southern Baltic in 1977. Int. Counc. Explor. Sea Comm. Meet. (Baltic Fish Comm.) J: 15: 1–4
Lønning, S., Solemdal, P. (1972). The relation between thickness of chorion and specific gravity of eggs from Norwegian and Baltic flatfish populations. FiskDir. Skr. (Ser. Havunders.) 16: 77–88
Mangor-Jensen, A. (1987). Water balance in developing eggs of the codGadus morhua. In: Fish physiology and biochemistry, Vol. 3. Kugler Publications, Amsterdam/Berkely, p. 17–24
Mielck, W., Künne, C. (1935). Fischbrut und Planktonuntersuchungen auf dem RFD Poseidon in der Ostesee 1931. Wiss. Meeresunters. (Abt. Helgoland) 19: 1–120
Otterlind, G. (1984). On fluctuations of the Baltic cod stock. Int. counc. Explor. Sea Comm. Meet. (Baltic Fish Comm.) J: 14: 1–10
Solemdal, P. (1967). The effect of salinity on buoyancy, size and development of flounder eggs. Sarsia 29: 431–442
Solemdal, P. (1973). Transfer of Baltic flatfish to a marine environment and long term effects on reproduction. Oikos (suppl.) 15: 268–276
Solemdal, P., Sundby, S. (1981). Vertical distribution of pelagic fish eggs in relation to species, spawning behaviour and wind conditions. Int. Counc. Explor. Sea Comm. Meet. (Mar. envirl Qual. Comm.) G: 77: 1–16
Strodtmann, S. (1918). Weitere Untersuchungen über Ostseefische, III. Wiss. Meeresunters. (Abt. Helgoland) 14: 31–95
Sundnes, G., Leivestad, H., Iversen, O. (1965). Buoyancy determination of eggs from the cod (Gadus morhua L.). J. Cons. perm. int. Explor. Mer 29: 249–252
Wieland, K. (1987). Distribution and mortality of cod eggs in the Bornholm basin (Baltic Sea). Int. Counc. Explor. Sea Comm. Meet. (Ref. L) G: 56: 1–14
Wieland, K. (1989). Small-scale vertical distribution and mortality of cod and sprat eggs in the Bornholm basin during two patch studies in 1988. Int. Counc. Explor. Sea Comm. Meet. (Ref. L) J: 19: 1–15
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Communicated by T. Fenchel, Helsingør
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Nissling, A., Westin, L. Egg buoyancy of Baltic cod (Gadus morhua) and its implications for cod stock fluctuations in the Baltic. Mar. Biol. 111, 33–35 (1991). https://doi.org/10.1007/BF01986342
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DOI: https://doi.org/10.1007/BF01986342