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Possible explanations to Baltic cod reproduction problemS: a short review
Pickova, J.; Larsson, P.-O.; Kiessling, A. (2000). Possible explanations to Baltic cod reproduction problemS: a short review, in: Norberg, B. et al. (Ed.) Proceedings of the 6th International Symposium on the Reproductive Physiology of Fish, Bergen, Norway, July 4-9, 1999. pp. 92-94
In: Norberg, B. et al. (Ed.) (2000). Proceedings of the 6th International Symposium on the Reproductive Physiology of Fish, Bergen, Norway, July 4-9, 1999. Department of Fisheries and Marine Biology, University of Bergen: Bergen. ISBN 82-7461-048-2. 499 pp., more
In: International Symposium on the Reproductive Physiology of Fish. Museo Nacional de Ciencias Naturales, more

Available in Authors 
    VLIZ: Proceedings [4145]

Keyword
    Marine

Authors  Top 
  • Pickova, J.
  • Larsson, P.-O.
  • Kiessling, A.

Abstract
    Disturbances in Baltic cod reproduction, additional to the basic problems related to low salinity and oxygen content, are discussed. Abnormal cod embryos appeared first in 1979 and have been observed since. Still recruitment has been relatively well correlated to the "reproductive volume" (sufficient salinity and oxygen content) until year-class 1991. Since that year, year-class strengths have been lower than expected considering available reproduction volume. Many experimental investigations on Baltic cod reproduction have shown a lower hatching success of Baltic cod compared to other cod stocks. Simultaneously with cod, other fish species in the Baltic Sea have experienced reproduction problems. Several hypotheses regarding the causes of the reproductive disturbances are reviewed, including a mis-match of hatching and environmental factors, including food availability. Also the impact of xenobiotic substances on peroxidation of unsaturated lipids (polyunsaturated fatty acids and cholesterol) as well as reactive intermediates, as DNA adducts, and their effects on the quality of spawning products are discussed. Altered hormone levels in induction of maturation and spawning resulting in a delay of spawning activities are also suggested to be caused by anthropogenic substances. We conclude that the causes of reproductive problems in Baltic Sea cod include factors other than overfishing and salinity - oxygen interactions.

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