• PRELIMINARY OBSERVATIONS ON THE LARVICULTURE OF WITCH FLOUNDER (GLYPTOCEPHALUS CYNOGLOSSUS)

  • J. Rabe, J.A. Brown, D. Bidwell, W.H. Howell

  • Abstract:

  • Little is known about the life history of cold water marine finfish despite the fact that these species are of major commercial importance. Witch flounder (grey sole) once formed an important component of Newfoundland's flatfish resource. Its high market value and consumer acceptability makes it an excellent candidate species for aquaculture. However, few attempts to culture this species have been made as field observations suggest that its life history is characterized by a long larval period and slow growth rates. In 1997 we began a feasibility study on the potential of this species for aquaculture.

  • Witch flounder eggs were stripped at sea aboard a commercial fishing vessel in the Gulf of Maine, USA. Larvae grew well on a diet of culture enriched rotifers and Artemia. Larval length and age at metamorphosis was 6.5 cm and 1,300 degree days respectively. Survival was high (70%) during the extended larval stage. Weaning to an artificial diet was not complete until 1,600 degree days. Metamorphosed juveniles displayed low (20%) occurrence of pigmentation and eye migration abnormalities. Protocols for maintaining wild broodstock are being developed. The foraging behavior of witch flounder is unique. The larvae exhibit reduced occurrence of characteristic feeding postures compared to other species which hatch at a similarly undeveloped stage, such as cod and yellowtail flounder. This suggests that larvae of similar sizes may display different survival strategies.

  • Our preliminary observations allow us to conclude that the potential for commercial aquaculture of witch flounder is high as larvae exhibit high survival and good growth in culture systems. Furthermore, its high survival in culture, large size at metamorphosis, and reduced foraging activity make this species an excellent model for life history studies and may provide insight into the selective pressures acting on marine fish in the wild.

  • (Ocean Sciences Centre, Memorial University of Newfoundland, St. John's, NF A1C 5S7, Canada)

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