n African Zoology - Patterns of egg deposition and egg development in the catsharks and : research article

Volume 48, Issue 1
  • ISSN : 1562-7020
  • E-ISSN: 2224-073X
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Patterns of egg deposition and rates of egg development were examined for two endemic South African scyliorhinid shark species: , the leopard catshark, and , the dark shy shark. laid their eggs at an average depth of 18.95 m (min: 7.4 m; max: : 26.8 m) preferentially attaching their eggs singly onto sea fans and laid their eggs at an average depth 3m (min: 1 m; max: 30.7 m) and attached their eggs, predominantly in pairs, to the seaweed . The average temperature at which eggs were found were similar (15°C) and eggs were laid year-round. Embryo development was observed in the laboratory under constant controlled environmental conditions of 14 and 17°C. Embryo length-age relationships were linear for both species and there were significant differences in growth rate at the two temperatures. For average growth rate was 0.37 mm/day at 14°C and 0.79 mm/day at 17°C. The average incubation period was 266 days at 14°C and 125 days at 17°C. Embryos thus grew two times faster and development time was 53% shorter when the temperature was raised by only 3°C. For , the average growth rate was 0.49 mm/day at 14°C and 0.78 mm/day at 17°C. The incubation period was 242 days at 14°C and 190 days at 17°C. The embryos thus grew 1.6 times faster and incubation time was 21.5% shorter when temperature was raised by only 3°C.

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