Reproductive biology of carpenter seabream (Argyrozona argyrozona) (Pisces: Sparidae) in a marine protected area
The carpenter seabream (Argyrozona argyrozona) is anendemic South African sparid that comprises an important part of the handline fishery. A three-year study (1998−2000) into its reproductive biology within the Tsitsikamma National Park revealed that these fishes areserial spawning late gonochorists. The size at 50% maturity (L50) was estimated at 292 and 297 mm FL for both females and males, respectively. A likelihood ratio test revealed that there was no significant difference between male and female L50 (P>0.5). Both monthly gonadosomatic indicesand macroscopically determined ovarian stages strongly indicate that A. argyrozona within the TsitsikammaNational Park spawn in the astral summer between November and April. The presence of postovulatory follicles (POFs) confirmed a six-month spawning season, and monthly proportions of early (0−6 hour old) POFs showed that spawning frequency was highest (once every 1−2 days) from December to March. Although spawning season was more highly correlated to photoperiod (r = 0.859) than temperature(r = −0.161), the daily proportion of spawning fish was strongly correlated (r= 0.93) to ambient temperature overthe range 9−22oC. These results indicate that short-term upwelling events, a strong feature in the TsitsikammaNational Park during summer, may negatively affect carpenter fecundity. Both spawning frequency and duration(i.e., length of spawning season) increased with fish length. As a result of the allometric relationship betweenannual fecundity and fish mass a 3-kg fish was calculated to produce fivefold more eggs per kilogram of body weightthan a fish of 1 kg. In addition to producing more eggs per unit of weight each year, larger fish also producesignificantly larger eggs.
| Main Authors: | , |
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| Format: | article biblioteca |
| Language: | English |
| Published: |
2005
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| Subjects: | Biology, Ecology, Fisheries, |
| Online Access: | http://hdl.handle.net/1834/26221 |
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