| Summary: | 碩士 === 國立臺灣大學 === 漁業科學研究所 === 86 === The reproductive biology of painted lizard fish,
Trachinocephalus myops, in the southern Taiwan Strait was
studied from histology. Furthermore, the study evaluated
exploiting status of spawners for this species from decrease
rate of spawning adults combined with yield isopleth diagram.
The results were as follows:
(1) Four sexual maturity stages of ovaries were evaluated by
naked eyes, i.e., immature, developing, mature and spent
stage. Each month had these four stages except February and
March.
(2) Oocytes development was divided into four stages by
histological observation, i.e., immature, developing, mature
and spent.
(3) A logistic curve was used to fit the relationship between
the fraction of maturity and fork length. The minimal mature
fork length(ML50) was estimated as 18.0cm for female as well as
18.8cm for male, that is the age of 0.98 and 1.03.
(4) The sexual differentiation is apparent for this species.
The monthly changes of Gonadosomatic index (GSI) were between
0.17 and 0.64 for female as well as between 0.06 and 0.23 for
male.
(5) The reproductive activity occurred almost in the whole
year. The main spawning seasons appeared in February-April and
July-October. The GSI were between 0.52 and 0.64 for female as
well as between 0.11 and 0.23 for male in these periods.
(6) The monthly variation of condition factor (CF) was same
with GSI. The phenomenon implied that the species stocked many
nutritions at the reproductive activity, and released them at
the end of reproductive seasons.
(7) Almost each month can be observed every stages of oocytes
development except February and June. That is almost each
month has reproductive activity. The phenomenon is also
observed from GSI.
(8) The fecundity were from 11,075 to 426,240 oocytes for this
species. The relationship between fecundity(F) and fork length(
FL) as
F=6.0000×10-4FL5.8514, r2=0.6932.
(9) Sex ratio was 0.5137, which was no significant difference
with 0.5 by χ2 test.
(10) The age compositions were all 7 age groups, i.e.,
0,1,...,6 from 1996 to 1998. The major catch groups were all
at age 0.
(11) The exploited status of spawners for this species from
decrease rate of spawning adults combined with yield isopleth
diagram. Showed that all the fishing mortality rates from 1994
to 1998 located above 1/2 curve. In other word, the rate of
spawning adults were still under favorable phase.
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