Vardelli Rishika

1. REPRODUCTIVE BIOLOGY OF
Mugil cephalus
Presented by:
V.Rishika
MFK1711

2. INTRODUCTION
• Mugil cephalus is commonly called as flat head grey mullet.
• It is found in coastal tropical and subtropical waters worldwide.
• It shows catadromous migration.
SCIENTIFIC CLASSIFICATION:
Kingdom : Animalia
Phylum : Chordata
Class : Actinopterygii
Order : Mugiliformes
Family : Mugilidae
Genus : Mugil
Species : cephalus

3. DISTRIBUTION
• It is found in fresh ,brackish, marine habitats in depths ranging between 0-
120 metres and with temperatures between 8-24◦C.
• It is catadromous in nature migrating into marine waters for spawning.
• It is commonly called as flat head grey mullet,striped mullet, black mullet,
and sea mullet.
• The maximum length of M.cephalus is 120cm and with a maximum weight of
12kg.
• It is euryhaline species

4. DESCRIPTION
• It is characterised by the presence of 5 dorsal spines ,7-9 dorsal soft rays,3
anal spines and 8-9 anal soft rays.
• Body is slightly compressed and cylindrical in cross-selection
• Head is broad and flattened.
• It is characterized by the presence of well developed adipose eye lid.
• 1-6 rows of fine teeth are present

6. INTRODUCTION
• Fishes of the family Mugilidae represents one of the major commercial resources of tropical
and warm temperate estuaries and their ecological function in food webs is of the greatest
importance.
• In the past, Mugilids were believed to be the most abundant species in almost all the
estuaries along the Indian coast and hence formed a very important species for the local
fishery.
• Unfortunately, after extensive land reclamation of lagoons and brackish water lakes together
with the constant pollution from agriculture and upstream industries and high fishing
pressure, the status of Mugilids is now fragile.
• Flathead grey mullet, M.cephalus is becoming endangered and rare .
• The mullets form one of the important fisheries of the estuaries and coastal waters of India
constitute less than 0.3% of the total marine landings.

7. OBJECTIVES
• Present aim of the study described their maturation; ova-diameter studies, gonado-somatic
index, spawning season and fecundity of M.cephalus were presented.
• Knowledge of spawning season and fishing location are instrumental in establishing time and
area closures to protect essential fish habitats along with modification of fishing gear to
enhance the survival of heavily exploited species .
• An increase in understanding the reproductive biology of mugilids is essential to determine
the parameters to be used in age-structured models of stock assessments.

8. MATERIALS AND METHODS
• This work was based on the examination of specimens collected from Krishna Estuarine
Region, East Coast of Andhra Pradesh.
• After measuring the total length and weight of each specimen, the belly was cut open to note
the sex, colour and general appearance of the gonads which were then weighed to the
nearest 0.1 g and preserved in 10 percent formalin.
• Observations on the maturation of gonads in adults, and the determination of the spawning
season has been carried out mainly on the basis of examination of the ovaries, since the
male gonad (testis) did not show identifiable changes during maturation.
.

9. • Ova diameters were taken on the ova collected from anterior, middle and posterior regions of
the left ovary.
• Ova were taken out on a micro slide and they were measured under the compound
microscope with the help of an ocular micrometer at a fixed magnification.
• At this magnification one micrometer division (md) in the ocular micrometer is equivalent to
0.02 mm.
• The ova diameter studies were carried out by measuring 70 ova from each ovary (stage III
and IV) in 50 individuals in the length range 14-30 cm Total length.

10. FECUNDITY
• Fecundity is defined as the number of ripening, ripe eggs found in the ovaries prior to
spawning.
• It is estimated to study the differences between stocks of fish.
• Fecundity can be used to identify a particular stock.

11. RESULTS AND DISCUSSIONS

12. DEVELOPMENT OF OVA TO MATURITY
• The percentage frequency distribution of ova diameters in different stages of maturity are
estimated.
• In stage I the ova are smaller in size, irregular in shape and measure in size (diameter)
between 0.12 and 0.32 mm.
• In the ovaries in maturing stage, the ova range in size between 0.26 and 0.44 mm.
• In mature stage the size of ova varies between 0.44 and 0.62 mm.
• Few ripe ova present in the mature ovary range between 0.56 and 0.74 mm. in diameter.
• In the present study the frequency distribution of ova diameters in the mature ovary exhibit a
single group of ova that are released in a single spawning act.
• Mullets show a non-intermittent spawning, which is an indication of unimodal type of ova
diameter frequency distribution .

13. LENGTH AT FIRST MATURITY
• Estimation of minimum length of the fish at first maturity in a fish stock helps in the
determination of the spawning stock.
• Maturation of gonads starts before the spawning season and the ova become ripe.
• The size at which the fish becomes mature varies among different fish stocks.
• Length at first maturity in a species is determined on the basis of the minimum length at
which 50 per cent of individuals in stock become mature and spawn during the spawning
season.
• The present study on the minimum size at first spawning in the stocks of M. cephalus from
the Krishna estuarine region is based on 220 individuals collected from the fish landing
centre.
• Studies on the spawning season of M. cephalus show that the mature individuals migrate to
the off-shore areas for the purpose of spawning from late January to february.

14. • Females with maturing, mature and ripe ovaries were utilized in the study.
• In the samples collected, individuals measuring less than 13 cm were with immature
gonads, the smallest female with mature gonads was observed to belong to 13cm group.
• Females larger than 18cm are with mature gonads.
• 50 percent of the individuals in the 16cm length group are with mature gonads and hence
16cm length group was considered as the minimum size at maturity in this stock.

15. GONADO-SOMATIC
INDEX

16. • The present study is based on gonad weights of fish collected from 132 female individuals in
the size range 13.4 to 30.5cm TL.
• The Gonado-Somatic index (GSI) values were considerably low (0.32 to 3.8) from February
to September, with the lowest value in the month of March.
• During this month the gonads are in spent condition as the fish are known to spawn from
January onwards.
• The development of gonads in the female fish commences from October and the Gonado-
Somatic index was ranged from 8.1 to 11.5 percent from October to January.
• The maximum value of Gonado-Somatic index was recorded in December.
• The Gonado-Somatic index from January onwards showed a decline indicating the beginning
of spawning

18. SPAWNINg
• M.cephalus is known to mature in coastal waters and migrates into in the deeper oceanic
waters for the spawning.
• Hence in the present area of study only few specimens with ripe gonads were collected.
• Presence of a single group of ripe ova indicates that the ova develop synchronously in the
ovary and they spawn in a single spawning act.

19. SPAWNING SEASON
• In the present study spawning season of M. cephalus is determined based on indirect
evidence collected from the studies on the stages of maturation and Gonado-Somatic index
in the samples during different months.
• From late January, in the coastal waters, individuals with spent gonads started appearing in
catches.
• In the month of February number of individuals with spent gonads increased in number and
reached a peak.
• In March few individuals with spent gonads were noticed.

20. • The above data indicates that individuals of M. cephalus after becoming mature migrate to
the oceanic waters; spawn and the spent individuals migrate back into near coastal waters in
this region.
• From the above evidence on the stages of maturation of ovaries, and the Gonado-Somatic
Index it can be concluded that spawning takes place in this region during late January and
February.
• In South African waters M. cephalus was known to spawn two times in a year suggests that
M. cephalus may spawn more than once during a long spawning season

21. FECUNDITY
• In the present study fecundity in M. cephalus was estimated in adult females in length ranges
from 14.0 to 30.5cm TL whereas in weight ranged from 28 to 248g.
• Absolute fecundity in these specimens ranged from 0.4 to 5.2 million. In one specimen of
30cm TL weighing 248g absolute fecundity was estimated to be at 8.2 million.
• Earlier studies on fecundity of M. cephalus from India show that in Lake Pulicat the fecundity
ranged between 0.43 and 4.71 million in the specimens in the length range from 22 to 50cm
TL.
• A comparison of present data with the earlier studies on fecundity from Lake Pulicat show
that the stocks of mangrove swamp exhibit higher fecundity.
• Similar observations has been made out previously by several authors on the fecundity of
M. cephalus from India.

22. SEX-RATIO
• Knowledge of the sex-ratio in a fish population during different months or seasons is
essential to know their relative abundance in the spawning stocks.
• The adolescent and adult fish migrate in to offshore regions after the maturation of gonads
for spawning.
• After spawning they migrate back in to coastal waters and enter the water bodies near the
estuary.
• The migratory behaviour of the stocks accounts for the changes in the sex- ratio in the
samples.
• Earlier studies on sex- ratio of M. cephalus in the Lake Pulicat show that the sex ratio 1.56:
1 indicating the preponderance of males.
• Recently in Gulf of Mexico lagoon observed in the two species of Mugil, the sex-ratio
between males and females in 1: 1.1.
• The sex-ratio observed in the present study is 1.99: 1.

23. CONCLUSION
• Spawning season has observed from end of the January to February.
• Males outnumbered the females in the spawning stocks.
• In the present study area it is observed that M.cephalus is a non-intermmitent or single
spawner.
• Knowledge of the spawning season and reproductive biology helps in the effective
management of M.cephalus and useful for stock assesment studies.

25. INTRODUCTION
• The Flathead grey mullet M.cephalus is a catadromous pelagic species found in various
habitats from shallow brackish and marine waters to lagoons, estuaries and rivers deltas.
• It tolerates salinity extremes as well as abrupt water quality changes.
• M.cephalus is common in the shallow waters of the eastern Mediterranean and Black sea .
• Like most Mugilids, this species reproduces at sea, after which fry undertake a trophic
migration shoreward to continue their development in food rich lagoons, estuaries, rivers
and even lakes .

26. OBJECTIVE
• The aim of the present work is to describe the reproductive physiology of M. cephalus in
Benghazi coast – eastern Libya.
• This study may prove useful to fishery management by providing information on seasonality
of spawning.

27. MATERIALS AND METHODS
• Monthly samples of M.cephalus were collected during the period from September 2014 to
August 2015 by trammel and gill nets from fishing landing site in Benghazi coast, eastern
Libya .
• A total 530 specimens of M.cephalus were sampled for studying the reproductive
physiology.
• The total length ranged from 19.5 to 47.4 cm, and total weight from 71.3 to 1231.8 gm.
• Fish was dissected to determine sex then the gonads were weighted to the nearest gm.,
state of maturity for each individual fish was determined into five stages: Immature, Mature,
Nearly Ripe, Spawning and Spent .

28. RESULTS AND DISCUSSIONS

29. SEX-RATIO
• Sex ratio is more for females (fish = 56.2 %) than males (232 fish = 43.8 %) for the whole
population.
• Overall sex ratio was 1: 1.28 for males to females .
• The sex ratio was not constant throughout the different months; the numbers of females
exceed males in all months.
• The maximum percentage of females was recorded in December (59.0 %), January (60.0
%) and August (59.5 %).

31. LENGTH AT FIRST SEXUAL MATURITY
• First maturation size for males is(L50 = 32.3 cm) .
• First maturation size was determined for females (L50 = 34.1 cm).

32. Gonado-Somatic Index (G. S. I.)
• M. Cephalus have a spawning season which extends from July to October.
• G. S. I for male was lower than that of female.
• In male, gradual increase was 4.67 % recorded in July reach 5.99 % in October.
• In females the average G. S. I. values were increased in July (7.57 %) to 8.93 % in October.

33. OOCYTE DIAMETERS
• The recorded average oocyte diameter of M. cephalus during the whole period of the
study was recorded.
• The minimum average oocyte diameter was recorded in April (188 µ ± 2.33) a sharp
increase in the average oocyte diameter was evident in July (489 µ ± 5.34), then
increased continued in the following months reaching the maximum values in August
(599 µ ± 11.04).
• The egg diameter in fish samples was very minute and difficult to measure in the period
from December till March.

34. FECUNDITY
• Ovaries of 225 M. cephalus were examined .
• Absolute fecundity ranged from 578981 to 3332599 for fish total length ranging from 19.5 to 47.4 cm
with overall average 1244657 ± 682896.3 whereas the average relative fecundity ranged from 29036 to
57352 / cm wit overall average 35375 ±10389.8.

35. • A total of 530 specimens of M. cephalus were sampled for studying the reproduction during
the period from September 2014 to August 2015 from fishing landing site in Benghazi coast,
eastern Libya.
• In the present work the overall sex ratio was 1: 1.28 for males and females of M. cephalus,
and these results are in agreement with those results of M. cephalus in Suez Canal, Egypt
(El-Mor, 1993).
• The sex ratio is not constant throughout the different months, particularly during the breeding
season of each species (Oren, 1975).
• Females are dominant sex in mullet populations (Peterson & Shehadeh, 1971).
• It is possible that the females are heavy and get caught in the gear in large numbers,
resulting in an unbalanced sex ratio (Broadhead, 1953).

36. • Generally, in the natural fish community males mature first before the females and are nearly
to participate in spawning activity (Mohammad, 1982).
• In the present work, the maturation size was determined for females L50 = 34.1 cm and for
males L50 = 32.3 cm.
• These values are more than that they have been recorded by (El-Mor, 1993) in Egyptian
Mediterranean Sea which L50 for males 30.1 cm and L50 for females 33.3 cm.
• These variations in the beginning of maturity sign may be depend on the water temperatures
or the different fishing methods in all different stations (Fimucane et al., 1978).
• In the present study, from the average gonado-somatic indices (G. S. I.) of males and
females M. cephalus have a definite breeding season, which extends from July to October.
• This is on agreement with the spawning season of M. cephalus in Egyptian Mediterranean
Sea (El-Mor, 1993).

37. • An increase in Oocyte diameters was evident in July (489 µ ± 5.34), and this increase
continued in the following months till October (599 µ ± 11.04), this is an agreement with the
spawning season of M. cephalus in the present study.
• The increase in egg diameters is mainly due to the deposition of large amounts of proteins
and lipids in the developing eggs.
• A part of these materials comes directly from ingested food but major proportion comes from
reserve of food deposits, during the active season in organs such as liver, muscles and fat
bodies (Larson, 1974).
• The number of eggs produced by females varies greatly according to species, size, age,
region, thus a considerable variability has been shown in different populations of mullets
(Oren, 1975).

38. CONCLUSION
• All individuals have definite breeding season which extends from July to October.
• An increase in Oocyte diameters was evident in July (489 µ ± 5.34), and this increase
continued in the following months till October (599 µ ± 11.04).
• The absolute fecundity ranged from 578981 to 3332599 for fish total length ranging from
19.5 to 47.4 cm, whereas relative fecundity ranged from 29036 to 57352 / cm.
• Females outnumbered the males in the spawning stock.

39. FINAL CONCLUSION
• Spawning season for M.cephalus in Krishna estuary is end of January to February and for
M.cephalus in Benzhagi coast is July to October.
• In Krishna waters males outnumbered females and in Benzhagi coast females outnumbered
males.
• In both the coasts there is a single spawning season.
• M.cephalus is a single spawner.
• Reproductive biology of M.cephalus is useful for stock assesment studies.

40. REFERENCES
• Rangaswamy CP.,1973 .Studies on the age and growth and food habits of the grey mullet
Mugil cephalus of the Lake Pulicat. J. Inland Fish. Soc. India.
• Das HR. 1977 The fecundity of the grey mullet, M. cephalus along Goa coast, Mahasagar.
10:79-82.
• Cardona L. 2001. Non-competitive coexistence between Mediterranean grey mullet
(Osteichthyes, Mugilidae): evidence from seasonal changes in food availability, niche
breadth and trophic overlap. J. Fish Biol. 59:729-744.
• Prasadam RD. 1970.Preliminary observations on the food and feeding habits of the grey
mullet Mugil macrolepis from Pulicat Lake, J. Zoo. Soc. India. 22:63-67.