this is my presentation based on research paper title "Reproductive biology of the milk shark Rhizoprionodon acutus (Rüppell, 1837) from the Gulf of Suez, Red Sea, Egypt" This was written by Amgad M. Shaaban et al., 2018 Which have Impact factor: 1.98

1. Reproductive biology of the milk
shark Rhizoprionodon acutus
(Rüppell, 1837) from the Gulf of
Suez, Red Sea, Egypt
Amgad M. Shaaban et al., 2018
Impact factor: 1.98
Sana Haroon
Synopsis & Research Methodology

2. Introduction
• Chondrichthyan fishes play a crucial functional
role by exerting an effective top–down control on
the function and structure of coastal and oceanic
ecosystem (Heithaus et al., 2012).
• Therefore, declines in shark populations can lead
to cascading effects in ecosystems (e.g., reduction
of commercial scallops in northeast Atlantic,
Myers et al., 2007).

3. Conti..
• These fishes are incidentally caught as bycatch in
many fisheries (Dulvy et al., 2014).
• Globally, more than 700,000 tons of Chondrichthyan
fishes are catched annually (Frisk et al., 2001).
No previous studies have been conducted on the milk
shark, Rhizoprionodon acutus, from the Gulf of Suez.

4. Conti..
• The milk shark, Rhizoprionodon acutus, is a species of
requiem shark, and part of the family Carcharhinidae,
whose common name comes from an Indian belief
that consumption of its meat promotes lactation.
• Of the seven species of the genus Rhizoprionodon,
Rhizoprionodon acutus has the widest geographic
distribution that occurs from West Africa to the
western Pacific (southern Japan) (Compagno, 1984).

5. Conti..
• The International Union for Conservation of
Nature (IUCN) has listed the milk shark under
least concern; despite being heavily fished, it has a
wide distribution and remains fairly common
(Simpfendorfer, 2003)

6. Conti..
• The paucity of biological data for most shark species
constitutes a barrier for the determination of their
specific susceptibility to overexploitation and has
subsequently obstructed the efforts made for shark
management and conservation (Frisk et al., 2001).
• Therefore, the gathering of biological data should be
a crucial element for biologists, fisheries scientists and
resource managers (Cope, 2006).

7. Conti..
• The periodicity and success of reproduction in
fish can be affected by
 Growth rates
 the availability of mates
 resource competition, food availability
 the removal of individuals
(Pianka, 1970; Winemiller, 2005)

8. Aims & Objectives
• Aim: These data will be useful for designing effective
management strategies for shark fisheries and consequently help
in the conservation of sharks.
• Objective: To study
 sexual maturity in males & females
 Gonadosomatic (GSI) and hepatosomatic (HSI) indices
 Biological traits of females
 Embryonic development and gestation
 Fecundity
 Sex ratio

9. Hypothesis & Impact factor
• To study the life history traits of this species by investigating
 the length at 50% maturity
 the length at birth
 the ovarian and uterine fecundities
 the reproductive cycle.
• Egyptian journal of aquatic research impact factor = 1.98

10. Materials and methods
• The study area
The Gulf of Suez (Fig. 1) is a large semi-closed
area of a length extends about 346 km. The
average width is about 54.2 km and mean depth
of about 40 m. The total surface area of the Gulf
of Suez is about 10,510 km2 (Hamed and Emara,
2006).

12. Conti..
• Sampling and data collection
Shark specimens were collected from the
commercial trawling and artisanal fisheries
operating in the Gulf of Suez. A total of 357 R.
acutus (Table 1) were collected between October
2012 and December 2015 from the Ataka landing
site in Suez City (Long, 32 34/ E, Lat, 29 56/N).

13. Conti..

14. Conti..
a. Sex was recorded
b. Total length (TL) was measured to the nearest millimeter from
the tip of the snout to the end of the upper lobe of the caudal
fin.
c. Total body weight (TW) was measured to the nearest gram.
d. According to Collenot (1969), the claspers inner length (CLI)
was measured from the forward rim of the pelvic girdle to the
distal edge of the claspers to the nearest millimeter.

15. Conti..
• Male reproductive systems were investigated to
assess the status of the testes and seminal vesicles.
• Testes were isolated from the epigonal system and
weighed to the nearest 0.1 g.
• Calcification of claspers, the condition of the testes
were reported to assess the maturity stage according
to Henderson et al. (2006), maturity scale (Table 2).

16. Conti..
• Female reproductive systems were inspected for determination of
the maturity stage according to Henderson et al. (2006), maturity scale
(Table 2).
• The number and diameter of developing and ripe follicles were
recorded.
• The number, the total length and total weight of developing and near-
term embryos were recorded.
• Embryos were sexed when possible.
• The oviductal gland weights were recorded to follow up their changes
throughout different maturity stages.

17. Conti..

18. Results
Sexual maturity in males
•The smallest recorded male was 44.6 cm TL
and 376 g TW.
•While the largest male measured 88.5 cm TL
and 2995 g TW.
•The smallest estimated mature male measured
70.4 cm TL,
•while the largest immature male was 79.8 cm
TL.
•The length at 50% maturity for males was
estimated to be 76.5 cm

19. Sexual maturity in females
• The smallest recorded female was 47.8
cm TL and 421.7 g TW,
• while the largest female was 97.2 cm
TL and 4355 g TW.
• However, the smallest mature female
was 73.1 cm TL and 1770 g TW,
• the largest immature female was 78 cm
TL and 2093 g TW.
• The estimated TL at 50% maturity or
the length at first maturity was
estimated to be 74 cm

20. Embryonic development and gestation
• The embryonic development after the depletion of the yolk sac, is
through placenta.
• A total of 116 embryos were contained in the 39 gravid females,
comprising 56 males, 55 females and 5 undifferentiated ones.
• The smallest embryos were 7 and 8.7 cm TL and weighted 1.8 and 2.7
g respectively, while the largest embryo was 39.5 cm TL, which
weighted 259 g.
• The length frequency of R. acutus embryos showed a normal
distribution pattern (Fig. 11).
• The smallest individual collected during the study was 44.6 cm TL and
376 g TW.
• Based on the near-term embryos and neonates, the length at birth
ranged from 39.5 to 44.6 cm (mean 42.05 ± 2.55) and the weight
ranged from 259 to 376 g (mean 317.5 ± 58.5).

22. Gonadosomatic (GSI) and hepatosomatic
(HSI) indices
• The gonadosomatic index for males and females varied
seasonally with a peak in summer but with no significant
difference among seasons (ANOVA, d.f. 3 and 74, p = 0.66 for
male and d.f. 3 and 107, p = 0.29 for females) (Fig. 8).
• However, the hepatosomatic index of males and females
exhibited the same pattern of variation in which there is a
decrease of the HSI in summer but with a significant difference
among seasons (ANOVA, d.f. 3 and 102, p = 0.01 for males and
d.f. 3 and 133, p = 0.003 for females) (Fig. 9).

24. Conti..
• The gonadosomatic index (GSI) and
heptosomatic index (HSI) were estimated as
indicators of the reproductive cycle for males and
females.
 GSI ¼ ½ weight of the gonad=whole body weight 100
 HSI ¼ ½ weight of the liver=whole body weight 100

25. Conclusion
• The milk shark, Rhizoprionodon acutus, in the Gulf of Suez
appear to reproduce throughout the year with a peak in summer
(partially seasonal reproductive cycle).
• The vitellogenesis and embryogenesis occur concurrently with
no resting period between parturition and ovulation and there is
no distinct parturition season.

26. Future perspective
• To design effective management strategies for shark fisheries
• To help in the conservation of sharks.

27. References
• Ba, A., Ba, C.T., Diouf, K., Ndiaye, P.I., Panfili, J., 2013. Reproductive biology
of the milk shark Rhizoprionodon acutus (Carcharhinidae) off the coast of
Senegal. Afr. J. Mar. Sci. 35, 223–232.
• Bass, A.J., D’Aubrey, J.D., Kistnasamy, N., 1975. Sharks of the east coast of
southern Africa. 3. the families Carcharhinidae (excluding Mustelus and
Carcharhinus) and Sphyrnidae. investigational report. Oceanogr. Res. Inst.
Durban 38, 4–100.
• Cadenat, J., Blache, J., 1981. Requins de Méditerranée et d’Atlantique (plus
particulièrement de la cote occidentale d’Afrique). (Sharks from the
Mediterranean and Atlantic [especially from the western coast of Africa]).
Faune Tropicale Series 21. Paris, ORSTOM.
• Capape, C., Diatta, Y., Diop, M., Guelorget, O., Vergne, Y., Quignard, J., 2006.
Reproduction in the milk shark, Rhizoprionodon acutus (Rüppell, 1837)
(Chondrichthyes: Carcharhinidae), from the coast of Senegal (eastern tropical
Atlantic). Acta Adriat. 47, 111–126.

28. • Capapé, C., Diop M. and N’dao M., 1994. Observations sur la biologie de la
reproduction de dix-sept espèces de Sélaciens d’intérêt économique captures
dans la région marine de Dakar-Ouakam (Sénégal, Atlantique oriental
tropical). (Observations on the reproductive biology of seventeen species of
economical interest captured in the marine area of Dakar-Ouakam [Senegal,
Eastern Tropical Atlantic]) Bulletin de l’Institut Fondamental d’Afrique Noire
A. vol. 47 pp. 87–102
• . Castro, J.I., 1996. Biology of the blacktip shark, Carcharhinus limbatus, off
the southeastern United States. Bull. Mar. Sci. 59 (3), 508–522.
• Collenot, G., 1969. Eutude biome´trique de la croissance relative des pte´
rygopodes chez la roussette Scyliorhinus canicula (L.). Cah. Biol. Mar. 10,
309–323. Compagno, L.J.V., 1984. FAO species catalogue. vol. 4 sharks of
the world. anannotated and illustrated catalogue of shark species known to
date. part 2. Carcharhiniformes. FAO Fish. Synop. 4 (2), 251–655.

29. • Compagno, L.J., 2001. Sharks of the World: An Annotated and Illustrated
Catalogue of Shark Species Known to Date (Vol. 1). Food & Agriculture Org.
• Cope, J.M., 2006. Exploring intraspecific life history patterns in sharks. Fish.
Bull. 104, 311–320.
• Craik, J.C.A., 1978. An annual cycle of vitellogenesis in the elasmobranch
Scyliorhinus canicula. J. Mar. Biol. Assoc. U.K. 58, 719–726.
• Devadoss, P., 1988. Observations on the breeding and development of some
sharks. J. Mar. Biol. Assoc. India 30, 121–131.
• Dulvy, N.K., Fowler, S.L., Musick, J.A., Cavanagh, R.D., Peter, M., Kyne, L.R.H.,
Carlson, J.K., Davidson, L.N., Fordham, S.V., Francis, M.P., Pollock, C.M.,
Simpfendorfer, C. A., Burgess, G.H., Carpenter, K.E., Compagno, L.J., David,
A., Ebert, C.G., Heupel, M.R., Livingstone, S.R., Sanciangco, J.C., Stevens, J.D.,
Valenti, S., White, W.T., 2014. Extinction risk and conservation of the world’s
sharks and rays. 3, 1–34