Reproductive cycles - Semelparity & Iteroparity Maturation & Maturity stages Spawning periodacity

1. Reproductive cycles -
Semelparity & Iteroparity
Maturation &
Maturity stages
Spawning periodacity

2. Semelparity
• The word semelparity comes from the Latin
semel - once and pario - to beget.
• Characterized by a single reproductive episode
before death
• E.g. Pacific salmon (Oncorhynchus spp.), which
lives for many years in the ocean before
swimming to the freshwater stream of its
birth, for laying eggs and dying.

3. Semelparous species
Common name Scientific name
Pacific lamprey Entosphenus tridentatus
Sockeye salmon Oncorhynchus nerka
Caribbean reef squid Sepioteuthis sepioidea
Giant Pacific octopus Enteroctopus dofleini
Australian giant cuttlefish Sepia apama
Australian sea lion Neophoca cinerea

4. Iteroparity
• The term iteroparity comes from the Latin
itero- to repeat and pario- to beget.
• Characterized by multiple reproductive cycles
over the course of its lifetime
• It includes most of the fishes

5. Models based on non-linear trade-offs

6. Maturity Stages in Males
Stage 1 (mature): Testis small,
translucent, whitish, long, thin strips
lying close to the vertebral column
Stage 2 (maturing): Testis white, flat,
convoluted, easily visible to the
naked eye, about ¼ length of the
body cavity
Stage 3 (mature): Testis large,
opalescent white, drops of milt
produced when pressed or cut
Stage 4 (spent): Testis shrunk, flabby,
dirty white in colour

7. Maturity Stages in Females
Stage 1 (mature): Ovary small, firm, no
eggs visible to the naked eye
Stage 2 (maturing): Ovary more
extended, firm, small oocytes
visible, giving ovary a grainy
appearance
Stage 3 (mature): Large, filling or
swelling the body cavity, when
opened large ova spill out
Stage 4 (spent): Ovary shrunken,
flaccid, contains a few residual eggs
and many small ova

8. Shellfishes- Females
Stage I Immature Translucent and stingy ovary. Anterior and lateral
lobes are poorly developed
Stage II Early maturing Ovary is in process of development. It presents a
creamy white to yellowish colour.
Stage III Late maturing Ovary much developed, occupying almost totality of
dorsal portion. It’s visible across the carapace. Its
colour is greenish yellow to light green.
Stage IV. Mature Ovary occupies the totality of dorsal portion. Its
colour is dark green
Stage V Post-spawning Ovary is similar to that stage 2, but more developed
and flabby.

10. Males
Stage I Immature Petasma is small and not much visible
Stage II Early maturing Petasma appears visible with non joined
endopodites
Stage III. Late maturing Petasma well developed and nearly joined.
There are no spermatic masses in seminal
ampullae
Stage IV Mature Petasma completely joined. There are
spermatic masses in seminal ampullae.

11. Cephalopods - Females
Immature The ovary appears as a thin white patch in the coelomic space in the
posterior part of the mantle cavity beneath the dorsal mantle wall.
Eggs can be distinguished only by microscopic examination.
Maturing The ovary is bigger in size, the eggs with accumulating yolk are small
and are visible to naked eye.
Mature Have eggs fully grown. Ripe eggs are translucent with reticulate surface.
The mature ovary is compact, occupying a large space in the posterior
part of the mantle cavity. The nidamental glands are full and glossy
white and the accessory nidamental glands orange red.
Spent Have only a few number of eggs and the mantle becomes flaccid;
nidamental glands become thinner and less glossy. Accessory
nidamental glands turn pink. Spent females weigh considerably less
than the gravid one of corresponding length.
Recovering Recovering ovary contains developing eggs in addition to a few residual
eggs.

12. Males
Immature Immature males can be identified only by microscopic
examination of the testis which appears as a thin and pale
white mass in the gonadial part of coelomic space, very
close beneath the dorsal mantle wall in the distal part of
the mantle cavity.
Maturing Maturing males can be distinguished by thicker pale white
testes which are bigger compared to the previous stage.
Mature Ripe testes are thick and turgid containing spermatozoa.
The spermatophore sac is bulged with spermatophores
Spent After spawning, the testis becomes flaccid and pale and the
spermatophore sac shrunken with a few seprmatophores
only.

13. Spawning periodacity
Total
spawners
Multiple or
fractional
spawners
Protracted
spawners

14. • Total spawners
– Shed a single batch of eggs in a short
spawning period.
• Multiple or fractional spawners
– Ripen successive batches within a season.
• Protracted spawners
–Spawn a single batch over an extended
period.

15. Spawning periodacity
• Total spawners • Multiple or fractional
spawners And
Protracted spawners

16. • Multiple and protracted spawning strategies
expose young fishes to variable environmental
conditions, such that individuals and cohorts
may experience spatial or temporal variations
in food and habitat availability, predation and
pollution .
• Species that adopt multiple or protracted
spawning strategies are likely to have a
greater size range of young at the end of the
growing season than those that do not.

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