Know more

Our use of cookies

Cookies are a set of data stored on a user’s device when the user browses a web site. The data is in a file containing an ID number, the name of the server which deposited it and, in some cases, an expiry date. We use cookies to record information about your visit, language of preference, and other parameters on the site in order to optimise your next visit and make the site even more useful to you.

To improve your experience, we use cookies to store certain browsing information and provide secure navigation, and to collect statistics with a view to improve the site’s features. For a complete list of the cookies we use, download “Ghostery”, a free plug-in for browsers which can detect, and, in some cases, block cookies.

Ghostery is available here for free: https://www.ghostery.com/fr/products/

You can also visit the CNIL web site for instructions on how to configure your browser to manage cookie storage on your device.

In the case of third-party advertising cookies, you can also visit the following site: http://www.youronlinechoices.com/fr/controler-ses-cookies/, offered by digital advertising professionals within the European Digital Advertising Alliance (EDAA). From the site, you can deny or accept the cookies used by advertising professionals who are members.

It is also possible to block certain third-party cookies directly via publishers:

Cookie type

Means of blocking

Analytical and performance cookies

Realytics
Google Analytics
Spoteffects
Optimizely

Targeted advertising cookies

DoubleClick
Mediarithmics

The following types of cookies may be used on our websites:

Mandatory cookies

Functional cookies

Social media and advertising cookies

These cookies are needed to ensure the proper functioning of the site and cannot be disabled. They help ensure a secure connection and the basic availability of our website.

These cookies allow us to analyse site use in order to measure and optimise performance. They allow us to store your sign-in information and display the different components of our website in a more coherent way.

These cookies are used by advertising agencies such as Google and by social media sites such as LinkedIn and Facebook. Among other things, they allow pages to be shared on social media, the posting of comments, and the publication (on our site or elsewhere) of ads that reflect your centres of interest.

Our EZPublish content management system (CMS) uses CAS and PHP session cookies and the New Relic cookie for monitoring purposes (IP, response times).

These cookies are deleted at the end of the browsing session (when you log off or close your browser window)

Our EZPublish content management system (CMS) uses the XiTi cookie to measure traffic. Our service provider is AT Internet. This company stores data (IPs, date and time of access, length of the visit and pages viewed) for six months.

Our EZPublish content management system (CMS) does not use this type of cookie.

For more information about the cookies we use, contact INRA’s Data Protection Officer by email at cil-dpo@inra.fr or by post at:

INRA
24, chemin de Borde Rouge –Auzeville – CS52627
31326 Castanet Tolosan CEDEX - France

Dernière mise à jour : Mai 2018

Menu Logo Principal

reprofish

Zone de texte éditable et éditée

Reproductive Strategies

Reproductive Strategies
© Schulz.R
Although there are rare cases of parthenogenesis, such as in the Amazon molly (Poecilia formosa), the large majority of teleosts reproduce through sexual reproduction.

A reproductive strategy is defined as the way in which a species allocates or budgets energy to produce viable offspring. Energy is diverted into actual offspring and into parental care. One usually distinguishes the R-strategy, in which energy is invested in a multitude of offspring that receive little or no parental care, and the K-strategy, wherein energy is invested in a few, large offspring that require considerable parental care. Teleost fish have developed a large variety of reproductive strategies and reproductive behaviours, ranging from mass spawning to parental care, from strict gonochorism (separate sexes) to simultaneous hermaphrodism, and from oviparity to vivparity.
Gonochorism and sex change

Most fish are gonochoric, that is their sexes are separate and determined once, for life (e.g. rainbow trout, Onchorynchus mykiss). However, many fish exhibit sex change during their lifetime. This is called successive hermaphrodism, which can be protandrous if the fish changes from a male to a female, such as the gilthead seabream (Sparus aurata). Other species are protogynous hermaphrodites and change from a female into a male (e.g. orange spotted grouper). Simultaneous hermaphrodites also exist, which behave almost simultaneously as males or females with cross-fecundation taking place; indeed individuals can change within minutes from displaying male sexual behaviour, with sperm release, to female sexual behaviour, with egg laying (e.g. western Atlantic serranid black hamlet).
Release of offspring: Oviparous or Viviparous

In oviparous fish, eggs are fertilised externally, after spawning. In viviparous fish, such as the guppy (Poecilia reticulata) or the mosquito fish (Gambusia affinis), the fertilised and developing eggs remain inside the body of the mother for a certain period of time and the offspring are released as free-swimming young. In fact, it is more appropriate to speak of ovoviviparity as there are no real exchanges between the mother and the embryos.
Ovarian development: Synchronous, Group synchronous, Asynchronous

Synchronous fish reproduce only once each year, or once in their lifetime. In such species, all oocytes develop simultaneously and are at the same developmental stage at a given time. This is the case for salmonids, for example. Group synchronous fish have two or more distinct populations of oocytes present at the same time and ovulate once in a season, or undergo multiple ovulations over a few days or weeks within the spawning season. Asynchronous fish, such as the zebrafish, are capable of ovulating on a regular basis, sometimes every day, over a prolonged period.
Spawning strategies

Most teleost fish are are either determinate of indeterminate batch spawners. In determinate spawners, the potential annual fecundity is fixed prior to the spawning period. The total number of eggs spawned per female in a year is called the realised annual fecundity. For indeterminate spawners, the potential annual fecundity is not fixed before the onset of spawning. In such species, eggs can develop at any time during the spawning season.
Some fish species are single or total spawners. Total spawners release their eggs as a unique event, or over a short period of time but as part of a unique event (as opposed to being spawned in several batches). Single spawners release all their eggs in a single lifetime event.
Spawning type
Pelagic spawners allow their eggs to be carried freely by the currents, however spawning is precisely timed and takes place in specific locations; this is either to minimise egg predation, to maximise dispersal, or to provide the best conditions for the pelagic larvae to survive upon hatching.
Some fish are nest spawners, for example, the male stickleback (Gasterosteus aculeatus) builds a nest and attracts the female to this nest to spawn. Others are demersal spawners, attaching their eggs to a substrate such as the vegetation or the stream bed (e.g. cyprinids and salmonids respectively).
Mouthbrooders care for their eggs and / or larvae and protect them from predation by taking them into their mouths (e.g. tilapia). Some fish breed inside invertebrates, for example the European bitterling deposits its eggs into a living mussel. Other forms of parental care include egg brooding in special pouches, such as in the seahorse male ("pregnant" males); and skin brooding, which involves the attachment of eggs and developing embryos to the skin of one of the parents (e.g. pipefish).

This factsheet was prepared with the expert assistance of scientist Alexis Fostier.

See also

Jalabert, B. 2005. Particularities of reproduction and oogenesis in teleost fish compared to mammals. Reprod Nutr Dev 45:261-279.