14 Feb 2014

Happy Valentine’s Day! Fish mating strategies

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In honor of today’s celebration of love, please enjoy the first series of post for this blog on fish mating strategies!  Check back weekly for new additions to the “Fish-ionary.”

Promiscuous: A mating system where both sexes have multiple partners during the breeding system.  In fishes, this is the most common mating system.  Breeders make little or no mate choice and spawn with multiple partners, either sequentially or at the same time.

Breeding aggregations of promiscuous spawners can make some fish species particularly vulnerable to fishing.  The fish generally assemble according to environmental cues (e.g., temperature, moon phase) that are known to fishermen.  Overfishing on spawning aggregations can be particularly devastating to fish populations because the high fecundity (fertility) individuals are readily removed from the population.  The Nassau grouper (Epinephelus striatus), for example, once supported an important Caribbean fishery but is currently endangered because of overfishing on these spawning aggregations.

Nassau Grouper is a promiscuous spawner

Nassau Grouper is a promiscuous spawner

 

Polygamous: A mating system in which an individual of one sex has multiple partners during the breeding system but individuals of the opposite sex have only one partner.  Evolutionarily, these systems are purported to have an increased chance of passing on “good genes” from individuals that compete for the ability to mate with multiple partners.  This mating system can occur with one male and many females (see polygyny) or one female and multiple males (see polyandry).

 

Polygyny: A polygamous mating system where a male has multiple female partners during the breeding season.  This is the more common form of polygamy.  Polygynous males, like slimy sculpins (Cottus cognatus), setup territories and are visited by multiple females.  Other polygynous males, like some African cichlids (such as Mchenga eucinostomus), form leks, where they congregate and perform breeding displays to attract female passers-by. And still other polygynous males, like wrasses (Labridae), form harems where a large male protects a number of females with which he, alone, can mate. See polygamous; polyandry.

Bluehead Wrasse form polygynous harems

Bluehead Wrasse form polygynous harems

 

Polyandry: A polygamous mating system where a female has multiple male partners during the breeding season.  This is a relatively uncommon form of polygamy and has only been reported in anemonefish (Amphiprioninae) and could be the case for deep sea anglerfish (Ceratiidae).  Though anemonefish are generally monogamous, polyandry has been reported in some circumstances.  In Deep Sea Anglerfish, multiple males can be attached to a large female, almost in a parasitic relationship where their circulatory system merges with the female’s. See polygamous; polygyny.

Deep Sea Anglerfish have parasitic males that could be considered polyandrous

Deep Sea Anglerfish have parasitic males that could be considered polyandrous

 

Monogamy: A mating system where partners live and exclusively mate with only each other.  These pair bonds can be transitory, just for a single breeding season, extend for several years or even a lifetime.  Fish that form strong pair bonds include: American freshwater catfish, some cichlids, and many butterflyfish.  The Four-Eyed Butterflyfish (Chaetodon capistratus) is one such fish that mates for life – very rare in the fish world.

Four-eye butterfly fish mate for life

Four-eye butterfly fish mate for life

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