Illustrated by Hannah Dean; Written by Abigail Lynch.

“There are plenty of fish in the sea” is often used as consolation for someone going through a breakup.  Relationships are tough, the quote implies, but remember there’s always other opportunities for love out there.  That’s how it works for all those fish in the sea, right?  …or does it?

From the free love fest of Nassau Groupers to the one, true love of the Four-eyed Butterflyfish, this Valentine’s Day, The Fisheries Blog take a look at the different forms of fish love.  Because fish are the most diverse group of vertebrates (there are more fish species than all other vertebrate species combined), it’s not surprising that fish mating strategies span the spectrum from life-long monogamous relationships on one side to fully promiscuous breeding aggregations on the other.

Promiscuity: A mating strategy where both sexes have multiple partners during the breeding season.  This is the most common form of fish love.  Grouper spawning aggregations are among the most spectacular illustrations of promiscuous mating strategies.  Nassau Grouper (Epinephelus striatus) are endangered because their large spawning aggregations (as many as 100,000 fish) are very easy for fishermen to exploit.

Polygamy: A mating strategy where an individual of one sex has multiple partners during the breeding season but individuals of the opposite sex have only one partner.  Polygamy is hypothesized to have evolved as a means for “better” genes to propagate in the next generation though some form of competition.

Polygyny: A polygamous mating system where a male has multiple female partners during the breeding season.  Bluehead wrasse (Thalassoma bifasciatum) have a complex social system (including sequential hermaphrodism) where an aggressive “terminal” male guards his harem of females in return for the privilege of solo rights (mostly) to the females in his harem.

Polyandry: A polygamous mating system where a female has multiple male partners during the breeding season.  Polyandry is not a common mating strategy in the fish world but it has been reported in anemonefish (though monogamy is more common).

Monogamy: A mating system where partners live and exclusively mate with only each other.  Usually, these relationships only last the duration of the breeding season.  But, in rare cases, such as the Four-eyed Butterflyfish (Chaetodon capistratus), mates are bonded for life.  Of all the fish in the sea, these two are meant to be!

Happy Valentine’s Day from The Fisheries Blog!

♥ Fish Love ♥