Mother Nature employs many different reproductive strategies. Most mammal species produce very small numbers of young, often just one at a time. The youngster develops inside its mother long enough to be viable, is born, and depends on Mom for food and protection for a substantial length of time after birth as it matures. Mom eventually cuts the apron strings when the youngster is ready to survive on it’s own. (Insert your own joke here about college grads returning home to live in their parents’ basements.)
But few fish replace themselves via this strategy. In fact, many fish species take nearly the opposite approach by scattering thousands or even millions of free-floating tiny fertilized eggs, which develop and hatch untended. Then the larval fish, which may not look anything at all like their parents, must find fend for themselves in a tough, hard world.
When you’re tiny and tender and you live in a big ocean, there are lots of larger things which would like to eat you. While the eggs are many, few are likely to survive long enough to become adult fish. But if enough eggs are produced, even a very small survival rate can be sufficient to keep the species going.
Tarpon are an example of a fish which spawn this way, traveling many miles out into the Gulf to spray uncountable numbers of eggs, which hatch into minuscule eel-like larvae and drift as plankton with the currents while they develop.
Other fish take different tacks. Some species lay eggs in a nest and then guard the eggs until they hatch. A few species even guard the newly hatched fry for a while after they hatch and leave the nest. Species which go this route generally don’t lay nearly as many eggs as do the broadcast spawners described above, because the survival rate is higher with this strategy and not as many eggs are needed.
Nest-building is very common in freshwater species including bass, bluegill and others. Tilapia are even known to allow their babies to take refuge in their mouths, keeping them safe from threatening predators. This strategy is less common for saltwater fish, although clownfish are well-known practitioners (as seen in “Finding Nemo”). Triggerfish are an example of local saltwater fish which are nest-builders.
Other species, most notably some of the sharks and rays, carry their young inside long enough for the youngsters to develop into fully functional miniature versions of the parents, then give live birth to babies which are almost immediately ready to swim off and start acting a lot like adults.
Most species which reproduce in this manner produce very small numbers of young at a time — sometimes in single digits, or in the case of cownose and manta rays, just one. It’s a sound strategy because such advanced offspring are much more likely to survive to adulthood. But these kids get no help from Mom, who splits as soon as they are born.
There are plenty of variations on these procreative programs. For example, snook are broadcast spawners and most of them spend most of their lives scattered throughout the estuaries. When it’s time to spawn in the spring and early summer, they tend to congregate around the Gulf passes. After spawning is done, they disperse back into the estuaries.
Redfish are also broadcast spawners which gather near the passes to spawn, but mature redfish spawn in the fall. And redfish are offshore fish, which live most of their adult lives in the open waters of the Gulf. They move in to the passes to spawn, then move back offshore after spawning. It’s kind of the opposite pattern as snook, even though young redfish (up to around 30 to 36 inches in length) live in the same estuarine waters as snook.
There’s another interesting difference in the spawning routines of snook and redfish: All snook begin life as males. Later in life, most of those that live long enough will change genders and become female. So a group of spawning snook is mostly made up of older females cavorting with younger males. In human society, this type of behavior generates raised eyebrows and wagging tongues. But in the snook world, that’s just the way it works.
Gender change is common among fish, but not all of them do it the same way as snook. Gag groupers, for example, are all born as females. But a few of the largest and most aggressive will change into males, each of which accumulates a harem of females during their winter spawning season.
Another interesting thing about redfish is related to their “other” name: Red drum. Have you ever caught a redfish and heard it make a low-pitched drumming or croaking noise? Have you noticed that not all the redfish that you catch make this sound? That’s because only male redfish do it, and it’s primarily used during spawning season. There is no human/redfish translation book or app, but that drumming noise, when generated during the spawn, is apparently the equivalent of “Hey baby, you’re looking good. Wanna get busy?” Who knew?
Capt. Ralph Allen runs the King Fisher Fleet of sightseeing and fishing charter boats located at Fishermen’s Village in Punta Gorda. He is an award-winning outdoor writer and photographer, and is a past president of the Florida Outdoor Writers Association. Contact him at 941-639-2628 or Captain@KingFisherFleet.com.