There’s not much that tops the sight of a tuna clearing the water as it attempts to engulf a frisky live bait splashing on the surface, or the unmistakable sound of a snook popping baits deep under overhanging mangroves. Recreational sport fishing comes with many rewards, but perhaps the most memorable is the level of satisfaction associated with persuading a powerful game fish into slamming a perfectly presented bait or lure. The very last moment when a predator commits to attacking is truly remarkable. The precise sequence of events that unfolds leading up to the strike is incredibly complex and leaves us wanting to learn more about the behavior and biology of the game fish we seek.
Osteichthyes, or bony fish, are the largest and most diverse taxonomic class of vertebrates on the planet. With fossil records dating back roughly 420 million years, fish have evolved in numerous ways to capture prey and meet various nutritional necessities.
For predators that depend on crushing lobster, crab and whole finfish, power is much more important than suction.
Common characteristics of this scientific superclass of cold-blooded fish include the presence of cranial bones, a series of vertebrae that give way to connective tissue, gills, fins, operculum, scales and an ever-important jaw structure with mandibular muscles. Everything is in perfect balance.
If you’re anything like me, studying and observing game fish physiology, ecology and behavior is incredibly exciting. Broadbill swordfish do not attack squid in the same way that golden tilefish do, and tarpon slurping shrimp under a dock light do not feed in the same manner as redfish in the marsh searching for the very same crustaceans. Fully understanding the dynamics and complexities of how fish strike is beneficial to anglers in all venues.
Thankfully, miniature digital action cameras capable of recording in 4K and available at reasonable entry prices have enabled anglers to capture nature’s raw power like never before. Whether mounted on a dredge teaser, drone, push pole, or rod clamp, POV cameras don’t miss a beat and what you uncover after a day of fishing and filming will undoubtedly amaze. Like professional athletes watching tape and studying their opponents before competition, the action can only benefit your on the water exploits.
While there are nearly 30,000 species that fall under the classification of bony fish, almost all are opportunists and the feeding behavior of the predators we love to target can be broken into three categories—suction, ram and biting—with most all game fish relying on different combinations and variations of these foraging methods.
Suction feeding is the winning approach for many sought-after predators, though the feeding mechanics of this behavior are very complex. The dynamics of a fish’s ability to generate negative pressure in the mouth and produce strong suction is the result of specialized bone structure, pivot points, ligaments and muscles that enable fish to flare up laterally and quickly open and close their mouths.
Biomechanical analysis of fish skulls determined that the length and structure of a fish’s lower jaw are in direct correlation with the speed and suction power associated with opening and closing the mouth. Through evolutionary design, snook, tarpon, and largemouth bass ambush prey with elongated lower jaws that are ideal for maximum expansion and jaw protrusion to enhance suction, hence the term bucketmouth. Unsuspecting prey are in the gullet before they know what’s gone wrong.
Conversely, the bone structure of reef-dwelling cubera snapper and black grouper is very different. Long lower jaws are still designed for suction power, but bone structures have higher densities, a characteristic common to all demersal species that prefer to hole up and wait for ideal ambush opportunities. For predators that depend on crushing lobster, crab and whole finfish, power is much more important than suction.
Ram feeding is a speed-oriented method of attack where predators inflict a fatal blow through swift and aggressive forward motion. The method is common among most pelagic predators and those that rely on forward motion to push water over their gills.
For game fish like tuna, mackerel and billfish that cannot stop swimming, ram feeding is only accomplished through accurate and powerful speed and acceleration to track and overtake evasive for-age species in open water. Though, not all ram feeders rely on ram ventilation. Barracuda are notorious ram feeders, but can also hover in hiding before going in for the kill with a wide gape enhanced with teeth designed for puncturing.
While ram and suction feeding are generally used to attack prey in the water column, biting feeders attack items lodged to substrate and can even remove pieces of flesh from other fish. Triggerfish and sheepshead are prime examples, but with this method of attack the precise and timely opening of the mouth isn’t as critical to feeding success since food items typically aren’t very elusive or capable of escaping at a rapid pace.
Through biting is a unique attack method, its still a ram-dominated event that requires forward motion to bring a fish’s jaws within striking distance. Suction is also highly reliant upon ram capabilities, since fish can’t successfully attack prey if it’s unreachable. Most feeding events are a result of ram, even though it may appear that suction is generated as a result of forward motion. Though ram is a necessary component in both suction feeding and biting, it is the only feeding behavior that can occur completely on its own.
Whether scavenging, stalking or ambushing, predators do whatever it takes to find their next meal and differences in hunting strategies and feeding mechanics can vary greatly depending on a fish’s surrounding environment. It can even vary within the same species.
Field studies and the analysis of bone structure in red snapper inhabiting the northern Gulf of Mexico have revealed interesting observations regarding skull and body morphology within species regarding diet and preferred feeding mechanism. Juvenile red snapper that settled over muddy substrate in the Gulf were found to have a deeper head and body profile that relates to the preferred behavior with slower to open, yet stronger jaws.
Juvenile red snapper living and foraging over hard bottom ridges exhibited tendencies of suction feeding behavior that relied on faster closing jaws for a diet of softer prey items. Additionally, since the mud-inhabiting fish consumed harder prey and finfish more typical to the diet of adult red snapper, they benefitted from increased growth rates and higher recruitment into adult populations.
While these findings are fascinating, there’s more than meets the eye. Data like this is critical to fully understanding species dynamics and changes in population as a result of feeding behavior and associated habitat. Without this knowledge it’s impossible for managers to properly enact fisheries rules and regulations. Hopefully future studies shed light on the benefits of an ecosystem-based approach compared to traditional single-species focused management practices.
As anglers we take great pride in the hunt and try our hardest to mimic the defined diet and eating methodology of our target species. While modern angling has evolved into a science with extremely technical equipment and innovative approaches, it is absolutely critical that anglers first and foremost know their opponents. By combining the knowledge attained through first hand observations of fish habitat utilization and preferred feeding methods, anglers will gain a more complete understanding of the predators we seek and ultimately improve our catches.