Why Fish Move: How to Stay One Step Ahead
March 27, 2019
To be successful on the water, you must understand where and why fish move.
As a fishermen, all you have to do is find fish and then get them to bite. That simple statement encapsulates everything that we do on the water. Yes, we must pick a destination, a target species, and the equipment we’ll use to pursue them, but ultimately, once we’re on the water, we have to locate our finned adversaries before we can make them bite.
Fish move. Even an angler with limited experience will soon recognize the seasonality, and the predictability, of fish movements within their favorite lake, river or reservoir. Statements declaring, “that bay is terrific for springtime bass, but by the Fourth of July, they’re out on this weedline,” are commonplace. But why do fish move and how do we stay one step ahead of them?
Prime fish locations, and the transitions among them, are driven by a set of species-specific factors, each revolving around particular biological requirements. For any fish we chase, these are (1) reproduction, (2) forage availability and (3) environmental factors, such as water temperature. Understand these needs from the perspective of your target species and you will be able to quickly locate them wherever you fish.
Fish will engage in spawning behavior once they reach reproductive maturity, with annual movements dictated by this primal urge. Water temperature, length of day and moon phase all work together to trigger predictable transitions of fish to their eventual spawning grounds.
Consider the reproductive behavior of bass as an example: both largemouth and smallmouth will be in a breeding mood once water temperatures stabilize above 60 degrees but their preferred habitats will frequently be quite different. Smallmouth will fashion a nest in a hard-bottomed area, one comprised largely of sand, gravel and rock.
On the other hand, largemouth are willing to spawn in soft-bottomed, vegetated areas. Once you appreciate these species-specific habitat preferences, you’ll be able to locate spawning bass.
Now, let’s eat and stay comfy: once the next generation has been created, fish movements will be largely dictated by forage availability and environmental considerations. These two factors are tightly coupled with the movement of prey items (and the predators that follow them) resulting from their own reproductive cycles, forage needs and environmental requirements.
Consider the movement of bass once spawning is complete: largemouth will remain in shallow, weedy areas for some time because these areas are brimming with prey options, especially juvenile panfish and baitfish. Summer heat will drive these smaller fish into two areas that provide shelter from the sun and from predators: deep weedlines and shallow slop. Because their prey is abundant there, finding summer largemouth in the thick stuff should come as no surprise.
In contrast, smallmouth bass will slide onto rocky flats and deeper, hard-bottomed areas. These movements are again coupled to the distribution of their preferred forage items: crawfish, small baitfish and, where present, gobies. On larger bodies of water with populations of soft-finned forage (smelt, alewives and ciscoes), smallmouth bass will notoriously suspend off cover, especially in summer and fall. In these instances, baitfish relate to the thermocline to accommodate their own temperature requirements, grazing on concentrations of plankton moving up and down within the water column, and smallies are never far behind. Frequently, these suspended fish are the largest.
Fish are simple creatures. During any given year, they need to reproduce, find plenty to eat and avoid getting too hot or too cold.
Understanding these fundamental biological requirements, and how your favorite targets will move to address them, will help you put more fish in the boat all year long.