How Trout Anglers Should Prepare For The Seasonal Transition Game

The following appears in the May issue of California Sportsman:

By Cal Kellogg

There’s a moment every year when trout fishing changes. It doesn’t happen overnight, and it doesn’t come with a clear signal, but if you spend enough time on the water you feel it.

The easy, shallow spring bite starts to fade, the fish begin to slide out and suddenly, the patterns that produced limits a few weeks earlier don’t seem quite as reliable. That’s the spring-to-summer transition, and it’s where the wheels come off for a lot of anglers.

For those who understand what’s happening beneath the surface, it’s actually one of the most productive – and consistent – windows of the entire year. The key is recognizing that trout don’t disappear; they simply reposition. They follow temperature, oxygen and food, and if you track those three things, you can stay on fish from May right through the heat of summer.

THE HEAT IS ON

In California reservoirs, this transition is driven by warming surface temperatures and the gradual development of stratification. In early spring, lakes are typically well mixed. Water temperatures are relatively uniform from top to bottom, oxygen is abundant and trout can roam freely. That’s why you can catch fish in the top 10 feet of water and tight to shore, often within casting distance of the bank.

As days lengthen and the sun gains strength, the upper layer of the lake – the epilimnion – begins to warm. Because trout are coldwater fish, they’re comfortable in water generally ranging from the mid-40s to low 60s. Once surface temperatures push beyond that comfort zone, fish begin to drop. Not because they want to, but because they have to.

GIVE THE BAND A HAND

At the same time, the lake begins to separate into layers. You get warmer water on top, colder water below and eventually a transition zone – the thermocline – where temperature and oxygen levels create a band of ideal habitat. That band becomes thehighway trout use to travel, feed and hold through the summer. For the trolling angler, everything revolves around finding and fishing that band.

Early in the transition – from late April into May and even early June at many foothill lakes – trout may still be relatively shallow, often 10 to 25 feet down. This is the window where a lot of anglers continue to do well flat-lining or using minimal weight. Fish are still spread out, still willing to move and still feeding heavily on spring forage.

That forage is a mix of emerging aquatic insects, small baitfish and opportunistic food sources like worms and terrestrials that end up in the water. This is why traditional trolling offerings – think small spoons, minnow plugs, spinners and trolling flies – are so effective. They mimic a range of prey items and trigger both feeding and reaction strikes.

INTO THE DEEP

As you move deeper into May and June, things change. Surface temperatures climb and trout begin to consolidate. Instead of being scattered throughout the upper water column, they start to group up along the most favorable temperature and oxygen levels. In many California reservoirs, that means 25 to 50 feet down, sometimes deeper depending on the lake and the year. This is where precision becomes critical.

If you’re trolling above the fish, you might as well not be fishing. Trout will move up a few feet to intercept a bait, but they won’t come up 20 feet. You need to be in their zone. That’s where downriggers, leadcore, divers or weighted line systems come into play. They allow you to consistently present your lures at the depth where trout are actually living.

Electronics are a huge advantage here. Modern sonar units make it easy to identify bait schools, individual fish and the general depth where life is concentrated. If you’re marking fish at 35 feet, that’s where you need to be. Not 20; not 50; 35.

I WANNA TROLL FAST

Trolling speed also becomes more important as the season progresses. In cooler water, trout will chase. In warmer conditions, they tend to be more deliberate. Speeds in the 1.6- to 2.2-mile-per-hour range are a good starting point, but subtle adjustments can make a big difference. Pay attention to what your gear is doing. Watch your rod tips. Let the fish tell you what they want.

Structure plays a major role during the transition as well. Trout don’t just suspend randomly in open water. They relate to features such as old river channels, points, drop-offs, submerged reefs and areas where the bottom contours change. These features concentrate both bait and fish.

One of the most productive approaches is to follow the edge of structure at the depth you’re targeting. If the thermocline sets up at 30 feet, work that 30-foot contour along points and channel edges. This keeps your lures in the strike zone while also intersecting fish that are using structure as travel routes.

LIGHT, LURE AND COLOR VARIABLES

Another key factor is light. Trout are extremely light-sensitive, and as water clarity increases and sunlight penetrates deeper, they often shift their feeding activity to low-light periods. Early morning and late afternoon can be prime, especially in clear reservoirs. That doesn’t mean midday fishing is dead; it just means you may need to fish deeper or adjust your presentation.

Lure selection during the transition should match both depth and forage. Small spoons remain a staple because they imitate a wide range of prey and can be fished effectively at various speeds. Minnow-style plugs come into play when trout are keyed on baitfish. Trolling flies are deadly when fish are feeding on baitfish.

Color can matter, but not in the way many anglers think. It’s less about finding a magic color and more about visibility. In deeper water, dark lures, glow lures and UV finish lures tend to stand out. In clearer, shallower conditions, more natural tones – silver, blue, brown or bright colors like pink or orange – often produce better results.

BANK STAYS OPEN

While trolling dominates during this period, bank anglers still have opportunities if they understand the same principles. As trout move deeper, shore fishing becomes more location-specific. Anglers need to focus on areas where deep water comes close to shore. Steep banks, dam faces and points that drop off quickly are good starting points.

Fishing bait off the bottom can still produce, particularly if you’re targeting that transition zone where trout move in and out. Inflated nightcrawlers, PowerBait and similar offerings remain effective. The key is depth and patience. You’re no longer fishing for cruising fish in shallow water, but rather waiting for fish to come to you along deeper travel routes.

Casting hardware – spoons, spinners, small plugs – can also be effective during low-light periods when trout move more shallow to feed. Early mornings and evenings are your best windows, especially in late spring and early summer.

BE INVENTIVE, CONFIDENT

One thing that separates consistently successful anglers from the rest is adaptability. The spring-to-summer transition is not static. It evolves week by week, sometimes day by day. Water temperatures change, fish adjust, forage shifts. Anglers who pay attention and make adjustments stay on fish. Those who stick to what worked last month often struggle.

It’s also a time when confidence matters. When the bite slows or changes, it’s easy to start second-guessing everything. But if you understand the fundamentals we’ve run down – temperature, oxygen, food, structure – you can make informed decisions and stay in the game.

EMBRACE THE TRANSITION

From a guide’s perspective, this is one of my favorite times of year. Spring’s crowds thin out, the fish settle into predictable patterns and anglers who are willing to learn can experience some of the best fishing of the season.

The transition from spring to summer isn’t the end of good trout fishing. It’s the start of a more refined, more technical and often more rewarding phase. The fish are still there. In many cases, they’re feeding heavily and growing fast. You just have to go with them. Follow the temperature. Follow the food. Follow the structure.

Do that, and you’ll stay on trout from the first warm days of spring all the way through the long, bright days of summer, and you’ll do it with consistency that most anglers never achieve. CS

Editor’s note: Cal Kellogg is a longtime Northern California outdoors writer. Subscribe to his YouTube channel Fish Hunt Shoot Productions at youtube.com/ user/KelloggOutdoors.