Can I Fish in a Lake During an Algal Bloom? 

In the summertime, you have more daylight and warmer temperatures, two factors that are very conducive to fishing. Well, except when you arrive at your favorite lake only to find that the waters are blue-green. Then you realize an algal bloom has occurred. Can you still go fishing?

If you really want to, you can fish in a lake during an algal bloom, but only if the bloom is blue-green algae. Golden algae, which is less common, is usually deadly to fish. The cyanotoxins that cause blue-green algae can sometimes be toxic as well, so don’t eat the fish you catch.

Ahead, we’ll explain what an algal bloom is, the various types, and whether it’s worth fishing in an algal bloom. If you do proceed with your fishing rod, we’ll present some tips for fishing success as well, so keep reading! 

What Is an Algal Bloom? + Algal Bloom Types

Understanding Algal Blooms

An algal bloom, as you likely guessed, is comprised of algae. Algae, singular form alga, refer to a type of eukaryotic photosynthetic organism. As algae appear, it’s not all from one clade, but several.

Algae occur when water becomes anoxic. In other words, the amount of dissolved oxygen decreases. The sediments in the body of water, such as a lake, produce phosphate that enters the water column. Algae then show up.

When algae accumulate in large masses, this is an algal bloom. Although the appearance of the water will change in different ways depending on which type of algae causes the bloom, what’s for certain is that your favorite lake will look radically different. We’ll talk more about that in a moment.

Algal blooms, like alga itself, are likelier to occur in the summertime. Other times of year that can trigger the development of algal blooms are unseasonably warm periods. 

Thus, due to the way that climate change has affected the average temperatures, you could see algal blooms in the autumn, spring, and sometimes even the winter.   

The Types of Algal Blooms

Although red algae can sometimes occur, the two most recognized forms of algal blooms are blue-green algae and golden algae. Let’s take this section to talk in more detail about both algal bloom types. 

Blue-Green Algae

The most common algal bloom is blue-green algae. Comprised of cyanobacteria, blue-green algae are teeny-tiny organisms that develop not only in lakes but in saltwater, brackish water, and ponds too. 

Cyanobacteria will photosynthesize much the same way that algae can. This allows the cyanobacteria to spread.

You’ll know that blue-green algae have developed on your favorite lake because the lake will be noticeably discolored. The blue of the algae will be a much deeper blue than the color the lake usually is. 

The green of blue-green algae is that same noxious, neon green that you usually see when algae appear on the surface of the water. 

Golden Algae

The other type of algal bloom is triggered by the Prymnesium parvum bacteria and is known as golden algae. 

Once contained mostly to oceans, golden algae have since begun appearing in freshwater lakes, reservoirs, and rivers. High levels of minerals raise the salinity of the water, which then invites golden algae to propagate. 

Both blue-green algae and golden algae are caused in part by climate change as well as slow or still waters and nutrient pollution.

Allow us a moment to talk about nutrient pollution, as it’s quite interesting. Plants like algae require phosphorus and nitrogen. When these nutrients accumulate in excess, usually due to runoff, then microorganisms such as algae can grow very fast. 

Table showing pictures of blue-green algae compared to Golden Algae. Blue-green algae is comprised of cyanobacteria and is found in lakes, saltwater, brackish water, and ponds. Golden Algae is comprised of prymnesium parvum bacteria and is found in oceans, freshwater lakes, rivers, and reservoirs.

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Is Fishing in a Lake During an Algal Bloom Safe?

Now that you better understand the algae that have spread across your favorite lake, you have one question. 

Is it safe to go fishing? Let’s explore. 

The Pros of Fishing in an Algal Bloom

Most of the time, especially if you’re dealing with blue-green algae, yes, you can fish.

If anything, you can sometimes use the algae to your advantage. Thick blooms of algae can cover the surface of the water, which can make it hard for some fish to peer up. Others will go about like business as usual though. 

The Cons of Fishing in an Algal Bloom 

However, fishing in an algal bloom is not without its risks. 

Those same cyanobacteria that comprise blue-green algae can sometimes produce cytotoxins. These intracellular toxins are usually released when a cell ruptures or dies, although not exclusively. It depends on the type of cyanobacteria.

Three genera of cyanobacteria can make cytotoxins, Planktothrix, Dolichospermum (formerly known as Anabaena), and Microcystis. The latter is the most common of the three and is toxic in almost all cases.

Microcystis can produce microcystins, also known as cyanoginosins. These are a toxin class exclusive to this cyanobacteria. 

A Microcystis algal bloom has a consistency like wet paint. The texture can sometimes be granular as well, which means it’s textural. The algae will have a sickly neon green color. 

Once the algal bloom passes, the scum residue from Microcystis can linger. The microcystins may remain in the water for months. This is dangerous, as microcystins are known liver toxins and may be a carcinogen in people as well. 

Should any animal drink the water that the remaining microcystins are present in, they could fall ill or die. Fish and birds that live in or near the lake will also die if cyanobacteria are prevalent.

That’s only blue-green algae. What about golden algae?

The Prymnesium parvum bacteria is deadlier in some ways and less deadly in others. As of this writing, it does not appear that the bacteria in golden algae affect human health the same way that the cyanobacteria in blue-green algae can.

However, golden algae kill fish off in much higher numbers than blue-green algae do. 

Tips for Fishing During an Algal Bloom

Fishing during an algal bloom is doable and can even lead to some big catches, especially if you follow these handy tips. 

Check with Your Local Health Department or Parks and Rec Association

You can’t eyeball the algae in your favorite lake and know for sure whether the green-blue stuff contains cyanobacteria. Rather, the only way to be sure is to consult with the experts.

Contact your neighborhood health department. Unless the algal bloom is a brand new occurrence, then the experts at the health department should be well-versed in which type of algae it is and how safe it is.

If not them, then check in with the parks and rec association that manages the lake. They should be able to provide you with more information on how safe the fishing is. 

Fish in Shallower Waters

The presence of an algal bloom can change the behavior of some fish species, especially walleye. Remember, an algal bloom represents a lack of dissolved oxygen. This will cause the fish to want to be nearer the surface of the water.

In shallow areas, especially those that are weedy, you’re unlikely to find many other anglers. What you could find waiting for you instead is plenty of fish to catch. 

The Thicker the Bloom, the Worse the Fishing

Algal blooms, especially blue-green ones, can be thick and goopy like wet paint. The thickness of the bloom will cause the opposite phenomenon to the one we described above. 

Rather than seek shallower waters, in a thick algal bloom, fish will plunge deeper into the water to breathe. You won’t be able to catch much of anything on days like this.

To Avoid Algal Blooms, Watch Your Timing

The reason they’re called algal blooms is that algae will spread and then vanish depending on the conditions. Earlier in the morning before the sun is up, algae aren’t prevalent. It’s too cool for the algae. That’s also true after the sun goes down. 

As the morning sunrises and shines throughout the afternoon, the algae blooms will begin to grow in size. 

If you are fishing very early in the morning or after dusk, double-check the rules for your lake before you go. 

Change Your Lure Color

Do you usually use patterned baitfish as your artificial lure of choice? Maybe you typically have good luck with an old-fashioned white lure.

Not in blue-green algae-infested waters, you won’t. You need a lure that will stand out against the thick, colorful algae. We recommend brighter, attention-grabbing hues such as pink, orange, chartreuse, black, blue, or purple. 

Pictures showing suggested lures to use when there is a algal bloom. We recommend brighter, attention-grabbing hues such as pink, orange, chartreuse, black, blue, or purple. 

Try a Vibrating or Reflective Lure

Another way to cut through the din and get your lure noticed is to ensure it does something to captivate a fish’s attention as the fish swims among an algal bloom. 

For example, perhaps you try a reflective spoon lure, a spinning lure, or a lure that induces vibrations. You might find that more walleye and bass swim your way that would otherwise ignore your line. 

Take Your Time

As we mentioned before, visibility in the lake decreases during an algal bloom. The fish can’t see quite as well, so if you’re rushing your fishing line this way and that, you could miss out on a good fishing opportunity because you went too fast. 

Whatever your favorite fishing technique, slow it down a few paces. You should have better results. 

Use Scents to Your Advantage

We wouldn’t recommend live bait quite as much when fishing in an algal bloom, but perhaps you can use live bait to infuse an artificial lure with an appealing scent? That aroma could entice the fish to bite. 

Don’t Eat the Fish 

Hooray! You caught a good number of fish today among the algal bloom. Even if the fishing was safe, we still wouldn’t recommend you eat the fish you caught. It’s just not a good idea from a health standpoint. 

Related Reading: Can I eat fish out of a lake during a algal bloom?

Final Thoughts 

You can fish in a lake during an algal bloom in most cases unless the bloom is golden. Then the fish are likely dying off anyway. Blue-green algae may contain cyanobacteria that can be deadly to fish and potentially humans alike, so keep that in mind too.

It’s always best to get the green light from your parks and rec association or your local health department before you fish in an algal bloom. Be safe out there!

Tim Butala

My name is Tim and I have been a fisherman my whole life. My favorite fish to go after is a Striped Bass.

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