Fishing Responsibly for Trout During Warm/Low Water Conditions

Maine is well-known for our abundance of coldwater fish populations such as landlocked Atlantic salmon and trout. These coldwater species thrive in cool (≤ 68°F), clean, well-oxygenated water. During summers when water levels and flows can be low due to lack of rainfall, water temperatures rise causing additional stress on trout and salmon.

Thanks to Maine’s unique hydrography of interconnected streams and lakes, many of these fish will move between flowing and non-flowing waters (Jackson & Zydlewski, 2009). This interconnectivity combined with an abundance of deep natural lakes provides vast areas for stream dwelling trout to seek thermal refuge during periods of high stream temperatures.

Anglers are reminded to consider these conditions and take some personal responsibility when fishing for coldwater fish species such as trout and landlocked salmon during warm temperatures or low water levels and flows.

There are a few simple steps you can take to reduce stress on coldwater species, such as trout and landlocked salmon:

Frequently Asked Questions

Are warmwater species, such as bass, pickerel, and perch, impacted by the warmer surface temperatures?

July and August are great months to target warmwater species such as bass, pickerel, and perch. These species thrive in warmer water, unlike salmon and trout, and can often be found cruising the shoreline of ponds and lakes, often creating an action-filled fishing day. Targeting these species is a great way to introduce someone to the sport of fishing, and to keep kids engaged. A simple bobber, small hook, and worm is a popular setup.  Check out the monthly fishing report or the Maine Fishing Guide for tips on where to go, and mefishwildlife.com/fishinglaws to view Maine’s fishing laws.

Where do coldwater fish go when the water temperatures rise?

To beat the heat in streams and rivers, brook trout seek deeper pools and shaded areas that are cooler and better oxygenated. Small, colder tributaries are also locations where these fish will seek thermal refuge. In ponds, they will seek spring holes and move to deeper cooler areas of the lake. When fish are in these less than optimal situations, they are under stress and more susceptible to predators.
When a stream dwelling brook trout, that has hunkered into a cool 50-degree streamside seep, is hooked by an angler the fish is played out in the main stream where water temperatures may be in the mid 70’s, approaching the fish’s thermal limits. Trout and salmon that reside in our deeper, colder lakes can also be impacted by mid-summer weather. A lack of rain and consecutive days with above average temperatures can cause surface water temperatures to be warmer than usual, with some lake surfaces approaching the 80-degree mark. Trout and salmon will stay below the thermocline, where temperatures can be in the 45-55 degree range. A fish caught below 40 feet of water and then brought to the surface may experience a temperature difference approaching 35 degrees! This type of temperature swing can put a great deal of stress on a fish. 

In extreme cases, dry summers can result in fish kills in some shallower and smaller ponds, due to reduced groundwater inputs and less oxygen as it becomes warmer.  (For more information on fish kills and when to be concerned about them, check out this blog by MDIFW Fish Pathologist David Russell: When to be Concerned About Finding Dead Fish on Maine’s Lakes, Ponds, and Rivers this Summer.)

Has the Department considered temperature-based fishing restrictions?

Recent drought conditions and associated potential increases in water temperatures have prompted questions to MDIFW from the angling public regarding the value of implementing temperature-based fishing restrictions to reduce angling related stress and mortality. Many anglers already promote abstaining from fishing when they believe the water is too warm. MDIFW also provides general guidance to the angling public regarding fishing practices that reduce angling stress, particularly when environmental conditions are less optimal in late summer, and has established closures of areas providing critical seasonal refugia.

The public advocacy conveyed appears to be born out of concern that angling above a certain water temperature will negatively impact the targeted fish population. Given the more recent extremes in weather patterns, and expressed public concern, MDIFW conducted a comprehensive review of temperature-based coldwater fishery restrictions to better understand the strategies and science behind these restrictions. This review process included scientific literature, popular articles, and information provided by other state fisheries management agencies across the US. Click here to open the Issue Profile: A Review of Temperature-based Fishing Restrictions (PDF).

A Review of Temperature-based Fishing Restrictions (PDF)

Reminder

Anglers are also reminded that beginning August 16, the general law for fishing in rivers, streams, and brooks is restricted to the use of artificial lures and flies only. General law length and bag limits apply, except there is a daily bag limit of one landlocked salmon and one brook trout.  These "terminal tackle" regulations are applied to reduce mortalities in released fish. Be sure to use MDIFW’s Fishing Laws Online Angling Tool to check for any special regulations on your favorite water!