ArraySeptember 21, 2018 at 1:32 pm
[caption id="attachment_3130" align="alignright" width="404"]
Small streams remain open and offer some excellent fishing for brook trout.[/caption]
By MDIFW Fisheries Biologist Frank Frost
Fishing for brook trout in small streams remains a popular late-summer pursuit for a small number of anglers in northern Maine. One of the most common questions the regional office in Ashland receives is “are the brooks still open to fishing?”. There is a common misconception that on August 16th each year, flowing waters close to fishing; that is simply not true – the regulations change from general law to “artificial lures only” and a daily bag limit on trout of one fish on August 16 and remain open until the end of September. For those anglers wishing to wade small streams this time of year in pursuit of small, colorful brook trout, you likely won’t see anyone else and have miles of water all to yourself.
We also field many questions about how weather affects these small, seemingly fragile, stream habitats and the fish they support. Those questions and concerns intensify when the weather turns hot and dry. The summer of 2018 marks the third year in a row with below normal rainfall and all it takes is a short drive to a few stream crossings to see just how low the water levels are right now. However, it has been the heat of 2018 that is noteworthy – it has been hot! I recently spoke with Ted Shapiro, meteorologist at WAGM News in Presque Isle, who has summarized National Weather Service data collected at Caribou. The three month “summer” period at Caribou, June/July/August, was the warmest on record with an average temperature of 66.3 degrees F. The previous record was 66.0 set in 1973. August 2018 was the all-time warmest August on record with an average temperature of 68.9 F, 5.3 F above the 1981-2010 average! The record setting August followed the all-time warmest July which happens to be the all-time warmest month ever recorded at Caribou. The 70.9 F average was 5.3 degrees above average. Record keeping at Caribou began in 1939.
So, what does the warm, dry weather mean for brook trout populations in these small habitats? We have certainly seen the effects on water temperatures this summer. Some streams have gone higher than 70 F while in the past they rarely exceed this threshold. While we’ll likely have some direct mortality of individual brook trout due to these extreme conditions, most populations should remain intact if there is moderate to high quality habitat available for the trout to use. For instance, deep pools with adequate cover in the form of rocks, woody debris, or overhanging banks are important as are inputs of cooler ground water to mitigate the high air temperatures. Trout will congregate in these areas during extreme conditions; if there is adequate cover in the deep pools, trout are better able to avoid being captured by bird and mammal predators. In areas of degraded habitat, as occurs with heavy development with expanses of impervious surfaces (i.e., parking lots) or excessive tree removal as occurs in some forestry operations, trout are much less able to cope with extreme weather. The worst-case result is local extinction or a contraction in the species range on a very limited scale. Once the weather calms down and returns to “normal”, trout will re-populate these areas through their tendency to be highly mobile which is likely an adaptation to just such extreme weather conditions.
Small streams remain open and offer some excellent fishing for brook trout.[/caption]
By MDIFW Fisheries Biologist Frank Frost
Fishing for brook trout in small streams remains a popular late-summer pursuit for a small number of anglers in northern Maine. One of the most common questions the regional office in Ashland receives is “are the brooks still open to fishing?”. There is a common misconception that on August 16th each year, flowing waters close to fishing; that is simply not true – the regulations change from general law to “artificial lures only” and a daily bag limit on trout of one fish on August 16 and remain open until the end of September. For those anglers wishing to wade small streams this time of year in pursuit of small, colorful brook trout, you likely won’t see anyone else and have miles of water all to yourself.
We also field many questions about how weather affects these small, seemingly fragile, stream habitats and the fish they support. Those questions and concerns intensify when the weather turns hot and dry. The summer of 2018 marks the third year in a row with below normal rainfall and all it takes is a short drive to a few stream crossings to see just how low the water levels are right now. However, it has been the heat of 2018 that is noteworthy – it has been hot! I recently spoke with Ted Shapiro, meteorologist at WAGM News in Presque Isle, who has summarized National Weather Service data collected at Caribou. The three month “summer” period at Caribou, June/July/August, was the warmest on record with an average temperature of 66.3 degrees F. The previous record was 66.0 set in 1973. August 2018 was the all-time warmest August on record with an average temperature of 68.9 F, 5.3 F above the 1981-2010 average! The record setting August followed the all-time warmest July which happens to be the all-time warmest month ever recorded at Caribou. The 70.9 F average was 5.3 degrees above average. Record keeping at Caribou began in 1939.
So, what does the warm, dry weather mean for brook trout populations in these small habitats? We have certainly seen the effects on water temperatures this summer. Some streams have gone higher than 70 F while in the past they rarely exceed this threshold. While we’ll likely have some direct mortality of individual brook trout due to these extreme conditions, most populations should remain intact if there is moderate to high quality habitat available for the trout to use. For instance, deep pools with adequate cover in the form of rocks, woody debris, or overhanging banks are important as are inputs of cooler ground water to mitigate the high air temperatures. Trout will congregate in these areas during extreme conditions; if there is adequate cover in the deep pools, trout are better able to avoid being captured by bird and mammal predators. In areas of degraded habitat, as occurs with heavy development with expanses of impervious surfaces (i.e., parking lots) or excessive tree removal as occurs in some forestry operations, trout are much less able to cope with extreme weather. The worst-case result is local extinction or a contraction in the species range on a very limited scale. Once the weather calms down and returns to “normal”, trout will re-populate these areas through their tendency to be highly mobile which is likely an adaptation to just such extreme weather conditions.
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