The Fisheries Management Report for Tim Pond

We received an email from one of the Maine Fisheries Resource Biologists who had visited Tim Pond to survey the Pond. Here is a summary of what the report found.

Key Findings From the August 2024 Survey

Age of the Trout

Out of the 40 fish samples, the age classes identified were from 1+ to 5+ years old.

Size and Condition

  • The average brook trout measured 9.56 inches and had a condition factor of 0.88.
  • The largest fish measured 13.42 inches.
  • Only one brook trout in the sample was found with a hooking injury.

What Is a Condition Factor?

Condition factor, also known as Fulton’s K or “K factor,” is a metric fisheries biologists use to assess the overall body condition of a fish. It is calculated using a fish’s length and weight. For species such as brook trout, a condition factor around 1.0 generally indicates a very healthy fish.

What Tim Pond Brook Trout Eat

Stomachs were found with leeches, dragonfly larvae, diptera larvae, zooplankton, and scuds.

Summer Habitat and the Thermocline

Water quality measures found limited suitable habitat within the thermocline. Water temperatures within the thermocline were suitable, although dissolved oxygen levels were low, which left a narrow 1-foot band of cool and oxygenated habitat.

What Is a Thermocline?

The thermocline is the layer where water temperatures drop rapidly compared to surface waters. This layer is critical for coldwater species such as brook trout, which require cool temperatures to survive. In addition to cooler water, adequate dissolved oxygen levels are also necessary. Together, these conditions within the thermocline layer provide essential summer habitat for coldwater species until surface waters cool again in the fall. During the summer months, water in lakes and ponds becomes stratified, meaning distinct layers of water with different temperatures form from the surface to the bottom.

Greenbush Inlet: A Summer Refuge for Brook Trout

Due to the limited habitat in the pond, hundreds of brook trout were found using Greenbush Inlet as a thermal refuge area. The tributary was cool at 16°C (60.8°F), and multiple age classes were observed.

A Healthy, Wild Brook Trout Population

The wild brook trout population remains abundant in Tim Pond. The age class structure of this sampling event is indicative of a healthy, robust population with good recruitment, as seen in the abundance of 2+ to 3+ year old cohorts in this sample as well as mature 5+ year old cohorts.

What Is Recruitment?

Recruitment into a fish population refers to when brook trout survive early life stages and successfully enter the population. In Tim Pond, the abundance of younger fish (ages 2–3) indicates strong survival from early life stages, including egg incubation, fry development, and growth into juvenile and adult fish. Early life stages are when brook trout are most vulnerable, so observing abundant younger fish in a wild population is a positive sign.

How Tim Pond Has Changed Over Time

Condition Has Improved Since 2015

Condition factors have improved since a 2015 rod and reel survey, increasing from 0.77 to 0.88. Variation in condition factors over time is likely due to how sensitive this small system is to environmental factors.

Greenbush Inlet Recovery After 2008

In 2008, Greenbush Inlet was impacted by siltation after a logging operation removed the riparian buffer in the area of the tributary. Impacts from this habitat degradation were reflected in 2012 sampling, with lower abundance, missing age classes, and high condition factors. Since then, Greenbush Inlet has had regrowth of riparian areas, and the brook trout population has stabilized.

What Is a Riparian Zone?

A riparian zone is the vegetated, transitional land area directly next to the pond. It acts as a vital connection point between aquatic and upland ecosystems. Riparian zones stabilize streambanks, filter pollutants, and provide crucial habitat for wildlife, such as shade-loving fish and birds.

Summer Water Quality

Summer water quality has shifted compared to prior sampling events. Despite limited suitable habitat in the pond during the warm months, the brook trout are finding thermal refuge and surviving.

Conclusion: Our Brook Trout Are Doing Well

The current regulations are appropriate, and no management recommendations are necessary at this time.

Please Avoid the Inlets During Spawning

The biologists do recommend not fishing near any of the three inlets (Greenbush, Alder, and Hack) during spawning, to keep stress levels down for the fish.

Quick Answers

Are the brook trout in Tim Pond healthy?

Yes. The state survey found an abundant, wild population with strong recruitment and improving condition, and no management changes were recommended.

How big are the brook trout in Tim Pond?

The surveyed trout averaged 9.56 inches, and the largest measured 13.42 inches. Ready to try for one? See our fly fishing page.

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Categories:   Fishing & Conservation