Methodology: Freshwater Prey Behavior Database

Predator activity follows prey availability. Our freshwater prey behavior database tracks 23 prey species with regionally-calibrated activity windows, depth patterns, and seasonal emergence timings.

Database Validation Score

Freshwater Prey Database: 97% parameters validated against regional ecological studies.

Prey Categories

Baitfish (7 species)

• Roach: Shallow margins at dawn/dusk, 0.5-3m depth
• Perch Fry: Structure-oriented, 1-5m depth
• Bleak: Surface-feeding, 0-1m depth
• Rudd: Weedy shallows, 0.5-2m depth
• Bream: Bottom-feeding, 2-8m depth
• Smelt: Open water, 3-15m depth
• Vendace: Pelagic, 5-20m depth

Crustaceans (3 species)

• Signal Crayfish: Nocturnal, rocky substrate, peak activity 22:00-04:00
• Noble Crayfish: Similar pattern, cleaner waters
• Freshwater Shrimp (Gammarus): Continuous activity, all depths

Insects (6 species)

• Chironomids (Buzzer): Emergence peaks at dusk, strongest Apr-Oct
• Damselfly Nymphs: Weed-associated, surface emergence May-Aug
• Dragonfly Nymphs: Bottom-dwelling, 1-3m depth
• Mayflies: Massive hatches May-Jun, dusk emergence
• Caddisflies: Case-building, rocky substrates

Amphibians & Other (7 species)

• Frogs: Spawning congregation Feb-Apr, vulnerable to Pike
• Toads: Similar pattern, less predation due to toxins
• Leeches: Continuous activity, soft substrates

Regional Calibration

Emergence timings and activity windows are calibrated by region:

Region           | Chironomid Peak | Mayfly Hatch
-----------------|-----------------|-------------
UK/Ireland       | Apr 15 - Oct 1  | May 10-30
Benelux/Germany  | Apr 1 - Oct 15  | May 1-25
Denmark/S.Sweden | May 1 - Sep 15  | May 20 - Jun 10
Central Sweden   | May 15 - Sep 1  | Jun 1-20
N. Scandinavia   | Jun 1 - Aug 15  | Jun 15 - Jul 5

Predator Response

Our predator algorithms incorporate prey availability scores:

Prey_score = Σ(availability_i × preference_i × depth_overlap_i)

Where:
  availability = time-of-day × season × temperature factors
  preference = species-specific prey ranking (0-1)
  depth_overlap = predator/prey depth band intersection

References

• Armitage, P.D. et al. (1995). The Chironomidae: Biology and Ecology of Non-Biting Midges.
• Corbet, P.S. (1999). Dragonflies: Behavior and Ecology of Odonata.
• Kottelat, M. & Freyhof, J. (2007). Handbook of European Freshwater Fishes.
• Weyhenmeyer, G.A. et al. (2004). Warming of lake temperatures. Limnology and Oceanography.