Stoneflies
Gammarids
- Ecology: Good
- Chemical: Unknown
WFD classification · FRHR161
Rules at a glance
- Permit required
- Fly only
Water temperature for Grayling
Warm — slow15°C est.ideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
Midday window — grayling feed best from late morning into early afternoon.
Where
Work runs and glides — grayling shoal in the bottom third of the water column.
Method
Tight-line nymph the bottom third with weighted patterns.
Kit
10 ft #3 rod, floating line, long leader to 4 lb fluoro for nymphs.
Why this works
Good — time of day is right today, though water temperature could be better.
Likely species
Hatch timeline · todayQuiet day
Hatch predictions
Today's headline hatch shown — see all 12 active hatches hour by hour as a supporter.
Start free trial14-day free trial. Cancel anytime.
Sub-surface · on the nymphunder the surface
Hatch predictions
Top nymph shown — see all 2 guilds as a supporter.
Start free trial14-day free trial. Cancel anytime.
Beyond the hatch · worth watchingambient prey(1)
Hatch predictions
Top prey shown — see all 3 as a supporter.
Start free trial14-day free trial. Cancel anytime.
Evidence
Survey-backed · regionalHigh confidence
Backed by regional invertebrate surveys; no sampling on this exact reach yet.
Through the year
0–3 scale · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Grayling seasonSeason
1
2
2
2
2
2
2
1
Freshwater ShrimpHatch
2
3
3
3
3
3
3
3
3
3
3
2
Mayfly (Green Drake)Hatch
2
2
Brown SedgeHatch
2
3
3
3
2
Small SpurwingHatch
2
3
3
3
2
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Ranked for today
Fly box · Grayling
Hook 14–18 · Fly
in season · matches water height
Permits & access
Permit required — see local rules.
- AAPPMA access
- Lower pressure than Arques or Bresle
- Several fly-only parcours.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
Terrain map
Water quality (WFD)
The full read · show the working · for Grayling · confidence 90%
How the 77 is built — score × weight = contribution
Temperature61 × 28%17.1
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time100 × 13%13.0
Pressure80 × 7%5.6
Insect activity69 × 12%8.3
Conditions total= 77
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Arquesproxy
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
Cooler water — back toward the 4–14 °C ideal band — would lift the score and ease welfare.
Directions
Seasons & zones
- Trout 2.º Saturday de March → 3.º Sunday de September
- Grayling 3.º Saturday de May → 31 December
France national rule: grayling opens 3rd Saturday of May in all waters. In 2nd category waters, grayling remains open until 31 December. Departmental regulations may impose earlier closing dates. Always check the relevant département's 2026 arrêté préfectoral.
Related guides
Booking & contacts
Yères
Water temperature for Grayling
Warm — slow15°C est.ideal 4–14°C
0°14°28°
How to fish it · for Grayling
When
Midday window — grayling feed best from late morning into early afternoon.
Where
Work runs and glides — grayling shoal in the bottom third of the water column.
Method
Tight-line nymph the bottom third with weighted patterns.
Kit
10 ft #3 rod, floating line, long leader to 4 lb fluoro for nymphs.
Why this works
Good — time of day is right today, though water temperature could be better.
Likely species
Hatch timeline · todayQuiet day
Hatch predictions
Today's headline hatch shown — see all 12 active hatches hour by hour as a supporter.
Start free trial14-day free trial. Cancel anytime.
Sub-surface · on the nymphunder the surface
Hatch predictions
Top nymph shown — see all 2 guilds as a supporter.
Start free trial14-day free trial. Cancel anytime.
Beyond the hatch · worth watchingambient prey(1)
Hatch predictions
Top prey shown — see all 3 as a supporter.
Start free trial14-day free trial. Cancel anytime.
Evidence
Survey-backed · regionalHigh confidence
Backed by regional invertebrate surveys; no sampling on this exact reach yet.
Through the year
0–3 scale · October highlighted
J
F
M
A
M
J
J
A
S
O
N
D
Trout seasonSeason
1
2
2
2
2
2
1
Grayling seasonSeason
1
2
2
2
2
2
2
1
Freshwater ShrimpHatch
2
3
3
3
3
3
3
3
3
3
3
2
Mayfly (Green Drake)Hatch
2
2
Brown SedgeHatch
2
3
3
3
2
Small SpurwingHatch
2
3
3
3
2
Numbers are intensity 0 (none) to 3 (peak) — a guide, not a guarantee.
Ranked for today
Fly box · Grayling
Hook 14–18 · Fly
in season · matches water height
Permits & access
Permit required — see local rules.
- AAPPMA access
- Lower pressure than Arques or Bresle
- Several fly-only parcours.
What's coming
Plan ahead
5-day outlook
Other water nearby · 5
Gallery · 2
Terrain map
Water quality (WFD)
- Ecology: Good
- Chemical: Unknown
WFD classification · FRHR161
The full read · show the working · for Grayling · confidence 90%
How the 77 is built — score × weight = contribution
Temperature61 × 28%17.1
Flow80 × 22%17.6
Clarity85 × 18%15.3
Feeding Time100 × 13%13.0
Pressure80 × 7%5.6
Insect activity69 × 12%8.3
Conditions total= 77
Can you trust it?
Water temperatureair-to-water estimateestimated
Level / flowproxy via Arquesproxy
Prey activitysurvey-backed invertebrate datasurvey
What would change the calculation
Cooler water — back toward the 4–14 °C ideal band — would lift the score and ease welfare.
Directions
Seasons & zones
- Trout 2.º Saturday de March → 3.º Sunday de September
- Grayling 3.º Saturday de May → 31 December
France national rule: grayling opens 3rd Saturday of May in all waters. In 2nd category waters, grayling remains open until 31 December. Departmental regulations may impose earlier closing dates. Always check the relevant département's 2026 arrêté préfectoral.
Related guides
Booking & contacts