Recognition

Marking of Salmon

What should fishermen look out for particularly in connection with any salmon they catch?

Biologists who work with salmon often mark the fish that pass through their hands in any of the ways depicted below. Capture of a marked salmon should be reported at once to the appropriate fishery authority. Frequently the address is on the tag or mark. Usually the information required is: date, place and method of capture; length, weight and sex of fish and a sample of scales taken from between the dorsal and anal fins at above the lateral line.

Notes

Tagging should be carried out only by trained and authorised personnel.
Fins that have been clipped do, with the exception of the adipose, regenerate.
The adipose fin should not be removed, as clipping is internationally recognised as an indication that the fish has been micro-tagged.
If adipose clipped fish are killed, the head (where the micro-tag is located) should if possible be sent to the nearest fisheries laboratory.

Identification of Atlantic Salmon

How do you tell the difference between Salmon and Sea Trout?

	Salmon	Sea Trout
General appearance	Slender and streamlined	More round and thickset
Head	Pointed	More Round
Position of the Eye	Maxilla (bony plate usually alongside mouth) does not extend beyond rear rear of eye	Maxilla extends beyond eye
Colour	Relatively few spots	Often heavily spotted
Scale count (number from adipose fin to lateral line)	10-13	13-16
Fork of tail	Usually forked	Usually square or convex
Wrist of tail	Slender	Broader
Handling	Easy to pick up by tail	Tail slips through hand

Sea Trout

Salmon

What is the difference between a salmon parr, salmon smolt and a young trout?

Salmon Parr

Salmon Smolt

Trout

Salmon Parr

Body
More slightly built and torpedo shaped, very slender about the tail.

Tail
Distinctly forked and with more pointed lobes.

Head
Forepart shorter, gill-covers comparatively long.

Eyes
Comparatively larger and set more forward in head. A perpendicular line drawn from the back of eye will not touch the maxillary bone.

Mouth
Comparatively small, measured to the back of the maxillary bone Nearly twice the diameter of the eye.

Pectoral or Breast Fin
Longer, more slender and pointed, when laid back will generally reach to the front of the dorsal (back) fin.

Adipose Fin
No red colour. Finger Marks. 8 to 12, smoky blue in colour, even in width, well defined and regularly placed along the sides.

Spots
1 to 4 black spots on the gill-covers. No spots below the median line and not so many above. Usually one red spot between each finger- mark and few, if any, elsewhere.

Salmon Smolts

When the salmon parr begin to migrate to the sea, usually in March, April and May, they gradually become more elongated and the fins darken. A layer of guanine crystals is laid down in the skin. rendering the body more silvery in colour and obscuring the spots and finger-marks, except on the gill-covers. They then become Smolts.

Trout

Body
Thicker, clumsier looking, and especially so about the tail.

Tail
Comparatively shorter and when spread out is nearly square and the points more rounded.

Head
Forepart longer and head deeper and less pointed.

Eyes
Smaller in proportion to size of head and set further back. A perpendicular line drawn from the back of the eye will either pass through or touch the maxillary bone.

Mouth
Comparatively large, measured to the back of the maxillary bone, 2.5 to 3 times the diameter of the eye.

Pectoral or Breast Fin
Shorter and blunter, when laid back will not reach so far.

Adipose Fin
Generally coloured with orange or red.

Finger Marks
Not so numerous, more irregular in size, less defined and irregularly placed along the sides and lower part of the back.

Spots
Usually more than four brownish black spots on the gill-covers. Numerous spots above and below the median line. Red spots irregularly placed on various parts of the back and sides.

How can salmon be recognised at the different stages of their life in fresh water?

Fresh Run Salmon

Kelt

Cock

Hen

Cock in Breeding Dress

Hen in Breeding Dress

Fresh-Run Salmon

Recognised by the pristine condition and bright silver flanks. Fish straight from salt water have loose, easily detached scales and many carry sea lice which drop off within a few days. Hen salmon (illustrated) have a tiny kype on the lower jaw but unlike cocks they retain normal head proportions while in the river.

Kelt

Kelts are salmon which have spawned. Usually identified by the thin shape, distended vent and presence of "gill maggots" on the red gill filaments, they are often encountered by anglers in spring when they regain a silvery appearance and can be mistaken for fresh run Springers. Kelts must be returned unharmed to the water.

Maturing Cock and Hen

Cock: The combination of "tartan" colours is typical although shades vary - the fully developed kype, used in fighting rivals, and the enlarged adipose fin, are the most consistent indicators of maturity.

Hen: These are usually less coloured than cocks of similar age and they never have enlarged jaws. This one will have spent a few weeks in river or estuary - note the coloured head and lack of true silver flanks.

Cock and Hen In Breeding Dress

Cock: The combination of 'tartan' colours is typical although shades vary - the fully developed kype, used in fighting rivals is the most consistent indicator of maturity.

Hen: This is a summer fish - springers are often darker by spawning time while late entrants may still be silver flanked. Fully mature hens have soft, swollen bellies and spawning is imminent if they also have protruding vents.

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