I have just had a rather interesting, but exhausting three days up a creek (yes, with a paddle) counting salmon fry and smolts.
One of the salmon bearing creeks in the Inlet has had a 'Rotary Screw Trap' put in to catch fry and smolts so that they can be counted, weighed and measured. This trap is rather large and had to be lowered in with a helicopter. This was done in early April and has been checked every few weeks or so since. On this particular trip I was asked to go along and help with the data collection.
First you have to get to the shore and then walk a trail of about 1 Km. The walk takes between 40 mins and 1 Hr depending on conditions! The big boat was anchored in the bay then we paddled ashore with a rubber dingy.
The trap is a 'U' shaped construction with a large cone surrounding a screw. The cone is lowered in the water as in the picture above and the water flow makes it turn. The fish swim in are funneled down the screw and into a holding tank.
All the fry, infact any fish caught, have to be dipped out of the holding tank. Fry are put in one bucket, smolts in another and notes are taken of any other species that may be present.
Fry are this years hatching so are about 2.5cm long. The smolts are about a year and heading out to the ocean. These are about 6 to 8 cm long. The fry we counted back into the river and took a sampling of about 30 smolts which were weighed, measured and a scale smear taken for DNA.
To handle them we put a small amount of anesthetic in a bucket and placed them in a few at a time. They soon become dozy so can be handled with out any harm.
Not a very flattering picture, but here I am counting fry and putting them back in!
A classic Coho smolt on the measuring board.
The white bucket is fry and the blue one misc fish. The larger fish in here is a rainbow trout. We also caught scuplin and eels.
After catching and recording etc all the fish were released back and the trap was winched up so the cone was out of the water. This allows the water flow around but no fish can get trapped. In the coming months a helicopter will be called in to take the trap out where it can be used elsewhere.
A very interesting project and important to gather data about fish returns, health and habitat in the creek.
The trap is a 'U' shaped construction with a large cone surrounding a screw. The cone is lowered in the water as in the picture above and the water flow makes it turn. The fish swim in are funneled down the screw and into a holding tank.
All the fry, infact any fish caught, have to be dipped out of the holding tank. Fry are put in one bucket, smolts in another and notes are taken of any other species that may be present.
Fry are this years hatching so are about 2.5cm long. The smolts are about a year and heading out to the ocean. These are about 6 to 8 cm long. The fry we counted back into the river and took a sampling of about 30 smolts which were weighed, measured and a scale smear taken for DNA.
To handle them we put a small amount of anesthetic in a bucket and placed them in a few at a time. They soon become dozy so can be handled with out any harm.
Not a very flattering picture, but here I am counting fry and putting them back in!
A classic Coho smolt on the measuring board.
The white bucket is fry and the blue one misc fish. The larger fish in here is a rainbow trout. We also caught scuplin and eels.
After catching and recording etc all the fish were released back and the trap was winched up so the cone was out of the water. This allows the water flow around but no fish can get trapped. In the coming months a helicopter will be called in to take the trap out where it can be used elsewhere.
A very interesting project and important to gather data about fish returns, health and habitat in the creek.
