Totally tubular!

Zero or hero?

In the world of salmon enhancement there are six words that used to mean the difference between going home happy, and packing a literal ton of gear in and out of the bush for nothing. At the Thornton Creek Enhancement Society , they would often be uttered in hushed tones...

She's not ready, let her go.

After going through the effort of either seining or gill-netting mature salmon out of a remote river system, you are left with a stark reality - the female fish you (hopefully) have collected may or may not be ready to spawn. This status, called ripeness, refers to how far along the eggs within the salmon are and whether they have detached from the membrane, or skein which contains them through development. If the eggs are not loose in the belly cavity of the fish, they may not be ready to be fertilized, and that fish cannot yet be used. In years past this meant that the fish would be carefully released back into the river to either breed naturally or potentially (if you were really lucky) caught once more at a later date and checked again.

And therein lies the rub, because no matter how hard you try or how well you plan - you don't always get lucky.

It is fishing, after all.

The spawning season is a relatively short window, spanning weeks through the Fall and early Winter, during which significant rainfall events can occur, meaning much of the time it simply isn't possible to get where you need to be and do what you need to do.

When you add this connundrum to the grim reality that you are sometimes targeting a group of fish that can be counted on two hands, the odds fall further from your favour.

An old idea gets a birthday.

The concept of holding fish while they ripen is not a new one, and the methods used have ranged from wood and wire cages, to fabric bags. Both fish welfare and accessibility posed problems to using these methods of containment, as variable river flows, bears, or even people could pose a threat to the precious cargo held inside.

A new take was needed to create something secure, safe, and portable that could be easily built out of (mostly) off-the-shelf materials.

The Salmon Tube v2.0 was born.

Using different sized PVC sewer pipe (12" for Chinook, 10" for Chum or Coho), stainless hardware, and some custom aluminum angle fabrication, a fish-friendly option was crafted to turn the odds back in the favour of enhancement workers.

Maximum success per unit of effort.

Utilizing the newly updated holding tubes has meant that every fish caught can be held in their source river securely for days at a time, giving crews time to either wait out high water conditions or simply bide their time while the captive salmon continue their natural process of sexual maturity.

Depending on their size, up to 3 fish can be placed in each tube, separated by sex and flagged with details if needed.

The tubes are weighted with a lead cannon ball, and linked in tandem or "pigtailed" in a row on the river bottom in an area of appropriate depth and flow by a drysuit clad swimmer.

Once the conditions and timing are right, the crew returns to the river and collects the tubes in order to sort the fish at the shore. Females are carefully squeezed to see if they will express any eggs - meaning they are ready to spawn - and males are given the same treatment for their readiness to provide milt.

The fish are usually feisty, having been safely and comfortably housed at the bottom of the river with their heads facing into the constantly refreshing current. Those that are not ripe are returned to tubes once again and the process can repeat as needed.

Handy dandy units.

Aside from in-river use, the holding tubes have also been put to work back at the hatchery, where the ability to isolate and hold individual fish has meant that the process of sorting fish on-site now means far less stress for the salmon and staff.

Whereas fish were once freely swimming around in cap troughs, and needed to be netted prior to checking them, they can now be grouped by sex, status, and time/location caught for easy handling and data collection.

Reversing diminishing returns.

The Thornton Creek Hatchery conducts enhancement activities on a number of remote systems in Barkley Sound, with their base of operations being just outside of Ucluelet.

By using these holding tubes the hatchery has been able to collect and incubate eggs from threatened populations of salmon in an effort to restore and maintain runs.

If you would like to support the group in their efforts to continually improve both their own abilities and the natural world around them, you can do so here: https://www.canadahelps.org/en/dn/70666