Tees fish survey 2018

One of the questions we get asked regularly is how many fish are typically in our waterways.

Seal signs at Tees Barrage Seal signs at Tees Barrage

If you’ve been following our blogs about the fish pass at the Tees Barrage, you’ll know that our fisheries and Tees Barrage teams work closely with the Environment Agency to monitor fish numbers through the pass and in the River Tees generally. In fact, keeping our fish stocks flourishing is one of our key roles.

Fish numbers, and perhaps even more importantly the diversity of fish, are fantastic indicators of a waterway’s health. Not just how clean it is but how many other wildlife species it can support.

Technology does the counting

Having installed the fish pass at the barrage, we are now able to more accurately count and even see the fish that use it. The EA have been out and about for most of July looking at the data. This is just one of the several sonar images of the fish underwater taken from a boat on the river.

Tees Barrage fish count sonar image Tees Barrage fish count sonar image

The EA have shared this short poster with us to explain the sonar imagery.  

But the old-fashioned way works too

The EA were also out in August doing a survey from a boat in the white water canoe course. They carried out a single sweep of a 30m net and caught a large number of fish. They only measured and counted a proportion (roughly a third of the total catch).

The results of this sub sample are: 

There was a wide range of sizes, including good numbers of this year’s fry (mainly roach and dace). So good was the catch that the team commented that they: “couldn’t believe the amount of course fish in the river, it’s a shame the salmon and sea trout counts through the fish pass are very disappointing.”

Lowest count in July for years

The current situation at the barrage is that the very low rainfalls we have experienced this summer mean that river flows down the river are very low and not really high enough to encourage salmon migration upstream. Plus, the high water temperatures on the freshwater side also put the fish off from moving. You can see the monthly count of adult fish for July here (as recorded by the EA fish counter in the fish pass). And yes, the results are low numbers.

Bypassing the fish pass

Of course, we know that fish use up to four other routes to bypass the barrage, most jump the gates. Plus, the team at the barrage have still been able to operate the 'fish rule' whereby gate 1 is lowered at high tide to release water and encourage fish to swim over the gate. However, this route is not routinely monitored to count the fish.

Seals steal the show

The seals are still around and catching what salmon they can. The acoustic deterrent devices (ADD) are now located in the navigation channel up to the lock and we are hoping that this will be more effective in the confined space of the channel compared to previous locations at the mouth of the channel at the junction with the main river. We’ve volunteers monitoring the presence, or not, of seals in this area on a regular basis.

The situation on the Tees is similar to some other east coast rivers. The drought has been taking its toll on our canals and rivers in so many ways.

You can help. You can get involved with the Tees team either monitoring the fish or monitoring the seals. And you can support our fisheries and angling team as they travel around the country making sure the fish in our waterways don’t just stay alive but thrive.

Last date edited: 30 August 2018