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Penstock Lagoon - Brown Trout Population Assessment May 2018

Published on May 17, 2018
IFS Staff member, Storm Eastley with a large yet average size Penstock Lagoon brown trout from the  2018 Fishery Performance Assessment.
IFS Staff member, Storm Eastley with an average size Penstock Lagoon brown trout from the 2018 Fishery Performance Assessment.

With the brown trout season closed, we took the opportunity to assess the fishery at Penstock Lagoon. We wanted to see the number, and the condition, of the fish remaining after the 2017-18 season. The results were very positive.

During the first week of May, we undertook a survey using box traps.  Over two nights, we captured 446 brown trout and 10 rainbow trout.

An interesting outcome is the number of fish identified from 2014 and 2016 adult brown trout transfers.

The 2014 brown trout were marked with an adipose fin clip. These fish represented 12% of the catch. They had increased in weight by an average of 148% to 1.27 kg.

The 2016 brown trout were marked with a distinctive punch in the adipose fin. These fish represented 16% of the catch. They had increased in weight by an average of 32% to 1.31 kg.

Unmarked brown trout weighed an average of 1.18 kg.  It is likely these are brown trout transferred last year. These fish came from multiple trap sites and were a wide range of sizes.

The average weight for the all brown trout caught was 1.25 kg with 45% weighing between 1.25 – 1.75 kg.  The heaviest fish weighed in at 2.3 kg.

The average length of the brown trout was 477mm.  There were some smaller fish, around 290-310 mm length.  These are probably last year’s transfers.

The condition of the fish was good to excellent. We caught very few fish of poor condition.

These are preliminary results; we will post a full technical report on our website in a few months.


Length and weight for adipose marked brown trout from 2014 & 2016 and unmarked fish (most) from 2017 transfers.


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