Shannon Lagoon Fisheries Assessment Survey – April 2014
As part of the feasibility review for establishing Shannon Lagoon as a viable fishery, the Service undertook a survey to gain information on the trout and native fish populations of the lagoon. Over a three day period 7-9 April, a combination of box traps, fyke nets and electrofishing were used to capture primarily brown trout.
In general, the catch rate per unit of fishing gear set was very low and likely reflects the low abundance of brown trout within the lagoon.
In total, 42 brown trout were captured; however, just 28 of these were adult fish, the remainder (14) were young of the year fry between 55-82mm length. Of the 28 adult fish captured, the average weight was 942 grams with the average length 433mm. Fifty four percent of fish were nevertheless, 1 kg or over, with the largest fish being 1.32kg. The majority of fish (86%) were in good to excellent condition with only 4 fish being classified as poor. No rainbow trout were evident.
There was only one brown trout captured in the 100-320mm length range suggesting one to two years of minimal recruitment (see figure 1).
A large number of the native spotted galaxias (112) and the threatened fish species the Shannon paragalaxias (40) along with two climbing galaxias were captured while electrofishing the inflow stream.
Figure 1: Percentage of brown trout in each 20mm length range – Shannon Lagoon.