A Sad Time for Arthur's Pool

In the interest of full transparency, I would like to share a sad update regarding Arthur's Pool.

Over the past two weeks, we have unfortunately experienced a small number of fish mortalities at Arthur’s Pool here at Caistor Lakes. The first fish loss was discovered on 30th April and, since then, several further carp have sadly died without any immediately obvious cause.

At present, the issue appears to be isolated specifically to carp within Arthur’s Pool only. No other species have been affected, and there have been no similar concerns identified elsewhere on the fishery.

As soon as the mortalities were identified, a number of precautionary and investigative measures were put in place:

• Aeration systems have been running continuously, 24 hours a day

• Our Fishery Management Co. were consulted for specialist guidance

• The Environment Agency was contacted immediately and attended site

• Photographs of the deceased fish were taken as record

Following their visit, the Environment Agency carried out a full series of water quality tests and confirmed there were no immediate environmental concerns. Results recorded on site showed healthy and stable water conditions:

• Oxygen saturation: 103.8%

• Water temperature: 14.5°C

• Ammonia: 0.03

• NH4: 0.90

• PH: 8.10

• Salinity: 0.21

  
  

At this stage, there is no confirmed single cause for the mortalities. However, there are several factors that may have contributed to what is believed to be a stress-related event; this spring has brought particularly unstable weather patterns, with rapid fluctuations in temperature that can place significant stress on carp as they move into spawning season. These changing conditions may have caused repeated “start-stop” spawning behaviour, which is physically demanding on the fish. Other contributing factors could include sudden changes in air pressure or potentially age-related vulnerability, as the fish affected so far have all appeared to be of a very similar size range, approximately 15-20lb.

As a fishery, this situation is deeply upsetting for our team. We care enormously about our stock and the welfare of our lakes, and for us this has always been far more than simply a business and this loss is something we take very seriously. We also understand any fish loss is concerning for our anglers and fishery community, and we want to reassure everyone that the situation is being monitored closely. We will continue working alongside the relevant authorities and fisheries specialists while maintaining enhanced aeration and observation across the lake.

We would like to reassure anglers that Arthur’s Pool continues to hold a healthy number of carp, crucian, bream, pike and perch, and we fully expect visitors to still enjoy a positive fishing experience on the lake.

That being said, once we are confident the situation has fully stabilised, we will also review and adjust stock levels where necessary to help address the loss of these fish and maintain the balance and quality of the fishery. However, this will only be considered once we are satisfied that conditions within the lake have remained stable over a sustained period.

Thank you for taking the time to read this update. We appreciate everyone’s patience, understanding and support while we continue to monitor the situation and gather further information as needed.

Kind regards,

Aimee

General Manager

Arthur's Pool, 2026