A Nevada marina has 100,000 dead fish to deal with. Sparks Marina is just a six-minute drive from Reno and is hugely popular with local people who swim, fish, and paddle in its waters. Sadly, over the last month over 100,000 of the fish, in what was the largest urban fishery in Nevada, has died. The cause of the death was initially a great mystery and disturbed local residents.
The marina is usually full of trout, bass and catfish, having been converted from a gravel pit fifteen years ago. When officials started looking into the mystery, people were wondering if a chemical spill had killed all the fish, and whether they needed to stop using the park due to potential threats to human health. It was already known that there had been a large fuel spill into the pit 30 years earlier and questions were raised as to whether this was a related incident. Especially as local residents also remember the site being used as a general dump as well.
However, after an investigation, state wildlife and environmental officials are now convinced they know what happened, as it has been seen before. The most likely cause is now believed to be a significant drop in the oxygen content in the marina’s water. This news lead to many inquires as to whether it was safe for local residents to allow their dogs into the water, but they were assured it was safe as this was a rare event affecting only the fish.
The underlying mechanism to the issue, is that algae, that hungrily eat up oxygen, sit at the bottom of the marina. When there is a prolonged cold snap, the warmer water at the top of the body of water cools and sinks to the bottom. The oxygen in the previously well aerated upper layer gets used up by the algae, and there is none left over for the fish. The consequence in this case was a Nevada marina with 100,00 dead fish.
Experts from local universities also back up the explanation and state that similar events have been seen all over the world. Reno enjoyed a long hot summer and this may well have significantly increase the amount of algae in the marina, and when the turning over of the water occurred through the cold spell, each new batch of surface water had its oxygen content used up by the algae.
The kill off happened in several steps over a period of a month, and although experts hoped it would be a limited event, it sadly grew and appears to have killed all the fish in the lake.
The marina is annually stocked with around 30,000 fish, but plans for this year may have to put on hold unless oxygen levels return to normal. The current levels are around two parts-per-million, where a minimum of five is need for fish to survive, and seven to nine for them to thrive in the water there.
The usual restocking with 26,000 trout and 4,000 catfish will have to wait until officials have verified it is safe to return the fish to the water.
The marina is usually home to some of the largest fishing events in Nevada, but they have never got close to killing 100k of fish before.
By Andrew Willig