We had all the chum broodstock necessary to meet our goals – 150,000 adults for 160 million eggs destined for release at Kasnyku (50.5 million), Takatz (50.5 m), SE Cove (35 m), and Deep Inlet (24 m). A set of environmental circumstances has somewhat thwarted our efforts. Before there is any panic, we have 131 million eggs incubating and expect to get more (we took 6 million on Sunday).
Eggtakes began normally in mid July, a little early but not unusual. The low snowfall last winter affected late July freshwater flows at Hidden Falls which we have had to deal with in past years. When the waterfall stops spilling dissolved oxygen plummets particularly in the lagoon where the chum stage just prior to entering the fish ladder. Standard protocol when this occurs is to meter the fish through the weir to a maximum of 10,000 adults, start aeration bubblers, spray water onto the lagoon surface, and redirect some effluent water to the fish ladder. These procedures ameliorate the dissolved oxygen and it has allowed us to manage around the situation in the past. If it were not for needing to meter in the fish we would likely have been able to take 14 million eggs per day as we did last year and get through our egg takes in short order.
However, the result of this, is fewer fish get to the spawning table than would otherwise on a given day. The best fix is rain, which we got after a week, but so much rain that it created flood conditions. Flood conditions can create a different problem. That is, many of the chum can’t swim against the high velocity and they exhaust themselves trying to get past the flooding weir, a several foot drop. The flooding went on for several days but finally subsided. On July 30th we had 110 million eggs in the hatchery and an estimated 50,000 chum in the inner bay and lagoon, more than enough fish to complete the job. The next day the majority of those fish were not to be seen. The estimate fell to 10,000 fish.
Eggtakes numbers dropped off the next several days as expected. Some thought the fish swam away, some thought they might still be there, and some thought our estimates were off, but a dive survey proved that the fish expired and went to the bottom. There were thick piles of dead chum where the currents deposited them within the inner bay behind the barrier net. Mystery solved, but not the problem. We have never experienced low water for a week followed by flooding the next week resulting in the loss of approximately 40,000 brood fish.
Additional fish are coming in and we expect to get another 5 million eggs. We have contacted Port Armstrong and offered to purchase eggs if they have a surplus, but they need another 5 million eggs to meet their goal before they can take eggs for us. Finally, we could take extra eggs at Medvejie if there are surplus. It is too early to know if that is a possibility and is a topic for the next chapter.
The plan to address these circumstances in the future is two redirect some of the coho rearing effluent water via new pipelines and valves to the base of the fish ladder in the lagoon. The effluent water has higher dissolved oxygen but will also be infused with supplemental oxygen as needed. The expectation is the lagoon could handle 15,000 brood fish at times of low flow water conditions with these fixes. The flooding is more difficult to address but another new pipeline slated for installation in 2015 will allow us to waste a large volume of water to the inner bay. This routing of water would circumvent the lagoon and weir, reducing the water volume during floods.
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