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Night on the net pens

A familiar whale, Pelican, feeds near the hatchery dock.

Cruising along the slick evening waters of Chatham Strait, heading north toward my evening dwelling, I watch the clouds move slowly through the mountains. With the low ceiling and the bundled squeeze of 4 layers and a mustang suit, it is easy to feel cozy and safe as we cut smoothly through the southeast coast. Chatham Strait is a bipolar creature. Some days you can look across and feel like you can ice skate to the other shore in 5 minutes and other days you can’t see the other side through thick rain, high winds, and monstrous swell whipping your boat around like loose chain in a washing machine.  As we round the corner into Kasnyku Bay, the site of Hidden Falls Hatchery, and pull up to the net pens, the excitement starts to rise inside me in anticipation of that crisp sound that will break the surface and reveal the hidden creature below.

Hidden Falls Hatchery is a salmon enhancement facility. When Alaska salmon harvests plummeted to record lows in the early 1970s, salmon fisheries enhancement programs were born. By 1974, voters approved a constitutional amendment to establish limited entry to commercial fisheries and the development of aquaculture in the state. This allowed Alaska lawmakers to authorize nonprofit corporations (PNP) to operate salmon hatcheries to rehabilitate the state’s depressed salmon fishery. Additionally, the legislature approved the formation of regional associations comprised of representatives from local communities and authorized to operate hatcheries and conduct other enhancement activities that benefit fisheries resources. In southeast Alaska, there were two regional associations established: The Northern Southeast Regional Aquaculture Association (NSRAA) and the Southeast Regional Aquaculture Association (SSRAA). NSRAA has its headquarters in Sitka and SSRAA is based in Ketchikan. 

Hidden Falls Hatchery net pen at night.

Established in 1978, NSRAA facilities reared chum, sockeye, chinook, and coho salmon. Also in 1978, the state built the Hidden Falls Hatchery and the state operated it until 1988, after which NSRAA took over operations. Hidden Falls Hatchery, located in Kasnyku Bay on Baranof Island on Chatham Strait, rears Chinook, coho, and chum. Historically, Hidden Falls produced a larger chum return for the salmon fishery than any other facility in North America. The chum returns averaged 1.7 million from 2001-2010. Hidden Falls has been considered the most economically important program in the Southeast region. Hatcheries in Alaska have continued to operate alongside commercially viable wild salmon populations. However, During the same time that the hatchery production was increasing during the 1980s, the humpback whale population was starting to recover from the industrial whaling days. The occurrence of humpback whales directly feeding on released fish from hatcheries is a relatively recent phenomenon within the last decade. Since 2008, hatcheries have been reporting these baleen predators directly targeting released fish right off the docks and around net pens of Hidden Falls Hatchery. These whales are bold and intimate with the hatcheries. To address this new challenge, hatcheries have started experimenting with releasing larger fish, trickling fish out at a slower rate, changing the timing, and dragging net pens to different release areas. These strategies have shown a slight reduction in predation by humpback whales, but they can unintentionally increase predation from other predators such as sea birds, larger fish, and harbor seals. 

This is where I come in. My name is Madison Kosma. I am a second year graduate student with the University of Alaska Fairbanks (UAF), College of Fisheries and Ocean Science. My first involvement with hatchery whale predation started in 2014 when I assisted on the project as a research technician. Two years later, I became a UAF masters student and my research focus was on this unique phenomenon. Currently I am in my second field season and am based out of the Alaska Whale Foundation in Warm Springs Bay. My project will help shed more light on this issue by continuing to document this behavior and hopefully getting close to answering what their impact is on these adolescent salmon. A comprehensive understanding of humpback predation on released juvenile salmon will help hatchery managers make knowledgeable decisions about release strategies and assist cooperative management of hatchery operations and release sites by the Alaska Department of Fish and Game and regional aquaculture associations. All in all, with the mission to maintain economically viable fishery yields for salmon fishermen. 

Now I am sure you are wondering, why do I have to sleep on the net pens to observe this predation? Well, it can be a hit or miss when you have your basecamp at a different location than your study subject. To avoid missing any action and to get the best understand of what is going on, I setup camp smack-dab in the middle of the buffet so I am guaranteed a front row seat. Additionally, this year the whales seem to be visiting the hatchery more often at dusk and dawn. Tucked in for the night, it is extremely hard to sleep with the anticipation of every sound being a whale blow. During southeast Alaskan summers, it never gets completely dark, so all night I can see silhouette of mountains, structures, and creatures. Even with the night light, I mostly rely on noises to determine what is going on around me. With my eyes closed, I have my ears opened as wide as possible to hear any evidence of a marine guest swimming below. With the mundane pitter patter of water hitting the top of my tent and the cold damp winds blowing through, it can be easy to drift off to sleep. Right when I am about to drift, there it is! The blow mutes all sounds around me and my instincts kick in. I Jump out of bed, pull on my boots, and grab my camera. Lifting my head up out of my tent, I look out and see it: the mist from its breathe floats in the air as the slick black body sinks beneath the net pens. Beneath me. 

At the hatchery, the whales have little to no notion of fear when it comes to how close they get to docks, pens, boats, or people. Hobo is one of the original whales that has been feeding at the hatchery since the beginning. She swims in with the same comfort as I feel walking to my kitchen to throw together a sandwich for lunch. She cruises into the bay and has her routine, knowing every corner of the coves and all the structures on the surface. Flying through the shallow waters like a Boeing 737, dwarfing the boats tied up at the dock. The white pectoral fins glow in the shallow water as she sores toward the schools of juvenile salmon hiding in the dark. Tonight, I am not visited by Hobo. I am visited by Pelican. He has a much different style of feeding. He is considerable less graceful and has a little more fear in his movements than Hobo. Still, he is up close and personal with the net pens, the juvenile salmon, and me. 

Hidden Falls Hatchery net pens at night

The other sound that makes me jump out of my skin with excitement, is the first sound of bubbles breaking at the surface. Once you hear this, you have only seconds to run over and get as close as you can to the show. I hear the first bubble break the surface, “bloob”. The net pens are made of metal grid walkways fastened on top of blue plastic floats. They make a terribly loud sound if you step with too much force, so once I hear the bubbles I run as fast and as light as I can towards the source of the sound. Using the lights from the dock, I carefully place my steps. Once I am closer, I can start to see the bubbles breaking the surface. Only seconds now. The last few bubbles that break the surface are accompanied by the knobby black and white pectoral fin that slices through the water helping the whale make its final turn in its bubble net.   The pectoral sinks back below the dark waters and then the rostrum of the whale breaks the surface as the whale lunges up collecting as much prey in its lower jaw. Standing there I have a straight shot looking right into the whale’s month. The inside is all pink with the baleen on the upper jaw dripping with salt water. This particular whale, flaps its pectoral fins on both sides, almost like it is a bird taking flight, lifting its mouth high above the water. Just when you start to see the ventral pleats of its bottom jaw rise high above the water, the top jaw slams shut, pushing all the excess what out the baleen, and trapping the prey. What a site to see. Not just see, but be so close that I am literally standing in the bubble net when the whale is feeding. The net pens give you as a spectator, this incredible unique experience. Unlike a boat approach where you are lucky to get close before the show is over and unlike a dock where the whale can’t feed underneath it, the net pens are perfect for viewing this extraordinary event.  I must say, there is no other feeling in the world like standing on top of the water, looking down, and seeing bubbles come up around you, as this marine giant circles below. It is the closes you can possible get without being a salmon in the water. A salmon in its mouth.

View from the hatchery net pens as Pelican leaves the hatchery after feeding through the night

Pelican stayed with me all night. Dancing around the net pens, he performed the same show over and over again. I continued to run around following the sound of bubbles, hoping to get closer and closer each time. He would take breaks and leave the net pens, but would return again in an hour to feed. Other animals visited me that night. River otters swam out to the net pens, hop on, and snuck their way into the nets to feast on delicious baby salmon. Eagles swoop down and snatch up an early morning snack. Also, two herons landed on the pens, resting from their flight. Many visitors came and went, but nothing can compare to a huge giant mouth bursting out of the ocean, so close you can smell its breathe. The sky is bright now as 5am comes closer, I can feel my eyes getting heavy as Pelican leaves the bay. I make my way back to my tent, turn off my camera, take off my boats, lay down on my sleeping bag, and close my eyes. BUT. Never do I close my ears, always waiting to hear that ultimate sound that the show is about to begin…pwooohhfff!



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