Juvenile Salmon Netting Tests at Cowlitz with Tina Wyllie-Echeverria, July 21, 2007 · 23 July 2007, 21:37 by Julie Loyd
Cowlitz Bay was foggy at 10:45, clearing slightly to a misty drizzle by 16:00. In all, about 40 adults and children participated over the course of the day. Right at the beginning, a slowly moving group of about 50 seals were going east to west outside of the mooring buoys.
This is a narrative. A more organized report on similar material is posted above for July 27.
A baby seal waited silently for its mother on the beach just at the west side of the dock, watching us throughout the day. (It starved to death on the 24th.)
The purpose of the day was to figure out the best way to catch the juvenile salmon we see in the bay and, if we caught any, to look at their stomach contents. A few people have fish handling permits, which are required to touch them. Any boat used to catch fish should have a clearly visible “research” sign on it.
Tina showed us how to do a beach seine. The net is a rectangle 10×80 feet, with floats along the top and weights along the bottom. Someone holds on to one end at waters’ edge while people in a small boat pay out the rest of the net, making an arc in the water. Once the far end of the net has closed the water off against the beach, the people holding the two ends of the net walk towards each other and begin to tug the bottom of the net towards the join, making a bag. We did two seines in different places, both east of the dock.
In the first pull were three sculpins: a large staghorn, a buffalo, and a shortnose.
The second pull at 11:32 was the only one of the day that succeeded at our goal of catching salmon. They were both wild juvenile chinook, one 70 mm and the other 104. These are an endangered species and are hedged around by regulations. You need that fish handling permit, you need to wear gloves when touching them, and you certainly can’t kill them (well, you are allowed a 1% fatality rate, but considering that we only caught two, that doesn’t allow for wiggle room). Since the larger sculpins eat salmon, have two buckets handy to divide salmon from other fish you catch.
There’s a standard data sheet used for all research beach seines north of the Skagit River. There are 10 years of data in our area, but only two years from San Juan County. We said the tide was ebb, the sea vegetation was ulva (sea lettuce – you just pick the dominant type), the substrate was cobble, and the habitat type was “edge” (not a marsh or a tidal channel). Tina used a YSI meter (appx. $1200, as opposed to a refractometer at $200) to test temperature and salinity. She waded out to where the deepest part of the net had been and took two readings apiece at the surface and the bottom. If we’d been in a lagoon, she’d have tested oxygen content as well. Air temp was 14.0º, water temp 11.0, and salinity between 29.2 and 29.9 parts per thousand (ppt).
Tina sprinkled a small amount of anesthetic powder in a tub and put the two fish in. They soon lay on their side, gills panting. She wore gloves and handled them very gently, but even so a few scales were shed. To identify them, we looked for the adipose fin, a little flap of fatty tissue towards the tail from the dorsal fin. Hatcheries clip that one off, and since both fish had them, they were wild. All but two of the juvenile chinook caught in San Juan County have been wild (those two were caught in Griffin Bay). Parr marks, or big splodges of pigment, help identify the species of salmon. These had relatively thick marks that spread evenly above and below the lateral line of the fish, making them chinook. It was difficult to see the parr marks at certain angles of light. The book Field Identification of Coastal Juvenile Salmonids by Pollard, et al. is useful.
Tina snipped a 1mm square bit of tissue from the anal fin for DNA testing. Through genetic testing, you can tell which river it came from. To keep each sample clean, she washed the scissors in ethyl alcohol beforehand, wore gloves, and immediately dropped it in alcohol.
If they had been hatchery fish, the adipose fins would have been clipped. A percentage of hatchery fish have tiny identification wires in their nose. Long Live the Kings on Orcas does that. Some researchers might sacrifice such a fish to get data from its nose wire, but we did not.
Their hypothesis was that fish from each drainage would find a different spot in the County to grow up, but so far all the fish seem to be from one river only. Russel Barsh is working on that report.
Now that we had fish, and wild chinook at that, Tina wanted to look at their stomach contents. She had a hollow plastic tube, probably 1mm diameter connected to a water-filled syringe. Gently holding a salmon, she gently pushed the tube down its throat until she felt a slight resistance. If she’d syringed water into its stomach at this point, it would bloat and possibly die. So she held the fish with its head pointing down into a filter cup and pushed water into the stomach. The contents squeezed out around the tube and were washed into the cup. She put the fish into fresh, non-anesthetized water, and washed the cup contents into alcohol.
Salmonids eat at all levels, from benthic (ocean floor), in the water column, up to surface insects. They are not picky about the insects, eating anything of the right size. They do seem to select among plankton, looking for zauss and tisbe, which are tiny copepods.
Questions were asked and answered. Our waters are a “mixed stock” region, hosting both Canadian and American spawned fish. For that reason, jurisdiction is puzzling.
Salmon undergo changes to adjust from fresh to salt water or back, involving osmotic pressure in their cells. Juvenile coho were found in Cascade Creek in Orcas. Were they always there or did they return? Chum and pinks act differently, they don’t need fresh water and can spawn at the mouth of creeks. They hatch December/January and first show up in Cowlitz in February. Possibly they float here from the Frazer River on an ebb tide.
South Sound chinook grow nearshore April to May, and by August are a little further away from shore. Tina caught 50 of them outside of the moorage line in Cowlitz last August.
Winnie summarized the Orcas hatchery history. She said that Jim Youngren owns land up to the crest of the hill and activated neighboring landowners to manage their hillsides to be salmon-friendly. His goal was to get a salmon run started. Cascade drainages and the Columbia River are snowmelt dependent. In fifteen years, there may not be any significant snowmelt, so it is vitally important that smaller salmon runs in areas with year-round water are started and managed well.
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