Jan 22, 2009: Results from the 2009 Seines by Russel Barsh
This was a talk by Dr. Russel Barsh of the KWIAHT lab on Lopez, bringing together the results from this summer’s beach seines and the subsequent laboratory work done here and on Lopez.
All of the native salmon species in the Salish Sea have declined, particularly from the small rivers in the Puget Sound. For years the focus was on saving the rivers. What happens to salmon when they leave the rivers on their journey to the sea? This is the neritic life history phase. Neritic means shallow seas, which are 300 - 350 feet deep around here.
Advertisement: The KWIAHT lab on Lopez looks at nearshore trophic webs (our study), freshwater ecosystems, water quality (it’s the only lab looking at pollution in the San Juans), terrestrial biodiversity (bats, camas, flying squirrels, Northwestern salamander (Lopez only)), and science education.
Four teams worked on collecting the salmon data: Waldron Citizen Science, Lopez Community Salmon Team, Indian Island Marine Health Observatory, Friday Harbor Marine Health Observatory.
Background: Pilot studies in 2006 - showed that outbound juvenile Chinook from throughout the Salish Sea converge on the San Juan Islands in summer. Orcas, migrating seabirds, herring and salmon all converge here. Historically, those numbers were huge. Why do they come? How long do they stay? What do they eat? How do changing land use practices affect them?
Genetic studies show that we get fish from every major river system in the Salish Sea, mixed together. They arrive in spring at 3 inches long, bait sized. Their ability to survive in the open ocean depends on how fast they can grow before they get there. The larger they get, the fewer fish can eat them and the more they can eat.
Year One (2008): 12 seining days, 145 chinook caught, 4,305 prey items counted, mostly by us.
Year Two (2009): 19 seining days, 680 chinook caught, 13,048 prey items counted
All of the native salmon species in the Salish Sea have declined, particularly from the small rivers in the Puget Sound. For years the focus was on saving the rivers. What happens to salmon when they leave the rivers on their journey to the sea? This is the neritic life history phase. Neritic means shallow seas, which are 300 - 350 feet deep around here.
Advertisement: The KWIAHT lab on Lopez looks at nearshore trophic webs (our study), freshwater ecosystems, water quality (it’s the only lab looking at pollution in the San Juans), terrestrial biodiversity (bats, camas, flying squirrels, Northwestern salamander (Lopez only)), and science education.
Four teams worked on collecting the salmon data: Waldron Citizen Science, Lopez Community Salmon Team, Indian Island Marine Health Observatory, Friday Harbor Marine Health Observatory.
Background: Pilot studies in 2006 - showed that outbound juvenile Chinook from throughout the Salish Sea converge on the San Juan Islands in summer. Orcas, migrating seabirds, herring and salmon all converge here. Historically, those numbers were huge. Why do they come? How long do they stay? What do they eat? How do changing land use practices affect them?
Genetic studies show that we get fish from every major river system in the Salish Sea, mixed together. They arrive in spring at 3 inches long, bait sized. Their ability to survive in the open ocean depends on how fast they can grow before they get there. The larger they get, the fewer fish can eat them and the more they can eat.
Year One (2008): 12 seining days, 145 chinook caught, 4,305 prey items counted, mostly by us.
Year Two (2009): 19 seining days, 680 chinook caught, 13,048 prey items counted
Seines: Federal, tribal, and university researchers do beach seines very close to shore with an 80 or 120’ net, pulling it from shore in a loop. In 2009, when our group changed to a long line, set in 2 - 3 fathoms, we quadrupled our CPUE (catch per unit effort). This technique needs more people, so it’s ideal for a project that uses volunteers. Next summer, we’ll try putting the net a bit further out. The federal government this summer fished in deeper water, 500 yards to mid-channel, and did not catch much. All the studies in South Sound find that the juvenile salmon hang out closer to the beaches, but by the time they’ve swum here, they’re older and like it deeper.
Lavage: 99.4% of our fish survive the lavage process. We use aerated buckets, gentle sedation, a quick procedure to cause it to reflux the last 8 hours of its diet, and then a recovery bucket.
Fins and Guts: Each fish gets two tubes, filled with 70% ethanol. One is for the fin samples, sent to a DNA lab, the other is for the stomach contents, counted by volunteers on Lopez and here.
Gut Contents: This year we found a stingless scorpion, ladybugs, and a dragonfly in the samples!
More typical was illustrated by an image showing Hyperiid amphipods, midges, and wasps, and another of a partly digested sandlance.
In 2008, not many sandlances were found in chinook bellies, but in 2009 we found a lot of them. Few other fish such as smelt or larval fish appeared. Despite the fact that recovery work in the county is focused on smelt, it turns out that smelt don’t hang out where salmon do, in rough, exposed, energetic bays like Cowlitz.
In both years, salmon love larval crabs at all stages from the swimming to the settled larvae. They like amphipods (sand fleas), the mice of the sea. Everything likes to eat amphipods.
Thus, beaches and uplands (wetlands and wet woodlands) were important sources for the juvenile chinook diet in 2009.
Lavage: 99.4% of our fish survive the lavage process. We use aerated buckets, gentle sedation, a quick procedure to cause it to reflux the last 8 hours of its diet, and then a recovery bucket.
Fins and Guts: Each fish gets two tubes, filled with 70% ethanol. One is for the fin samples, sent to a DNA lab, the other is for the stomach contents, counted by volunteers on Lopez and here.
Gut Contents: This year we found a stingless scorpion, ladybugs, and a dragonfly in the samples!
More typical was illustrated by an image showing Hyperiid amphipods, midges, and wasps, and another of a partly digested sandlance.
In 2008, not many sandlances were found in chinook bellies, but in 2009 we found a lot of them. Few other fish such as smelt or larval fish appeared. Despite the fact that recovery work in the county is focused on smelt, it turns out that smelt don’t hang out where salmon do, in rough, exposed, energetic bays like Cowlitz.
In both years, salmon love larval crabs at all stages from the swimming to the settled larvae. They like amphipods (sand fleas), the mice of the sea. Everything likes to eat amphipods.
Thus, beaches and uplands (wetlands and wet woodlands) were important sources for the juvenile chinook diet in 2009.
Graphs: You can evaluate prey by number or by weight. Based on numbers, both Lopez and Waldron chinook mostly ate crustaceans, followed by terrestrial insects (more insects on Waldron than on Lopez). On both islands, the bays where 90% of the fish were caught looked similar, with big wetlands behind the beach and prevailing winds blowing out to the water.
On Waldron in June 2009, about 80% of the diet biomass was fish, in July and August, 75%, and in September, 15%. One fish is equivalent to about 100 insects. Late arriving fish relied predominantly on crustaceans. Sandlance eggs are in the water now, and they’ll hatch out in a couple months. They’ll keep growing, and by September will be too big to conveniently catch. Insects, however, are abundant in September.
2009 Crustaceans: 53% crab larvae (congregate close to shore), 23% Hyperiid amphipods (pelagic swimmers, close to the surface), 17% gammarid amphipods (live in sand and gravel in shallow water), 4% calanoids, 1% euphausids. 70% of their diet is of things within view of our homes and beaches.
2009 Terrestrials: 42% midges, 11% other flies; 8% of them larvae (unexplained how they got there!). As a group, 11% bark lice 13% ants, 9% wasps; they swarm in late summer. 2% lacewings, 2% termites, 7% bugs, 1% beetles, 1% spiders. 27 families of insects have been found in our salmon!
We assumed the hatchery fish would be bigger than wild fish, but no. They eat more insects than crustaceans; it’s the lowest energy option.
Does piscivory increase as the fish grow larger? Yes. Often, a chinook will either have one, two, or three fish in its stomach, or crustaceans and insects, but not both. The bigger a chinook is, the more likely it will have eaten at least one fish.
Sand lance are tubular, like linguini. Herring are fatter. We should be measuring width of fish, not their length when doing trophic studies. That’s why sculpins have big heads, flatfish are wide and nobody eats them.
On Waldron in June 2009, about 80% of the diet biomass was fish, in July and August, 75%, and in September, 15%. One fish is equivalent to about 100 insects. Late arriving fish relied predominantly on crustaceans. Sandlance eggs are in the water now, and they’ll hatch out in a couple months. They’ll keep growing, and by September will be too big to conveniently catch. Insects, however, are abundant in September.
2009 Crustaceans: 53% crab larvae (congregate close to shore), 23% Hyperiid amphipods (pelagic swimmers, close to the surface), 17% gammarid amphipods (live in sand and gravel in shallow water), 4% calanoids, 1% euphausids. 70% of their diet is of things within view of our homes and beaches.
2009 Terrestrials: 42% midges, 11% other flies; 8% of them larvae (unexplained how they got there!). As a group, 11% bark lice 13% ants, 9% wasps; they swarm in late summer. 2% lacewings, 2% termites, 7% bugs, 1% beetles, 1% spiders. 27 families of insects have been found in our salmon!
We assumed the hatchery fish would be bigger than wild fish, but no. They eat more insects than crustaceans; it’s the lowest energy option.
Does piscivory increase as the fish grow larger? Yes. Often, a chinook will either have one, two, or three fish in its stomach, or crustaceans and insects, but not both. The bigger a chinook is, the more likely it will have eaten at least one fish.
Sand lance are tubular, like linguini. Herring are fatter. We should be measuring width of fish, not their length when doing trophic studies. That’s why sculpins have big heads, flatfish are wide and nobody eats them.
How much do individual Chinook vary in prey selection? A lot. On 9/11/09 in Cowlitz, of 24 fish: 1 ate a fish, 4 ate crabs, 2 gammarids, 3 hyperiids, 3 flies, 3 ants, 2 termites, 3 bark lice. Converted to biomass, the successful diets were fish, crabs, gammarids, hyperiids, flies, ants, and termites. About 70% of the fish ate “enough.” Hypothesis: A diversity of prey is necessary to assure that most juvenile salmon get through the day with food in their stomach. How much do these dietary patterns vary annually? What factors determine the availability of sandlance or crab larvae?
There was a big difference in diet from year to year. More fish ate crustaceans, as compared to insects, in 2009 than 2008. Probably this doesn’t have to do with the change in our fishing technique, since probably the fish hunt in a larger area.
How do insects compare to crustaceans as food? To find out, you’d have to burn them in a bomb calorimeter, which hasn’t been done yet.
How long do individual juvenile chinook spend in the islands? Do they feed on the run or do the islands represent a distinct life history stage? In 2009 we cut the anal fin in a distinctive way. We fished every two weeks, so if we recaptured one with a cut anal fin, it had been in the islands at least two weeks. Recapture rates peaked at 15% in August on Lopez, but a lower % in Cowlitz. Another clue is whether the mix of fish from different rivers changes over the summer, if so, we can deduce that they are very transient; if not, we don’t know.
Glen: What about the blackmouths (resident chinook)?
Madrona: Last year we found that some chinook in the juvenile population just kept getting bigger. Maybe they are a potential refugium for wild salmon, and we shouldn’t be fishing them. That is, they might be a failsafe population in case something happens in the ocean.
Glen: I caught a 22 inch blackmouth in August of 2009, at the same time that we were doing beach seines and catching smaller salmon.
Russel: It pays for a fish to have a diversified portfolio.
When other fish are in the same feeding areas as chinook, do they partition? Coho eat crustaceans, not too many insects or fish. Greenlings eat caprellid amphipods (skeleton shrimp), which hook their claws into algae on the sea floor. Chinook eat insects.
Students collected over 6,000 insects in pan traps, deadfall traps, and nets in wetlands and along beaches in 2009. Farmed seasonal wetlands seemed to produce the largest contribution to nearshore insect resources for fish.
Thanks to all the citizen volunteers, who did the bulk of the work.
There was a big difference in diet from year to year. More fish ate crustaceans, as compared to insects, in 2009 than 2008. Probably this doesn’t have to do with the change in our fishing technique, since probably the fish hunt in a larger area.
How do insects compare to crustaceans as food? To find out, you’d have to burn them in a bomb calorimeter, which hasn’t been done yet.
How long do individual juvenile chinook spend in the islands? Do they feed on the run or do the islands represent a distinct life history stage? In 2009 we cut the anal fin in a distinctive way. We fished every two weeks, so if we recaptured one with a cut anal fin, it had been in the islands at least two weeks. Recapture rates peaked at 15% in August on Lopez, but a lower % in Cowlitz. Another clue is whether the mix of fish from different rivers changes over the summer, if so, we can deduce that they are very transient; if not, we don’t know.
Glen: What about the blackmouths (resident chinook)?
Madrona: Last year we found that some chinook in the juvenile population just kept getting bigger. Maybe they are a potential refugium for wild salmon, and we shouldn’t be fishing them. That is, they might be a failsafe population in case something happens in the ocean.
Glen: I caught a 22 inch blackmouth in August of 2009, at the same time that we were doing beach seines and catching smaller salmon.
Russel: It pays for a fish to have a diversified portfolio.
When other fish are in the same feeding areas as chinook, do they partition? Coho eat crustaceans, not too many insects or fish. Greenlings eat caprellid amphipods (skeleton shrimp), which hook their claws into algae on the sea floor. Chinook eat insects.
Students collected over 6,000 insects in pan traps, deadfall traps, and nets in wetlands and along beaches in 2009. Farmed seasonal wetlands seemed to produce the largest contribution to nearshore insect resources for fish.
Thanks to all the citizen volunteers, who did the bulk of the work.