Fisheries and Introduced organisms

what are the 10 native fish species of Flathead lake

1. bull trout

2. Cutthroat

3. mountain whitefish

4. pygmy whitefish

5. sculpin

6. longnose sucker

7. largescale sucker

8. pikeminnow

9. pea mouth chub

10. redside shiner

what are the 11 non native fish in Flathead lake

1. lake whitefish

2. largemouth bass

3. lake trout

4. pumpkinseed sunfish

5. back bullhead catfish

6. brook trout

7. rainbow trout

8. kokanee

9. yellow perch

10. northern pike

11. brown trout

of the 11 non native fish in Flathead lake, what are the illegal introductions

northern pike and brown trout

what year were Kokanee introduced to Flathead lake

1916

how many kokanee did the spawning run range up to in Flathead lake

100 000 + fish

what did the annual harvest often exceed of kokanee in Flathead lake

100 000

what was Mysis considered to be before 2005, now what is it considered to be

circumpolar, now purely European species

when were Mysis introduced into upper catchments of Flathead valley

1968 to 1975

when was mysis first noticed in Flathead lake

1981

when did shrimp population levels reach 49 / m²

1985 (took four years)

what percent of the kokanee diet did mysis constitute

none

where did kokanee feed and live

feed in the day, lived in the top 30 meters of water column

where did Mysis feed and live

lived below 30 meters during the day and only came out at night

what do BOTH kokanee and Mysis feed on

Planktivorous - they compete for the same resource

what happened to the kokanee in 1980s

began to decline because none were being caught AND very few were spawning

what is the current status of kokanee in Flathead lake

runs are SMALL

why did Mysis suddenly decline

as they outcompeted each other for the same food source

what happened to the bald eagles? grizzly bears?

eagles

• used to be numerous as they fed on the kokanee

• as kokanee disappeared only 1 or 2 are seen in the fall

grizzly

• they became active later in the season to match when the kokanee ran (so their hibernation was later)

why were WT deer feeding on kokanee

for the calcium and antler growth

what was the major tourist draw to Glacier park

eagles and bears

how did tourism change pre 1983 (before kokanee declined) compared to after the decline

before decline": 46 500 tourists

after decline: 100 tourists

what were other contributors (beside Mysis) that led to the decline in kokanee

overfishing

water level fluctuations caused by dam

what was the Kootenay lake experience

introduction of Mysis into the lake system wasn’t very effective (declines were seen mostly by changes in hydrologic flow due to dam)

why was kokanee stocking done in Lake Tahoe

to provide food for the lake trout to divert the predation of cutties

why was Mysis introduced to lake Tahoe

to provide forage for kokanee

what was the overall experience in Lake Tahoe for lake trout and bull trout

lake trout

• young ones could feed on young mysis but as they get bigger mysis no longer a food base

bull trout

• small initial surge as they feed on lake whitefish (which had Mysis in their diet)

• as food sources declined so did the whitefish = bulls lost their food source too

did the Mysis survive in wateron

NO

what is whirling disease

name for symptoms caused by the infection of salmons via Myxobolus Cerebralis

what is the main vector of whirling disease

birds

is whirling disease only found in hatcheries ’

NO - also found in wild

how did whirling disease first enter the USA

via processed fish shipments from Denmark

what is whirling disease now considered

cnidarian w

what are symptoms of whirling disease

• deformities of the spine

• pug headness

• blackening of the tail

how many hosts and forms does the whirling disease parasite have

2 hosts and 2 forms

what is the lifecycle of whirling disease

will fish that eat the tubfex worm become infected with whirling disease

NO

what is the most susceptible species to whirling disease

rainbow trout

how many months does it take for NEW whirling disease spores to in fish

3 to 4 months

how can we monitor the effects of whirling disease

1. sentinel fish

2. tissue testing

3. filtering for tams

how are some methods for the control of whirling disease

• develop a vaccine

• impose strict regulations of fish transport

• raise large whitefish (4 to 5 inches)

• eliminate earthen ponds

• decrease habitat degradation