Biology--- April 2000
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Surprisingly little known (by non-natives) about the biology of this important fish. Why is it in decline throughout its range? “Ocean conditions” they say knowingly. |
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Strange Creature---from the literature (source here McLean et al.(1999)) Seems to come into freshwater only at age three; goes up a river ‘typically glacial fed” and spawns on sand, then dies. Almost as if a sacrifice for coastal life, to “stock up” on carbohydrates after the winter. (See the cooked eulachon page this site)
On the Skeena the run comes when the river at its lowest and slowest just before the beginning of the Spring Run off and the burst of life that gives to the coastal waters.
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Notes from conversations with Harvey
R.: There are 3 runs that come up the river. The first is the one that
you make the grease from. The second you “smoke” and the third you salt. That’s
because each run has less oil content. That last run comes in late May.
Things so bad this year HR does not expect to see any sign of 3rd on
the river. RH says not all die after spawn. Some do, but most go back down
the river. – They are very finicky -- sensitive to “smells”. The Kemano run
this year saw the eulachon come to the mouth, but then leave. Logging had
left too much bark in the water and they did not like it. They won’t come
back until things clear up. |
Many anadromous fish have become genetically distinct being separated from the main pool of there species when the breed, until recently it was supposed eulachon would follow this pattern. The timing of each river’s run was different. First Nations reported Eulachon from rivers close to each other ran at different times and even produced different tasting grease.
Still, recent research has not found significant differences at DNA level which present something of a puzzle. And a problem too, because if eulachon is ‘really’ all one stock then pointless to try to protect a single river if “conservation units” are seen as the basic unit to be conserved.
The same argument is emerging In the Skeena River coho salmon research, if all the “upper Skeena” are one stock then preserving the Sustut or Morice is not necessary.
Here are some links to this years “catch”
MOF PR Region http://www.for.gov.bc.ca/prupert/Research/Extension_notes/Enote32.pdf
Good quick biology, blames decline on ocean conditions, and says Forest Practices code sufficient to counter any problems. Males much outnumber females; broadcast spawners and carried upriver by the tide; hatch 3-4 weeks and then swept down stream where live in estuary unknown time; estimates 140T shrimp draggers in 97 taken. Suggests some level legal protection might be in order.
FishBase UBC
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Thaleichthys (eulachon) biology life cycle natal streams vulnerable extinction 10 years 3 generations “spends most of its life in the sea, returning to freshwater streams to spawn (Ref. 27547). There is evidence of return to natal streams (Ref. 10276). May migrate up to 160 km upstream. Feeds on plankton and only while at sea (11699, 10276). Excellent food fish and source of oil (15% body wt) |
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McLean, J.E., D.E. Hay, and E.B. Taylor. 1999. Marine population structure in an anadromous fish: life-history influences patterns of mitochondrial DNA variation in the eulachon, Thaleichthys pacificus. Mol. Ecol. 8: S143-S158. Figure right, my coloring their figure Note the Kemano mt DNA is slightly atypical. Authors state DNA does not support genetically based “populations” and even the less restrictive concept of “management units” is not helpful as separated by Alaskan peninsula anyways. Work is Masters thesis. Reprint article left at NWCC Prince Rupert library. |
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DFO Research ---
Trawl surveys— Are shrimp trawls causing the decline? Of some populations?
Best study of the group; -- 15 populations BC and 30-40 globally; Southern populations sharp decline recent years; 3-4 AK and 2 south of BC Columbia R population only decline since 1993. Some "northern BC rivers strong 98 (Skeena?) weak 99. ---3 different ratios discussed to estimate bycatch
Suggest estuary or equivalent “Head of Inlet” may be the unit of conservation / management
11 named: Portland, Skeena, 'head of Douglas', 'head of Garner' etc.
Suggest retained upper waters of impoverished inlets to avoid predation.
http://www.dfo-mpo.gc.ca/csas/csas/DOCREC/1999/pdf/99_179e1.pdf
PSARC document
Kitimat one of the earliest and Fraser one of latest. Most larval captured surface to 15M; but reside freshwater only minutes to hours and small size means not imprint there-therefore reside estuary from weeks to months and imprint there. Thus annual discharge rates could also affect spawners. Central coast several small runs in comparison to Fraser but Nass may be equal in size. "It is not clear if Nass still retains that large of a biomass but a 1983 estimate was 1700 tonnes (catch 239 ton). - the catch between 135 and 100 but some earlier catches much larger
http://www.dfo-mpo.gc.ca/csas/csas/DOCREC/1999/pdf/99_177e.pdf
Web Search—
As Forage Fish
NOAA site forage Fish with Herring
Prominence as low on food chain but Abundance critical for ecosystem and life above from sea birds to mammals to ground fish
"It appears that there is a direct correlation between the availability of forage fish and production of young murrelets..." (Exxon Valdez Oil Spill Restoration Plan Update , Jan. 1999)
http://www.fakr.noaa.gov/trawl/osm/osmerids.htm
In Washington state
the Columbia River “population” has been put on the “species of concern” list but treated differently from more common forage fish like herring.