HomeMy WebLinkAboutAPA1832a1Jor\{ Plan I~o,. D Job !i:o. I Sr;~~~i~ H~bits cf Gra1li~g in_Interior
Alask~. By .:<rar:k J. Hojcik
Prior to 1954, most of t~e data on spa~-.rning ha'cits of grayling were
obtained from stream fish. Therefore, tte 1954 season ;,.-as spent gathering
~pa>-'Y'ling dc_ta on lake grayling. The following data ·,.rere obtained:
1. Dates the streams used for spawning started to flow.
2. Dates the fish entered the streams.
3. Ter;,per·ature and other physical conditions of the st:::-eaw at the
time fish entered.
4. Length of time fish remained in the stream.
5. Dates of spatming.
6. Sex and age composition of spawners.
7. Spa1ming sites.
8. Ds. ta on 1<het~1er all grayling spaw"!l in streams, or whether some
spa:'<m in the lake.
9. Number of eggs per female, and quantity of milt per male.
10. P0rcant fertility.
11. Dates of hatohing.
The major portion of this study "..r&S conducted at one of the inlets of
F:2-eldi;;.g lake. Grayling were observed moving upstream through channels in
the ice as soon s.s the strea;:n started flowing; about Hay 15, 1954. \~'hen
\i3-t.er conci:i..ticns -~rere suitable (Eay 24), an upstream trap w-as set. It ~-.~s
kept in operation for 12 days, in which time, 87 grayling were taken.
Pei·tinent data were collected from these fish, and then they were tagged
and released.
The migrants continued upstreaw and distributed themselves through-
out the stream. On JTI-~e 1 1 the males became active and established
territories. Fighting was corr.mon although not vehement.
Spa1..'11ing was
possibly 4r days.
ing and reached a
first observed on June 3, and continued for 3, and
The water terr;:oerature r,-as 380 F. at the start of spa,m-
maximum of 46o·F. at the end of spawning.
Spa-..ming occurred primarily in slow, shallow t.acb:aters, and not in
riffles as had been supposed. Resting females lay in the riffles above
the spa~'11ing area, but moved do~'TI when ready for egg deposition. }ales
rer::ained in or very near the spaw-ning area for the entire spawning period.
Spaw~ing observations agrsed closely with those recorded for grayling in
Nontana, Canada, and Europe. Houever, preferred spawning sites in Interior
hlaska apnear to differ from the sites used elsewhere.
As soon as the fish had shed their sex nroducts, they drifted down-
stream to the lake. The first downstream movement ~~s observed on June 4,
and continued through June 11. As soon as the do~~stream movement w~S
observed, the ~pstreaill trap was reversed. The do>mstream trap was kept in
operati0n for 8 days, in which time, 297 grayling were examined and tagged.
-10 -
Two catches or eggs we:-e collected and fert.ilizecL These ·,.;ere set
into a trough fed by ~~ter from the inlet. After 2 days, 1 batch of eggs
vas given to the Alaska De-partnent of Fisheries, and one batch ....as ke~t
at Fielding lake. Thus, b.JJ.tching data at t\./'o different "-'S.ter temper':itures
were obtained. The eggs kept at Fielding Lake eyed in 14 days and hatched
in 18 days, at an average ;rater te!?i.pera ture of 46° F. The eggs hatched by"
the Alaska Department of Fisheries hatched in 8 days at an average w~ter
temperature of 60° F.
The spaw~ing habits study will be continued next spring and all data
on hand will be presented upon completion of the project.
-11 -