Abstracts of Fisheries Management Reports, Technical Circulars
and Project Reports of the Fisheries Branch

Daiva O. Zaldokas & Debra L. Aird

B.C. Fisheries Branch, 2204 Main Mall, U.B.C.,
Vancouver, B.C. V6T 1Z4

Fisheries Technical Circular No. 91


Tredger, C.D., R.P. Griffith, and J.C. Wightman.  1989. Detoxification 
and decontamination of waters following chemical rehabilitation with 
Noxfish.  Prov. B.C. Fish. Tech. 
Circ. No. 84:8p.

Water samples were collected from three lakes which were chemically 
rehabilitated in 1986 by the Province of British Columbia, Ministry of 
Environment, Recreational Fisheries Branch. Samples were analyzed for 
rotenone and the Noxfish diluent, to determine both persistence and rate 
of detoxification.  Results indicated that both rotenone and the Noxfish 
diluent were essentially non detectable in water samples taken 7 months 
after fall treatments.  The rates at which rotenone became non detectable 
ranged from 17 to at least 77 days.  The Noxfish diluent reappeared after 
some period of absence in 2 lakes, including detection the following 
spring.  It was recommended that routine water sampling occur where 
waters are used for domestic purposes, and that monitoring programs 
similar to this be continued and expanded to cover other piscicide 
formulations as used.  Further programs to determine inert ingredient 
dissipation rates, pathways within lake systems for uptake and release of 
inert ingredients, and toxicity of inert ingredients to non target organisms 
are also required.

Billings, S.J.  1989.  Steelhead harvest analysis, 1987-88.  Prov. B.C. Fish. 
Tech. Circ. No. 85:45p.

Since 1966-67, at the end of the angling licence year, a questionnaire has 
been sent to a sample of anglers who fished for steelhead in British 
Columbia.  Information was requested on their fishing activity and catch 
success and incorporated into an annual summary of steelhead sport 
catch.  Over this time there have been considerable changes in licence 
sales, the number of days spent fishing, catch and release of steelhead, and 
freshwater angling regulations in B.C.  In the 1987-88 season, 31,263 
steelhead angling licences were sold, 11% of which were to nonresidents 
of B.C.  Questionnaires were sent to 56% of licensees and a response was 
received from 55% of those contacted.  Of the respondents, 74% reported 
going steelhead fishing and 60% of these `active' anglers successfully 
landed a fish.

The provincial steelhead catch has increased significantly since 1982.  In 
the 1987-88 season, steelhead anglers fished for 258,101 days in the 
province catching 153,489 fish.  Wild steelhead made up the largest 
component of the catch at 124,348 fish; hatchery catch numbered 29,141 
fish.  Catch per angler day was 0.62.  Provincial catch and effort were 
down from previous year's (1986-87) record highs of 188,417 fish and 
279,505 days.

The increasing trend in steelhead catch in recent years is a combined result 
of increased stock abundance, sizeable returns of hatchery fish to some 
rivers, and repeated captures of released fish.  The Chilliwack/Vedder 
River was, once again, the most heavily fished stream in the province with 
54,171 angler days. This river supported more than half of all the steelhead 
fishing activity in the Lower Mainland.

Reduced possession quotas as well as steelhead release regulations have 
resulted in a decreased proportion of the steelhead catch being kept.  The 
ratio of fish kept has dropped from 63% in 1970-71 to under 13% in the last 
four years.  Of the active anglers, 32% kept between one and five steelhead 
and only 2% kept more than five steelhead.

The Chilliwack/Vedder River reported the most fish caught (23,795) 
followed by Stamp/Somass/Sproat (11,401), Dean (9,505), Cowichan 
(9,151), Bulkley (7,717), and Skeena (7,707) rivers.

Overall, Vancouver Island reported the highest number of steelhead 
caught followed by the Skeena Mainland and Lower Mainland areas.  
Hatchery fish, in 1987-88, comprised 19% of the total provincial catch 
compared to 27% in the previous two years.  The release ratio for hatchery 
fish averaged 70% compared to 94% for wild fish.

Sawada, J.O., and B. Warner.  1989.  Abstracts of fisheries management 
reports, technical circulars, and project reports of the Recreational 
Fisheries Branch, British Columbia Ministry of Environment 1985-88.  
Prov. B.C. Fish. Tech. Circ. No. 86:55p.

This publication is a compilation of 9 Fisheries Management Reports,  18 
Fisheries Technical Circulars and 96 Fisheries Project Reports of the 
Fisheries Branch of the British Columbia Ministry of Environment.  Only 
reports dated 1985 through 1988 were included. Where abstracts were 
unavailable summaries, introductions or titles were used.  The 
compilation was assembled from the files of the Research and 
Development Section of the Fisheries Branch, and may be incomplete.  To 
aid in future publications of this kind, please ensure that a standard 
abstract is included in all reports.

Parkinson, E.A.  1989.  Errors in ageing hatchery rainbow trout from 
small lakes in southern British Columbia.  Prov. B.C. Fish. Tech. Circ. 
No. 87:7p.

The ability of readers to correctly age rainbow trout was tested using 
scales from hatchery trout marked and released as spring yearlings.  After 
an initial learning phase, accuracy averaged 78% (range 73-85%).  Neither 
the differences in accuracy among readers nor a tendency to underage was 
significant.  Readers tended to make the same errors on individual scales, 
but most errors could be detected by discrepancies among pairs of 
readers. Errors in ageing had little effect on estimates of age structure or 
length at age 2+ for this data set in which readers discussed the true age of 
each scale before proceeding to the next.  Estimated age structure was 16% 
1+, 57% 2+ and 27% 3+ and older, whereas the true age structure was 18% 
1+, 50% 2+ and 32% 3+ and older. Estimated and true mean lengths at age 
2+ were 304 and 301 mm, respectively.  The small size of these 
discrepancies may be due to prior expectations and the continual feedback 
on true values for this data set.

Slaney, P.A., B.R. Ward, and L. Berg.  1990.  A preliminary assessment of 
the effect of external abrasion on the smolt-to-adult survival of net-pen 
cultured steelhead trout.  Prov. B.C. Fish. Tech. Circ. No.88:11p.

The effect of external abrasion of smolts on the return rate of maiden adult 
steelhead (Oncorhynchus mykiss) was assessed in a preliminary 
experiment at the Keogh River in south coastal British Columbia.  
Abrasion was defined by the incidence of scale loss, fin abrasion and 
opercular abrasion.  Smolts with "low abrasion" (7,300) and "moderate 
abrasion" (10,300) were marked and released at similar sizes in the lower 
Keogh River during early May, 1984. Based on population estimates of 
returning adults in 1986 and 1987, the survivals of the low and moderate 
abrasion groups were not significantly different:  8.7% and 7.2%, 
respectively.  Both groups returned at similar mean lengths after 2- and 3-
ocean years.  In addition, recoveries of adults as upstream migrants and 
downstream kelts combined were examined for differences between the 
two abrasion groups.  Recovery rates from the low and moderate abrasion 
groups were similar:  4.0 and 4.3%, respectively.  Corresponding 
recoveries of age 2-ocean steelhead were 2.1 and 2.3%, and for 3-ocean 
fish, 1.9 and 2.0%.  The established level of disparity of smolt abrasion was 
apparently insufficient to cause differential returns of adult steelhead.

Ward, B.R., J.A. Burrows, and D.L. Quamme.  1990.  Adult steelhead 
population size and salmonid migrants of the Keogh River during the 
spring, 1990.  Prov. B.C. Fish. Tech. Circ. No. 89:29p.

Data obtained in 1990 from a fish counting fence installed on the Keogh 
River, a coastal stream located on northeastern Vancouver Island near Port 
Hardy, B.C., added to more than a decade of information collected on wild 
steelhead trout (Oncorhynchus mykiss).  The total number of wild adults 
in 1990 was estimated to be 1,374; the sex ratio of which was 1:1.1, female 
to male.  Mean lengths and weights were obtained for wild spawners 
(males 795.4 mm, 5.8 kg; females 764.9 mm, 4.9 kg), and mean lengths 
were obtained for wild kelts (males 764.1 mm, females 758.6 mm).  Wild 
fish were estimated to comprise 72% and hatchery fish 28% of the total 
steelhead run on the Keogh River.  The migration of wild adult steelhead 
was biased to the late-run component, which was relatively abundant, yet 
preliminary estimates of oceanic survival were low for smolts which 
contributed to these returns. Preliminary returns of pen-reared smolts 
released early in May 1988 were compared to returns of fish which were 
released at the peak of wild steelhead smolts.  After two years at sea, the 
later release returned at a rate twice that of the early release.

All smolts were captured.  Total captures of wild fish were low compared 
to averages in past years:  steelhead smolts, 3,133 fish (mean length 166 
mm, mean weight 40.8 g); steelhead parr, 757 (103 mm, 11.6 g); coho 
smolts, 57238 (103 mm, 11.4 g); cutthroat trout, 205 (156 mm, 38.1 g); Dolly 
Varden adults, 721 (259 mm, 126.6 g); Dolly Varden smolts, 3,200 (145 mm, 
29.7 g); Dolly Varden parr, 50 (110 mm, 11.1 g); and cottids, 1,388 (125 mm, 
30.7 g). Peak migrations were May 7 (505 fish) and June 2 (362) for 
steelhead smolts; May 7 (76), May 8 (75) and June 12 (60) for steelhead 
parr; and May 7 (6,305) for coho smolts.  From May 16 to June 13, a total of 
1,423 steelhead smolts (45.4% of those captured) were manually tagged in 
the adipose fin with sequentially coded wire tags to examine the 
relationships of smolts' size, sex, migration time, and age and their 
subsequent survival and age-at-return.  From May 1-31 a total of 22,715 
coho smolts (39.7%) were coded-wire tagged, with tag numbers stratified 
into three time periods, as in 1988.

Balkwill, J.A.  1991.  Limnological and fisheries surveys of lakes and 
ponds in British Columbia 1915-1990.  Prov. B.C. Fish. Tech. Circ. No. 

An index to the 2,905 lakes and ponds in British Columbia that have been 
surveyed by the Ministry of Environment, Inventory Section and other 
provincial and federal agencies.  Surveys range from a partial to full 
reconnaissance level survey and some lakes may be surveyed several 
times.  The surveyed lakes are listed alphabetically along with the type of 
information available on each lake.

Lirette, M.G. 1991.  Angler harvest of lake char, kokanee and rainbow 
trout from Bridge Lake, 1990.  B.C. Ministry of Environment, Lands and 
Parks, Fish. Tech. Cir. No. 92:19p.

Between May and September, 1990, the recreational sport fishery on 
Bridge Lake was surveyed.  Aerial boat counts were used to estimate 
angler use at 10,133 angler days.  Effort in the 1990 fishery increased 30% 
over previous years.  A total of 699 anglers were interviewed throughout 
the summer at a fishing resort and a provincial campground adjacent to 
the lake.  The average number of anglers per boat was 1.86 and the 
average angler hours per angler was 4.0.  Anglers spent an estimated 
40,533 hours fishing to catch 4,965 lake char (0.12/hour), 4,154 kokanee 
(0.1/hour) and 1,216 rainbow trout (0.03/hour).  Ninety-six percent of the 
sport fish caught by anglers were killed.  The estimated total harvest for 
lake char was 5,000 kg or 3.6 kg per hectare of lake surface area. This was 
three to six times higher than the theoretical sustainable harvest for this 
species.  Lake char in the creel and on the spawning beds averaged 45.8 
and 45.3 cm fork length, respectively. Spawning lake char first mature at 7 
years of age.  They averaged 14 years old based on otolith samples and 9 
years old based on scale samples.  Ages have yet to be verified.  Total lake 
char yield indicates over exploitation while age and growth data suggests 
a slow growing stunted population of lake char which has not been 
heavily impacted.  A reduction in the regulated daily catch is 
recommended to offset increasing angling pressure on Bridge Lake.  A 
total of eleven different food items were identified in 36 stomach samples 
of char from Bridge Lake. Zooplankton, and aquatic insects each occurred 
in 60% of the fish while only 8% of the lake char had eaten fish.  The catch 
of kokanee and rainbow trout represented 5.0 and 0.9% of the fish stocked, 
respectively, into Bridge Lake.  Management recommendations are 

Abbott, J.C.  1991.  Feeding, aggression and growth in juvenile steelhead 
trout (Salmo gairdneri).  Prov. B.C. Fish. Tech. Circ. No. 93:110p.

Juvenile steelhead trout (Salmo gairdneri) compete for access to space and 
food, and the distribution of these resources within a population affects 
the relative growth and survival of individuals.  Aggression is a means of 
competing for these limited resources.  This thesis examines the causes of 
aggression and growth depensation (size divergence) in juvenile 
steelhead.  The sizes of socially isolated juveniles diverged less with time 
than those of groups of interacting steelhead, although average growth 
rates were equivalent, indicating that the presence of competitors affects 
relative growth.  A behaviourial mechanism resulting in unequal food 
acquisition or growth efficiency is indicated, as rations were in excess of 
requirements.  Size-matched pairs of steelhead established hierarchies in 
which dominants grew 12.3% faster than subordinates although rations 
were equal.  Therefore factors other than access to food (possibly stress) 
play a role in growth depensation.  Groups of steelhead grew faster when 
the inter-feeding interval was reduced, even though daily ration was 
constant.  Size divergence over time was unaffected at intervals ranging 
from 0.5 to 24-h.  Marked increases in aggression were consistently 
observed following feeding.  The magnitude of post-feeding peaks was 
inversely correlated with inter-feeding interval. Total daily aggression and 
frequency of various behaviours were unchanged.  Learning of feeding 
times and anticipatory aggression were demonstrated by recording 
behaviour on the fifth day of a feeding schedule and continuing to 
monitor behaviour for one day after feeding was discontinued.  Alpha and 
beta hierarchy positions were stable over a one week period.

Underwater observation of steelhead in hatchery production facilities 
confirmed the occurrence of aggression.  Various feeding regimes were 
presented to groups of steelhead in these facilities. No differences in 
growth, size divergence or fin damage were detected at four regular 
feeding intervals.  Randomly fed fish showed less size divergence than 
regularly fed fish but had equivalent growth rates.  This reduced growth 
depensation could result in a 6% increase in smolt production.  Trout 
fighting tactics varied depending on the response of the opponent.  
Analysis of aggressive attacks and patterns of fin damage indicate that 
agonistic behaviour is the major cause of fin damage observed in culture