Steelhead Of The Nanaimo River.. Aspects Of Their Biology And The Fishery From 3 Years Of Anglers'

a/ Steelhead Of The Nanaimo River.. Aspects Of Their Biology And The Fishery From 3 Years Of Anglers' Catches By David W. Narver and F. C. Withler > ; x v. H tf ><< # >( >\ x :< H x H H ><!H A X A H M X )i «X ; / *. " < ;-v N X >; # * < >: M H. X >i.-: M X M X *'. /:-*'.':'v-. a.' "'' ' ' *. '* H ''*,?* f*. '" "'* 'si- '"' A <* r"' H.-:*. ' *? <^i ''*\ /''' #.'M\ ' «A '". ' ^ -H r» *" '". '"':. *L-J». dfc, jfll dll A*.,A. Jfc. 4L JL.A. 4LA. j4l 4L A. jml JHL A.4JL A> mk- ^k JL Auft. A. ^L ^L. A. fll.«&. «L jfll. A. <4L. jfll ja ^L_^L.^ Fisheries and Marine Service Pacific Biological Station, Nanaimo, B.C. CIRCULAR NO. 99 DECEMBER 974

-*-*.- STEELHEAD OF THE NANAIMO RIVER -- ASPECTS OF THEIR BIOLOGY AND THE FISHERY FROM 3 YEARS OF ANGLERS CATCHES by David W. Narver and F. C. Withler FISHERIES AND MARINE SERVICE Pacific Biological Station, Nanaimo, B.C. ^n» Circular No. 99 December 974

^^2> INTRODUCTION Pressures on the natural stocks of steelhead in British Columbia are increasing steadily with continued expansion of the forest industry, hydroelectric projects, urbanization and angler numbers. To cope with these pressures we can expect intensive management of steelhead including both the maintenance of wild stocks and the development of artificial techniques such as hatcheries and rearing ponds. But as we discussed earlier (Narver and Withler 97), part of the data required for more intensive management programs are age, size and frequency of spawning of steelhead in each major river as well as information about the sport fishery. In 969 anglers in the Nanaimo vicinity, through the Nanaimo Fish and Game Club, were given the opportunity to help collect this necessary information through a voluntary steelhead sampling program. Anglers were asked to submit information about the fish they caught along with scale samples for age interpretation. The anglers' samples were collected by the Fish and Game Club over three fishing seasons (winters) and delivered to us as collaborators in the program. The samples were tabulated and analyzed by us at the Pacific Biological Station. The purposes of this report are to put on record the relatively extensive information about Nanaimo River winter steel head so obtained and to provide fishermen who participated in the program a summary of the results. j* The methods described below are taken in part from Narver and Withler (97). METHODS Mimeographed instructions accompanied by 3 X 5 inch (969/70) and 2 /3 X 4 inch (970/7-97/72) scale envelopes were distributed to anglers and to sporting goods stores in the Nanaimo, British Columbia, area. Anglers were asked to take 6-2 scales from each fish in 969/70 (20 scales in 970/7-97/72) from the 3 scale rows above or below the lateral line in the area lying between the rear of the dorsal fin and the front of the anal fin. It was pointed out that lateral line scales themselves are not suitable for interpreting ages, but that either side of the fish could be used. On the scale envelope the angler was asked to record the locality, date, sex, fork length (tip of nose to fork of tail), weight (dressed or round to be noted) and other information that he thought important for each fish. The instructions asked that the anglers submit information for all of the steel head they caught--not just the big ones or the small ones--so that the information obtained would be as representative of anglers' catches as possible. Each sample of scales was soaked in water containing a small amount of detergent to separate them. Two scales which appeared to be undamaged were selected, rubbed between the fingers to clean them, and placed on the gummed paper of a scale card. Later the scale card was placed against a warmed plastic card and pressed so that the scale formed a permanent impression on the plastic (Koo 962). These impressions were used to interpret age and to make measurements of portions of the scales.

-2- The number of years spent in the ocean was deduced from examin ation of the scales magnified 00 times; a band of narrow rings (hereafter called "circuli") was interpreted as a winter growth zone (hereafter "annulus") (see Fig. ). Similarly the number of years spent in fresh water was deduced from examination of the projected images of the scale magnified 247 times narrow, broken circuli were interpreted as freshwater annuli (Fig. 2). (The common explanation for the wide spacing of circuli laid down in summer and the narrow spacing in winter is that the spacing reflects the fish's growth--rapid in summer and slow in winter.) For the 969/70 scales, measurements were made of the "lateral" (vertical) diameter of the freshwater growth zone (Fig. 2). For the 970/7 and 97/72 samples, measurements were made of the radius of the freshwater zone from the focus (center) to the anterior margin (top of Fig. 2). These diameter and radii were used in mathematical equations relating the scale diameter (or radius) of young steelhead to their length, to estimate for each fish in the sample its length at the time of migration to sea. The equation used for 969/70 scale expressing the relationship between lateral scale diameter and fish length came from juvenile steelhead originating in Chambers Creek, Washington (Vernon and McMynn 957). This relationship was derived from 96 steelhead that at 0 months of age ranged between 58 and 59 mm fork length. The equation used for 970/7 and 97/72 scales was the relationship between anterior scale radius and fish length from juvenile steelhead in Carnation Creek, Vancouver Island: Y = 9.39304 +.68654X where Y = fork length and X = scale radius. This relationship was derived for 83 juvenile steelhead ranging in length from 37 to 200 mm. Age interpretations for the 969/70 samples were derived from independent readings by two experienced scale readers who mediated conflicting interpretations (24% of the "freshwater age", 28% of the "ocean age" and 39% of the "total age" readings) by discussion and/or information which was presumed to be related to age (such as length or weight). The 970/7 and 97/72 samples were interpreted entirely by Narver. In this report age and certain life history information about individual fish has been coded for brevity. To interpret the code for a particular fish one should keep in mind that steelhead spawn in late winter or early spring and that the young emerge from the gravel in late spring of the same year. They then take up residence in the stream. After one or more years in the stream they migrate in the spring or early summer to the sea where they spend one or more years. They return to the rivers in the summer, fall or winter prior to spawning in late winter or early spring. Some return to sea after spawning and return again to spawn a second, and occasionally, a third time. It is believed that most steelhead, like salmon, return to their river of origin to spawn. To illustrate, a fish designated to a 2.2+ is a 5-year-old fish that spent two winters (2.) in the stream before migrating to sea where it spent two full winters (.2) before entering the river on its spawning migration during the third winter of its ocean life (+.). The + sign in this case indicates that it had not completed its third winter in the ocean and thus

-3- was in its fifth year of life when caught. Specifically, the fish is believed to have emerged from the gravel in the late spring of 965 (its parents spawned in the winter of 964/65), to have spent the winters of 965/66 and 966/67 (and the intervening summers, of course) in the stream, to have migrated to the sea in the spring of 967 (2.), to have spent the winters of 967/68, 968/69 and part of the winter 969/70 in the ocean, and to have returned on its spawning migration in late winter 969/70 when it was caught (.2+). Its scales would look like the one illustrated in Fig. 3. A + sign after the number designating the freshwater age of a fish is used to record the presence of closely-spaced scale circuli following the last freshwater winter annulus, suggesting that the fish grew for a period in fresh water prior to its migration to the sea where scale circuli are laid down farther apart. A steelhead designated as a 2+.S+ is a fish that had returned to the river to spawn for a second time, when it was 5 years old. Its total age and its early freshwater life history would be similar to the 2.2+ fish described previously, except that it grew some in the spring prior to migration to sea (2+.). It migrated to sea in the spring of 967, but it spent only the winter of 967/68 and part of the winter of 968/69 in the ocean. It returned to a river in late winter 968/69, spawned in the early spring, 969 (.IS), survived and returned to sea later that spring as a socalled "kelt". It presumably spent the summer, 969, and part of that winter in the ocean, returning to the Nanaimo River where it was caught in the winter of 969/70 (.S+). Its scales would look like the one illustrated in Fig. 4. Note that the S designation includes both a winter and a spawning check. The age designation system used here has been changed slightly from that of Narver and Withler (97) to provide for a common system usable for both winter and summer steelhead as well as other anadromous salmonids. RESULTS Anglers turned into the Nanaimo Fish and Game Club and to the B.C. Fish and Wildlife Branch 308 scale samples from Nanaimo River steelhead caught in the winters of 969/70, 970/7 and 97/72. Among these 308 scale samples, 306 were usable for interpretation of ocean age. Of these 306 scales, 8 were from repeat spawners and have been treated separately in the analysis that follows. After the repeat spawners and the scales with regenerated freshwater zones were removed from the original sample size of 306, 288 samples contained scales suitable for freshwater age interpretation. Among steelhead, the partial regeneration of a portion of the freshwater zone is common. The regenerated portion is blank, with none of the circuli that characterize the undamaged scale. Such regeneration is caused presumably when the young trout in the stream lose scales through physical interaction with one another for feeding territory or by hiding in the rocky bottom during the winter.

_4- age (freshwater plus ocean) The ages of the 228 steelhead in the sample were composed almost entirely of fish spending two or three years in fresh water followed by two or three years in the ocean (Table ). The most common single age group was 2.+ (4.2%) followed by 3.+ (25.9%). There were no major differences in age composition between sexes in the three years. Freshwater age Nearly two-thirds (63.6%) of the 228 scale sample with usable freshwater zone had spent two winters in fresh water (Table 2). Most of the remainder had spent three winters in fresh water (35.%) while three fish (.3%) had spent four winters in the stream. There was no noticeable difference in proportions of age groups between the sexes. Ocean age Of the 288 samples of scales usable for interpreting ocean age, two-thirds (66.0%) had returned in their second ocean winter (.+) (Table 3). The remaining one-third of the sample was composed almost entirely of fish having returned to the Nanaimo River during their third ocean winter (.2+) (32.6%). A total of only four (.4%) jacks (and jills), fish that returned in their first ocean winter, were reported by anglers. There is some indication that on average over the three years of data females tend to stay longer in the ocean than do males. Among fish returning in their second ocean winter, the ratio of males to females was :.3 while for fish returning in their third ocean winter the ratio was :2.25. Sex ratio Of the 280 scale samples that were readable for ocean age, and for which we know the sex (Table 3), the sex ratio was 0 males to 70 females (:.57). Among the 8 repeat spawners discussed below, 2 were males and 6 were females. This gives a sex ratio of :8, supporting the common belief that females are able to survive the rigors of spawning better than males. Repeat spawners Of the 306 scale samples for which post-smolt life history could be interpreted, 8 or 6% came from fish that were returning to spawn for a second or third time (Table 4). As already mentioned, 6 of these 8 repeat spawners were females. The most common post-smolt life history type among the repeat spawners was.s+ (66.6%). These are fish that first returned to spawn in their second ocean winter, spawned late that winter or spring, spent the next summer in the ocean, and returned in the next winter when caught by t anglers. The second most common type of life history was.2s+ (22.2%). This m> type is identical to the above except that it returned in its third ocean winter for its initial spawning. Of the 8 spawners only one had spent an

-5- entire year (actually two summers and an intervening winter) in the ocean before returning for its second spawning. The other 7 when captured were returning to spawn in the winter immediately following their last spawning. Lengths and weights The fork length vs. round weight relationship for Nanaimo River steelhead reported by anglers is shown in Fig. 5. This relationship is very similar to those given for both winter and summer steelhead in British Columbia (Withler and Narver 974; Narver 974) and in the State of Washington, In this relationship on average a 24-inch fish weighs 5 lb, a 28-inch is 8 lb, a 30-inch is 0 lb and a 32-inch is 2 lb. Weights and lengths of steelhead that had spent different periods of time in the ocean are shown in Table 5. Fish that had spawned previously are not included as they may not be as long or heavy as maiden fish of the same age. The wide range in lengths and weights is normal but may be accentuated by anglers' errors in measuring, weighing or sexing their fish. For a given age, male steelhead are longer and heavier than females. Among fish that spent nearly two years in the ocean (.+) the males on average weighed 7.2 lb and the females 6.6 lb. Among the age.2+ fish the males on average were 2.5 lb heavier than the females (2.9 compared with 0.4). Smolt length The average estimated length of fish at the time of migration to salt water (smolt length) was 5.3 inches and ranged from 3.3 to 8 inches for a sample of 25 fish (Table 6). As might be expected, the mean length of each age group was greater with increased age. A large number of Nanaimo River steelhead scales showed additional freshwater growth (narrowly-spaced circuli) after the last freshwater annulus but prior to entry into salt water (Fig. 4). This fresh water "plus growth" can add substantially to the length of the smolt. Such plus growth was common among the Nanaimo River steelhead of this study, with scales of 68.2% of the age 2. fish and 4.6% of age 3. fish showing such a pattern. The estimates of smolt length includes any plus growth (Table 6). Length of smolts apparently influences the number of years spent in the ocean. Age.+ maiden steelhead (sexes combined) had a mean estimated smolt length of 5.5 inches (n = 32, s =.908), while age.2+ fish had a mean smolt length of 5.6 inches (n = 64, s =.947). The age.+ fish had a significantly larger smolt length than the age.2+ fish (t,~2 ga = 2.456). Time of adult run The numbers and percentages of steelhead reported caught by anglers in the Nanaimo River is shown by two week periods in Table 7. In all three years the number of fish caught peaked either in the first or second half of February. However, as steelhead anglers know all too well, weather and runoff

-6- conditions over any two-week period can severely influence catches. On a monthly basis for the three years most steelhead were caught in February (40%), second-most in March (30.8%), followed by January (6.2%), April (0.7%) and December (.9%). Lures The numbers and percentages of adult steelhead caught ort various types of lures are compared in Table 8. Most steelhead in this sample of 6 (not all anglers reported the lure used) were caught on steelhead or salmon roe (47.8%) followed by "spin-glos" (32.3%) and "strawberry-spins" (3%). * The sex ratio (proportion of males to females) as revealed in the catches by the three main types of lures, differed markedly both between lures and from the overall sex ratio of all the steelhead samples collected during the study. The overall sex ratio of fish reported in this study (n = 280, Table 3) was one male to.54 females. The sex ratio for the 6 fish for which lure was noted was one male to.64 females. This is significantly different at p =.0 from the overall sex ratio (X3idf =.4). Among the 77 fish reported caught on roe the sex ratio was one male to 2.2 females--a much higher proportion of females than in the overall sample (*2ldf = 75-?8, significant at p =.0). Of the fish reported taken on spin-glos^ females comprised a lower proportion (:.36) than in the overall sample (x ldf = 0.8, significant at p =.0). The 2 fish reported caught on strawberry-spins had a sex ratio of :., clearly a much lower proportion of females than in the overall sample (:.54). The average lengths (inches) of fish within either sex were not significantly different among the three major types of lures: Roe Spin-glo Strawberry-spin c? 27.9 28.4 27.5 9 27.6 27.3 28.7 However, the proportion of fish 30 inches or greater in length was significantly different for some lures compared to the overall sample for which lures were reported (6): 30 inch or greater: Lure n less than 30 inches Roe 77 :3.8 Spin-glo 52 :3.00 Strawberry-spin 2 :.20 sample 6 :3.47 The proportion of smaller fish was highest in the catches by anglers using roe. It was significantly higher than for the whole sample of fish for which anglers reported the type of lure used (X^f = 75.50, significant at p =.0). Conversely the proportion of small fish in the catches of anglers

-7- using spin-glos and particularly those using strawberry-spins was significantly lower than for the total sample. DISCUSSION It can not be emphasized too strongly that the data reported in this study represent only the fish caught and not the entire run. This is particularly important in considering sex ratio and adult size composition. Nearly all steelhead sport fisheries appear to catch more females than males (Withler 966; Narver and Withler 97; Hemus 974), but a lengthy study of a California stream where fish were trapped and examined as they migrated upstream and where there was no fishery, showed that the sex ratio was essentially : (Shapovalov and Taft 954). Although to our knowledge it has never been demonstrated, it is possible that a sport fishery tends to select on average smaller or larger fish. Nevertheless it seems likely that sport-caught steelhead provide a fair representation of migration time and freshwater life history, including estimated length at smolt migration. As we have indicated earlier (Narver and Withler 97) it is probably reasonable to assume that anglers' catches, while selective, tend to be selective in about the same way from river to river. If we accept this assumption, it is possible to compare the relative abundance"of different groups of fish among runs to different streams. Our information on Nanaimo River winter steelhead can be compared with similar data for other winter steelhead streams (Table 9). The dominant age group in Nanaimo River is 2.+ followed by 3.+ and 2.2+. A sample from other Vancouver Island streams showed a similar picture although the second and third most common age groups were reversed. However, lower mainland winter steelhead runs were considerably different in age composition from that in Nanaimo River. Only samples from 2 out of 8 rivers had 2.+ fish as the most common age group. In the other 6 rivers 3.+ or 3.2+ was the most common age group. With the exception of the Chilliwack and Alouette Rivers (which are similar to the Nanaimo in having a high proportion of 2 year freshwater fish) the lower mainland streams produce mainly smolts that have spent 3 years in the stream (Table 9). The ocean ages are not grossly different between the Nanaimo and lower mainland runs. Of the 306 steelhead scales that were readable for ocean age, 8 or 5.9% were repeat spawners. This is considerably less than the 6.7% we obtained from 4 steelhead samples from other Vancouver Island streams (Narver and Withler 97). The percentage of repeat spawners in anglers' catches in eight lower mainland streams ranged from 5 to 3.3% with an average of 0.3% (Withler 966). Factors influencing the proportion of repeat spawners in a steelhead stock are unknown. The estimated lengths of young steelhead at time of seaward migration (including "plus growth") for our Nanaimo River sample are smaller in comparison with other winter steelhead stocks. In our sample the overall

-8- mean was 5.3 inches (3.3 to 8.0) as compared with 6. inches (3.3 to 9.5) for other Vancouver Island streams (Narver and Withler 97) and 6.0 inches for the Chilliwack River (Maher and Larkin 954). In all three studies the major freshwater age groups are 2. and 3 A comparison of mean smolt lengths estimated from adult scales shows: Age 2. Age 3. Nanaimo River 5.2 5.5 Other VI streams 5.8 6.6 Chilliwack River 5.7 6.8 Nanaimo River smolt lengths showed an overall range of 3.2 to 8.3 inches and an overall mean of 5.3 inches (Table 6). This means that the 8 inch minimum length limit for trout probably prohibits the removal of significant numbers of steelhead smolts by sport fishermen. The scales of maiden Nanaimo River steelhead showed that age.+ fish had been, on average, larger smolts than the age.2+ fish. In other words, the small (4.5-0 lb, Table 5) steelhead resulted from larger smolts than did the large (8-6 lb) fish. This phenomenon has an important implication for a steelhead hatchery program and has already been noted in Oregon and Washington. There, in streams heavily planted with hatchery fish, the catch is composed mainly of age.+ (small) maiden fish (Royal 972). Apparently, since hatchery smolts are reared to an optimum size (7-8 per pound) that maximizes the numbers of returning adults (Wagner 970), there are larger than wild smolts (about 7 or 8 inches compared with 5.3 inches for Nanaimo River), and result in quick-maturing, age.+ fish rather than slow-maturing, age.2+ fish. However, it should be noted that smolt age may confuse this relationship; hatchery fish are reared to smolt size in one year while wild smolts are 2 or 3 years old. The estimates of mean smolt length derived from adult scales is likely to be biased and to indicate a larger mean smolt size that actually occurred in the smolt outmigration. This is because in working from adult scales we are only looking at the smolt length represented by the survivors (see Methods). It is well established that larger smolts result in greater adult returns (Wagner 970) presumably because their larger size at time of entry into the ocean gives them survival advantage over their smaller brethern (Ricker 969). On the basis of this study (assuming that catches for other years are similar to those of the three-year study period) an angler using roe can expect, on average, one out of every 3.8 steelhead he catches will be 30 inches in length or greater and that 2 out of every 3 fish will be females. An angler using "strawberry-spin" could, on average, expect that nearly one out of every two steelhead caught will be 30 inches or over in length and that about one in every two fish will be female.

-9- SUMMARY. In 969 steelhead anglers were given the opportunity via the Nanaimo Fish and Game Club to help collect information basic to the establishment of a more intensive management program on the Nanaimo River, 2. Anglers were asked to take scale samples for age interpretation from each fish they caught and to submit along with the sample, information on date, length, weight, and lure. 3. Anglers turned in 380 scale samples from Nanaimo River steelhead caught in the winters of 969/70, 970/7 and 97/72. 4. The most common single age group was 2.+ (4% - fish in 4th year of life) followed by 3.+ (26% - fish in 5th year of life). 5. Nearly two-thirds (64%) of the sample had spent two winters in fresh water with most of the remainder (35%) having spent three winters. 6. The most common ocean age was fish returning in their second ocean winter (.+, 66%) with the remainder composed of fish returning in their third ocean winter (.2+). 7. The sex ratio of maiden fish was 0 males to 70 females (:.57), while among the 8 repeat spawners were 2 males and 6 females (:8). 8. Of the whole sample only 8 (6%) were fish returning to spawn for a second or third time. Seventeen of these were returning to spawn in the winter immediately following their last spawning. 9. The relationship between fork length and round weight for Nanaimo River steelhead is very similar to those reported for other British Columbia streams and in the State of Washington. On average a 24-inch fish weighs about 5 lb, a 28-inch fish about 8 lb, a 30-inch fish about 0 lb, and a 32-inch fish about 2 lb. 0. The average length of smolts was estimated to be 5.3 inches with a range of 3.2 to 8.3 inches.. Scales of maiden steelhead showed that smolts that were larger than average tended to mature a year earlier in the ocean (.+) while smaller-than-average smolts tended to spend an extra year in the ocean before maturing (.2+). This observation is relevant to a steelhead hatchery program since hatchery smolts tend to be large and result in small adults (.+). 2. During the three study years most fish were reported caught on the Nanaimo River in February (40%) followed by March (3%), January (6%), April (%) and December (2%). 3. Most steelhead were caught on steelhead or salmon roe (487«), followed by "spin-glos" (32%) and "strawberry-spins" (3%).

-0-4. Anglers using roe caught a greater proportion of small (less than 30 inches) steelhead and a greater proportion of females than anglers using "strawberry-spins". 5. Age composition of Nanaimo River winter steelhead is similar to that of other Vancouver Island streams but differs from most lower mainland rivers where 3-year rather than 2-year smolts are most common. 6. The proportion of repeat spawners in the Nanaimo River samples (5.9%) is low compared to those from other winter steelhead streams with proportions ranging from 5 to 3%. 7. Mean length of Nanaimo River steelhead smolts estimated from adult steelhead scales was 5.3 inches which is somewhat shorter than for other Vancouver Island streams and the Chilliwack River. ACKNOWLEDGEMENTS Mrs. P.L. Miller tabulated all the data and calculated the regression. Without the enthusiastic cooperation of the Nanaimo Fish and Game Club the information contained in this report would not exist.

-- LITERATURE CITED Hemus, Dennis. 974. Dean River summer steelhead--observations on life history, population, and the fishery in 973. Typed report, Fish Wildl. Branch, Victoria. 64 p. Koo, T.S.Y. 962. Age and growth studies of red salmon scales by graphical means. Univ. Washington Publ. in Fish., New Ser. (3): 49-22. Maher, F.P., and P.A. Larkin. 954. Life history of the steelhead trout of the Chilliwack River, British Columbia. Trans. Amer. Fish. Soc. 84: 27-38. Narver, D.W. 974. Age and size of Nahmint River summer steelhead in anglers* catches, 973. Fish. Res. Board Can., Nanaimo Biol. Sta. Circ. 97. 5 p. Narver, D.W., and F.C. Withler. 97. Age and size of steelhead trout (S. gairdneri) in anglers' catches from Vancouver Island, British Columbia,.streams. Fish. Res. Board Can., Nanaimo Biol. Sta. Circ. 9. 26 p. Ricker, W.E. 969. Effects of size-selective mortality and sampling bias on estimates of growth, mortality, production, and yield. J. Fish. Res. Board Can. 63: 479-54. Royal, L.A. 972. An examination of the anadromous trout program of the Washington State Game Department. Mimeo. Rep. to Director, Dept. of Game, Olympia. 76 p. Shapovalov, L., and A.C. Taft. 954. The life histories of steelhead trout (Salmo gairdneri gairdneri) and silver salmon (Oncorhynchus kisutch). Calif. Fish and Game, Fish. Bull. No. 98. 375 p. Wagner, H.H. 970. Progress in game and sport fishery research--963-970. Rept. of the Oregon State Game Comm., Res. Div., p. 8r9. Withler, I.H. 966. Variability in life history characteristics of steelhead trout (Salmo gairdneri) along the Pacific coast of North America. J. Fish. Res. Board Can. 23: 365-393.

-2- Table. Numbers and percentages of male and female steelhead of different age-groups among anglers' catches from Nanaimo River in the winters of 969/70, 970/7 and 97/72. Fish that had spawned in previous years, as determined from scale examination, are not included. age Year Sex 2.+ 2.+ 2.2+ 3.+ 3.+ 3.2+ 4.+ 4.2+ 969/70 d,nl733 -- 6 % 6.3 43.7 8.7 6.3 8.7 6.3 9 n - 7 5-7 - 29 % 58.6 7.2 24.2 n 24 8 0 - - 45 % 2.2 53.4 7.8 2.2 22.2 2,2 970/7 o* n - 0-52 - 9 % 52.6 5.3 26.3 0.5 5.3?nl 2 4-8-2 28 % 3.6 42.9 4.3 28.6 3.6 7. n 22 5-3 3 2 47 % 2. 46.8 0.6 27.7 6.4 2. 4.3 97/72 d* n - 7 5-20 - - 53 % 32. 28.3 37.7.9 9 n - 3 2-6 5 - - 83 % 37.4 25.3 9.3 8.0 n * 48 36-36 6 - - 36 % 35.3 26.5 26.5.7 ct n 34 9 28 4-88 %. 38.6 2.7. 3.8 4.6.? n 60 30-3 6 2 40 % 0.7 42.8 2.4 22.2.4.5 n 2 94 49 59 20 2 228 % 0.9 4.2 2.5 0.4 25.9 8.8 0.4 0.9

-3- Table 2. Numbers and percentages of male and female steelhead of different freshwater age-groups among anglers' catches from Nanaimo River in the winters of 969/70, 970/7 and 97/72. Fish that had spawned previously are not included. Year Sex 2. Freshwater age 3. 4. 969/70 n % 68.8 5 3.2 6 n 22 % 75.9 7 24. 29 n 33 % 73.3 2 26.7 45 970/7 n % 57.9 7 36.8 5.3 9 n 7 % 60.7 9 32. 2 7. 28 n 28 % 59.6 6 34.0 3 6.4 47 97/72 n 32 % 60.4 2 39.6 53 n 52 % 62.7 3 37.3 83 n 84 % 62.0 52 38.0 36 n 54 % 6.4 33 37.5. 88 n 9 % 65.0 47 33.6 2.4 40 n 45 % 63.6 80 35. 3.3 228

-4- Table 3. Numbers and percentages of male and female steelhead of different ocean age-groups among anglers' catches from Nanaimo River in the winters of 969/70, 970/7 and 97/72, Fish that had spawned previously are not included. Year Ocean age Sex + -+ -2+ 969/70 c? n 2 0 4 6 9 % 2.5 62.5 25.0 n - 28 6 34 % 82.4 7.6 Unknown n - % n 2 38 5 % 3.9 74.5 2.6 970/7 tf n - 23 5 28 % 82. 7.9 9 n 2 26 0 38 % 5.3 68.4 26.3 Unknown n - % 50.0 50.0 n 2 50 6 68 % 2.9 73.5 23.5 97/72 a n - 47.9 66 % 7.2 28.8 9 n - 5 47 98 % 52.0 48.0 Unknown n - 4 5 % 80.0 20.0 n - 02 67 69 % 60.4 39.6 d n 2 80 28 0 %.8 72.7 25.5 9 n 2 05 63 70 %.2 6.8 37.0 Unknown n - 5 3 8 % 62.5 37.5 n 4 90 94 288 %.4 66.0 32.6

- -5- Table 4. Numbers and percentages of different post-smolt age-groups of repeat spawners among anglers' catches from Nanaimo River in the winters of 969/70, 970/7 and 97/72. Fish that had spawned previously are not included. Year Sex.S+.S+ Ocean age.ss+ T2S+" 969/70 n % n 5 7 fo 7.4 2 28.6 n 5 % 7.4 2 28.6 970/7 n % 00 n % 33.3 2 66.7 n % 25 25 2 50 97/72 n % 00 n 5 % 83.3 6.7 n 6 % 85.7 4.3 n 2 % 00 n 0 % 62.4 6.3 6.3 4 25.0 6 n 2 % 66.6 5.6 5.6 4 22.2 8

-6- Table 5. Round weights (lb) and fork lengths (in) of male and female steelhead of different ocean age among anglers' catches from Nanaimo River in the winters of 969/70, 970/7 and 97/72. (Fish that had spawned previously are not included. Weight information was not submitted for all fish.) Year Sex Ocean age Weight (pounds) Length (inches) Average Range Number Average Range Number 969/70 Male.+.+.2+ 7.9 3.7 7-9 2.5-5 7.9 27.4 3.2 7.5-8.2 25.5-30.3 30.5-32 2 3 2 Female.+.+.2+ 6.9 5-9.5 6 26.0 23.5-28 26.0 8-4 6 30.9 29-34 6 970/7 Male.+.+.2+ 7.5 5.7 5-9.6 5.5-6 2 2 26.9 35 24-3 33-36 22 5 Female.+.+.2+ 6. 2.4 4.5-7.5 8-4 5 9 5.2 26.2 32.0 4.5-6 23-29 29-37 2 25 0 97/72 Male.+.+.2+ 6.9 2.3 4.5-0 8-6 26 3 26.6 32.2 23-29.5 29-34 47 9 Female.+.+.2+ 6.7 9.7 2.5-9 4-5 25 28 26.4 30.2 23.5-30.5 28-33 48 42 Male.+.+.2+ 7.2 2.9 4.5-0 8-6 47 7 7.9 26.8 32.7 7.5-8.2 23-3 29-36 2 82 26 Female.+.+.2+.0 6.6 0.4 4.5-9.5 8-5 56 43 5.3 26.2 30.6 4.5-6 23-30.5 28-37 2 99 58

-7- Table 6. Means and ranges of estimated fork length (in) at time of seaward migration according to freshwater age of adult steelhead in anglers' catches from Nanaimo River in the winters of 969/70, 970/7 and 97/72. (Sexes are combined. Repeat spawners as well as fish for which no sex information was provided are included.) Range Freshwater age Mean Minimum Maximum n. 6. 2. 5.2 3.2 8.3 58 3. 5.5 3.5 7.5 88 4. 6.3 6. 6.6 4 Weighted mean 5.3 3.2 8.3 25

- 5-8- Table 7. Numbers and percentages in two-week periods of adult steelhead reported caught by anglers from Nanaimo River in the winters of 969/70, 970/7 and 97/72. 969/70 970/7 97/72 Period n % n % n % n % %(monthly) Nov. 5-30 - Dec. -5 - - - - - - -.6.3.3.6.3 Dec. 6-3 - - 5 7.2 -.6.9 Jan.: -5 - -.4 3.7 4.3 Jan. 6-3 7.7 7 0. 29 6.7 47 4.9 6.2 Feb. -5 5 24.2 4 20.3 22 2.6 5 6.2 Feb. 6-29 2 9.3 6 23.2 37 2.3 75 23.8 40.0 Mar. -5 0 6. 6 8.7 29 6.7 45 4.3 Mar. 6-3 9 4.5 3 8.8 30 7.2 52 6.5 30.8 Apr. -5 5 8. 7 0. 4 8.0 26 8.2 Apr. 6-30 - - - - 8 62 69 74 35 4.6 8 2.5 0.7

-9- Table 8. A comparison of the numbers and percentages of adult steelhead caught on various types of lures as reported in anglers' catches from Nanaimo River in the winters of 969/70, 970/7 and 97/72. Lures Roe Spin- Strawberry- Spinners- Others2 glo spin spoon Number caught Males n 24 2 4 63 % 3.2 42.3 52.4 50 60 39. Females n 53 30 0 2 3 98 % 68.8 57.7 47.6 50 40 60.9 n 77 (48%) 52 (32%) 2 (3%) 4 (3%) 7 (4%) 6 Hjith or without another lure such as bead or yarn. s0akie-drifter, yarn, bead, fly, etc.

Table 9. Percentages of different age groups among first-time spawners in winter steelhead anglers' catches from different rivers. Age group Sample.+.+.2+.3+ 2.+ 2.+ 2.2+ 2.3+ 3.+ 3.+ 3.2+ 3.3+ 4.+ 4.+ 4.2+ size..4 770 58 5. 39 74.4.9 228 I o I Alouette 2.3 4.6.5 32. 32..5 6.0 8.3.8.8 3 Coquitlam.7 23.3 9.6 49.3 3.7 2.7.7 46 Chehalis 8.2 0.8 33.3 34.2.9 8. 4.5 Cheakamus 5.6 25.0 4.7 34.4 5.6 3.2.6 64 Chilliwack.0.8.2 3.0 30.6.. 7.9 7.3.4 Capilano 25.7 20.0 40.0 2.9.4 70 Seymour.7 8.9 2. 3.4 37.9 22.4.8.8 Coquihalla 5. 5.4 7.7 48.8 7.9 Other Vancouver Island streams'.4.4 36.5 28.2.4 2.6 8..4 Nanaimo.9 4.2 2.5.4 25.9 8.8 Withler 966. Carver and Withler 97.

-2- ] START OCEAN WINTER OCEAN SUMMER OCEAN WINTER OCEAN SUMMER FRESHWATER fc?«< - J* Fig.. Photomicrograph of a steelhead scale with the ocean and freshwater growth zones marked.

-22- Fig. 2. Photomicrograph of the freshwater growth zone of a steelhead with the first and second annuli marked.

-23- Fig. 3. Photomicrograph of a steelhead scale with the annuli or winter growth zones marked and with an age designation of 2.2+. See text for explanation. (The "accessory check" we believe was caused by a slowing of the fish's growth prior to the first ocean winter. Such checks might be caused by an injury to the fish. They are not uncommon on steelhead trout and Pacific salmon scales.)

-24- Fig. 4. Photomicrograph of a steelhead scale with the annuli and a spawning check marked and with an age designation of 2+.2S+. See text for explanation.

- 25- ROUND WEIGHT (pounds) o ro * e> 09 o to * 0> 09 * i i i i i 5> 5 o -n O TO IN} to - to k j. m z H X ro : * \,. : to o *. \ *\ ** CJ o ^v V- OJ to \^v * OJ 0). W 09 l i i " i i Fig. 5. Lengths and weights of individual fish reported by steelhead anglers on the Nanaimo River in the winter and spring of 969/70, 970/7 and 97/72. The line is the calculated average relationship between weight and length for this sample of fish.