/,J-7 -YL -k LLs IN~OTUT~ Fo ~i~ -F-~I: -p: 1 84-8 FISHERIES DIVISION TECHNICAL REPORT Platte River Harvest Weir and Coho Salmon Egg-Take Report, 1983 I 9 and ";Zz) ooz:::::D Number 84-8 'ctober 4, 1984 I I I I U I, ' - I I ' Michigan Department of Natural Resources /1 Pt MICHIGAN DEPARTMENT OF NATURAL RESOURCES FISHERIES DIVISION Fisheries Technical Report 84-8 October 4, 1984 PLATTE RIVER HARVEST WEIR AND COHO SALMON EGG-TAKE REPORT, 1983 Charles H. Pecor and George B. Beyerle 2 Introduction Since 1966, the Platte River in Benzie County, has been the primary source of brood fish for Michigan's coho salmon stocking program. Eggs are collected each fall at the Platte River State Fish Hatchery, located 4 miles east of Honor (Fig. 1). The young coho are raised to the smolt stage (about 5 inches long) in 1.5 years and stocked at selected sites throughout Michigan. Prior to 1979, annual plants of 400,000 to 600,000 coho smolts in the Platte River produced sufficient adults for egg-take operations plus a spectacular Lake Michigan sport fishery from Frankfort to Platte Bay in August and September. Since 1979, the annual plant has approximated 1,000,000 smolts. Annual returns from the larger plants have ranged from 123,000 to 168,000 adults, or 12.7% to 16.4%. The Platte River has two salmon blocking weirs. The lower weir is located 1.5 miles upstream from the river mouth (Fig. 1). Since 1980 it has been the primary site for harvesting surplus salmon. Steelhead runs are monitored there also. The upper weir, located at the Platte River Hatchery, has facilities for holding adults and collecting eggs. Current in-state and out-of-state commitments require the collection of 16,000,000 coho eggs annually. Depending on the size of the returning coho, the egg-take requires about 6,500 - 7,500 adult females (age 1.1). To assure that enough females are available for egg-take, the Fisheries Division has directed that 30,000 first-run salmon at the lower weir be passed upstream (allowed to swim through the open weir). An additional 3,000 salmon~are passed each week to maintain a sport fishery in the river. However, the above numbers may be modified by the biologist-in-charge as conditions dictate. 3 Other salmon blocked by the lower weir (including surplus coho adults, a moderate run of chinook and, in recent years, a few pink salmon) are collected and harvested. Coho jacks (age 1.0) are small enough to swim upstream through the weir grates. Trout that are collected during harvest operations are counted and released upstream. This includes a moderate run of steelhead plus small runs of brown trout and lake trout. All salmon collected at the upper weir are harvested, including the coho used for eggtake. Lower Weir Operation, 1983 The 1983 salmon run in the lower Platte River was typical. The salmon produced an excellent open-water fishery in the Frankfort-Platte Bay areas for over 3 weeks. The fish ran the river when expected and also in numbers expected. Unfortunately, the fish that were passed upstream at the lower weir swam up to the hatchery in just a few days. Consequently, anglers frequently complained that there were " no" fish in the river or connecting lakes. The lower harvest weir was in place and ready for operation on September 6. The weir was manned 24 hours per day from September 9 to October 24. Very few salmon appeared at the weir until September 14. However, by September 17, the major run was in the river. Harvesting began September 16 and ended October 24. Thirty-two semitruck loads of salmon were shipped out. From September 10 to October 20, a total of 37,239 salmonids (salmon plus trout) were allowed to swim upstream 4 Coho salmon A total of 120,758 adult coho weighing 827,717 pounds were harvested (Table 2). About two-thirds of the harvest occurred during the week beginning September 18. Mean weight of the harvested fish was 6.8 pounds. An estimated 35,600 additional adult coho were passed upstream (Table 1). At approximately weekly intervals biological samples of 100 or more randomly selected coho were sexed, measured, and weighed. Analyses of these data showed that the size of adult male coho increased significantly from 26.6 inches and 6.7 pounds in mid-September, to 27.3 inches and 7.3 pounds in late September, to 27.9 inches and 7.5 pounds in early October (Table 3). Size of adult female coho also increased, from 26.0 inches and 6.4 pounds in mid-September to 26.7 inches and 7.2 pounds in October. The weighted mean lengths and weights were: males, 26.9 inches and 6.88 pounds; females, 26.4 inches and 6.86 pounds. For both sexes combined, mean length was 26.6 inches and mean weight was 6.9 pounds. In summary, a total of 156,358 adult coho salmon reached the Platte River lower weir in 1983, 67,377 (43.1%) males and 88,981 (59.9%) females (Table 3). The total adult run was 15.6% of the 1982 plant of 1,000,010 age 1.0 smolts (Table 4). Chinook salmon As usual, most of the chinook run came after the peak of the coho run and was not nearly so concentrated. The main part of the run occurred from September 27 through October 12. A total of 4,839 chinook (jacks and adults combined) weighing 71,250 pounds were harvested (Table 5). Mean weight was 14.7 pounds. Because no scale samples were taken, the chinook could not be enumerated by age groups. It was estimated that 1,275 chinook were passed upstream at the lower weir (Table 1). 5 The total of 6,114 chinook reaching the lower weir in 1983 was the largest run since full-scale operation of the weir began in 1980 (Table 6). All chinook were either strays from other plants, escapees from the Platte River Hatchery, or the result of natural reproduction. Chinook have not been stocked in the Platte River since 1972. Pink salmon The first pink salmon (two fish) were harvested at the lower weir in 1981. In 1983, over 35 pink salmon were harvested and a few others were observed above and below the lower weir. Steelhead The 1983 steelhead run peaked during the weeks beginning September 24 and October 3, after the major run of coho was over. This pattern has been consistent since 1980, although the dates have varied from year to year. The run was the largest since full-scale operations began in 1980. A total of 1,545 fish were counted and passed upstream in 1983 (Table 7), compared with 1,276 in 1982, 682 in 1981, and 124 in 1980. In addition, an estimated 353 steelhead passed through the weir (Table 7), making a total run of 1,898 steelhead in 1983. They averaged 7.5 pounds and consisted of 53.5% males and 46.5% females. No scale samples were taken from steelhead, so age and growth data could not be determined. However, the length frequency distribution by sex (Fig. 2) showed two groups of steelhead in the run, fish which had probably spent just 1 year in Lake Michigan (mode of 18 inches, almost exclusively males) and fish which had spent 2 or more years in the lake (mode of 26-27 inches, almost equal numbers of males and females). 6 Brown trout and lake trout Brown trout and lake trout are only minor components of the salmonid run 'in the Platte River (Table 7). A total of 58 brown trout were passed upstream in 1983 as compared to 38 in 1982, 78 in 1981, and 7 in 1980. Lake trout first appeared in the 1982 run (38 passed). Only 7 were passed in 1983. Upper Weir Operation, 1983 Coho salmon Weir stop-logs were in place by September 1 and the fish holding-egg taking facility was fully operational by September 6. The first coho (2 adults and 15-20 jacks) reached the holding ponds by September 2. The main run began September 16 and all six holding ponds were full by September 27. Additional fish were held in the river below the weir. The fish in the holding ponds were checked for egg condition (degree of ripeness) on October 5 and October 10. The percentage of ripe females was 12.5% on October 5 and 46.5% on October 10'. A total of 16,062,700 eggs were collected and fertilized on 14 working days between October 13 and November 1. Of these eggs, 8,578,500 (53%) were for in-state rearing and 7,484,200 (47%) were for out-of-state commitments (i.e., Indiana, 0.5 million; Wisconsin, 1.2 million; Illinois, 2.0 million; Pennsylvania, 2.5 million, and Ohio, 1.2 million). The 1983 egg-take was carried out as a routine operation with no problems encountered. The fish matured 7 77.1% with a daily (6 days) range from 73.1% to 87.7%. Coho eye-up rates in recent years were 63.0% in 1979, 82.2% in 1980, 71.4% in 1981, and 55.9% in 1982. The egg-take and harvest operations at the upper weir accounted for 33,421 coho, including 6,553 (19.6%) jacks and 26,868 (80.4%) adults (Table 8). The number of adults harvested at the upper weir was 75.47% of the estimated total of adults passed at the lower weir. Assuming that the number of jack coho harvested at the upper weir (6,553) was also 75.47% of the total number of jacks that passed the lower weir, the total 1983 jack run was estimated to be 8,683 fish. This is 0.9% of the total coho smolt plant in 1983 and 5.3% of the total estimated run of 165,041 coho in the Platte River in 1983. Mean length and weight of jacks, calculated from periodic biological samples, were 16.4 inches and 1.6 pounds, respectively (Table 9). The mean weight of jacks, calculated from the harvest data, was the same, 1.6 pounds (Table 10). Two jacks out of 177 (1.1%) taken for biological samples had an adipose clip. The Great Lakes Fisheries Commission has no record of an adipose clip being approved for coho smolts planted in 1983 (Margaret Ross, personal communication). Chinook salmon Almost two-thirds of the chinooks at the upper weir were harvested during the first 10 days of November (Table 11). The total harvest of 296 fish was only 23.2% of the estimated number of chinook passed at the lower weir. 8 Summary The 1983 run of coho salmon in the Platte River consisted of 156,358 adults (43.1% males and 56.9% females) and 8,683 jacks. This is a return rate of 16.5% on the smolts planted in 1982. Mean lengths and weights were 26.9 inches and 6.9 pounds for adult males, 26.4 inches and 6.8 pounds for adult females, and 16.4 inches and 1.6 pounds for jacks. A grand total of 154,175 coho adults and jacks weighing 1,004,225 pounds were harvested. A total of 147,626 adult coho (94.4% of the total run) were harvested, 120,758 at the lower weir and 26,868 at the upper weir. The upper weir harvest included 6,961 stripped female coho weighing 37,868 pounds from which the 1983 complement of 16,062,700 eggs was taken. The total weight of 140,665 coho adults harvested in the round was 955,892 pounds, 827,717 pounds at the lower weir and 128,175 pounds at the upper weir. Jack coho (6,553 fish, or 7.5% of the total jack run, weighing 10,465 pounds) were harvested only at the upper weir. The 1983 run of 6,114 chinook was the largest ever recorded at the Platte River lower weir. Ultimately, 5,135 of these chinook (84.0%) were harvested, 4,839 at the lower weir and 296 at the upper weir. Total weight of the harvested chinook was 74,496 pounds of which 71,250 pounds were taken at the lower weir and 3,246 pounds were taken at the upper weir. Other salmonids reaching the lower weir in 1983 included 1,898 steelhead (the largest run ever recorded), 58 brown trout, 7 lake trout, and about 35 pink salmon. Recommendations for 1984 To maintain uniformity throughout the statewide harvest weir system, all length and weight measurements in harvest weir reports should be in the English system. 9 Reporting of fish harvested and passed should be done on a daily and calendar week basis, as in the 1983 report. Platte River Lower Weir Daily record of fish processed For each anadromous species, record the daily, weekly, and cumulative number and weight of fish harvested and number of fish passed. Weekly biological sampling For coho, each week measure, weigh, and sex every adult coho (about 135 fish) in one randomly selected box (tote). For chinook, as soon as possible during the chinook run, scale sample 50 males and 50 females covering the size range from 28 inches to the largest available. Fish in good, bright condition facilitate scale taking and reading. In addition, each week of the run measure and weigh 100 (or two totes) randomly selected chinook (all sizes, including jacks). For steelhead, each week of the run measure, weigh, and scale sample 50 randomly selected fish (mortalities can be used as part of the weekly samples). No biological data need be collected from brown trout, lake trout, or pink salmon. Platte River Upper Weir Daily record of fish processed For each species of salmon, record the daily, weekly, and cumulative number and weight of fish harvested. The harvest of coho jacks should be recorded separately. During the coho egg-take, record the daily number and weight of stripped females and number of eggs taken. 10 Weekly biological sampling For coho jacks only, each week measure and weigh 50 randomly selected fish. No other biological sampling need be done at the upper weir.;/ 11 LAKE MICHIGAN PLATTE BAY ~ BENZIE CO. LINE WEIR PLATTE RIVER HATCHERY AND UPPER HARVEST WEIR PLATTE BEULAH MILES 0 1 2 Figure 1. Location of the Platte River Hatchery and the upper and lower harvest weirs. 12 20 U MALE I FEMALE -F CI) LiLL0 C-r 10 m z 5 0 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 LENGTH (INCHES) Figure 2. Length-frequency by sex of 100 steelhead from Platte River lower weir, October 4, 1983. 13 Table 1. Total salmonids, and estimated coho and chinook salmon, passed upstream at the Platte River lower weir, 1983. Coho Chinook Sal- Percent' Estimated Percent' Estimated monids in number in number Date passed harvest passed harvest passed 9/10 4 Weekly total 4 100.00 4 0.0 0 9/11 5 9/12 35 9/13 267 9/14 3,819 9/15 880 9/16 550 9/17 15,000 Weekly total 20,546 98.24 20,185 1.66 341 9/19 5,000 9/21 1,000 9/22 2,000 9/23 2,000 Weekly total 10,000 99.35 9,935 0.32 32 9/25 2,000 9/27 500 9/29 500 10/1 1,200 Weekly total 4,200 94.54 3,971 3.67 154 10/4 1,000 10/8 1,000 Weekly total 2,000 68.48 1,370 24.24 485 10/9 157 Weekly total 157 27.16 43 59.42 93 10/17 135 10/18 98 10/19 57 10/20 42 Weekly total 332 37.85 92 50.95 170 Annual total 37,239 95.60 35,600 3.42 1,275 'Percentage of the harvested were either coho or chinook. or handled salmonids which 14 Table 2. Summary of adult coho salmon harvested at Platte River lower weir, 1983. Coho harvested Total Cumulative weight Date Live Mortalities total (pounds) 9/16 5,130 0 5,130 33,345 9/17 4,995 0 10,125 32,467 Weekly totals 10,125 0 65,812 9/18 4,050 0 14,175 26,325 9/19 9,450 123 23,748 65,479 9/20 14,580 0 38,328 99,725 9/21 24,470 0 62,798 167,373 9/22 12,690 208 75,696 88,224 9/23 9,990 0 85,686 68,331 9/24 4,860 0 90,546 33,241 Weekly totals 80,090 331 548,698 9/25 9,450 0 99,996 64,639 9/26 4,455 0 104,451 30,472 9/27 2,632 70 107,153 19,319 9/29 4,455 0 111,608 31,852 10/1 2,970 335 114,913 23,629 Weekly totals 23,962 405 169,911 10/4 3,780 0 118,693 27,972 10/7 457 525 119,675 7,266 Weekly totals 4,237 525 35,238 10/12 210 370 120,255 4,242 10/14 270 0 120,525 1,997 Weekly totals 480 370 6,239 10/17 205 15 120,745 1,729 Weekly totals 205 15 1,729 10/24 13 0 120,758 90 Weekly totals 13 0 90 Annual total 119,112 1,646 120,758 827,717 15 Table 3. Estimated number of adult male and female coho salmon processed and their mean length (inches) and weight (pounds), based on weekly biological samples at the Platte River lower weir, 1983. Number of coho Mean Week beginning Harvested Passed Total Length Weight Age 1.1, male 9/11 9/18 9/25 10/2 10/9 10/16 10/23 Total Weighted means Age 1.1, female 9/11 9/18 9/25 10/2 10/9 10/16 10/23 Total Weighted means 3,756 34,501 11,452 2,624 468 121 7 7,490 4,262 1,866 755 24 51 0 11,246 38,763 13,318 3,379 492 172 7 26.6 26.8 27.3 27.9 27.91 27.9' 27.9 26.9 6.69 6.72 7.33 7.51 7.511 7.511 7.511 6.88 52,929 14,448 67,377 6,369 45,920 12,915 2,138 382 99 6 12,699 5,673 2,105 615 19 41 0 19,068 51,593 15,020 2,753 401 140 6 26.0 26.5 26.5 26.7 26.71 26.71 26.71 26.4 6.41 6.93 7.00 7.22 7.221 7.221 7.221 6.84 67,829 21,152 88,981 Sexes combined 120,758 35,600 156,358 26.6 6.86 'Assumed to be the same as samples taken week of October 2. 16 Table 4. Summary of adult coho salmon runs at the Platte River lower weir, 1980 through 1983. Adult coho (age 1.1) Yearling Estimated plant in number Number Total previous Percent Year passed' harvested run year return 1980 76,4802 46,633 123,113 973,032 12.7 1981 38,874 129,175 168,049 1,028,038 16.3 1982 38,951 90,412 129,363 944,205 13.7 1983 35,600 120,758 156,358 1,000,010 15.6 195.60% of total salmon pass upstream. 2Fish not counted. Estimated from harvest at upper weir. 17 Table 5. Summary of adult chinook salmon (jacks and adults combined) harvested at Platte River lower weir, 1983. Chinook harvested Total Cumulative weight Date Live Mortalities total (pounds) 9/16 91 0 91 1,184 9/17 80 0 171 1,040 Weekly totals 171--> 0 9/18 48 0 219 624 9/19 58 0 277 906 9/20 10 0 287 157 9/21 86 0 373 1,358 9/22 53 0 426 838 Weekly totals 255 0 9/25 84 0 510 1,327 9/26 82 0 592 1,294 9/27 174 0 766 2,262 9/29 240 0 1,006 3,119 10/1 350 0 1,356 4,549 Weekly totals 930 0 10/4 600 0 1,956 9,061 10/7 900 30 2,886 14,043 Weekly totals 1,500 30 10/12 975 0 3,861 14,722 10/14 75 0 3,936 1,131 Weekly totals 1,050 0 10/17 375 8 4,319 5,783 Weekly totals 375 8 10/24 470 50 4,839 7,853 Weekly totals 470 50 Annual total 4,751 88 4,839 71,253 18 Table 6. Summary of chinook salmon runs (jacks and adults combined) at the Platte River lower weir, 1980 through 1983. Estimated number Number Total Year passed' harvested run 1980 2,7362 1,699 4,435 1981 1,391 2,172 3,563 1982 1,393 1,606 2,999 1983 1,275 4,839 6,114 '3.42% of total salmon passed. 2Fish not counted; estimated from harvest at upper weir. 19 Table 7.- Number of trout passed upstream at the Platte River lower weir, 1983. Steelhead Brown trout Lake trout Swam Swam Date Handled up Handled up Handled 9/16 6 1 9/17 3 0 Weekly total 9 18 1 2 0 9/18 10 0 9/19 9 0 9/20 23 3 1 9/21 76 6 9/22 64 5 9/23 45 7 9/24 16 2 Weekly total 243 30 23 3 1 9/25 74 3 9/26 82 3 9/27 87 1 9/29 57 3 10/1 142 2 Weekly total 442 73 12 2 0 10/4 286 3 10/7 157 3 1 Weekly total 443 143 6 2 1 10/11 145 3 1 10/14 86 1 1 Weekly total 231 21 4 0 2 10/17 147 2 2 10/20 4 0 1 Weekly total 151 -68 2 1 3 20 Table 8. Number of coho salmon harvested at the Platte River upper weir, 1983. Adults Females Date Jacks Males Round Stripped Mortalities 10/13 1,359 833 694 450 0 10/14 809 I,1i0 694 509 84 Weekly total 2,168 1,943 1,388 959 84 10/17 708 1,202 740 660 93 10/18 600 770 590 571 0 10/19 600 ii0 555 670 45 10/20 686 925 370 620 0 10/21 209 275 90 220 102 Weekly total 2,803 4,282 2,345 2,741 240 10/24 413 648 92 612 86 10/25 163 431 93 473 28 10/26 140 400 60 430 0 10/27 126 740 40 520 180 10/28 90 463 93 546 96 Weekly total 932 2,682 378 2,581 390 10/31 146 465 0 515 75 11/1 360 2,117 1,713 125 20 Weekly total 506 2,582 1,713 640 95 11/10 113 508 532 40 70 Weekly total 113 508 532 40 70 11/29 31 324 351 0 0 Weekly total 31 324 351 0 0 Annual total 6,553 12,321 6,707 6,961 879 21 Table 9. Mean lengths coho salmon, Platte River (inches) and weights (pounds) of jack from biological samples taken at the upper weir, 1983. Mean Week Total fish beginning harvested Length Weight 10/9 2,168 15.7 1.61 10/16 2,803 16.9 1.61 10/23 932 16.9 1.61 10/30 506 15.8 1.44 11/6 113 15.81 1.441 11/27 31 15.81 1.441 Total 6,553 Weighted mean 16.4 1.59 'Assumed to be the same as samples taken week of October 30 22 Table 10. Pounds of coho salmon harvested at the Platte River upper weir, 1983. Adults Females Date Jacks Males Round Stripped Mortalities 10/13 2,186 5,439 4,365 2,489 0 10/14 1,303 7,249 4,365 2,815 538 Weekly total 3,490 12,688 8,730 5,304 538 10/17 1,140 7,853 4,654 3,651 595 10/18 966 4,936 3,840 3,089 0 10/19 966 7,114 3,613 3,624 293 10/20 1,105 5,928 2,410 3,353 0 10/21 335 1,764 586 1,190 659 Weekly total 4,512 27,595 15,103 14,907 1,547 10/24 666 4,153 604 3,333 556 10/25 262 2,762 604 2,560 181 10/26 225 2,564 390 2,326 0 10/27 203 4,742 260 2,813 1,153 10/28 146 2,967 604 2,954 622 Weekly total 1,502 17,188 2,462 13,986 2,512 10/31 236 2,976 0 2,780 481 11/1 518 13,655 11,049 675 130 Weekly total 754 16,631 11,049 3,455 611 11/10 163 3,276 3,430 216 452 Weekly total 163 3,276 3,430 216 452 11/29 44 2,090 2,273 0 0 Weekly total 44 2,090 2,273 0 0 Annual total 10,465 79,468 43,047 37,868 5,660 Mean weight 1.60 6.45 6.42 5.44 6.44 23 Table 11. Number and weight (pounds) of chinook salmon (adults and jacks combined) harvested at the Platte River upper weir, 1983. Males Females Mortalities Date Number Weight Number Weight Number Weight 10/13 1 7.9 1 11.9 0 10/14 2 9.5 2 18.5 0 Weekly total 3 17.4 3 30.4 0 0 10/17 2 9.0 1 14.3 0 10/18 4 19.0 0 0 10/20 3 18.1 0 0 10/21 1 4.0 0 0 Weekly total 10 50.1 1 14.3 0 0 10/24 10 72.1 2 30.0 0 10/25 15 149.0 1 13.0 2 20.9 10/26 5 26.0 0 0 10/27 8 52.0 0 0 10/28 21 214.1 5 82.9 0 Weekly total 59 513.2 8 125.9 2 20.9 10/31 11 76.1 3 45.0 0 11/1 94 943.6 34 548.9 0 Weekly total 105 1,019.7 37 593.9 0 0 11/10 34 339.5 25 405.6 0 Weekly total 34 339.5 25 405.6 0 0 11/29 4 39.9 5 75.0 0 Weekly total 4 39.9 5 75.0 0 0 Annual total 215 1,979.8 79 1,245.1 2 20.9 '1 I! I 'I I WI ~1 II