R.J. Beamish, R.M. Sweeting and K.L. Lange

Transcription

1 A preliminary interpretation of coded wire tag recoveries from juvenile coho and chinook salmon released into the Strait of Georgia and Puget Sound from 1997 to 26 R.J. Beamish, R.M. Sweeting and K.L. Lange Abstract We report the results of an analysis of over 4, coded-wire tag recoveries of ocean age coho and chinook salmon captured in our surveys from 1997 to 26. In general, the pattern of release and recaptures indicated that coho salmon released into the Strait of Georgia virtually never enter Puget Sound and only a few percent of the chinook salmon released in the Strait of Georgia enter Puget Sound. An average of 9.6% of coho salmon that were released into Puget Sound move into the Strait of Georgia and 8% were from the Nooksack / Skagit area. Coho salmon released into this area were not common in our catches in Puget Sound. Most coho salmon left Puget Sound in August and the Strait of Georgia in ember. Chinook salmon remained in Puget Sound through ember. A comparison of observed recapture percentages with expected percentages identified hatcheries and release areas that were consistently above and below expected recoveries in the Strait of Georgia and Puget Sound. Keywords Juvenile coho salmon, juvenile chinook salmon, coded wire tag, Strait of Georgia, Puget Sound Introduction The distribution, abundance and ecology of juvenile coho (Oncorhynchus kisutch) and chinook (O. tshawytscha) salmon in the Strait of Georgia and Puget Sound were studied from 1997 to the present (Beamish et al. 2a; Beamish et al. 27; Sweeting et al. 23). We started our surveys in 1997 to determine the causes of a declining marine survival of coho and chinook salmon. We completed surveys in the Strait of Georgia in and ember each year, except for 23 when we were not given ship time. We surveyed less frequently in Puget Sound as less time was available and there were restrictions relating to the number of juvenile chinook salmon that could be caught. An important aspect of our study was a comparison of the ecology of hatchery and wild rearing types. In this paper, we report the preliminary interpretation of information obtained from Pacific salmon in our catches from 1997 to 26 that had a coded wire tag (CWT). Results are preliminary because we report recaptures and assess the importance of the recaptures relative to releases; and we are not comparing recapture percentages with specific marine survival estimates for the particular release sites. Comparisons with site specific marine survival estimates require a careful analysis of catch and escapement information that includes a measure of detective work to assess the reliability of the data. We expect to make the comparisons with marine survivals, but we will need more resources than we currently possess. The results are also preliminary because some recapture information is incomplete. However, we captured over 4, coho and chinook salmon with CWTs which were sufficient to identify patterns. Information from the CWTs obtained in our catches helps to evaluate the efficiencies of individual hatchery releases as well as facilitate comparisons between the dynamics of hatchery and wild rearing types. We believe that the information provided in this report is the first comprehensive assessment of CWT data from juvenile coho and chinook salmon from these two major ecosystems. 1

2 Methods Annual surveys occurred in and ember from 1997 until the present (26). The survey methodology, the net design and the processing of catch have been reported previously (Beamish et al. 2b, Sweeting et al. 23). The track lines shown in Figure 1 required about eight days to complete in the Strait of Georgia and two days to complete in Puget Sound. Some cruises were longer or shorter, depending on schedules. In the Strait of Georgia, sets were 3 min in duration whereas they were mostly 1-1 min in Puget Sound. In some surveys, additional sets were made in adjacent areas, and in Puget Sound some track lines were not fished, due to vessel breakdowns and fishing restrictions. There was no survey in 23. We standardize catches to account for differences in fishing times as the number of fish that would be caught in one hour. In this report, we include catches in areas adjacent to the standard track lines in the Strait of Georgia and Puget Sound. All coho and chinook salmon were examined for missing fins and scanned with a hand-held coded-wire tag detector (Northwest Marine Technology, Wash., USA) to determine if a CWT was present. Fork lengths were recorded to the nearest mm. Fish with a CWT were sampled to remove the CWT which was subsequently decoded to identify the release site. In this report we are not including recaptures of coded wire tagged wild coho and chinook salmon. Results The track lines for the Strait of Georgia and Puget Sound are shown in Figure 1. There were 1,78 sets made in the Strait of Georgia and 236 sets made in Puget Sound from 1997 to 26 (Tables 1 and 2). In, the standardized catch or catch per unit effort (CPUE) for juvenile chinook salmon was approximately ten times larger in Puget Sound than in the Strait of Georgia (Table 1). The CPUE of juvenile chinook salmon declined in both areas in ember, but the CPUE in Puget Sound remained much larger (five times) than in the Strait of Georgia. In, the CPUE of coho salmon was about 3. times larger in Puget Sound than in the Strait of Georgia. However, by ember catches and the CPUE of coho salmon in Puget Sound dropped dramatically, indicating that large numbers of juvenile coho salmon left Puget Sound between and ember. Catches and the CPUE of coho salmon in the Strait of Georgia also declined in ember, but were about twice the size of catches and CPUE in Puget Sound. In another study (Beamish et al. 27) we show that the decline in catch in ember in the Strait of Georgia probably results from mortalities and not from movement out of the Strait of Georgia. There were 4,6 CWTs obtained from juvenile coho and chinook salmon in both areas from 1997 to 26. The CWTs from the 26 survey are included in Table 3, but not used in this analysis as not all tags have been decoded. In the Strait of Georgia, we obtained 822 CWTs from juvenile chinook salmon, of which 11 were from hatcheries in the United States. There were nine recaptures from releases on the west coast of the United States, three from the Columbia River and six from the Snake River. The remaining were from hatcheries or release sites in WA1 (2), WA2 (34), WA3 (7), WA4 (1), WA (2) and WA6 (1). These release areas are show in Figure 1 and the release sites listed in Table 4. There were 1,71 CWTs recovered from juvenile coho salmon in the Strait of Georgia with 241 CWTs from hatcheries in the United States, all of which were in Puget Sound. Hatcheries in the 2

3 Nooksack / Samish area (WA1) area contributed 8% of these CWTs, with the remaining CWTs from the other sites in Puget Sound. Figure 1. Map of Strait of Georgia and Puget Sound showing survey track lines. Inset map shows boundaries and names of areas in Puget Sound used in the paper. Track Lines In Puget Sound, we recaptured 1,74 juvenile chinook salmon with CWTs. All but 1 were from release sites within Puget Sound. The 1 CWTs from Canadian releases were all from mainland hatcheries with 6% coming from the Chilliwack hatchery. Other recaptures were from releases from Capilano, Spius Creek, Inch Creek, Salmon River and Chehalis hatcheries. The 419 coho salmon with CWTs in Puget Sound all were from Puget Sound releases. No CWTs from coho salmon originating from hatcheries around the Strait of Georgia were recaptured in Puget Sound. In the Strait of Georgia, the percentage of coho salmon from Puget Sound ranged from % to 1%, averaging 11% in and 9% in ember (Table ). This percentage is the calculated number of coho salmon from Puget Sound in the catch. The CWT tagging percentages in hatcheries around Puget Sound were used to expand the recaptures in the Strait of Georgia to produce an estimate of the total hatchery coho salmon from Puget Sound. Trends in recapture percentages Trends in recaptures are shown as anomalies from the expected recapture percentages. The number of coho and chinook salmon with a CWT was determined for all releases in the Strait of Georgia and Puget Sound. If these marked fish were randomly mixed, and if the survey randomly sampled this population,catching large numbers of fish with CWTs, then the recapture 3

4 Table 1. Summary of catches and catch per unit effort (CPUE) in for the Strait of Georgia and Puget Sound. Strait of Georgia Puget Sound Coho Chinook Coho Chinook Year # of Catch CPUE Catch CPUE # of Catch CPUE Catch CPUE Sets Sets , , , , , , , , , , , ,26 1, , , , , , , , , , , , , , , Total ,8 21, 11 7,229 16,28 Ave Table 2. Summary of catches and catch per unit effort (CPUE) in ember for the Strait of Georgia and Puget Sound. Strait of Georgia Puget Sound Coho Chinook Coho Chinook Year # of Catch CPUE Catch CPUE # Catch CPUE Catch CPUE Sets ofsets ,14 3 3, , , , , , , , , ,2 4 1, , , , , , Total 91 12,31 17, ,624 1 Ave percentages would be expected to approximate the release percentages. If the number of recaptures of fish with a CWT is smaller, then not all releases would be expected to be in the sample and some releases would be over-represented while others would be under-represented. However, there would not be any trend unless a particular release was consistently less available for capture. Thus, we used the anomaly of each release by subtracting the observed percentage in the catch from the expected percentage to compare recaptures. For any particular survey, the anomaly percentage may simply represent a sampling bias. However, if there is as trend in the anomalies, we suggest that it is an indication that the fish from that particular release were either more or less available for recapture. 4

5 Chinook salmon in the Strait of Georgia Observed recapture percentages were compared to expected recapture percentages for 12 major hatcheries representing about 88% of all releases. For each year, the number of juvenile chinook salmon receiving a CWT was determined for each hatchery and the expected recapture percentage of all CWT releases was determined (see example in Table 6). The observed recapture percentage for these hatcheries was determined from the catch and the anomalies of the observed minus expected were compared among surveys. Table 3. Summary of number of CWTs recaptured in and ember for the Strait of Georgia and Puget Sound. ember Strait of Georgia Puget Sound Strait of Georgia Puget Sound Year Coho Chinook Coho Chinook Coho Chinook Coho Chinook a 4 a a 97 a lost data b lost data b no survey no survey no survey no survey no survey no survey a 14 a 2 lost data b lost data b a 166 a a 13 a a Reporting of CWT is incomplete and data not used in this analysis. b In 22 and 2, samples were not recovered from the freezers on the vessel, thus release location is not available. Trends in anomaly percentage were observed for about one half of the hatchery releases. Negative trends were observed for releases from the Cowichan, Quinsam, Chilliwack and Chehalis hatcheries. Strong positive trends were observed for the Puntledge and Nanaimo River hatcheries. The pattern in the other hatcheries was more random (Figure 2). Tenderfoot and Powell River hatcheries did not release CWT fish in all years, thus the time series are shorter. In, 23% of the recoveries from mainland hatcheries and 41% of the recoveries from Vancouver Island hatcheries were observed to be equal to or exceed the expected recapture percentages in our catch. A chi-square test (P =.13), indicated that these percentages were not significantly different. In ember, 17% of the mainland and % of the Vancouver Island recoveries from hatcheries were observed to be equal to or exceed the expected recapture percentages. The Vancouver Island observed recaptures were significantly larger than the mainland recoveries (chi-square test, P.1). We used recapture percentage anomalies exceeding two times the expected as an indication of very good recoveries. Puntledge and Nanaimo River hatcheries consistently had very good recaptures percentages, while five hatcheries were never observed to have any recapture percentage anomalies that exceeded two times the expected (Table 7).

6 Table 4. Release hatcheries and sites in Puget Sound. WA1 (OK) (British Columbia border to Skagit River) Glenwood Springs Lummi Net Pens (Tribal) Bellingham Hatchery Kendall Creek Nooksack River Hatchery Skookum Creek (Tribal) Samish River Hatchery Swinomish River (Tribal) Puget Power (Public Project) WA2 (SKAG) (Skagit River to Stillaguamish River) Skagit River Hatchery Marblemount Stillaguamish River (Tribal) Whitehorse Ponds Oak Harbor (Island) Whidbey Island (Island) WA3 (STIL) (Stillaguamish River to Snohomish River) Tulalip Skykomish WA4 (MPS) (Snohomish River, south to Tacoma Narrows) Montlake (Federal) University of Wash. Seattle Aquarium Elliot Bay Net Pens Issaquah Creek Tolkul Creek Reiter Ponds Wallace River NW Steelheaders Green River Crisp Creek Keta Creek WA4 (SPS) (Snohomish River, north to Hood Canal) Totem Marina (Tribal) Puyallup (Tribal) Puyallup River, includes tributaries Diru Ck, Rushing Water, Cowskull Ponds Narrows Net Pens Chambers Creek Garrison Springs Deschutes River Allison Springs Nisqually River White River Lakewwod Icy Creek Soos Creek Voights Creek Kalma Creek Skookumchuk River Tumwater Falls South Sound Net Pens (Squaxin) Shaw s Cove Net Pens Gig Harbor Net Pens Hupp Springs Filucy Bay Net Pens Fox Island Net Pens Minter Creek Coulter Creek WA (HOOD) (Hood Canal to Port Townsend) George Adams Shelton Enetai (Tribal) Hoodsport Gorst Creek Grovers Creek (Tribal) Port Gamble Net Pens (Tribal) McKernan Hood Canal Fox Island Net Pens Manchester (Federal) Suquamish Net Pens (Tribal) Quilicene River (NFH) WA6 (JUAN) (Juan de Fuca Strait to Neah Bay) Hurd Creek Sol Duc Dungeness River Lower Elwha (Tribal) Elwha Channel UPWA (NWC) & LWWA (GRAY) (west coast of Washington State) Hoko Ponds Makah (NFH) Lonesome Creek Soleduck River 6

7 Table. Percentage of coho salmon from Puget Sound captured in the Strait of Georgia. Year (%) ember (%) no survey Average 11 1 Table 6. CWT releases, CWT recoveries, expected recaptures, observed recaptures and percentage recapture anomalies for chinook salmon originating from Strait of Georgia hatcheries in Number Tagged CWT (N) CWT (N) Hatchery Release % Expect. Observ. Anomaly Observ. Anomaly % % % Chehalis 3,72, , Chilliwack 2,33, , Powell River 376, , Tenderfoot 1,76, , Shuswap 984, , Spius 477, , Big Qualicum 3,961, , Cowichan 262, , Little Qualicum 2,639, , Nanaimo River 23, , Puntledge 1,367, , Quinsam 1,72, , All other releases 2,67, , Table 7. Recapture percentage anomalies for major hatcheries producing chinook salmon in the Strait of Georgia that exceeded two times the expected percentage. Hatchery % of surveys where recapture percentage anomaly exceeded 2X the expected Puntledge 3 Nanaimo 4 Spius 27 Little Qualicum 27 Big Qualicum 2 Powell River 13 Shuswap 13 Qunisam Cowichan Chilliwack Chehalis Tenderfoot 7

8 Figure 2. CWT recapture percentage anomaly for chinook salmon in the Strait of Georgia. Open bars are samples and dark bars are ember samples. 1 Cowichan 1 Chilliwack Puntledge 3 2 Chehalis Big Qualicum 2 1 Shuswap Little Qualicum Spius Quinsam Tenderfoot Nanaimo River 1 Powell River

9 Coho salmon in the Strait of Georgia Eight major hatcheries produce an average of 8% of all coho salmon released into streams and rivers flowing into the Strait of Georgia. Expected and observed recapture percentages and resulting anomalies were determined for each cruise for these 8 hatcheries (Table 8) as were determined for chinook salmon. Capilano, Chehalis and Tenderfoot hatcheries did not apply CWTs in all years of the survey (Figure 3). Only Quinsam hatchery releases consistently were below the expected recapture percentage, although releases from Tenderfoot hatchery were negative in four of the five surveys. Releases from Inch Creek and Chehalis hatcheries were consistently close to or exceeded the expected recapture percentages. In recent years, there was a tendency for the recoveries from Big Qualicum hatchery to be below the expected (Figure 3). Table 8. Example of the summary produced for each year that includes the number of CWT recoveries, expected recaptures, observed recaptures and percentage recapture anomalies for coho salmon originating from Strait of Georgia hatcheries in Hatchery Release % Number Tagged Expect. % CWT (N) Observ. % Anomaly CWT (N) Observ. % Anomaly Chilliwack 1,87, , Quinsam 1,411, , Big Qualicum 1,322, , Chehalis 1,171, , Inch Creek 84, , Puntledge 689, , Capilano 3, , Tenderfoot 323, , All other releases 1,461, , In, 7% of the major coho hatcheries on the mainland had recapture percentages equal to or exceeding expected, compared to 33% from Vancouver Island (chi-square test, P =.14). In ember the mainland percentage dropped slightly to % while the Vancouver Island percentage dropped to 27%, significantly lower than the mainland percentage (chi-square test, P =.3). Recapture percentages from the Inch Creek hatchery were more than double the expected percentages in 29% of the surveys. The other 7 major hatcheries had double the expected recapture percentages in14% (Chehalis, Capilano), 7% (Chilliwack, Big Qualicum, Puntledge) and % (Quinsam, Tenderfoot) of surveys. Puget Sound The hatcheries producing chinook and coho salmon around Puget Sound were grouped into areas identified by the Pacific Salmon Commission (Kuhn et al. 1988, Table 4). For convenience, we retained a designation of Washington Areas (WA) 1 to 6 (Table 4). Juvenile chinook salmon recapture percentage anomalies from releases in WA1, WA2 and WA6 were consistently negative (Figure 4). It was interesting that juvenile chinook salmon released from areas WA1 and WA2 were the most common chinook salmon from Puget Sound that were found in our catches in the Strait of Georgia. We did not capture chinook salmon released in WA6 (Juan de Fuca Strait) in Puget Sound as expected. Most releases were 9

10 into WA4 and our recapture percentages of these fish consistently exceeded the expected. The consistently positive recapture anomalies indicated that our survey area included mostly the releases from hatcheries in areas WA3, WA4 and WA. Hatchery releases that consistently exceeded the expected recaptures are identified in Table 9. Kalma Creek and Grovers Creek hatcheries stood out as consistently having very good recapture percentages. Figure 3. CWT recapture percentage anomaly for coho salmon in the Strait of Georgia. Open bars are samples and dark bars are ember samples. 3 2 Inch Creek 1 Puntledge Chilliwack 1 1 Capilano - no tagged releases Quinsam 1 Chehalis Big Qualicum Tenderfoot

11 Figure 4. CWT recapture percentage anomaly for chinook salmon in Puget Sound. Open bars are samples and dark bars are ember samples. 1 WA1 6 WA WA WA WA WA Recapture percentage anomalies were consistently negative for coho salmon released into WA1, WA and WA6. Releases into WA3 and WA4 consistently resulted in positive anomalies (Figure ). The recapture percentage anomalies were always (1%) greater than expected in these two areas with the largest anomalies resulting from releases into area WA3 indicating that large abundances of coho salmon from these release areas were in our survey area. Most of the coho salmon from Puget Sound that were recaptured in the Strait of Georgia were released into WA1; thus it appears that few of these coho salmon rear in the survey area in Puget Sound. A ranking of hatcheries that had the largest anomalies is shown in Table 9. Releases from Wallace River hatchery ranked as the releases that most frequently exceeded the expected recapture percentages. 11

12 Table 9. Hatcheries in Puget Sound that producing chinook salmon that most frequently exceeded expected returns in catch. Hatchery Release Area Percentage of surveys in which recapture percentage anomaly exceeded 2X the expected Kalma Creek Hatchery WA4 3% Grovers Creek Hatchery WA 22% Nisqually Hatchery WA4 17% Soos Creek Hatchery WA4 14% Puyallup Tribal Hatchery WA4 14% White River Hatchery WA4 8% Garrison Hatchery WA4 8% Hupp Springs Hatchery WA4 8% Issaquah Hatchery WA4 6% Figure. CWT recapture percentage anomaly for coho salmon in Puget Sound. Open bars are samples. Since coho salmon typically leave Puget Sound in August, there were very few recaptures during the ember surveys. WA1 4 WA DATA DATA WA2 1 WA DATA -1 DATA WA3 WA DATA - -1 DATA

13 Discussion This is a preliminary report of the CWT information from our surveys. Our analysis in this report is sensitive to small sample sizes. This may cause some extreme estimates of recapture anomalies in any particular survey. However, we propose that consistent trends in the anomalies indicate that a particular release is over- or under-represented in our catches. We suggest that these trends are a measure of early marine survival if it can be shown that the juveniles are not leaving the survey area. Major conclusions from this analysis are that no coho salmon from the Strait of Georgia hatcheries move into Puget Sound. However, an average of 9.6% of the hatchery coho salmon in the Strait of Georgia were from Puget Sound hatcheries and about 8% came from releases in WA1. In the Strait of Georgia, coho salmon from Inch Creek hatchery consistently exceeded the expected returns, possibly indicating that they probably have the highest early marine survival of all releases. Chinook salmon releases from the Puntledge and Nanaimo River hatcheries consistently exceeded the expected recapture percentages, indicating that releases from these hatcheries probably have higher than average early marine survival. It was noteworthy that a small number of juvenile chinook salmon from the Columbia River hatcheries (n = 23) and Snake River hatcheries (n = 6) were captured in the Strait of Georgia. Coho salmon in Puget Sound in areas WA3 and WA4 consistently had recapture percentages that exceeded the expected, with releases from Wallace River and Elliot Bay Tribal hatcheries having very good early marine survival. Kalma Creek, Grovers Creek and Nisqually hatcheries consistently had higher than expected recapture percentages of chinook salmon, possibly indicating above average early marine survivals. The very large densities of juvenile coho salmon and chinook salmon in Puget Sound compared to the Strait of Georgia were remarkable. Acknowledgements This paper was funded in part by the Pacific Salmon Commission. We appreciate the support of the captains, officers and crew of C.C.G.S. W.E. Ricker and other vessels that were responsible for ensuring that the sampling was completed. We thank Greg Bargmann, Carol Cooper, and Elizabeth Duffy for their assistance with the collection and analysis of some data. We also thank Lana Fitzpatrick for her assistance with figures and manuscript preparation. References Beamish, R.J., D.J. Noakes, G.A. McFarlane, W. Pinnix, R. Sweeting, and J. King 2a. Trends in coho marine survival in relation to the regime concept. Fisheries Oceanography 9: Beamish, R.J., D. McCaughran, J.R. King, R.M. Sweeting, and G.A McFarlane. 2b. Estimating the abundance of juvenile coho salmon in the Strait of Georgia by means of surface trawls. North American Journal of Fisheries Management 2: R.J. Beamish, R.M. Sweeting, K.L. Lange and C.M. Neville. 27. Changes in the trend in the percentages of hatchery and wild coho salmon in the Strait of Georgia. (in press) 13

14 King, J.R. 2. Report of the study group on fisheries and ecosystem responses to recent regime shifts. North Pacific Marine Science Organization (PICES) Scientific Report No p. Kuhn, B.R., L. Lapi, and J.M. Hamer An introduction to the Canadian database on marked Pacific salmonids. Canadian Technical Report of Fisheries and Aquatic Sciences 1649: viii+6p. Sweeting, R.M., R.J. Beamish, D.J. Noakes, and C.M. Neville. 23. Replacement of wild coho salmon by hatchery-reared coho salmon in the Strait of Georgia over the past three decades. North American Journal of Fisheries Management 23: