Fishing / Shellfishing - Selective Fishing
Date Published: February 23, 2009
Number of Pages: 61
Author(s): Peter McHugh, Mark Baltzell, and Laurie Peterson
The Washington Department of Fish and Wildlife (WDFW) implemented quota-based mark-selective Chinook fisheries (MSFs) in Marine Areas 9 and 10 for the second time from July 16 through August 15, 2008. Consistent with the 2004 Puget Sound Chinook Harvest Management Plan (Puget Sound Indian Tribes and WDFW 2004) and the intent of previous Puget Sound/Strait of Juan de Fuca mark-selective Chinook fisheries, the primary goal for this fishery was to provide meaningful opportunity to the recreational angling public while minimally impacting ESA-listed Puget Sound Chinook salmon. WDFWes Puget Sound Sampling Unit (PSSU) implemented an intensive monitoring program in Areas 9 and 10 during their respective summer quota seasons in order to collect the data needed to provide in-season catch estimates (i.e., for assessing catch status relative to quotas1) and to estimate key parameters characterizing the fishery and its impacts on unmarked salmon. Sampling activities included dockside creel sampling, test fishing, and on-the-water effort surveys. Among other parameters, efforts emphasized data collection needs for the estimation of: i) the mark rate of the targeted Chinook population, ii) the total number of Chinook salmon harvested (by size [legal or sublegal] and mark-status [marked or unmarked] group), iii) the total number of Chinook salmon released (by size/mark-status group), iv) the coded-wire tag- (CWT) and/or DNA-based stock composition of marked and unmarked Chinook mortalities2, and v) the total mortality of marked and unmarked double index tag (DIT) CWT stocks.
Creel samplers staffed eight different access sites (4 in Area 9, 4 in Area 10; 2 total in each area on any given sampling day) on 24 of the 30 and 31 days, respectively, that Areas 9 and 10 were open to Chinook retention under mark-selective regulations. Samplers interviewed an estimated 24% and 29% of all anglers fishing in Areas 9 (n = 4,679 private, 304 charter) and 10 (n = 3,430 private, 632 charter), respectively. Additionally, they sampled 19% (Area 9) and 23% (Area 10) of all marked Chinook harvested in the two areas (n = 788 in Area 9, 232 in Area 10). Other PSSU staff conducted 11 on-the-water effort surveys (5 in Area 9, 6 in Area 10), and spent 43 days (255 hours) on the water pursuing Chinook using test-fishing methods, in support of Areas 9 and 10 monitoring efforts.
Based on the combination of sampling activities, we estimated that nearly 35,000 angler trips (20,399 in Area 9, 13,808 in Area 10) were completed by private and charter anglers in the two combined areas between July 16th and August 15th. With a season-wide CPUE of 0.198 Chinook retained per angler trip in Area 9 and 0.075 in Area 10, these anglers harvested a grand total of 4,045 and 1,031 marked Chinook in the two respective areas (5,076 total), nearly 2,000 fish shy of the combined-area quota (7,000). Anglers additionally released an estimated 9,242 Chinook (3,808 marked, 5,434 unmarked) in Area 9 and 1,212 Chinook (317 marked, 895 unmarked) in Area 10 (i.e., 10,454 releases overall). Overall, catch rates as well as catch and effort totals were substantially lower during the 2008 compared to the 2007 Areas 9 and 10 summer quota seasons.
Over the two areas, harvested Chinook averaged 73 cm (range: 55 to 95 cm) in total length and were larger than the legal minimum size limit (>22 in or 56 cm TL) in most instances (dockside marked Chinook observations, >99% of legal size). In both areas, more than four-fifths of all harvested individuals were 3-year olds (i.e., brood year 2005). In addition to taking length measurements and scale samples, ramp samplers recovered 97 CWTs from marked Chinook harvested in the Areas 9 (n = 70) and 10 (n = 27) fisheries. The majority of Area 9 tag recoveries (58%) were from Central Puget Sound (27%) and Hood Canal (31%) release sites. Among individual CWT release regions, Central Puget Sound fish were most abundant among Area 10 CWT recoveries.
During their one month of sampling in Areas 9 and 10 while they were open under mark-selective regulations, test fishers encountered 101 (66 in 9, 35 in 10) Chinook salmon, ~60% (59% in 9, 60% in 10) of which were marked and on average half (47% in 9, 74% in 10) of which were of legal size. With a "CPUE" (legal-marked Chinook encounters / angler trip) of 0.52 in Area 9 and 0.43 in Area 10, test fishers encountered legal-marked Chinook at a higher rate than private fleet anglers but at a rate similar to that of charter anglers. As was the case for private fleet anglers, test fishers experienced substantially lower catch rates during the 2008 compared to the 2007 summer quota season. Test-fishery Chinook total lengths averaged 47 cm (marked and unmarked mean, range: 14-85 cm) in Area 9 and 63 cm (range: 22-87 cm) in Area 10. Thus, Chinook total lengths were on average greater in Area 10 than Area 9, but highly variable in both areas. This was assumedly due to the presence of both juvenile resident and mature migrant Chinook in both Areas during the latter half of the season. For the entire one-month season, we estimated the season-wide size/mark-status composition at 35% legal-marked (LM), 12% legal-unmarked (LU), 24% sublegal-marked (SM), and 29% sublegal-unmarked (SU) in Area 9 and 51% LM, 23% LU, 9% SM, and 17% SU in Area 10.
By combining dockside-sampling results (i.e., legal-marked Chinook harvest estimates), test fishery encounters data, and charter census results, we generated size/mark-status group-specific estimates of encounters and mortalities for the two areas. In total, 13,290 Chinook were encountered (retained and released) during the Area 9 fishery, with 4,632 of these being legal-marked, 1,611 legal-unmarked, 3,222 sublegal-marked, and 3,826 sublegal-unmarked individuals; in Area 10, 2,246 Chinook were encountered (1,155 LM, 513 LU, 193 SM, and 385 SU). Among released encounters, an estimated 108 legal-marked, 317 legal-unmarked, 680 sublegal-marked, and 842 sublegal-unmarked Chinook (1,948 overall, 89% in Area 9, 11% in Area 10) were estimated to have died due to handling and release effects of the Areas 9 and 10 fisheries combined. Thus, in total, 5,865 marked (86% due to direct harvest) and 1,165 unmarked Chinook mortalities occurred as a result of the Areas 9 and 10 fisheries. Overall, estimated impacts were similar to (Area 9) or considerably less than (Area 10) what was expected based on pre-season Fishery Regulation Assessment Model runs (model run 2108). Finally, regarding impacts of MSFs on the coded-wire tag (CWT) program, we estimated that 16 and 6 unmarked Chinook belonging to double-index tag (DIT) groups may have died due to the handling-and-release impacts of respective Areas 9 and 10 fisheries.
1 Areas 9 and 10 were managed to a combined-area landed catch total of 7,000 marked Chinook, with pre-season guidance emphasizing target catches of 4,000 in Area 9 and 3,000 in Area 10. If fisheries did not close due to catch totals meeting quotas, the latest day of scheduled fishing was August 15th, 2008, for both areas.
2 Though the necessary tissue samples have been collected, DNA-based estimates of stock composition are presently unavailable for Puget Sound/Strait of Juan de Fuca mark-selective fisheries. In the present report, CWT-based (unexpanded) estimates of the stock composition of marked Chinook harvest are provided.
Marine Areas 9 and 10 Mark-Selective Recreational Chinook Fishery, July 16-August 15, 2008 Post-season Report. Revised Draft: February 23, 2009. 60 pp. Washington Department of Fish and Wildlife. Olympia, Washington.