Fishing / Shellfishing - Selective Fishing
Date Published: June 28, 2010
Number of Pages: 65
Author(s): Mark Baltzell, Steve Caromile, Karen Kloempken, and Laurie Peterson
The Washington Department of Fish and Wildlife (WDFW) implemented mark-selective Chinook fisheries (MSFs) in Marine Areas 9 and 10 for the third time, from July 16 through August 31, 2009. 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. WDFW’s Puget Sound Sampling Unit (PSSU) implemented an intensive monitoring program in Areas 9 and 10 during their respective summer seasons in order to collect the data needed to provide in-season catch estimates 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 mortalities1, 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) for a total of 68 sampling-site days in each of Areas 9 and 10. Samplers interviewed an estimated 22% and 28% of all anglers fishing in Area 9 (n = 9,255 private and 6 charter anglers) and Area 10 (n = 6,482 private and 76 charter anglers), respectively. Additionally, they sampled 19% (Area 9) and 30% (Area 10) of all marked Chinook harvested in the two areas (n = 629 in Area 9, n = 483 in Area 10). Other PSSU staff conducted 12 on-the-water effort surveys (6 in Area 9, 6 in Area 10), and spent 66 days (353 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 65,480 angler trips (42,225 in Area 9, 23,255 in Area 10) were completed by private and charter anglers in the two combined areas between July 16th and August 31st. With a season-wide CPUE of 0.08 Chinook retained per angler trip in Area 9 and 0.07 in Area 10, these anglers harvested a grand total of 3,229 and 1,621 marked Chinook in the two respective areas (4,850 total). Anglers additionally released an estimated 12,895 Chinook (8,718 marked, 4,177 unmarked) in Area 9 and 3,807 Chinook (2,708 marked, 1,099 unmarked) in Area 10 (i.e., 16,702 estimated releases overall).
Over the two areas, harvested Chinook averaged 73 cm (range: 18 to 99 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, >93% of legal size). For both areas combined, approximately 49% all harvested individuals were 3-year olds (brood year 2006), and 40% were 4-year olds (brood year 2005).
In addition to taking length measurements and scale samples, ramp samplers recovered 105 decoded CWTs from marked Chinook harvested in the Areas 9 (n = 57) and 10 (n = 48) fisheries. The majority of Area 9 tag recoveries were from Hood Canal (30%), South Puget Sound (28%), and Central Puget Sound (23%) release sites. The remaining Area 9 recoveries were from release sites in North Puget Sound (12%), Columbia River (5%), and British Columbia (2%). As for individual hatcheries, tag recoveries from the Hoodsport Hatchery were most abundant (19% of fishery total), followed by Garrison Hatchery (12% of total) and Nisqually Hatchery (11% of total). Ten of the Area 9 CWT recoveries were from double index tag (DIT) releases. Of the 48 CWTs recovered in the Area 10 fishery, over half (52%; 25 tags) originated from Central Puget Sound release sites. The remaining 23 recoveries consisted of Chinook from South Puget Sound (29%), Hood Canal (15%), and North Puget Sound (4%) production facilities. Of the individual release sites, Grover’s Creek tags had the greatest representation (23% of total) in the Area 10 fishery. Finally, 16 of the 48 CWTs were associated with DIT releases.
During their 1.5 months of sampling in Areas 9 and 10 while the areas were open under mark-selective regulations, test fishers encountered 154 (100 in 9, 54 in 10) Chinook salmon, 76% (74% in 9, 80% in 10) of which were marked and on average one-third (30% in 9, 33% in 10) of which were of legal size. With a “CPUE” (legal-marked Chinook encounters / angler trip) of 0.33 in Area 9 and 0.26 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. Test-fishery Chinook total lengths averaged 49 cm (marked and unmarked mean, range: 15-93 cm) in Area 9 and 47 cm (range: 15-100 cm) in Area 10. Thus, Chinook total lengths were on average slightly greater in Area 9 than Area 10, 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 47-day season, we estimated the season-wide size/mark-status composition at 22% legal-marked (LM), 8% legal-unmarked (LU), 52% sublegal-marked (SM), and 18% sublegal-unmarked (SU) in Area 9, and 32% LM, 2% LU, 48% SM, and 19% 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, 16,143 Chinook were encountered (retained and released) during the Area 9 fishery, with 3,552 of these being legal-marked, 1,291 legal-unmarked, 8,395 sublegal-marked, and 2,905 sublegal-unmarked individuals; in Area 10, 5,450 Chinook were encountered (1,725 LM, 104 LU, 2,604 SM, and 1,017 SU). Among released encounters, an estimated 102 legal-marked, 203 legal-unmarked, 2,149 sublegal-marked, and 784 sublegal-unmarked Chinook (3,238 overall, 77% in Area 9, 23% 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, 7,100 marked (68% due to direct harvest) and 1,028 unmarked Chinook mortalities occurred as a result of the Areas 9 and 10 fisheries. Overall, estimated impacts were considerably less than what was expected based on pre-season Fishery Regulation Assessment Model runs (model run 2309) for both Areas 9 and 10.
Finally, regarding impacts of the Areas 9 and 10 summer 2009 MSFs on the coded-wire tag (CWT) program, we estimated that a total of 16 (10 in Area 9 and 6 in Area 10) unmarked Chinook belonging to double-index tag (DIT) groups may have died due to the handling-and-release impacts in the fisheries.
1 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.
approximately 49% all harvested individuals were 3-year olds (brood year 2006), and 40% were 4-year olds (brood year 2005)