Fishing / Shellfishing - Selective Fishing
Date Published: February 20, 2009
Number of Pages: 49
Author(s): Mark Baltzell, Peter McHugh, and Laurie Peterson
The Washington Department of Fish and Wildlife (WDFW) implemented a winter (season: January 16.April 15, 2008) mark-selective Chinook fishery (MSF) in Marine Area 9 for the first time. 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 pilot 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 Area 9 throughout February in order to collect the data needed to estimate key parameters characterizing the fishery and its impacts on unmarked salmon. Sampling activities included inclusive of 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 and 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 two of four different access sites on 64 of the 91 days that Area 9 was open under mark-selective harvest regulations. Samplers interviewed an estimated 15% of all participating anglers (n = 1,007 angler trips) and sampled 17% of all marked Chinook harvested (n = 227). Additionally, other PSSU staff conducted eight on-the-water effort surveys, and spent 51 days (240 hours) on the water pursuing Chinook using test fishing methods, in support of Area 9 monitoring efforts. Based on these activities, we estimated that 6,887 angler trips were completed by a combination of private fleet, charter, and derby anglers between mid-January and mid-April. With a CPUE of 0.20 Chinook landed per angler trip for all angler groups combined, these anglers harvested a grand total of 1,409 marked Chinook; they released an estimated 2,162 Chinook (1,484 marked, 679 unmarked). Harvested Chinook averaged 66 cm (range: 53 to 92 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, 215 legal /227 total or 95%). Over half (55%) of all harvested individuals were 3-year olds (brood year 2005), with brood year 2004 making up the 45% remainder. In addition, 24 CWTs were recovered from harvested fish, the majority of which (91.7%) were from Puget Sound (83.3%, predominantly from north Puget Sound facilities) and Hood Canal (8.3%) release sites.
During their three months of sampling in Area 9, test fishers encountered 94 Chinook salmon, 51% and 81% of which were of legal size and marked, respectively. With a "CPUE" of 0.92 (i.e., LM Chinook encounters / angler trip), test fishers encountered legal-marked Chinook at a higher rate than did at-large private fleet anglers but at a rate comparable to that experienced by charter anglers. Chinook encountered by test fishers averaged 57 cm in total length and were predominantly 3 years in age (89% of marked and 81% of unmarked totals). For the fishery as a whole, we estimated the size/mark-status composition at 42.6% legal-marked, 8.5% legal-unmarked, 38.3% sublegal-marked, and 10.6% sublegal-unmarked.
By combining dockside sampling results (i.e., legal-marked Chinook harvest estimates), test fishery size/mark-status composition data, and charter census results, we generated size/mark-status group-specific estimates of encounters and mortalities. In total, 3,570 Chinook were encountered (retained and released) during the Area 9 fishery, with 1,528 of these being legal-marked, 307 legal-unmarked, 1,360 sublegal-marked, and 375 sublegal-unmarked individuals. Among released encounters, an estimated 29 legal-marked, 46 legal-unmarked, 258 sublegal-marked, and 75 sublegal-unmarked Chinook (408 overall) were estimated to have died due to handling and release effects. Thus, in total, 1,816 marked (83% due to direct harvest) and 124 unmarked Chinook mortalities occurred as a result of the Area 9 fishery. Although estimated legal-marked Chinook impacts were within ~20% of what pre-season Fishery Regulation Assessment Model runs predicted (model run 3907), field estimates for the three other size/mark-status (i.e., for sublegal-marked fish and unmarked fish of all sizes) groups were considerably less (50-74%) than what was expected. Finally, regarding impacts of MSFs on the coded-wire tag (CWT) program, we estimated that 7 unmarked Chinook belonging to double-index tag (DIT) groups may have died due to the handling-and-release impacts of the pilot Area 9 fishery.
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.
Marine Area 9 Mark-Selective Recreational Chinook Fishery, January 16 – April 15, 2008 Post-season Report. Revised Draft: February 20, 2009. 49 pp. Washington Department of Fish and Wildlife. Olympia, Washington.