Fishing / Shellfishing - Selective Fishing
Date Published: February 20, 2009
Number of Pages: 48
Author(s): Peter McHugh, Mark Baltzell, and Laurie Peterson
The Washington Department of Fish and Wildlife (WDFW) implemented a mark-selective Chinook fishery (MSF) in Marine Area 7 for the first time during February 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 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 7 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 dockside creel sampling, test fishing, and aerial 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 five different access sites on 20 of the 29 days that Area 7 was open under mark-selective harvest regulations. Samplers interviewed an estimated 39% of all participating anglers (n = 1,970 angler trips) and sampled 33% of all marked Chinook harvested (n = 438). Additionally, other PSSU staff conducted eight aerial effort surveys, and spent 18 days (118 hours) on the water pursuing Chinook using test fishing methods, in support of Area 7 monitoring efforts. Based on these activities, we estimated that 4,862 angler trips were completed by a combination of private fleet, charter, and derby anglers during February. With a CPUE of 0.28 Chinook landed per angler trip, these anglers harvested a grand total of 1,324 marked Chinook; they released an estimated 1,639 Chinook (440 marked, 1,195 unmarked, and 4 unknown mark-status). Harvested Chinook averaged 71 cm (range: 51 to 96 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, 429 legal /438 total or 98%). Over half (58%) of all harvested individuals were 4-year olds (brood year 2004), with age-3 fish making up the catch remainder. In addition, 75 CWTs were recovered from harvested fish, the majority of which (94.7%) were from Puget Sound (89.3%, predominantly from north Puget Sound facilities) and Hood Canal (5.3%) release sites.
During their month of sampling in Area 7, test fishers encountered 31 Chinook salmon, 77% and 42% of which were of legal size and marked, respectively. With a "CPUE" of 0.28 (LM Chinook encounters / angler trip), test fishers experienced a similar legal-marked Chinook encounter rate as did charter, derby, and at-large private fleet anglers. Chinook encountered by test fishers averaged 63 cm (range: 48 to 89 cm) in total length and were predominantly 3 years in age (67% of marked and 71% of unmarked totals). Given the limited number of test fishery encounters, we chose to pool data across sources (test fishery, charter/derby angler VTRs) in order to estimate the mark rate and size/mark-status composition of the pool of Chinook encountered in the Area 7 fishery. As a result, we estimated the overall mark rate at 59% and size/mark-status composition at 50.3% legal-marked, 35.4% legal-unmarked, 8.9% sublegal-marked, and 5.3% sublegal-unmarked.
By combining dockside sampling results (i.e., legal-marked Chinook harvest estimates), test fishery/VTR size/mark-status composition data, and charter/derby census results, we generated size/mark-status group-specific estimates of encounters and mortalities. In total, 2,968 Chinook were encountered (retained and released) during the Area 7 fishery, with 1,500 of these being legal-marked, 1,044 legal-unmarked, 267 sublegal-marked, and 155 sublegal-unmarked individuals. Among released encounters, an estimated 30 legal-marked, 156 legal-unmarked, 49 sublegal-marked, and 31 sublegal-unmarked Chinook (266 overall) were estimated to have died due to handling and release effects. Thus, in total, 1,403 marked (92% due to direct harvest) and 189 unmarked Chinook mortalities occurred as a result of the Area 7 fishery. Although estimated marked Chinook impacts greatly exceeded expectations set by pre-season Fishery Regulation Assessment Model runs (model run 3907), the impact of the Area 7 fishery on unmarked Chinook was similar to what was anticipated. Finally, regarding impacts of MSFs on the coded-wire tag (CWT) program, we estimated that 10 unmarked Chinook belonging to double-index tag (DIT) groups may have died due to the handling-and-release impacts of the pilot Area 7 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 7 Mark-Selective Recreational Chinook Fishery, February 1-29, 2008 Post-season Report. Revised Draft: February 20, 2009. 48 pp. Washington Department of Fish and Wildlife. Olympia, Washington.