Fishing / Shellfishing - Selective Fishing
Date Published: June 17, 2010
Number of Pages: 49
Author(s): Mark Baltzell, Karen Kloempken, Steve Caromile, and Laurie Peterson
The Washington Department of Fish and Wildlife (WDFW) implemented a winter mark-selective Chinook fishery (MSF) in Marine Area 10 for the second season, from December 1, 2008 through January 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 pilot 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 Area 10 throughout the fishery in order to collect the data needed to estimate key parameters characterizing the fishery and its impacts on wild 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 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 a total of five different access sites on 39 of the 62 days that Area 10 was open under mark-selective harvest regulations. Samplers interviewed an estimated 26% of all participating anglers (n = 518 angler trips) and sampled 25% of all marked Chinook harvested (n = 64). To obtain estimates of Chinook encounters by mark/size class in the Area 10 winter fishery, test fishers spent 30 days (126.9 hours) on the water pursuing Chinook using test fishing methods.
Additionally, PSSU staff conducted six on-the-water effort surveys (total-Area counts of the number of boats and anglers), in which samplers interviewed 132 boats with 257 anglers; of these, 165 anglers (64%) exited the fishery via sites within the sample frame. During the six effort surveys, we encountered a total of 3 charter vessels with 8 anglers, comprising just 3% (8 out of 257 total anglers; Appendix E) of the total (i.e., charter and private) boat effort surveyed. Charter boat effort was included in the estimated proportion of effort outside of our sample site frame (i.e., in expansions for never-sampled sites); therefore, estimates of catch and effort from charter boats were part of our total-Area creel estimates for the entire fleet.
Based on our creel sampling activities, we estimated that 2,029 angler trips were completed by the private fleet during the fishery. With a CPUE of 0.12 Chinook landed per angler trip, these anglers harvested a grand total of 251 marked and no unmarked Chinook; they released an estimated 1,545 Chinook (1,047 marked and 498 unmarked). Harvested Chinook averaged 67 cm (range: 54 to 79 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, 64 legal /65 total or 98%). Most of the Chinook harvested were of brood year 2006 origin (i.e., age 2 fish in December or age 3 fish in January). In addition, 4 CWTs were recovered from harvested fish, all of which were from Puget Sound release sites.
During their two months of sampling in Area 10, test fishers encountered a total of 202 Chinook salmon; of these, 18% were legal-size and 72% were marked. The test fishers had an overall catch per unit of effort (“CPUE”) of 0.53 legal-marked Chinook encounters per angler trip. Chinook encountered by test fishers averaged 42 cm (range: 25 to 81 cm) in total length and were predominantly 1 and 2 years in age (66% of marked and 91% of unmarked totals). We estimated the overall mark rate at 72% (89% for legal-size Chinook only) and size/mark-status composition at 15.8% legal-marked, 2.0% legal-unmarked, 56.4% sublegal-marked, and 25.7% sublegal-unmarked.
By combining dockside sampling results (i.e., legal-marked Chinook harvest estimates) and test fishery size/mark-status composition data, we generated size/mark-status group-specific estimates of encounters and mortalities. We estimated that a total of 1,796 Chinook were encountered (retained and released) during the Area 10 fishery, with 284 of these being legal-marked, 36 legal-unmarked, 1,013 sublegal-marked, and 462 sublegal-unmarked individuals. Among released encounters, an estimated 6 legal-marked, 5 legal-unmarked, 202 sublegal-marked, and 92 sublegal-unmarked Chinook (305 overall) were estimated to have died due to handling and release effects. Thus, in total, we estimated that 459 marked (54% due to direct harvest) and 98 unmarked Chinook mortalities occurred as a result of the Area 10 fishery.
All Chinook impacts were less than expectations set by pre-season Fishery Regulation Assessment Model (FRAM) runs (model run 2108). The impact of the Area 10 fishery on unmarked Chinook was approximately 20% of what was anticipated, with 98 unmarked total mortalities (landed + released) estimated via creel surveys compared to 480 unmarked total mortalities predicted by FRAM.
Finally, regarding impacts of MSF’s on the coded-wire tag (CWT) program, we estimated that one unmarked Chinook belonging to double-index tag (DIT) groups may have died due to the handling-and-release impacts of the two-month Area 10 winter mark-selective Chinook 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.