Fishing / Shellfishing - Selective Fishing
Date Published: March 21, 2006
Number of Pages: 44
Author(s): Steven L. Thiesfeld and Angelika Hagen-Breaux
During the summer of 2005, the third year of a recreational Chinook salmon Oncorhynchus tshawytscha (“Chinook”) fishery that was limited to retention of marked (adipose clipped) hatchery Chinook salmon occurred in Marine Area 5 and the western portion of Marine Area 6 in Puget Sound. Objectives were: 1) increase recreational fishing opportunity while meeting conservation goals for Puget Sound Chinook salmon defined by the Puget Sound Chinook Harvest Management Plan; and 2) collect information necessary to enable evaluation and planning of future potential Chinook mark-selective fisheries. Marine Areas 5 and 6 are located in Washington waters of the Strait of Juan de Fuca. The Chinook Selective Fishery was scheduled to begin on July 1, 2005 and continue through August 10 (41 days) or until a ceiling catch of 3,500 Chinook was kept, whichever occurred first. The fishery started on July 1, 2005 and ran continuously for 41 days through August 10 without the quota being reached.
Chinook and coho catch and catch rates in 2005 were less than observed in 2003 and 2004. For the first time in the three years of the fishery, the Chinook ceiling was not reached and the fishery extended through the entire 41 day period. We estimated that anglers made 34,086 trips during the Chinook Selective Fishery (July 1 – August 10). Those anglers kept an estimated 2,078 Chinook, 3,723 coho salmon O. kisutch (“coho”), and 14,850 pink salmon O. gorbuscha (“pink”). Area 5 accounted for 88% of the effort (30,115 angler trips) and 80% of the Chinook kept (1,669) for a rate of 0.06 Chinook kept per angler trip. Area 6 accounted for 3,971 angler trips and 408 Chinook kept for a higher catch rate of 0.10 Chinook kept per angler trip. Based on interviews, Area 5 anglers released an estimated 5,772 Chinook, 10,381 coho, 3,894 pink, and 118 other or unidentified salmon. Also based on interviews, Area 6 anglers released an estimated 636 Chinook, 50 coho, 10 pink, and 2 other or unidentified salmon.
During the Chinook Selective Fishery (July 1-August 10), samplers fishing from test boats landed 137 Chinook in Area 5 and 17 Chinook in Area 6. In Area 5, 98% of the Chinook encountered and landed by the test boat were caught using downriggers, even though they were only fished 87% of the time. In Area 6, all the Chinook encountered and landed by the test boat were caught using downriggers, even though they were only fished 75% of the time. Utilizing other gear types resulted in fewer encounters and fewer biological samples for both areas than would have occurred if the test boats had used downriggers exclusively as they did in 2003.
During the Chinook Selective Fishery time period, 55% of the legal-size fish caught by test boats were marked in Area 5 and 41% of the legal-size Chinook were marked in Area 6. The mark rate on sublegal-size Chinook was 47% (n=64) for Area 5, but no sublegal-size Chinook were caught by the test boat in Area 6. Chinook caught on test boats were larger in Area 6 than in Area 5. The percent of legal-size chinook (22” or larger) was significantly different (X2 = 85.4, ñ < 0.0001) between Area 6 (100%) and Area 5 (53%).
Sixty-four Chinook were recorded on Voluntary Trip Reports (VTR’s) in Area 5 during the 2005 Chinook Selective Fishery, while 40 Chinook were recorded on VTR’s in Area 6. In Area 5, 45% of the fish recorded on VTR’s were legal-size and 31% of these were marked. In Area 6, 92% of the Chinook encountered were legal-size and 35% of these were marked.
Thirty-three double index coded wire tags were recovered in Areas 5 and 6 from July 1 through August 10. Based on the proportion of the catch that was sampled and the ratio of marked to unmarked double index coded wire tagged Chinook for each hatchery, we estimated that anglers caught and released 105 legal-size, unmarked double index tagged Chinook, and that the mortality of unmarked legal-size double index tagged Chinook due to this selective fishery was 11 fish.
Using the total number of Chinook encounters from the creel survey (8,495) and apportioning into four categories of legal-size marked, legal-size unmarked, sublegal-size marked, and sublegal-size unmarked (as encountered on test boats in Area 5 and as encountered by test boats and anglers reporting their catch on Voluntary Trip Reports in Area 6) suggests that anglers released 665 legal-size and marked Chinook, or 30% of the fish they could have kept. We also estimated the number of encounters by assuming that anglers kept all Chinook that were legalsize and marked. For this second method, total encounters were estimated by dividing the number of legal-size marked fish that anglers retained by the weighted proportion of legal-size marked fish from the test boats (and a combination of test boat and VTR data in Area 6). The number of encounters in the remaining three categories was then obtained by multiplying the total encounters by the proportions for each corresponding category. Using this method, we estimated the total encounters at 6,240 Chinook. The true number of encounters likely lies between the two estimates of encounters, i.e. between 6,240 and 8,495 Chinook.
Using the encounters from the creel survey and a release mortality rate of 15% for legal-size fish and 20% for sublegal-size fish, we estimated the total mortalities of Chinook in the selective fishery at 3,197, of which 785 were unmarked. Using the encounters estimated by assuming anglers kept all legal fish and a release mortality rate of 15% for legal-size fish and 20% for sublegal-size fish, we estimated total mortalities at 2,810 fish, of which 588 were unmarked fish.
Although we believe the true number of mortalities lies between our two estimates, we used the higher number to compare estimated mortalities against pre-season predictions of mortalities. Based on the estimated number of total encounters from the creel survey and apportioning them based on the test boat catch rates, we estimated the 2005 fishery resulted in the mortality of 413 unmarked legal-size Chinook and 372 unmarked sublegal-size Chinook. These estimates are well below the predicted mortalities of 1,701 unmarked legal-size Chinook and 975 unmarked sublegal-size Chinook as produced in the final pre-season run of the Fishery Regulation Assessment Model (FRAM; Model 2705, April 8, 2005), and suggests this fishery did not hinder nor jeopardize achievement of the overall conservation goals for Puget Sound Chinook.
Compliance with existing regulations, and the regulation prohibiting bringing unmarked salmon on board a vessel, was considered an integral part of a successful fishery. Only a few citations or warnings were issued for retention of unmarked Chinook, or for bringing an unmarked salmon on board a vessel.
In summary, the third year of the Area 5 and 6 Chinook selective fishery was successful with respect to the objective of increasing recreational fishing opportunity within conservation constraints for Puget Sound Chinook. Anglers were allowed to fish for and retain Chinook for 41 days in Areas 5 and 6, compared with only 10 days and 5 days in Area 5 in 2001 and 2002, respectively. Angler effort in Area 5 was double the effort in 2002 during the same time frame. Based on data from the test fishery sampling during the Chinook Selective Fishery, half of the legal-size Chinook encountered were marked and could be retained by anglers.
The fishery was also successful with respect to the objective of implementing monitoring and sampling programs to obtain management information for evaluation and planning of potential future selective Chinook fisheries. Estimated encounters were less than pre-season predictions. Compliance with fishing regulations was good during the fishery. The estimated number of mortalities of unmarked double index coded wire tagged fish was negligible.