860 



Abstract— Management of West Coast 

 groundfish resources by the Pacific 

 Fishery Management Council involves 

 Federal government and academic 

 scientists conducting stock assess- 

 ments, generally using the stock syn- 

 thesis framework, applying the 40-10 

 rule to determine harvest guidelines 

 for resources that are not overfished 

 and conducting rebuilding analyses 

 to determine harvest guidelines for 

 resources that have been designated 

 as overfished. However, this manage- 

 ment system has not been evaluated 

 in terms of its ability to satisfy the 

 National Standard 1 goals of the Sus- 

 tainable Fisheries Act. A Monte Carlo 

 simulation framework is therefore 

 outlined that can be used to make such 

 evaluations. Based on simulations tai- 

 lored to a situation similar to that of 

 managing the widow rockfish {Sebastes 

 entomelas) resource, it is shown that 

 catches during recovery and thereafter 

 are likely to be highly variable (up to 

 ±30'?f from one year to the next). Such 

 variability is far greater than has been 

 presented to the decision makers to 

 date. Reductions in interannual vari- 

 ability in catches through additional 

 data collection are, however, unlikely. 

 Rather, improved performance will 

 probably arise from better methods for 

 predicting future recruitment. Rebuild- 

 ing analyses include quantities such as 

 the year to which the desired probabil- 

 ity of recovery applies. The estimates 

 of such quantities are, however, very 

 poorly determined. 



Evaluating the efficacy of managing West Coast 

 groundfish resources through simulations 



Andre E. Punt 



School of Aquatic and Fishery Sciences 



University of Washington 



1122 NE Boat Street 



Seattle, Washington 98195-5020 



E-mail address aepunt@u. Washington edu 



Manuscript approved for publication 

 24 April 2003 by Scientific Editor 



Manuscript received 26 June 2003 



at NMFS Scientific Publications Office. 



Fish. Bull. 101:860-873 (2003). 



National Standard 1 of the Sustainable 

 Fisheries Act (SFA) of 1996 states that 

 "Conservation and management mea- 

 sures shall prevent overfishing while 

 achieving, on a continuing basis, the 

 optimum yield from each fishery for 

 the United States industry." The need 

 to satisfy this National Standard has 

 led inter alia to the requirement for the 

 eight Regional Fishery Management 

 Councils to develop control rules that 

 are used to assess whether overfishing 

 is occurring^ or a stock is in an over- 

 fished state (e.g. Restrepo and Powers, 

 1999). In addition, the SFA specifies 

 that a rebuilding plan has to be devel- 

 oped for any fish stocks that are des- 

 ignated as overfished. This plan needs 

 to include the time period by which the 

 stock will be rebuilt to fi^gY (the aver- 

 age biomass associated with maximum 

 sustainable yield, MSY), and the strat- 

 egy by which the stock is to be rebuilt. 

 The Pacific Fishery Management 

 Council (PFMC) has adopted the "40- 

 10" rule to manage groundfish stocks 

 that are not designated as being over- 

 fished. This rule determines the harvest 

 guideline for each groundfish stock by 

 computing the catch corresponding to 

 an i^MSY proxy (F^q,,/ for flatfish, FgQ.^ 

 for rockfish in the Sebastes complex, and 

 Fjjr; for other species ) and reducing it if 

 the spawning output is estimated to be 

 less than 40% of the estimated Bq. This 

 reduction in catch is linear with spawn- 

 ing output, being at 0.4Sq and lOO'J 

 at O.IBq. For stocks that are designated 

 as being in an overfished state (defined 

 for West Coast groundfish as being 

 that the spawning output is less than 

 0.25Bq) a rebuilding plan is developed. ■* 

 The main features of the technical as- 

 pects of a rebuilding plan (referred to as 

 a rebuilding analysis) identified by the 



Scientific and Statistical Committee of 

 the PFMC are outlined in Appendix 1. 

 In brief, the rebuilding analysis used by 

 the PFMC involves projecting the best 

 estimates of the current age-structure 

 of the overfished population forward 

 under a range of alternative fishing 

 mortality rates and selecting the fish- 

 ing mortality rate that has a Council- 

 selected probability that the population 

 recovers to the proxy for Bygv of 0.4Sg 

 within a time frame consistent with the 

 specifications of the SFA. 



Detailed stock assessments are avail- 

 able for only a small subset of the 81 

 species included in the PFMC Ground- 

 fish Management Plan. Of these species, 

 nine (bocaccio [Sebastes paucispinis], 

 canary rockfish [Sebastes pinniger[, 

 cowcod [Sebastes levis], darkblotched 

 rockfish [Sebastes crameri], lingcod 

 [Ophiodon elongates], Pacific ocean 

 perch [Sebastes alutus]. Pacific whiting 

 [Merluccius productus], widow rockfish 

 [Sebastes entomelas], and yelloweye 

 rockfish [Sebastes ruberhmiis]) have 

 been designated overfished and rebuild- 

 ing plans have been or are being devel- 

 oped for them. The direct consequences 



' In the present study, and consistent with 

 usage by the Pacific Fishery Management 

 Council, "overfishing" means that the level 

 of fishing mortality exceeds that associ- 

 ated with MSY and "being in an overfished 

 state" means that the current spawning 

 output is less than 25'7c of the pre-exploi- 

 tation equilibrium spawning output. Sq 

 (spawning output is the product of egg 

 production-at-age and numbers-at-age). 



2 F^,^ is the fishing mortality rate at which 

 the spawning output-per-recruit is reduced 

 to x% of its unfished level. 



3 One implication of this is that the 40-10 

 rule is not actually used if the stock is 

 assessed to be below 0.25B„. 



