Smith Bxeeuti ve Summary physiological changes associatedwith Japaneseflounder metamor- phosis were documented Tanaka!. A general biology session included two papers. The Bechtol paper addressedbiological characteristics of three abundant flatfish species in Kacheinak Bay,Alaska. The Meyer paper discussed characteristics of the southcentral Alaska sport halibut fishery and alluded to potential conflicts between commercial and sport fisheries. Nine papers addressed feeding and growth of flatfishes in session four. Four papers Yang, Lang, Chilton, and Yokoyaina! dealt with food habits and diet overlap. The Chilton and Yokoyama papers reported on single-species feeding habits, while the Yang and Lang papers exam- ined diet sitnilarity and diet overlap ainong several species.Otoliths were the focus of two papers; Blood compared age reading techniques on Pacific halibut otoliths, and Hagen examined inicrostructures and their deposition patterns in halibut. The three remaining papers addressed different aspects of food and energy requirements in three different flatfish species: brawn sale Toininaga!, yellowfin sole Smith!, and flathead sole Paul!. Session five was on abundance, biomass and distribution and consisted of 10 papers, 8 of which were single species studies. Those specieswere: English sole Shi and Sampson!, Greenland turbot Ianelli, Kodolov, and Vatulina!, Pacific halibut Kodolov and Hooge! and petrale sole Castillo!. Papers by McConnaughy and Ivankova dealt with rnultispecies populations. A session on pollution, parasites, and disease included four papers. Avoidance of hydrocarbons in sediments was discussed by Moles and contaminant effects on reproductive output was reported by Sol. Lesions and parasites were discussed by Smith while the utility of parasites as indicators of flatfish biological characteristics was described by Moles. Management and economics was the subject of the final session af contributed papers. Problems confronting the arrowtooth flounder commercial fishery were described by Cullenberg. Mortality of Paciiflic halibut caught incidental to other fisheries was described and ana- lyzed by Trumble and Williains. The Witherall paper addressed man- agement of flatfish in U.S. waters. The last session was a discussion of future research needs, Partici- pants identified a list of topics that require further research activity. The areas identified could serve as a guide for further cooperation between the agencies and institutions represented at this symposium. Further, it cauld serve as a reference for future research funding priorities. Proceedingsof the InsernationalSymposium on Xorrh PaciP'cFlatfi'sh Alaska SeaGrani CollegeProgram ~ AK-SC-95-04,l995 Raffish Management in the EasternPacific Ocean with Special Reference to Pacific Halibut Donald A. McCaughran International Pacific Hat but Commission Seattle, Washington USA Abstract Commercial flatfish harvesting began in the eastern Pacific in the late 1800s,Several vessels began fishing for Pacific halibut on the coast of Washington and British Columbia in 1883.The fishery quicklyex- pandedto British Columbia and Alaska, and by 1920harvesting of BeringSea stocks had begun. Harvesting of other speciesof flatfish began later than halibut mainly due to the ease of fishing halibut with longlinefishing techniques. Most species of flatfish aretoo small to be caughtwith longline gear.lt was not until the arrival of the modern "trawler"that fishingfor the other species of flatfish began. Early in the 1900sseveral steam-driven "otter" trawlers were broughtfrom New England and tried unsuccessfully to trawl for halibut. These vesselsdid not develop fisheries for other species of flatfish but insteadturned to longlininghalibut. Later,diesel poweredtrawlers were built, and sporadic trawling beganfor species such as English andpetrale sole, but it wasnot until after the SecondWorld War that intensive fishing for other flatfish species developed. A brief discussion of the various flatfish fisheries is given, and sincePacific halibut have been harvested for a much longer time, and have received a higher level of research and management, a more thorough discussion wifl be presented for that species. McCaughran Flatfish Management in the Eastern Pacific Ocean Table 1. Exploitedfiatfish speciesof the northeastPacific and easternBering Sea. Common name Scientific name Alaska plaice Pleuronectes quadri tuberculatus Arrowtooth flounder Atheresthes stomias Butter sole Pleuronectes isolepis Dover sole Microstomus pacificus English sole inopsetra ischyra Flathead sole Hi p poglossoides elassodon Greenland turbot Reinhardrius hi ppoglossoides Longhead dab Pleuronectes proboscidea Pacific sanddab Ci tharichrhys sordidus Pacific halibut Hi ppoglossus stenolepis Petrale sole Fopserta j ordani Rex sole Errex zachirus Rock sole Pleuronectes bi lineatus Starry flounder Platichthys stellatus Yellowfin sole Pleuronecresasper The Flatfish Resource The flatfish species that are currently being harvested in the eastern Pacific are given in Table 1. The estimated present 993! biomass and yield of each species is given for the eastern Bering Sea,Gulf of Alaska, British Columbia, and the Washington-Oregon coasts Table 2! Fargo 1994,NPFMC 1994,PFMC 1994!.The yields of flatfish amount to 12% of the total Bering Seagroundfish yield, 27% of the Gulf of Alaska, 9% of British Columbia and 9% of the Washington-Oregongroundfish yield. This amountsto a significantimpact on the total economyof our North American fisheries. The ex-vessel value of Pacific halibut alone is approximately 130 million dollars annually. Only Alaska pollockexceeds flatfishes in economicvalue, The importance of flatfish will continue to grow since many species are not exploited at their full poteritia, we have barely begun to exploit arrowtoothflounder for example.The only speciesfully exploited are Pacific halibut and yellowfin sole in the Bering Sea, and petrale sole, Dover sole,and English soleoff the Pacific Coast.All other species are under-utilized,particularly in the Gulf of Alaska. Proceedingsof the international Symposiumon North Pacific Flatfish dd O CI C CI ICI O Cd Cl CD Cl dd OCI O O0 O O CD O O ID CD CII O CI O IO O O O O CI O Id Id .Id dd dd OCd dd O Cd 'CI' COdd CY Id O CI E Ocrl O j'cs dd O O O O CI OCI C E hl Cl O OO O CI O I oO O O OddN CD 0 dltl IX! s' Cd O O O CI O O re! g O O CI O o Odc dd Cd cd c O E CIO CD Idc CLCO O Cdc Cd O O O O CI Cl E Cl dd CI O CD IJ Cd C Cd OCd iCE N2 I O O O W 0 C O I O Idc QlW dl dl w O O dl Cd 'O :d IC III O O ! Id O R 2 IIcO O O pdl cd Cd Cd O +CI J cO dl cdI III dl dl O dl cd O O 4 IX CI IB CCOal Z d a McCaughran Flatfish Managementin the EasternPacific Ocean Strange as it might seem, to those not familiar with these fisheries, it is often the bycatch of Pacifichalibut that controls the yields of many of the other species. Stockassessment and management Table 3 summarizes the methods used for stock assessment and harvesting strategy for most of the exploited flatfish species. Pacific halibut will be discussed in detail later because of its long history of exploitation and rnanagernent.Trawl surveys and catch at age analy- ses are the most cominon stock assessinent methods. Trawl surveys alone often give extreinely variable results, however when combined with age structure analysis satisfactory results can be obtained. The most coininon exploitation strategyused is the so-called Fss+ method developed by Dr. William Clark of the International Pacific Halibut Cominission Clark 1991!.Strangely enough, as we will see later, this method is not used for Pacific halibut. In addition, the older Fpi method is used with considerable successin British Columbia. Both the Fs5%and the Fp, inethods are largely empirical methods but seem to work quite well for many species. The test of any inethod is the "test of time." If "good" yields can be taken from a species over a long period of time and thereby creating stabilityin the supply side of the industry, then the method is deemed a "goodstrategy." The Fss+is relatively new in its deployment; only time will tell if this strategy combined with the current stock assessmentmethods produces a satisfactory inanagement and harvesting strategy. Pacific Halibut Pacific halibut Hippoglossus sretiolepis! is the largest of the Pacific Ocean flatfishes. It occurs from northern California throughout the Gulf of Alaska and Bering Seaacross to the coast of Russiaand south to northern Japan. In the eastern Bering Sea and the eastern Pacific it has the longest history of exploitation and management of any of the flatfishes, Its exploitation and management structure therefore are worthy of a detailed description. Historic catches Historically, the annual domesticyield of halibut has varied between 13,000 and 45,000 tons. The catches began with less than 100 tons in the 1880s and rose quickly to 40,000 tons by 1915 and dropped to 21,000 by 1918 Figure 1!. This drop in catches was a major concern Proceedingsof the international Symposiumon North Pacific Flatfish 0 cd 8 rd cd 0 Uo I0 crt V dl 0 tll dl O Ig 0 g 0 4 oV. I/I ctt rd ctt CJ 0 cd 0 ctldl I- z cd Qt 0 cd '0 0" 0 dtI 2 Ill 0 0 IJ cd Yl 4l 0 Etl d0 dl rh ctltdd 0 dc V o cd 0 Vd 0 cd 40 g 0 0 dl 0 dl o d0 t: cd cd Ld P. IJ U 0 dl dlld Ch0dl0 cc CI04l0 djdl dl dl CI 0 0 cd td ct cct 4l ctt cddtd 0 o 0 JC Ccc0 d0c cd 0 0 0 0 0o 0 O! dl JD 0 0 dl 0rdcd rrl p 0 0 0 0 ttt cd 0 Id O dl dl Ol 0 ctt 4t IJ 0dl 40tJ dl 4t Ydl 4t 0 0 cr 4 G 0- 0 a5 tcta3 0 McGa ughran Flatfish Management in the Eastern PaciPc Ocean oCll o 1940 1950 1960 1970 'I999 1 990 Veer Figure l.