FISHERY BULLETIN: VOL. 80, NO. 3 



evaluated the consequences of Lotka-Volterra 

 competition and predator-prey systems on 

 optimum exploitation strategies. Paulik et al. 

 (1967) examined the problem of maximizing the 

 yield from a fishery composed of mixed stocks, 

 each with a unique spawner-recruit curve. A 

 large body of descriptive work has documented 

 the successional nature of changing catch 

 composition which is often characteristic of 

 increasing exploitation in a multispecies fishery 

 (e.g., Regier 1973). Several recent multispecies 

 investigations present highly sophisticated eco- 

 system models that require numerical solution 

 and/or dynamic simulation, as well as numerous 

 parameter estimates (Parrish 1975; Andersen 

 and Ursin 1977; Laevastu and Favorite 1978 3 ). 



An alternative to this latter approach simply 

 treats multispecies fisheries as though they 

 behave as would a single species stock and 

 evaluates production by application of the total 

 biomass Schaefer model (TBSM) (Pope 1979). 

 Brown et al. (1976) estimated total finfish pro- 

 duction in the northwest Atlantic in this manner, 

 as did Brander (1977) for demersal fish and 

 shellfish in the Irish Sea. A review of this 

 approach shows that "these overall Schaefer 

 models generally seem to fit the data rather 

 better than the fits experienced with their 

 component stocks" (FAO 1978). Among the 

 possible reasons for this are 1) the TBSM really 

 presents a more realistic representation of multi- 

 species fisheries than does summing the yields of 

 individual stocks, 2) the better fit results from 

 some type of averaging process, 3) artifacts in the 

 method of fitting and/or shifts in preference 

 between species within a fishery may result in a 

 better fit when total biomass is evaluated (FAO 

 1978; Pauly 1979; Pope 1979). Several authors 

 have issued the caveat that a thorough under- 

 standing of trophic relations is fundamental to 

 managing any multispecies fishery and that 

 such considerations may easily invalidate the 

 application of the TBSM (May et al. 1979; Pauly 

 1979). 



This paper estimates the productivity of deep- 

 dwelling bottom fish stocks around the main 

 islands of the Hawaiian Archipelago using stock- 

 production methods. The fishery for these stocks 

 is conducted in offshore waters ranging in depth 

 from 60 to 350 m where a variety of species, prin- 



cipally snappers of the Family Lutjanidae, 

 abound. In addition to providing preliminary 

 productivity estimates for this fishery, an exam- 

 ination of the performance of the TBSM at 

 various levels of species aggregation is under- 

 taken. This latter analysis provides a quasi- 

 quantitative means of evaluating the applicabil- 

 ity of the TBSM to the Hawaiian offshore 

 handline fishery. 



SOURCES OF DATA AND 

 DESCRIPTION OF THE FISHERY 



In the State of Hawaii, all fishermen who sell a 

 portion of their catch must be licensed as com- 

 mercial fishermen by the Hawaii Division of 

 Fish and Game (HDFG). There is no licensing 

 requirement for recreational fishing. New com- 

 mercial licenses are issued every fiscal year and 

 once licensed, fishermen are required to submit 

 a monthly catch report whether or not they have 

 fished. These monthly catch reports require 

 from each fisherman entries on the days and 

 areas in which he fished, the types of fishing gear 

 used, the number of individuals and pounds of 

 the different species landed, and the dollar value 

 of the catch. Incomplete reporting is thought to 

 be common and raises the question of bias in the 

 data (Ralston 1979 4 ). Perhaps more serious is the 

 omission of any direct measure of fishing effort 

 or fishing power in the information concerning 

 bottom fish obtained from these reports. 



Monthly catch reports are coded, keypunched, 

 and stored on magnetic tape for future use by 

 H DFG. These data are the basis of this study and 

 currently span the 20-yr period 1959 to 1978 

 inclusive, comprising some 600,000 records. 

 While the date are voluminous, the extent of non- 

 reporting by recreational fishermen and of in- 

 complete or underreporting by commercial 

 fishermen is unknown. 



The complete HDFG data account for all types 

 of commercial fishing in the State of Hawaii; 

 therefore, only those catch records which list 

 deep-sea handline fishing gear were used in this 

 study. This reduced the data to one-fourth its 

 original size and defined the scope of the fishery. 

 Although the name suggests otherwise, the 

 fishing gear is primarily hydraulic or electric 



3 Laevastu, T., and F. Favorite. 1978. Numerical evalua- 

 tion of marine ecosystems. Part 1. Deterministic bulk biomass 

 model (BBM). NWAFC Process. Rep., Natl. Mar. Fish. Serv., 

 NOAA, Seattle, Wash., 22 p. (Unpubl. rep.) 



4 Ralston, S. 1979. A description of the bottomfish fisher- 

 ies of Hawaii, American Samoa, Guam, and the Northern 

 Marianas. A report submitted to the Western Pacific Region- 

 al Fishery Management Council, Honolulu, 102 p. (Unpubl. 

 rep.) 



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