It has bean confused with changes in the 

 accumulated stock* 



"But the opposite side of the picture 



-that production has failed to rise 



proportionately to the increased intensity 

 of fishing has not been given the atten- 

 tion it deseiTves. Tran this failure to 

 rise, it has become obvious that produc- 

 tion has a ceiling or limit that is ap- 

 proached during the relatively early 

 stages of increase in fishing. TTie only 

 argument has been whether this limit has 

 fallen, not as to its reality. 



"The existence of this limit means 

 that when a fishery esq^ands its effort the 

 annual catch is divided among more units 

 of effort. That is simply another way of 

 saying that as the limit is approached the 

 relationship between number of units of 

 effort (f) and catch per imit (c) approach- 

 es a reciprocal one (f x c " constant). 

 This is the basic relationship shown by 

 the history af the halibut fishery in this 

 report." li/ 



Ihe same conclusions have been drawn 

 by European biologists studying the North 

 Sea groundfisheries. Reference is made 

 to Special Scientific Report - Fisheries, 

 No. 13, 1950, ttiited States Fish and "Wild- 

 life Service, entitled The Rational 

 Exploitation of the Sea fisheries With 

 Particular Reference to the Fish Sto ck of 

 the North Sea . This is a translation of 

 a paper published by the Netherlands 

 Directorate of Fisheries. 



The principle of a maximum sustained 

 yield as substantially independent of 

 fishing effort is accepted by ICNAF advi- 

 sors. In his report to ICNAF on United 

 States research in 1952, Dr. Herbert ¥. 

 Graham, Director of the United States Fish 

 and Wildlife Service laboratory at Woods 

 Hole, Massachusetts, in specific reference 

 to the Georges Bank haddock fishery 

 declares: 



"The yield curve for the Georges Bank 

 fishery, based on l5 percent annual natu- 

 ral mortality, indicates that at the 

 present level of fishing intensity the 

 optimum age of first capture lies between 

 3 and 3z years. The first step in mesh 

 regulation will make the age of first cap- 

 tvire about 2^ years, so that a maximum 

 equilibrium yield would reqtdre about 50 

 percent increase in fishing effort. The 

 con5)utations further show that at any age 

 of first capture lying between 3 and h 

 years, the yield will be fairly close to 

 maximum over* a range of fishing efforts 

 varying from 73 to 200 percent of tl^e 

 present aYerage~annual effort. " /// 



A distinction must be made between 

 the maximim sustained physical yield and 

 the maximum net economic yield of a fishery. 

 The maximum net econocdc yield is the maxi- 

 mum difference between the total value of 

 landings and the total cost of fishing^ 

 It is unxisuaL for the. maximum sustained 

 physical yield of a fishery to coincide 

 with the maximum net economic yield. The 

 Georges Bank haddock resource, however, 

 was overfished in both a biological and an 

 economic sense prior to mesh regulation. 

 After mesh adoption the resource is still 

 overfished in economic terms. 



Ihe problem of achieving the maximam 

 net economic yield of a fishery must in- 

 volve consideration of the law of dimin- 

 ishing unit returns. H. Scott Gordon 

 notes in this context that "There are seme 

 fisheries in which the expansion of fishing 

 effort will, after a point, reduce the 

 total landing of fish. .. .Ohis is the case 

 especially where the average size of the „o / 

 fish is substantially reduced by fishing.!-/ 

 Some biologists believe that the latter 

 postulate is an explanation of the decline 

 in the Georges Bank haddock fishery from 

 the 1927-30 landings, peak. 12/ It is felt 

 by many, too, that greatly expanding 

 effort could substantially lower the yield 

 to be expected at present fishing levels. 



76/ Thonpson, William F. "The Effect of Fishing on Stocks of Halibut in the Pacific." 

 FlsHeries Research Institute, University of Washington, p, 58. 



77/ International Commission for the Northwest Atlantic Fisheries, Annual Proceedings, 

 Halifax, Nova Scotia, 1953, Vol, 3. for the year 1952-1953. p. 50 



78/ Gordon, H, Scott. "An Economic Approach to the Optimum Utilization of Fishery 

 Reso\irces.n Journal Fisheries Research Board of Canada, 10 (7), 1953. 



79/ Herrington, William C, Op. cit. p. J.U. 



hh 



