for the data collected by the sport fisheries. In the dis- 

 cussion that followed this session, it was recognized by 

 participants that although the sport fisheries for 

 billfishes represents a rich source of good data, 

 biologists are not fully utilizing this source. With a 

 few exceptions, the kinds of catch and effort data 

 collected by individual fishermen, sport fishing clubs, 

 and biologists vary so widely that the data cannot be 

 pooled. One shortcoming noted in sport fisheries data 

 is the lack of recorded zero catches. The importance of 

 this information was discussed in some detail. The 

 need to standardize the collection of billfish statistics 

 from sport fisheries was apparent. 



Although the billfish landings in some areas, e.g., 

 Taiwan, showed increases in recent years (possibly 

 reflecting increased effort), the general trends for the 

 several species of billfishes noted in the catch 

 statistics of the commercial and recreational fisheries 

 are downward. In the eastern Pacific Ocean the 

 decline in apparent abundance was especially noted 

 for sailfish. The catch rate dropped from 80 fish per 

 1,000 hooks in 1963, the first year of substantial long- 

 line fishing in the major sailfish grounds of the eastern 

 Pacific Ocean, to 11 fish per 1,000 hooks in 1970; a 

 decline of 86^t>. 



Similar declining trends of billfish catches were 

 reported for other areas of the world by Dr. Ueyanagi 

 in his review of the world commercial fisheries for 

 billfishes presented during the opening day's session. 



Special Session: Mercury in Billfishes 



This special session began at 2000 on 10 August 

 1972, at the Hale Halewai in Kailua-Kona, Hawaii. 

 Approximately 150 people attended; participants 

 were mostly from the sport fishing fraternity. The 

 purpose of the session was to provide participants in 

 the HIBT and the interested public with the latest 

 available information on the problem of mercury in 

 fish and the opportunity to discuss the situation with 

 experts on the subject. Presentations were made by 

 the five panel members; two were summaries of scien- 

 tific papers given at the International Billfish Sym- 

 posium; two described work done in the State of 

 Hawaii; and the fifth featured Dr. Kolbye, who 

 described the effects of mercury on humans, the role 

 of the FDA, and the rationale for its guideline level of 

 0.5 ppm mercury in fish. 



Presentations 



James S. Beckett 

 "Mercury in Northwest Atlantic Swordfish" 



Mr. Beckett reported that Canada banned the sale 

 of swordfish in 1970. Up until that time the annual 

 swordfish landings in Canada amounted to about 8 

 million pounds valued at $4 million. Beginning in 

 July 1971, a vessel of the Fisheries Research Board of 

 Canada conducted longline fishing from Cape 



Hatteras to the Grand Banks to obtain swordfish for 

 analysis of mercury levels. During cruises in July and 

 August 1971, 210 swordfish (lengths ranging from 74 

 to 247 cm fork length) were taken. Samples of dorsal 

 muscle analyzed for total mercury showed an average 

 of 1.15 ppm and a range of 0.09-4.9 ppm. Differences 

 in mercury level were noted between females and 

 males as well as between tissues; liver and kidney had 

 higher levels than brain tissue. Mr. Beckett reported 

 that swordfish appeared to pick up mercury in 

 southern areas and lose it during the summer on the 

 feeding grounds in northern areas. His conclusion was 

 that the source of mercury is volcanism in tropical 

 areas and that mercury is being picked up by fish 

 through the food chain. The full text of this paper is 

 included in Part 2 of the Proceedings. 



Richard S. Shomura 



"Mercury in Several Species of Billfish 



Taken Off Hawaii and Southern California" 



Mr. Shomura noted that since December 1970, 

 when the subject of relatively high mercury levels in 

 tunas and swordfish became news, NMFS has had an 

 ongoing sampling program to determine the mercury 

 content in several important sport and commercial 

 fish and invertebrate species. The 56 striped marlin 

 taken from waters off southern California and Hawaii 

 and analyzed for total mercury ranged in size from 56 

 to 231 pounds (25.4 to 104.8 kg). The total mercury 

 levels for white muscle tissue varied from 0.03 to 2.1 

 ppm; there was no obvious relationship with size of 

 fish. Although the white muscle of 37 blue marlin also 

 showed a wide variation, a trend of an increasing mer- 

 cury level with increasing size of fish was noted. The 

 mercury levels ranged from 0.19 to 7.86 ppm; fish size 

 ranged from 96 to 906 pounds (43.6 to 411.0 kg). Mr. 

 Shomura reported that the total mercury levels in 

 blue marlin livers ranged from 0.13 ppm to a 

 phenomenal high of 29.55 ppm. He stated that a com- 

 parative study of identical tissue samples analyzed by 

 two laboratories showed wide variations in results; 

 one laboratory reported higher values consistently. He 

 concluded by stating that the NMFS program was 

 collecting mercury data as it relates to the fishery 

 resources and was not presently addressing itself to 

 the effects of mercury on mankind. The full text of 

 this paper is included in Part 2 of the Proceedings. 



Cynthia D. Shultz 

 "Total and Organic Mercury in Marine Fish" 



Ms. Shultz reported that a part of their mercury 

 study was concerned with determining the proportion 

 of methylmercury in billfishes. A large number of 

 marlin samples obtained with the assistance of 

 NMFS were analyzed at the University of Hawaii 

 laboratory and also analyzed by an expert in Sweden; 

 the results of the two sets of analyses agreed very 



