future research on billfishes in Australia and New 

 Zealand (abstract only, in Part 2). Three papers dealt 

 with morphology: morphometries of eastern Pacific 

 billfishes; length-weight data of western Atlantic 

 billfishes; and length-weight relations of central 

 Pacific billfishes. Two papers were presented on mer- 

 cury content in billfishes: one on northwest Atlantic 

 swordfish and the other on billfishes from Hawaii and 

 southern California. The remaining three papers dealt 

 with various aspects of life history: food and feeding 

 habits of swordfish in the northwestern Atlantic 

 Ocean; maturation and fecundity of Hawaiian 

 swordfish; and gastric ulcers in blue marlin and black 

 marlin from Hawaii. 



The papers, and the questions and discussions 

 following the papers, reinforced the belief of biologists 

 that although several aspects of the biology of 

 billfishes are now known, much more must be learned. 

 The life history of any one species is far from being 

 completely known. 



Much data have been obtained in the past from tax- 

 idermists. The bias of using such data for certain 

 types of studies, such as growth, was explained. 



Two papers referred to parasites. The existence of 

 substantial literature on parasites of billfishes was 

 pointed out, along with a need to collate this material. 



Attempts at aging billfish by counting rings of hard 

 parts such as spines was reported for Atlantic sailfish 

 and Atlantic swordfish, but no success had yet been 

 attained owing to the inability to determine what 

 length of time a single ring represented. 



Pollution was mentioned as a possible factor in 

 decreased sailfish catches off south Florida. Sailfish 

 occur closer inshore than other species of billfishes, 

 and thus could be seriously affected. This was the 

 only time pollution was mentioned. 



Distribution. — During this section of the Sym- 

 posium it became apparent that many facets of 

 research on istiophorids and xiphiids are of interest, 

 not only to the billfish biologists but also to a much 

 wider scientific community. One report contained in- 

 formation which should be of particular interest to 

 zoogeographers; another was concerned with 

 oceanographic studies directed primarily towards 

 billfish biology. In the latter study ocean 

 temperatures were monitored by means of an airborne 

 infrared sensor, and the data obtained proved to be of 

 immediate use to meteorologists, environmental 

 engineers, and other scientific and technical groups. 



The Symposium audience was pleased to hear 

 repeatedly just how much the sportsmen have been 

 able to help the scientists. Billfish tagging illustrates 

 this very well. A great deal has been learned about 

 billfishes from recapture of marked fish. Although 

 most of the billfish tagging has been done by 

 sportsmen, the commercial fishery's role in tagging 

 operations cannot be overlooked. Activities of the 

 latter is limited mainly to tag returns, including ac- 

 companying data on the fish. Perhaps more billfish 



could be tagged during commercial operations; this 

 possibility deserves attention from fishery biologists. 

 During the presentation of reports, as well as during 

 the discussion periods, some concern was expressed as 

 to the need for careful planning prior to a tagging 

 program. This is to assure not only maximum inflow 

 of recapture data, but also inflow of data which would 

 definitely aid in analysis of the movements and 

 growth of the fish. An obvious need for better tags, 

 perhaps more sophisticated tags, and better tagging 

 techniques was stressed by several of the speakers. For 

 example, incorporation of tetracycline, lead chelate, 

 or some other compound in the tag could be used to 

 mark time in the bones of the tagged fish and thus aid 

 in age and growth studies by means of hard parts. 

 Most of the participants were greatly impressed with 

 the type of information which results from tracking 

 billfish tagged with the sophisticated "sonic" device 

 described by one speaker. 



Billfish larvae caught during various scientific 

 cruises provide us with valuable information of the 

 spawning habits of the adults, as well as on the early 

 life history of the istiophorids and xiphiids. Larval 

 studies are hampered by the considerable difficulties 

 encountered in separating the various billfish species. 

 The only exception is the swordfish which, even at a 

 very early life stage, can be separated readily from the 

 other billfishes. The problem of identification of the 

 billfishes is so great that at the conclusion of this 

 Symposium a 2-day workshop to treat this subject will 

 be held in Honolulu and be attended by several larval 

 billfish experts (Working Party on the Early Life 

 History of the Billfishes of the FAO Panel of Experts 

 for the Facilitation of Tuna Research). 



The problem of evaluating the fishing effort related 

 to the sport fishery catch was raised. This is a difficult 

 problem and will be discussed in the following session. 



Fisheries. — The papers presented in this section 

 dealt mainly with descriptive accounts of specific 

 fisheries, e.g., the sport fishery in the northeastern 

 Gulf of Mexico, the commercial longline fishery in 

 Hawaii, and the commercial fisheries of Taiwan, and 

 with the presentation and analyses of catch statistics. 

 From the results presented it became apparent that 

 major gaps in our knowledge of billfish biology and 

 population dynamics exist, particularly with regard to 

 age and growth, mortality rates, and stock structure. 



One paper specifically examined the in- 

 terrelationship of the environment and the distribu- 

 tion of striped marlin. 



On the basis of data collected to date, much of what 

 we know today of the time and space distribution of 

 billfishes is based on catch statistics collected by the 

 longline fisheries prosecuted by Japan, South Korea, 

 and Taiwan. In addition to being far-ranging, the gear 

 used by the various longline fisheries is essentially the 

 same; thus, the indices of abundance are comparable. 

 This comparability of data was not found to be true 



