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Towards the Future This atlas summarises most of the available information relevant to understanding the seasonal distribution and abundance of billfish species around the Coral Sea Rim. Clearly, many gaps in our knowledge remain. How might these best be filled? The development of local longline fisheries, such as those being explored at the time of writing in southeast Papua New Guinea, will greatly increase our understanding if appropriate data are collected (such as suggested below). There also remains considerable scope for exploring the effects of large-scale environmental variability, such as El Niño, on catch-rates and distributions using existing longline and environmental data. There is also a great opportunity to increase our knowledge using data collected by gamefish anglers themselves. Existing records of several Papua New Guinea gamefishing clubs have been very useful in compiling this atlas. However, as the club recorders are the first to admit, present records have certain limitations for this kind of study. The first two of these problems, in particular, are not limited to this region but are typical of many recreational fishing data sets. The limitations are, in descending order of significance: lack of effort data; fragmented records; identification difficulties; and lack of information on the sex of the fish caught. Below we explain the significance of these limitations and how they might be overcome. Effort is the amount of time spent fishing. Records might show five times as many billfish caught in one area as in another but this tells us nothing about the numbers present unless we know the relative amount of fishing done in each area. There may simply be five times as much fishing done in the first area as the second. Similarly, most fish might be caught during a particular season but this may simply be the time of year when most of the fishing is done, perhaps because the weather is calmest and fishing most pleasant. Unless the number of fish caught can be standardised to number of billfish caught per hour fished, for example, it is very difficult to compare catch-rates between areas or seasons. Days spent fishing when no fish were caught are just as important to record as the days when big catches are made. It is also important to know whether effort is targeted at billfish. For instance, specialised techniques will catch a lot more billfish than will trolling for spanish mackerel and tuna. A few clubs or individual anglers keep excellent long-term records, but these usually result from the efforts of dedicated individuals who remain in one locality for a long time. Outside the northeast Australian fishery, in particular, gamefishers tend to be transient. The fish too, are highly mobile, and building up a better picture of their seasonal movements will require the collection of standardised data from as many widely spread localities as possible. These data, from diverse sources, will then need to be collated and analysed to build up the big picture. To the inexperienced gamefisher (or researcher!), species of marlin can be difficult to tell apart. Catch records can only be of use if species identifications are good. Hopefully, the brief keys provided in this atlas will assist in this area. Because movements of black and blue marlin appear to differ between sexes, information on the sex of captured fish as well as their weight may greatly assist in the determination of age-specific and seasonal movements. Again, we hope that the information provided in this atlas will greatly assist in this area. To assist in the filling in of gaps in our knowlege of billfishes around the Coral Sea Rim, we propose to initiate a new database on billfishing around this region. It will be based on the simple data sheet which appears in this atlas. The design of this data sheet is based on our previous experiences in collecting data on billfish catches and is aimed at being as simple as possible, but still including the essential data outlined above. It is also designed to be a useful and simple log for the skipper/angler as well as a tool for research. We propose that these sheets be filled in by interested skippers/anglers and returned to the Australian Institute of Marine Science where they will be collated and analysed. Annual summaries of the results will be returned to those submitting data, as well as to their clubs and national associations. The success of this project will depend both on the willingness of anglers to participate and on the timliness and effectiveness of our feedback. Initially, we propose to cover the waters of Papua New Guinea, the Solomon Islands, Vanuatu and New Caledonia. Should there be sufficient interest, northeast Australian waters could be readily added to the database and thus greatly enhance the project. Such a database would also be extremely useful in our studies of the factors causing seasonal and year-to-year variability in the east coast fishery. However, given the much greater effort in these waters, and hence larger amounts of data that we would have to handle, further sources of funding would need to be sought to make it a viable project where the database could be kept up-to-date and appropriate feedback given to the contributors. web@aims.gov.au
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