RECENT TRENDS IN
NEW ZEALAND'S
STRIPED MARLIN FISHERY

The most productive grounds are off the north-east of the North Island, where fishing bases were established in the 1920's. The fishery is seasonal, from December through May, and almost all marlin are caught on artificial lures trolled at speeds ranging from 4 to 12 knots.

New Zealand's billfish anglers have been fortunate in that management decisions made over the last ten years have strongly favoured them over commercial fishers. The Ministry of Fisheries, which is responsible for making recommendations on fisheries management to the New Zealand Government, has also been fortunate, because almost all billfish anglers either belong to fishing clubs, or fish from charter vessels associated with fishing clubs. As a result, excellent records detailing the recreational marlin catch back over 70 years are available for study. These records include both accurate catch tallies and the weights of each individual fish caught up to the present day. While useful in itself, this information was limited because it does not account for variations in fishing effort that may have occurred over the years. The records show that the number of boats that were successful in catching one or more marlin each season is far higher than in the 1920's, and this clearly suggests that far more fishing effort has been expended in recent years than was previously the case. Also, the seasonal tallies for the top boats in the "good old days" were far higher than the tallies for the top boats in recent years, which further confirms that catch rates were better in days gone by.

In 1977 an annual survey of charter boat catch and effort was instigated in northern New Zealand. Since that time it has been possible to consider each season's catch in the light of changes of catch in relation to effort expended. Catch per unit of effort data (CPUE) have been used to identify real differences in fishing success from year to year.

In 1987, foreign tuna longline vessels were excluded from the area of the recreational fishery during the summer and autumn. This effectively reduced the commercial catch of marlin to zero, since the domestic commercial tuna fishery had scarcely commenced at that time. Simultaneously, considerable new emphasis was placed on voluntary tag and release of billfish in both the recreational and commercial sectors.

By 1994, foreign tuna longliners were completely excluded from the fishery, as the local fleet expanded. New measures were introduced to prevent the local fleet from targeting billfish. The present situation is that no commercial vessel may land any billfish other than swordfish in the New Zealand Exclusive Economic Zone. All live marlin must be released, and dead ones cut off the line. It is estimated that 80% of striped marlin caught by local tuna longliners are alive when brought alongside, and an increasing number of skippers are tagging these before release. Commercial fishers have also agreed to release live swordfish under 50kg in eight, and as a result relations between the commercial and recreational sectors have improved.

The net effect of all these measures is that the New Zealand marlin fishery has been allocated entirely as a recreational fishery

There have been several interesting trends in the catch since the implementation of the management strategy. Firstly, the striped marlin catch rose immediately after 1987, and since 1993 has reached the highest levels ever recorded. Secondly, the number of marlin tagged and released has risen from an insignificant proportion of the total to approximately 60% of the catch. While complicating analysis of fish size, this has substantially improved the chances of obtaining information on the seasonal movements of striped marlin in the South Pacific.

As previously noted, the increase in catch could be reflecting a number of factors. For example, more boats may have fished due to prolonged periods of favourable weather, or environmental conditions such as higher water temperature than in previous years may have seen more fish close inshore. However, it appears that no matter what the reasons are, the improvement in the striped marlin fishery is real. Charter vessel CPUE, which was at an all-time low in 1985, improved dramatically after 1987, declined somewhat during 1990-92 (though remaining well above the 1985 level) and then rose to an all-time high in 1994. The results from 1995 are preliminary, but indicate that the improvement has been sustained this year. A further point to note about Figure 2 is the number of days fished on average by each charter vessel. Following the decline in catch from 1985 onward, the number of days fished fell by approximately a third as angler expectations of being successful were reduced. If the increase suggested in the 1995 data is sustained, this is good news for the charter boat industry. Meanwhile, morale is very high among New Zealand anglers, many of whom are already anxiously awaiting the arrival of December, 1995, and the start of a new season.