There is no doubt that continuation of unmanaged coconut crab exploitation as it now occurs on Niue will result in disaster. Two basic forms of remedial management/conservation measures have been proposed. The first is promotion of the concept of self-regulation through making Niueans aware of the problems facing the crab, informing them of the measures they can take to help, and explaining the consequences of complacence. The second is government imposed hunting and export restrictions. Unfortunately, as explained in the previous section, there is reluctance on the part of the Niue Cabinet to endorse the proposed coconut crab legislation. As such the immediate future of the coconut crab on Niue rests on the success of the public awareness/education programme in promoting effective self-regulation.
Regular monitoring of the size and size-frequency distribution of the coconut crab population on Niue is required to evaluate the success, or otherwise, of the conservation measures instigated, particularly in light of the fact that government legislation may not eventuate for some considerable time, if at all, leaving only the process of self-regulation to ameliorate current exploitation to sustainable levels. Immediate feedback on the effect of self-regulation on hunting practices/levels is required in order that the situation is not permitted to degrade past a point of no return. If follow-up surveys indicate no, or minimal, improvement, additional measures could be employed, such as strong representation to the Niue Cabinet for immediate introduction of the coconut crab legislation.
A cornerstone of the coconut crab management problem faced by Niue is the calculation of a meaningful sustainable yield. Unfortunately the scope of the present study was insufficient to quantify directly the effect of current levels of exploitation on the size and size-structure of the coconut crab population. Quantification of the relationship between the magnitude of exploitation and changes in the population dynamics of the coconut crab can only be accomplished via a programme of regular annual, or possibly biannual, small-scale coconut crab population surveys. Such regular surveys will also provide data on temporal patterns of larval recruitment which is vital in development of meaningful long-term coconut crab management strategies.
As such the data from regular surveys of the coconut crab population on Niue are not only important to Niue but to all countries with coconut crabs. Niue could be used as a precedent setting case study in which the effectiveness of different conservation approaches in combating the decline in coconut crab numbers could be used as a reference by other countries as they attempt to develop their own coconut crab management strategies. The Australian Centre for International Agricultural Research (ACIAR) coconut crab project in Vanuatu (1985–1987) was similar in many respects to the present study, however the effectiveness of conservation measures implemented in Vanuatu is impossible to ascertain as no adequate programme of follow-up surveys is in place. In effect much useful data has been lost. The same mistake should not be made in relation to Niue. The small size of Niue makes it possible for small-scale follow-up coconut crab population surveys to yield much useful data. A proposed follow-up research programme for Niue is presented below.
Investigating the effect of exploitation on the population dynamics of the coconut crab requires monitoring of both exploitation levels and changes in crab population dynamics.
Exploitation of the coconut crab on Niue occurs at 3 levels and each must be monitored.
1 Subsistence-Based Exploitation
Monitoring of subsistence based exploitation will require the honesty and co-operation of crab hunters in completing hunting ‘information’ sheets. It is proposed that simple pro-forma data sheets be regularly distributed (Eg. monthly) to all hunters with the request that they complete the questions on the sheet and return it to DAFF. The sheets could include questions such as a) The number of days during the previous month coconut crab were hunted, b) The number of crabs caught over the previous month, c) The main area in which hunting was conducted, d) The number of crabs sent to market during the last month and e) The number of crabs captured for export over the last month.
If necessary the forms could be completed on an anonymous basis if hunters consider that the questionnaires could be used to monitor individuals. Alternatively a small inducement (a small sum of money or any other form of reward) could be used to encourage hunters to complete and return the forms. However, as was discovered when such a system was trialed in Vanuatu, there are ‘dangers’ associated with use of an incentive-based system and care needs to be exercised to ensure the system is not abused. It is suggested that a member of staff from DAFF could be made responsible for the distribution and collection of the forms and possibly entering the collected data into a computer database.
By cross-checking information on the number of crabs sold at the market or exported collected from the questionnaire sheets with the results from the direct methods outlined below, a ‘confidence level’ for the questionnaire data could be established.
2 Export-Based Exploitation (Air)
Quarantine Officers from DAFF are currently on duty at the airport for all flight arrivals/departures to inspect foodstuffs being exported as cargo or baggage. Where a quarantine certificate is required a small fee is charged. Given that all outbound passengers are currently questioned as to the presence of food items in their cargo or baggage, it is proposed that the quarantine officers could readily ascertain from passengers exporting coconut crabs the number and/or weight of crabs involved in their consignment. This information would then be passed on to the DAFF staff member looking after the data on coconut crab exploitation.
Possibly a local coconut crab clearance system, similar to that currently used for certain food items, could be instigated whereby all coconut crab exports must be examined by quarantine officers at the airport prior to export. For a small fee the consignments would be cleared and issued with a coconut crab export clearance sticker. The fee collected could then be used to fund the total exploitation monitoring programme (ie. subsistence, export and commercial exploitation).
3 Commercial-Based Exploitation (Markets)
During the period of the current survey regular monitoring of the number and, where possible, size of coconut crabs offered for sale at the local market was conducted by Mr Etuata from DAFF. Such monitoring normally required only 30 minutes or so each market day and it is proposed that a DAFF staff member could be assigned to permanently monitor market sales of coconut crabs.
It is proposed that follow-up surveys initially be conducted on an annual basis until the decline in the size of the coconut crab population has been reversed, where upon survey intervals could be increased to 2 years.
The survey programme proposed is of 5–6 weeks duration conducted during the months September-November. Surveys would be conducted along the same transects used in the present study although the number surveyed would be reduced from 35 to 30 through deletion of some Fernland and Light and Scattered vegetation category transects. Each transect would be surveyed twice to determine mean CPUE values. The period September to November is recommended because during these months most crabs would have completed moulting and emerged from their burrows. It is also before the onset of the wet season and would therefore minimise disruption of field-work due to inclement weather.
Transect surveys could be conducted by DAFF staff. Mr Colin Etuata (DAFF) was most competent in conducting transect surveys for the current study and either he, or someone trained by him, could complete the surveys.
Release of mature eggs into the ocean by coconut crabs is both synchronous and rhythmic and tends to be concentrated at specific coastal sites (Schiller 19988a, 1988b, Schiller et al 1991). It is proposed that a research programme be established to investigate the following areas:
1. Identification of the major coastal regions used by coconut crabs to release their eggs into the ocean. Release of eggs by female coconut crabs is restricted to a few days each month. The specific days of egg release for a given month in a given year can be calculated through use of a predictive model developed by Schiller et al (1991). As such it would be possible for a researcher to restrict coastal searches for egg-releasing females to calculated egg-release periods avoiding the necessity to search the same areas at different times of the month to ensure no reproductive activity was missed. Consequently it would be possible for the entire coastline of Niue to be surveyed in one reproductive season, from November to March.
Once the major egg-releasing sites have been identified area closures could be made much more localised both in terms of the actual area effected and the periods of closure necessary. This would have the effect of decreasing the impact of area closures as perceived by the public while at the same time increasing the effectiveness of the closures in affording protection to the coconut crabs and their eggs.
2. Conduct annual surveys of the major egg-releasing sites (as identified above) to monitor the number of egg-releasing females. This data could then be considered an index of annual reproductive effort and used to assess changes in the reproductive potential of the coconut crab stock on Niue. In terms of assessing the effectiveness of introduced management/conservation measures such information is crucial. The reproductive index in conjunction with annual stock survey data would provide an extremely reliable indication of changes in the size of the coconut crab stock.
The majority of the proposed follow-up research, collection of exploitation data and conducting of transect surveys, can be accomplished by staff from DAFF. However overall co-ordination of the research, development of transect survey programmes and analysis/interpretation of results would require an external consultant versed in such procedures. The combination of on-island field workers and off-island co-ordination used during the current study was a success in terms of data collection and minimising costs. It is suggested that continuation of such a working relationship would benefit Niue in terms of developing local research skills as well as providing for collection of long term data at minimal cost. Continued involvement by the Zoology Department, The University of Queensland, in any follow-up research is strongly recommended in that it will provide continuity of research plus access to a large coconut crab database covering information collected over many years from Christmas Island, Vanuatu, The Cook Islands, and Niue.