Kahawai FAP

Kahawai Final Advice Paper

Ministry of Fisheries

29 June 2004

Setting TACs

123. MFish proposed in the IPP that kahawai TACs were based on estimates of current utilisation. MFish’s estimate of current utilisation for the purpose of setting TACs has been revised from the IPP and is now based as follows:

1. The lowest estimate of recreational catch from 1999-00 and 2000-01 diary surveys for each stock management area;
2. Customary catches based on an altered proportion of estimates of recreational current utilisation (25% as opposed to 50% proposed in the IPP);
3. Revised estimates of other sources of fishing related mortality;
4. Commercial landings based on the average of landings reported for the five fishing years between 1998-03 (now with commercial landings adjusted by prorating up to catch landed data totals).

124. Revised estimates of current utilisation are now greater than the best available estimates of MCY for kahawai (7 600 and 8 200 tonnes). While these estimates are outdated and uncertain they remain the only reference points of sustainable yield for kahawai. Further an “ad hoc” revision of the MCY estimates based on a lower value of natural mortality suggests that they should be lower (although this is counterbalance if past recreational catches has been higher than previously thought).
125. There is a risk that current utilisation of kahawai stocks may not be sustainable and there are also widespread perceptions from the recreational fishing sector that a rebuild of kahawai stocks is required. MFish now considers that an alternative option of setting TACs for kahawai below the current level of use should be considered.
126. MFish proposes two TAC options for your consideration. The first option is to base TACs on current utilisation and the second option involves a proportional reduction in current commercial and recreational utilisation of 15% for key kahawai fishstocks. The percentage reduction proposed by MFish is arbitrary but is intended to strike a balance between the impacts of any reduction in current use and the increased certainty that the sustainability of kahawai stocks is ensured.
127. Alternative options for setting TACs have been suggested by submitters and these are outlined below along with the two MFish options. The options are evaluated as combined TACs as some are presented in submission in this manner with a variety of proposals to apportion these combined TACs between stocks.
128. Submissions containing specific information used to support TAC options proposed by stakeholders are addressed in Appendix 1.
129. Options identified for setting combined TACs are:

1. 9 595 tonnes based on current utilisation using an average of five years between 1992-97 (TOKM) apportioned between stocks on the basis of estimates of current utilisaton;
2. 8 757 tonnes a status quo option based on the revised estimates of current utilisation presented in this advice. (MFish current utilisation) apportioned between stocks on the basis of estimates of current utilisation;
3. 8 200 tonnes on the basis of the MCYsensitivity analysis estimate (Sanford) apportioned between stocks on the basis of the distribution of catches and catch estimates;
4. 7 612 tonnes based on a 15% reduction in commercial and recreational use in key kahawai stocks (KAH 1, KAH 2, KAH 3, and KAH 8) (MFish proportional reduction);
5. 6 900 tonnes on the basis of a revised estimate of MCYbase case (Non-Commercial Fishers) apportioned between stocks on the basis of the distribution of recreational catch estimates and the level of commercial bycatch; and
6. 6 685 tonnes based on reducing commercial catch to a bycatch level only (RFC and Mark Feldman).

130. TAC options are shown in Table 5. While submitters have different proposals for allocation underlying there proposals for combined TACs the setting of allowances and TACCs is a separate decision. In terms of choosing a combined TAC option for kahawai there is a balance between the risk to the stock and the level of impact on current fishers you may wish to impose given the uncertain information on the status of kahawai stocks. Lower TACs represent least risk but also impose a more significant impact on current users of the fishery.
     
     

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131. MFish notes the following are relevant factors for evaluating TAC options. There is:

1. a 1996 stock assessment with estimates of MCY of 7 600 tonnes and 8 200 tonnes;
2. the MFish preferred reference point was 7 600 tonnes in the IPP;
3. 1996 information on status of stock relative to BMSY (50%);
4. considerable uncertainty in the estimates of yield and stock status for kahawai;
5. a revised estimate of current utilisation beyond the best available estimates of MCY (7 600 and 8 200 tonnes);
6. some agreement by sectors for a target stock level above BMSY;
7. a commercial view that there is no evidence of declining recreational catches, numbers of schools of kahawai or changes in the level of bycatch in recent years;
8. a strong recreational perception about declining abundance, availability and size of fish in the main stocks; both long term and in recent years;
9. a revised estimate of MCY submitted by Non-Commercial Fishers (6 900 tonnes) as a basis for combined TACs; and
10. a revised stock assessment of kahawai is planned but results will not be available for management consideration until the 2006-07 year.

132. This option is intended to reflect the status quo management arrangements for kahawai and is based on revised estimates of current customary, recreational and commercial utilisation. MFish notes that the NIFCL supports the basis for assessing current utilisation (using revised values) and assuming that status quo management should continue. TOKM supports the basis for assessing current utilisation but prefers that the criteria years be 1992-97 for most of the fishstocks. Sealord supports the IPP basis for assessing current utilisation for KAH 1, KAH 2 and KAH 8 but submits that for KAH 3 current use should be based on the current CCL (1 500 tonnes).
133. Combined TACs for this option total 8 757 tonnes (9 595 for the TOKM proposal and 9 722 tonnes for the Sealord proposal). This level of utilisation is greater than the best available estimates of MCY for kahawai based on the preferred natural mortality parameter (7 600 and 8 200 tonnes). MFish retains its preference for the lower of these two reference points as providing the best balance between the uncertainty in parameters (natural mortality) and inputs (recreational catch) used in the assessment model. While yield estimates are uncertain, as are some estimates of current utilisation (and you need to take this uncertainty into account), there is a level of risk to the sustainability of kahawai stocks if combined TACs are set at this level of utilisation in the fishery. The risk is that kahawai stock sizes will not be maintained at or above BMSY.

134. Sanford propose that TACs be set on the basis of the 1996 MCYsensitivity analysis estimate (8 200 tonnes) apportioned between stocks. Sanford considers that this yield estimate is conservative and will provide for a level of harvest that will maintain stocks at or above BMSY.
135. MFish does not support the use of MCY sensitivity analysis as a conservative estimate of MCY. While it may be a better reflection of yield from the fishery if the pattern of catch used in the model to derive this estimate is correct, the actual trends in catch are not known. The base case MCY estimate remains MFish preferred option as a reference point.
136. A TAC of 8 200 tonnes is likely to present less risk to the sustainability of kahawai stocks than one based on current utilisation. It is uncertain, however, whether a reduction to this level will maintain stocks at or above BMSY. It represents only a 567 tonne reduction (6%) from estimates of current utilisation and is 1 395 tonnes less than the TAC proposed by TOKM using alternative commercial catch history years. Adopting this option would give less weight to the anecdotal information of declining stock size, availability and size of fish but would reduce the impact of any reduction on current fishers.

137. MFish considers that there is a case for a reduction in current use of kahawai because there is general uncertainty about the state of the stock.
138. Anecdotal information from recreational fishers suggests kahawai are less abundant. Anecdotal information is by its nature uncertain. The level of uncertainty should be factored into the weight you place on the information in determining your decision on TAC options. In this case MFish note that while the information is uncertain, the quantity of information from recreational fishers, and consistent concern expressed by submitters about the state of the fishery indicates the general concern recreational fishers have for the state of the stock.
139. In addition you should note the potentially important role of kahawai in the ecosystem, which might lead you into emphasising the need for caution in management.
140. MFish note that catch sampling and age structure data from the fishery are not providing information to support a recent decline in the size of fish in recreational catches and by implication biomass of the stock. The size and age of the fish sampled has remained relatively constant. However MFish notes that catch selectivity may influence these indicators and they may not reflect trends in stock abundance.
141. Estimates of current utilisation are above the best available estimates of sustainable yield (7 600 and 8 200 tonnes). However the 1996 assessment is dated and uncertain. This uncertainty is compounded by potentially counteracting effects of:

1. information on natural mortality which suggests the estimate used in the assessment might have been too optimistic; and
2. new information on recreational catch which suggests that the 1996 recreational catch estimates used in the assessments are unreliable (catch by this sector may be higher than that used in the assessment which would tend to increase MCY estimates but this is not known).

142. Nonetheless, MFish consider there is sufficient information (anecdotal information from recreational fishers and stock assessment information) to consider a reduction to current landings. Given the uncertainty in information about stock status and information on sustainable yield MFish considers that a nominal 15% reduction to the level of current removals could be considered.
143. MFish note that a 15% reduction of current utilisation (to 7 612 tonnes) would move landings close to the MFish preferred estimate of MCYbase case (7 600 tonnes ) for the fishery. This estimate, although uncertain, provides the best indication of possible sustainable yield for the fishery at this time. MFish note that a further stock assessment using updated information is proposed (although not yet confirmed) for 2005. Information from this assessment, if it goes ahead, would be available for use in considering management options for the 2006-07 fishing year.
144. MFish acknowledges that this combined TAC option is based on an arbitrary reduction from current levels of use but considers that a reduction of this amount provides a balance between providing greater certainty that kahawai stocks will be maintained and the level of impact imposed on existing users of the fishery

145. Non-Commercial Fishers propose a combined TAC of 6 900 tonnes based on a revised estimate of MCYbase case.
146. MFish notes that Non-Commercial Fishers support setting more conservative TACs to allow rebuilding of the stocks. Non-Commercial Fishers submit that recalculating MCY on the basis of M=0.18 will achieve this.
147. MFish notes that basing TACs on any level of MCY will not necessarily rebuild stocks although the risk of reducing stock size below BMSY is reduced with catch limits based on the more conservative estimates. In addition the Non-Commercial Fishers recalculation of the MCYbase case ignores the potential counter effect of higher estimates of recreational catch on MCY estimates.
148. MFish considers combined TACCs of 6 900 tonnes are more conservative than required for the fishery. There would be socio-economic impacts of adopting this level of fishing. Shared reductions by both the commercial and recreational sectors of around 25% from current levels of utilisation would be required to achieve fishing levels of 6 900 tonnes. MFish considers that on balance, this level of reduction is not required to ensure sustainability but notes that a reduction to this level would provide greater certainty that the kahawai stock would remain at or above BMSY.

149. This option is based on reducing commercial catch to a bycatch level only. MFish notes that the focus of this option is on allocating kahawai rather than on proposing sustainable limits on total removals from the fishery. However, by assuming current levels of utilisation for recreational and customary fishing and by basing the commercial component of TACs on bycatch levels a combined TAC total of 6,685 tonnes is suggested.
150. This proposal includes the proposition of removing the purse seine target fishery and discounting past commercial catches by this sector. This proposition is also contained in many email submissions as a result of the Option4 website. This proposal is considered more appropriately under the allocation section of this advice. With regard to the combined TAC level proposed, MFish advice is similar to that provided for the option of Non-Commercial Fishers.
151. There would be substantial economic consequences associated with this level of combined TAC. While MFish acknowledges that there would be more certainty that catches were sustainable MFish considers that this needs to be balanced against the level of impact on existing users. It is MFish’s view that adopting this option would give undue weight to potential environmental issues and the anecdotal information of declining stock size, availability and size of fish and ignore other indicators that suggest no recent change in kahawai abundance.