KAHAWAI SUBMISSION MARK FELDMAN

Kahawai Submission

by Mark Feldman

22 February 2004

Mark Feldman
Kerikeri

Northland

February 22, 2004

Regarding: Initial Position Paper on kahawai dated January 12, 2004.

The most significant problem with the IPP is that the Minister was not provided with a range of options to choose from.

Kahawai is an important species to over a million New Zealanders, many of lower socio-economic classes. There is not much “hard” data available about the species and virtually all the “soft” data available (much of it left out of the IPP) points towards a declining fishery. Despite these facts MFish has offered the Minister only one management choice, a choice that ignores the facts and proposes to increase the commercial catch at public expense.

With so many unknowns, the minimum expectation is that the Minister would be provided with a range of options based on different interpretations of the available data. Because kahawai is of far greater value to the recreational and tourist sectors one of those options would have to be making kahawai a by-catch only species.

The comments that follow relate to the item numbers on the left side of the page in the IPP.

2b: “The current biomass is unknown…reported landings are currently just within the range of MCY estimates…”
The biomass is unknown and the MCY is pure conjecture. Basing management decisions for an important fishery on inadequate evidence is reckless and irresponsible. Far more weight should be given to the data we have from recreational fishing sources, tagging studies, and fork length studies. These are summarised in Item 102 and reflect a declining fishery that is no longer able to provide adequate resources for the recreational sector.

2d: “Declining catch in QMA3 is associated with reduced purse seining in this area.” The question here is which came first, the reduced purse seine operations or the depleted fishery. MFish has accepted Sanfords story that they just chose to reduce their South Island operations for logistical reasons. But I do not believe that is correct.
In 1993 the scientists that had worked on “The Biology and Purse Seine Fishery of the Kahawai From Central NZ During 1990/91-1991/92” expressed grave concerns to me at the Plenary about the state of the fishery in Kah 3 as a result of the uncontrolled kahawai catches (14 million fish in a decade).
The rationalization that Sanford/Sealord provided was that weather conditions prevented them catching their quota in 1991-’92, but the continued failure to catch fish after that season convinced me their explanation was false. Events since then have confirmed my impression that they have withdrawn from Kah3 because it’s too hard to find the fish, NOT for any other reason.
You would have to be pretty naïve to believe Sealords and Sanfords stopped fishing QMA3 for any other reason than a reduced CPUE and it is inappropriate for MFish to accept that story without proof.

2F: “The recreational sector believes that the number of kahawai available to them and the average size of kahawai has decreased over time.”
This is true yet MFish suggests that the status quo is the preferred management plan. This is very poor reasoning when you consider Item 129 where MFish points out the value of the recreational fishery is 11-16 times greater than the commercial fishery, and Item 102 backing up the claims of the recreational/tourist sector that the fishery is stressed. The only conclusion I can come to from this reasoning is that MFish has a major commercial bias.
MFish has also left out of the IPP the results of tagging studies done between 1983-1991, and fork length studies, both of which strongly supports the arguments of the recreational sector. This issue will be examined under Item 102.

6: All of Item 6 and the IPP are focused on managing the kahawai fishery on the basis of MSY. This is ridiculous for two reasons:

1. We have no idea what the MSY is.
2. The recreational and tourist needs are not being satisfied now (very low CPUE, declining size of fish). Since the recreational fishery is much more valuable, satisfying the needs of the recreational and tourist sectors should be the basis of management NOT a MSY based on lousy data

11: “Trends in non-commercial catch during this period (since 1993-‘94) are unknown.”
This is not so. Again, Item 102 indicates that the recreational survey in 1997 showed that the fishery was still in decline. In addition, data from NZ Angling Ltd. reveal that kahawai catches in their tournaments show an ominously steady decline from 1994-2000. And the endless stream of concern about the fishery still continues unabated. That data is available on the option4 website: https://www.option4.co.nz/Fisheries_Mgmt/kahsnzal.htm

20: “The proposal to set TACs at the level of current utilization assumes that these perceptions are associated with a reduction in the kahawai stock to a level at or above Bmsy and not below that level.”
Again, we don’t have a clue what the MSY for kahawai is. We also have no idea what the biomass is. What we do know is that there are not enough fish in the water to satisfy the recreational needs and THAT should be the basis of management.

23: “Mfish considers that the disparity in relative value between the sectors supports the need for caution in setting catch limits for the fishery.”
This is correct. But the proposal to continue the status quo is NOT cautious. We already know the commercial catch is so high that it has reduced the CPUE for the recreational sector to an unacceptably low level.
Really, by now Mfish should have gotten the message that something is wrong with the management of the kahawai fishery.

34: “…currently there is no scarcity within the fishery.”
This is just plain dumb. What do you think Item 102 means? These recreational surveys and your own CPUE figure in Item 102 all indicate the kahawai are way too scarce to support a valuable recreational and tourist fishery.

35: “…TACCs have been calculated using average commercial landings for the period between 1997 and 2002.”
In a damaged fishery where the recreational sector has fewer and smaller fish, and the commercial sector has had declining catches in every QMA, Mfish wants to base the TACCs on the much higher catches of seven years ago.
That decision represents very poor judgement and is certainly NOT cautious management.

49: “...declining catches in QMA 3 is associated with reduced purse seining in this area.”
As in 2d, cause and effect are confused here. I believe the catch has declined because the fish aren’t there. That’s why the purse seiners don’t go there anymore.

50, 52: Here it’s proposed that “nominal” TACCs of 10 tonnes be set in Kah 4 and Kah 10, areas where there is no catch now.
In a depleted fishery, why would you want to do that?

65c: “Current recreational concerns with regard to the reduction in availability of kahawai to them are not addressed by setting TACs based on current levels of utilization.”
This is true but MFish has chosen to ignore it. Does Mfish seriously believe that a CPUE of 0.2 kahawai per hour is acceptable? Does MFish think it’s wise to throw away a high value recreational fishery for a very low value commercial one?

65e: “Kahawai fishing is not known to pose a risk to the long term viability of any associated or dependent species.”
This is scientific jabberwocky and is only true because MFish is keeping its eyes closed. Even a brief glance at the sea would reveal that terns and shearwaters are heavily dependent on kahawai to feed. The reduced number of kahawai schools explains the easily observed decline in their populations.

65L: “…uncertainty and the absence of information is not a reason for failing to provide for utilization at levels considered to be sustainable, however MFish notes that caution is required in this instance.”
MFish is clearly NOT being cautious here. Recreational fishers feel the kahawai fishery has NOT recovered from the gross overfishing of the previous 20 years and is still in decline. Since MFish has no better information available it would be cautious to substantially reduce the latest commercial catches, not increase them.

98: “Kahawai anglers are characterised as follows:…more likely to fish for eating purposes….more likely to fish from jetty or land platforms….have a lower average fishing expenditure…”
I’m sure these are all accurate statements but the MFish proposal to increase the TACC for kahawai ignores the needs of these anglers, who represent the lowest socio-economic classes; people that cannot afford fish unless they catch it. Does MFish think it’s reasonable for a financially disadvantaged person to have to fish for 15 hours to catch a feed of kahawai for his family? I hope not.

102: “Recreational groups have repeatedly expressed concern about the state of the kahawai stocks…In 1997 47% felt the kahawai had ‘declined significantly’ and 32% felt that they had ‘declined a little.”
What was left it out here is that over half these respondents had fished over 20 years. This represents a LOT of experience and is the best information available on the kahawai stocks, certainly heaps better than the “shit in, shit out” formulas in Items 108-114 in the IPP.

102: “Boat ramp surveys conducted by MFish….indicated that catch rates of kahawai by recreational fishers were <0.2 fish per hour, however these values included trips targeting other species and therefore may be artificially low.”
I don’t believe the catch rate of 0.2 fish per hour is artificially low for the following reasons:

1. Catch data from the Motu River mouth area shows a decline in CPUE from 4.2 for locals (2.6 for visitors) in 1982 to less than 0.1 in 1991. The fishery has certainly declined since 1991 so the CPUE figure is even lower now. Details are on pages 17-18.
2. The boat ramp and diary studies of the 1990’s indicated a catch of 0.4 kahawai per angler per trip. Any reasonable person would conclude that’s a very poor catch rate.
3. The CPUE for snapper in the North region is three times higher than the CPUE for kahawai and we know that the snapper fishery is below the Bmsy in the North

The other problem is with the term “targeting.” For the vast majority of today’s fishers the catch rate of all species is so low that virtually all fishers are targeting kahawai. Even if they’re ostensibly targeting snapper their techniques are equally effective for kahawai and, if a surface school of kahawai were to come by, they would try to take advantage of it since they’re most likely NOT catching anything else anyway.

102: Significant sources of data have been left out of Item 102. The material below has been obtained from the tagging studies done in 1983 and 1991 and the fork length studies done between 1983 and 1992. The information is as follows:

1. If a simple comparison is made between the returns from the tagging programs in 1983 and 1991 there’s a striking result. The comparison is between the tag returns from purse seine operations and recreational rod and reel fishers in the Bay of Plenty. In 1983 recreational anglers returned 72% of the tags. By 1991 the proportion had dropped to 27%. At the same time the proportion of returns from the purse seine vessels rose from 28% to 72%.
   
   I believe this indicates the recreational catch as a proportion of the total catch was much higher in the early 1980s than it is now. This implies a dramatic decrease in the recreational catch and CPUE over the decade. A more detailed explanation, including the original data, is available at the end of this report on pages 6-8.
   
   The essential message here is that, with the blessing of MFish and despite the objections of the recreational sector and warnings from MAF scientists, the kahawai resource was reallocated from the Kiwi public to Sanfords and Sealords. I object to the loss of those property rights and to MFish using past mistakes as a justification for giving those rights away in perpetuity by calling it the status quo.
2. Analysis of fork length studies done in 1983 and 1992 showed a decline of 5.7cm in the size of purse seine caught kahawai in the Bay of Plenty. A comparison of rod and line caught kahawai from various sites around the North Island showed a similar decline in fork length from 1983 to 1991 from every site examined. A more detailed explanation, including the original data, is available at the end of this report on pages 9-16 .

112: “The above estimates are uncertain and depend on the model assumptions and input data.”
You bet! This is the “shit in, shit out” principle. It is absurd for MFish to make important social/economic decisions on the basis of hypothetical data.
The data presented in Items 108-113 is much less reliable than that obtained by recreational surveys, MFish’s own ramp surveys and the data presented above under Item 102.

119: “Kahawai….make available the prey species to other predatory species.”. This statement is certainly correct but then the IPP goes on to say, “There is no information on whether current kahawai fishing activities are detrimental to the long term viability of any other species.” Like Item 65e, this is another example of scientific jabberwocky; the old “there is no evidence routine.”

The reality is that kahawai are especially significant for terns and shearwaters that are dependent for food on the kahawai. The vast flocks of these birds in the North have been dramatically reduced because they cannot feed without the help of the kahawai. This information should be included in the IPP and would be obvious to anyone that has spent time on the water over the past 20 years.

129: “…a commercial value for kahawai…which is approximately one sixteenth to one eleventh of the estimated value…of kahawai caught by recreational anglers.”

I’m sure this is just about right and I published similar data a decade ago. It is inconceivable that MFish would recognize this disparity in value and yet recommend an increase in the commercial catch for this stressed fishery. Imagine what it would be like in court if MFish had to justify destroying about a hundred million dollars in value to our society by recommending the continued purse seining of kahawai.

The kahawai issue will invite significant attention from the media and MFish will have to defend itself to the press and the courts unless major changes occur in the final position paper. It’s about time to rethink MFish’s strong commercial bias.

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A Comparison of the Rates of Recovery by Purse-seiners and Rod and Line Fishers of Tagged Kahawai from the 1983 and 1991 Tagging Studies in the Bay of Plenty

Summary
A comparison of the tag returns from the kahawai tagging programs in 1983 and 1991 was made. The comparison was based on the tag returns from purse-seine operations and recreational rod and line fishermen; it was limited to the Bay of Plenty.

In 1983 the rod and line fishers returned 72% of the tags. By 1991 that proportion had dropped to 27%. During the same period the proportion of kahawai tags returned by the purse-seiner operators rose from 28% to 73%.

We believe this indicates the recreational kahawai catch was much higher in the 1980’s than it is now, and the number of kahawai available to the recreational sector has declined significantly. A change needs to be made to the Working Group document to reflect the probability that the recreational catch and CPUE were higher in the 1980’s than they are now.

Background
The boat ramp and diary studies done by the Ministry during the 1990’s have revealed an average catch of one half of a kahawai per person per trip in the North Region; a poor catch by any measure.

Unfortunately there is very little data available to quantify the recreational catch in the mid 1980’s, before the sharp increase in purse-seine catches that were associated with the introduction of the QMS. Up until now only one study was available; a CPUE study at the Motu River mouth done in 1982. This study was never repeated in exactly the same manner, but a comparable study of the Bay of Plenty in 1991 suggested a severe decline.

In 1997, the results of the 1991 kahawai tagging study became available. For a number of reasons outlined by Elizabeth Bradford in her 1997 paper called, “Estimation of Kahawai Recreational Catch from Tagging Returns ….” It was not possible to use either the 1983 or the 1991 tagging studies to calculate a kahawai biomass or quantify the recreational catch. In both of these studies all the tags recovered were not returned, the amateur and commercial effort distributions were not the same and the tagged kahawai were probably not evenly distributed in the population.

Since both the 1983 and 1991 tagging studies suffer from the same flaws in the same way it is reasonable to assume the effects smooth out when the studies are compared. For instance, its well known that tags from individually handled fish are more likely to be returned than tags from purse-seine caught fish. That is not a problem if you only want to compare the studies, because tags recovered by purse-seiners had the same chance of being returned in both 1983 and 1991. Likewise, tags recovered by hook and line fishers had the same change of being returned in 1983 and 1991.

In a similar fashion, the differences between the amateur and commercial effort distributions were likely to be the same in 1983 and 1991, and the irregularities of the mix of tagged kahawai with the general population were probably equivalent too.

In 1983 most of the kahawai tagging operations were performed from June to September. In 1991 the tagging was completed in July. During the 1980’s- 1990’s the total recreational fishing effort was probably stable with population increases offset by a lower percentage of people fishing. Weather conditions, which influence the total recreational catch, were actually better after the 1991 tagging effort than after the 1983 effort, so weather was not the cause of the decline in the proportion of kahawai caught by the recreational sector. The total purse-seine catches in KAH1 during the periods 1983-87 and 1991-95 were almost identical so that is also not a factor in the relationship. The percentage of tag returns in the 1983 study was 9.7% (138/1427) and the percentage for 1991 was 11.9% (551/4622); certainly comparable return rates.

Results
During both the 1983 and 1991 tagging studies large numbers of kahawai were tagged in the Bay of Plenty. Records of tag returns were kept over the following years. These tag returns were divided between the purse-seine fishery and the recreational rod and line fishery. By using these tag return figures it is possible to calculate a relationship between the proportion of tag returns by the purse-seiners versus rod and line fishers in 1983 and 1991.

In 1983 72% of all tags returned in the Bay of Plenty were from rod and line fishers. In 1991 that proportion declined to 27% of all tag returns. The reverse was true for the purse-seine fishery; in 1983 28% of tag returns were from the purse-seiners. By 1991 that proportion had increased to 73% of returns.

Data and Sources
A Comparison of Total Tag Returns Between the 1983 and 1991 Kahawai Tagging Studies in the Bay of Plenty

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The Decline of Fork Length of Kahawai in the Bay of Plenty Purse-seine Fishery from 1983 to 1992

Summary
We believe there has been a decline of 5.7cm in the fork length of purse-seine caught kahawai in the Bay of Plenty between 1983 and 1992. This issue has been debated at the Pelagic Working Group before. However, there were two significant errors made at the Working Group:

1. We were misinformed about the nature of the 1983 catch samples. We were told the 1983 fish selected for measurement were the larger fish available. This is not correct. They were selected at random.
2. We were not presented with the results of a boot-strap analysis that concluded there was a 95% chance the 1991-92 catches did, indeed, have a smaller fork length than in 1983.

In addition, some new evidence has come to light about the fork length of line caught fish in 1983 which shows a general decline in the fork length of line caught fish throughout the North Island when compared to 1991 data.

Available Information
As part of a 1983 tagging study of kahawai the fork length of 332 kahawai were measured in the Bay of Plenty. Of these 332 fish, 32 were line caught. Their median length was 49.8cm (see page 12 for details).

The other 300 fish were purse-seine caught; three landings were sampled with 100 fish sampled in each landing. The first two landings measured represented a single school each. The last landing may have involved more than one school (Gavin James provided this information). The median length of the three landings of purse-seine caught fish were 52.7, 49.3 and 51.8cm. These fish were selected at random. The average of these means is 51.3cm.

In 1991-92 a shed study was done on kahawai. In 1991 five landings were sampled with 6778 fish measured. These landings also represented purse-seine targeted schools. The mean size was 46.1cm.

In 1992 seven landings were sampled. These landings also represented purse-seine targeted schools. A total of 12,431 fish were measured. The mean size in 1992 was 45.25cm.

The average of the 1991-92 means was 45.6cm.

Just recently an analysis was done comparing line caught kahawai in 1983 to line caught fish in 1991 in various locations around the North Island. In every location there was a decline in the fork length of the fish. This data is available on page 15.

The majority of line caught fish in 1983 were caught trolling. Most fish in 1991 were caught on bait. We were concerned about a possible difference in size of fish caught, based on whether a lure or bait was used. An analysis of available 1991 data indicates bait fishing usually catches the biggest kahawai so that cannot be a factor in the decrease in fork length we found. That data is available on page 16.

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Mean Fork Lengths of Kahawai
(target purse-seine only); 1983 vs. 1991-92

Discussion
Several points need to be made about the available data.

1. It would be difficult to imagine how the combined commercial and recreational fisheries in the Bay of Plenty could remove around 40,000 tonnes of kahawai (about 25 million fish) in a decade without a decline in fork length.
2. One of the arguments against accepting the 1983 data as representative is that kahawai school by size; therefore just sampling three or four schools is not adequate. It is true that kahawai school by size; never-the-less, those sizes vary widely. Even a casual glance at the graphs presented on pages 12 and 13 shows a 20cm range in the size of fish in each school. That’s a big difference; it increases the chances our 1983 sample is truly representative of purse-seine caught fish at the time because the concept of kahawai schooling “by size” is really not so accurate.
3. In 1994 Brian Jones did a bootstrap simulation of the data presented in Table 2 from his 1994 stock assessment paper (page 11 of this report). He selected any three of the 1991-92 means at random 600 times. The results were that 95% of the time the 1991-92 catches had a smaller fork length than in 1983.
4. The 32 line caught kahawai in the 1983 study had a mean size of 49.8cm, a figure close to the size of the purse-seine caught fish in 1983 and much larger than the sizes from the boat ramp surveys (42.1cm in 1991 and 44.1cm in 1994) this decade. This data is available on page 12.
5. The data presented on page 15 compares the fork length of line caught kahawai between 1983 and 1991. At all the locations with comparable data available the fork length of kahawai have declined. This further supports our argument that the fork length of kahawai available to recreational fishers has declined over the past decade.
   
   Table 2: Purse seine landings of kahawai sampled in the Bay of Plenty in 1983, 1991 and 1992 (n = number in sample, Mean = mean fork length, s.d = standard deviation).

(From: Kahawai information presented at the 1994 Stock Assessment by J.B. Jones)

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Biological Sampling

Data on length frequencies, sex composition, age frequencies (otolith readings), and stomach contents were collected from commercial landings and during tagging studies from damaged fish.

Age and length frequencies
Little information on kahawai spawning and nursery areas is available, but it appears that most sheltered bays and estuaries in the North Island are used as nurseries, especially those off the east coast, north of the Bay of Plenty. Apart from the sheltered estuarine waters in Tasman Bay and near Farewell Spit, juveniles have not been found in substantial numbers in South Island waters (NZ Ministry of Agriculture and Fisheries unpublished data).

Age and fork length measurements were taken from kahawai caught in several areas (Table 7). Although the catching methods varied, the lengths of the fish en each area did not vary with the method used (Tables 8a-d). Fish caught by purse seine were assumed to represent local fish because the mesh size of the nets was small enough to retain juvenile, as well as mature, kahawai. Relatively more small fish were caught by line than by purse seine, but this was probably because lining was usually used to catch fish in sheltered nearshore waters where smaller kahawai are often found. Within each area fish size did not vary substantially between schools, though fish in one of the two schools sampled from east Tasman Bay on 21 April 1983 were reported as being larger than usual for the area.

Although almost 20% of the sample taken by setnet from the Waitaki River in 1984 comprised small fish of about 40cm, the sample taken by line in 1983 from this area had no fish of this size. It is unlikely that this absence of small fish resulted from the fishing method used, because 40cm fish were caught by lining in other areas that year; it is more probable that there were no small fish in the sampling area in 1983. Excluding this sample, the length frequencies of fish caught by the two methods were similar.

Whole otoliths were read by the method described by Eggleston (1975). For otoliths which required burning to read, rings were clearer when the otolith was sectioned and polished before burning (Paul 1976, James 1984). The age – length relationships were similar to those reported by Eggleston (1975). An age – length frequency plot for all samples combined is given in Table 9. Although mean length and age increased with latitude on the east coast South Island, this trend was not apparent in other areas (see Table 7). Movement of tagged fish between the North and South Islands..

Table 7: Age and length data for kahawai from areas sampled

* Standard deviation
+ Minimum to maximum age

* Standard deviation
+ Minimum to maximum age

Table 8a: Length frequencies for Bay of Plenty samples by date and method of capture

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Appendix 1

Appendix 2