Stream 2000 pH Theory

To sustain a viable Trout Fishery in Hawke's Bay. Is it self-sustaining?

January 2001. It is now almost twenty months ago that we started to ask this question and to study seriously the non stocking program as proposed by the Hawke's Bay Fish & Game, to bring the Hawke's Bay region in line with the rest of New Zealand and other fish & game policies.

While both Hunter and Angler satisfaction are important according to policy statements made by the New Zealand Fish & Game, STREAM 2000 believe this is not now achievable within Hawke's Bay, in more than possibly 60% of its fishable waters. Similar feedback is also coming from the Gisborne region.

STREAM 2000 does realize the cost of maintaining a viable trout fishery is also a factor in the equation. Trout anglers that are members of STREAM 2000 are vigilant, observant, dedicated experts in their field of trout fishing, and extremely conscious of the environment and environmental issues. They have for many years witnessed the collapse of the East Coast trout fishery and came together to work towards putting the fishery back on an even keel instead of being a lone voice in the wilderness. We believe the failure in part to have been caused by Fish & Game, who have ignored the warning signs, and the failure of Councils to not protect the Habitat, are amongst the many things that have contributed to this decline. But they are not the only ones to blame; in a way we all have that responsibility and have done too little, too late.

STREAM 2000 has over the past twenty months tried to answer some of the problems that we now face and have been willing to work where possible to help try to correct or at least stem the deterioration of our once, world renowned trout rivers, especially those of the Hawke's Bay region.

How we have approached this task and our results are as follows:

As the result of reading a section on Trout from the Guinness Guide to Game Fishing, (published 1980, by Guinness Superlatives Limited, and written by W. B. Currie) it was noted that Trout in the Chalk streams in Hampshire and Wiltshire, U.K. (like the Test Iitchen and Wylie both world famous Chalk streams), were not self-sustaining as many believed, due to the high alkaline quality of the water. Although these waters produced large fish, the spawning was poor and extensive stocking and conservation policies have been in place for well over a century.

This posed STREAM 2000 the question of a similar situation here in Hawke's Bay, due to our high percentage of Limestone. A further article in The Treasury of Angling (by Larry Koller, Published in 1966) which was entitled TROUT, Chalk Stream and Rough Stream Fishing, Quoted: - "The acid nature of the water means there is little food, yet breeding conditions are perfect. Many Trout hatch out and survive to compete for a very limited food supply. pH Factors must exist."

We contacted Regional Councils from around New Zealand, and the Department of Conservation at Turangi, and asked for Water Quality Data. DOC in Turangi sent us in the direction of Norway, as although their particular problem stems from Acid Rain, the information was relevant to our concerns. This information along with that researched on our behalf by the Freshwater Fisheries Laboratory and Research Services in Perthshire Scotland, were all relevant, giving us the extreme pH value along with the fifteen pages of references and physiological mechanisms for toxic effect and resistance to Acid water, an ecophysiological and ecotoxicological approach. The Norwegian Institute of Water Research in Onslow, Norway, also included nineteen pages with references of both the scientific Studies and an understanding of the complexities of our problems, which were all coming to light in print.

Over the following twelve months, the information and relevant data on Water Qualities from each of the Regional Councils of New Zealand was collected, studied and filed to compare self-sustaining Trout Fisheries, Water pH Qualities etc. The Intemet became a tool along with the various articles gathered from Trout Unlimited and various reputable American Magazines. Ray de Zelva an eminent Chartered Biologist and Fisheries Consultant, now retired, explained pH in plain everyday English and after reading through our research added comments including the zero fertility at pH 6 for Rainbows and that all trout that are farmed, are farmed with a very slight alkaline water quality. From the Southern Regional Aquaculture Centre in USA came papers studying Trout Farming, carrying capacity and inventory management and the July 2000 Revised Northern Carolina State University, on surface waters where most Trout Farming takes place, showed these are poorly buffered (Total Alkaline < 10ppm) and have a pH reading averaging 6.5 to 7.0, the slightly acidic pH results in a high level (.99%) of ionised ammonia which is relatively non toxic to fish.

Most Regional Councils throughout New Zealand recognize management plans and that the levels of pH between 6.5 and 9.0 are harmless to the fish life, although fish susceptibility to various contaminants may be effected by change within this range. A pH above 9.0 is harmful to salmonoids. From this range, an optimum of pH 7.75 can be assumed. Similarly that the pH levels of rivers and streams within the Hawke's Bay region lie within a narrow range of 7.4 and 8.3 according to page 48 of the Hawke's Bay Regional Councils state of the environment dated 1997. However another Hawke's Bay Regional Council paper dated July 5^th 2000 shows 7 - 8.6. Yet more scientific data from the USA. actually indicate an optimum pH Value of between 7 and 8 giving 7.5pH as the best for Rainbows, as taken from the Life History of Rainbow and Steelhead Trout and Subspecies, by environmental Field Biology student Lewis Clark of State College, Lewiston, I.D., which contained references. Further papers indicated too low or too high a pH can cause the, following results. Deformed Egg s, Hatching Eggs turning Pale or white. Whereas this information mainly covered Rainbow Trout, the information on Brown Trout requiring a slightly lower pH optimum of around 7.3 pH was realized.

Information and relevant data collected from both the Fish & Game and DOC Turangi indicated values of 6.6 to 7.4. The most well known Trout Fishery being the Hatchery at Turangi works with water pH value of 6.8. The Taupo Streams vary between 7.1 to 7.4 in pH with the Rotorua Nongataha Hatchery being 6.6 pH The actual Nongataha Stream where Ova is collected for Browns is 7. 1. Tarawere Lake, although 8.1 is a good feeding ground for Rainbow Trout. The spawning stream, especially the Te Wairoa Stream is undoubtedly a lower pH, although this information was not available. The Hatchery Water at the Hawke's Bay Fish & game farm is 7.3 pH The Hatchery used to process Ova collected from the Mohaka in the Pakatutu area and these were mainly browns. I believe the water in this area and that of the Hatchery in Burness Road to be of a very similar pH, which of course is one of the reasons the rearing of these trout was so successful.

pH Water Quality at K.Y. water Watch. USA. asks why pH is important and states a pH 6 - 7.2 optimum as being the best range for all fish eggs, not only those of Trout. But as stated earlier, at a pH of 6, for trout there is zero fertilization in Rainbows, as Biologist/Fish Consultant Ray de Zylva stated Rainbow sperm does not survive at pH 6 or below.

It must of course also be remembered that an optimum pH factor is not the only factor that is important to a successful Trout spawning within the system. Self-sustainability considerations of Dissolved Oxygen of at least 80% saturation (mills 1971), temperature for successful spawning is between 6 -9 degrees Celsius (Behnke 1992) with water flow also being a trigger to spawning (Willers 1981). Clean silt free gravel and stable environment. all have to be present for an optimum amount of Ova survival. For example, if pH dissolved oxygen, temperature and flow are present, without gravel. The spawning would be non-surviving, thus a non-sustainable Trout population.

The Hawke's Bay Region has an abundance of this situation, where one or more of the factors are not present. It is in these cases that trout will and do take the best option open to them when it's their time to spawn. It may be that they elect to spawn in waters with a higher pH, but where all the other factors are present and it is due to this that STREAM 2000 is now convinced that the optimum cannot be reached and thus the spawning is not fully successful, with a lower return being all that is possible in these streams. It is in our opinion that a low return is unsatisfactory to the licence holder and that some periodic releases of hatchery trout is required for angler satisfaction. However we do believe a proper assessment is needed on a river by river basis to achieve a possible turn around from a declining trout fishery, with annual monitoring plans, bag limits all needing to be taken into account in each case.

Many factors apart from those previously mentioned also need to be understood. The Hawke's Bay and the Gisborne area suffers from time to time with strange weather patterns, which at times can be adverse to a good trout habitat.

Siltation throughout the region is now a major problem, which has stemmed back many years and it will not get any better until we address the problems that cause it, being the land use, or misuse of it being an on going problem. The logging of the regions forestry, clear felling, planting and new forestry blocks being planted as long term overseas money earners for New Zealand, has had a detrimental effect on many of our local trout fisheries. With recent verbal information from a Forestry planner and land owner, who informed STREAM 2000 that the use of toxic chemicals either sprayed by air or back-pack spraying onto shrubs as a defoliant was a far cheaper option to them with less than 25% of the usual cost. After twelve months, the landowner does a bum-off of the dead scrub. This could be a serious concern, as it will be difficult to create buffer zones of vegetation before forestry planting. The ash run-off can cause instant fish kills, as is well documented in other papers such as Trout Unlimited. U. S. A. these problems as well as more dairy farming in areas that have traditionally been sheep rearing areas, is or will show up major environmental issues with run-off of effluent and nitrates into rivers and streams without the proper protection of added buffer zones. Water extraction is another major issue, with the extractions of vast amounts of water from rivers and streams having a devastating effect on the juvenile trout that depend on them for the early stages of life.

In today's world we seem to he playing the very dangerous game of Russian roulette with our environment. The emphasis seems to be development and exploitation of any recourse with little to no understanding of the complexities of the ecological relationship and the devastating effects we have on other people and the environment on the whole. All these issues need to be dealt with by us all, but the Fishery managers and the department of Conservation managers all have to be diplomats, politicians, educators, biologists and ecologists in order to deal with the prime objectives of restoring our trout fisheries to something like the first class fisheries we all expect and deserve.
 

POSSIBLE PROTECTION MEASURES.

1. Re establishment of Natural Flood Cycles.
2. Development of buffer zones.
3. Re establishment of native vegetation to increase cover, food and woody debris.
4. Cattle management to prevent damage to sensitive areas and spawning redds.
5. Proper forestry management, consultation with the New Zealand Fish & Game.
6. Control of excessive water extractions.
7. A more effective way of moving shingle, other than the continued Beach Raking.
8. More information to the angler of positive ways he/she can help.
9. More communication with experienced local anglers.

STREAM 2000 has worked very seriously to put this paper together in plain English. None of us are University material, but we all have a passion for our sport and are very environmentally aware. We have read and researched many articles relating to pH and related issues, but with pH being our main aim in relation to a Trout rearing management and the matter of a self-sustaining fishery. However we do believe that in some cases where some elements are lacking, plans can be in time addressed and some sort of an overall plan and marginal areas do receive some stocking of trout for angler satisfaction. STREAM 2000 members are willing to work in any way possible to help achieve this.

All papers previously mentioned have been forwarded to the Hawke's Bay Fish & Game and your comments on our results would be appreciated.

The New Zealand Fish & Game Policy and Goal is stated: - To maintain sustainable populations of harvestable species at a level to provide for Angler and Hunter satisfaction, while negating adverse impacts of these species.

The sharing of Management with the Eastern district so far has seen the Hawke's Bay Fish & Game reaping the rewards of the combined knowledge and in particular their Field skills. River assessments are now taking place and it is through these that we will obtain an idea of fish numbers present. STREAM 2000 would like to see an even wider assessment, for example, an account of the type of land use in which these rivers flow, including the catchment area. The Regional Council should be able to provide this information.

The type of river bed, Single, Rock, Clay or Silt.

Any Spawning areas should be noted in particular for ongoing databases.

Future assessments and protection. Water quality tests of these areas could also be of importance to successful breeding, with the dissolved Oxygen and pH levels taken at the time of assessment.

Water Flows should also be noted.

Volunteers can visit periodically for further monitoring of spawning areas at appropriate times. The Regional Councils do water quality tests and invertebrate counts on various river systems and these need to be made readily available to the Fish & Game.
 

The Mohaka River is a truly self-sustaining Wild trout fishery, with its Upper Catchment of unmodified Native bush, with natural Buffer zones. However this may also come under stress in the future due to Diary Farming, mainly in the Taharua Tributary area, where it is believed cattle is not restricted from entering the river. Careful monitoring of these areas needs to be done more stringently for possible changes to the ecology of the river.
 

Ongoing angler pressure and natures traumas have instigated lower limit Bags, as to preserve the quality of the fishing. These suggestions have originated from individual Trout Fishermen and have been adopted with success. However mainstream forest harvesting in the Awaho Forestry block, will alter the water and habitat quality below this point and will also include the Ripia River when these areas are logged. Significant changes to the water quality may serve as a tool to visiting the need for buffer zones large enough to not only reduce man-made runoffs, but to elimate it as happens overseas.  

Of a major concern is the deterioration of the Esk River, which we believe to be almost irretrievable without a special protection plan and continued monitoring taking place urgently. The Upper River in the Berry Road area and above, is undoubtedly suffering from continued Forestry harvesting, causing major siltation. This we believe is the cause of such trauma to the river system that fish kills have been inevitable and the smothering of spawning redds have assured the possible demise of them entirely. Adverse weather conditions have also played a part in this rivers suffering, with serious droughts over the 1997/98199 years certainly taking their toll. A drift dive may assess this more clearly.
 

STREAM 2000 suggests some options.

1 . Close the river entirely to fishing for a three-year period and instigate a careful Monitoring programme, especially at spawning time.

2. Release say 200-tagged trout, we would suggest Browns, as these may suit the rivers makeup best, while the river is closed and being monitored.

3. Release 200 tagged trout and monitor with a total catch & release plan placed on this river.

4. Discuss with Forestry options of a volunteer Buffer zone, to protect the river and Monitor these results.
 

STREAM 2000 wishes to thank all parties responsible for supplying research information both written and on Compact Disc. On going study and field work is taking place and we will work with the Fish & Game New Zealand and in particular with Fish & Game Hawke's Bay, in every effort to enhance and preserve the Trout Fishery of the Hawke's Bay Region. And would appreciate a brief comment to this report.

BRIAN LOWE

STREAM 2000