Hale, J.
Evanescent as the morning mists on the shimmering waters of Puget Sound is the law of Indian treaties. One moment it is there, soon to vanish in a swirl of conflicting, diverging and incomprehensible precedents. Deci[105]*105sions intended to declare the meaning and to describe the effect and operation of Indian treaties tend in time to generate a system of judicial vapor trails which obscure more often than elucidate the treaties under consideration. This is another Indian fishing case that leaves unanswered more questions than it resolves.
In a written memorandum opinion, the learned trial judge aptly summarizes the operative events:
This was no crime of stealth, for the Muckelshoot Indians had announced days in advance that members of their tribe would drop their gill nets in the upper reaches of the Green River, and thus force an arrest by which means the Muckelshoots could test their claimed right to fish with gill nets at “their usual and accustomed fishing stations”.
Representatives of the newspaper^, television stations and the State Game Department were present to record the event. The first sweep of the defendants’ gill net failed to catch even a single fish, but another attempt, aided by rocks thrown by friends to scare the steelhead into the net, yielded eight steelhead.
The State Game protectors of course arrested the defendants, charging them with illegally fishing with gill nets, contrary to the provisions of RCW 77.16.060.
The defendants were all convicted in justice court, and this appeal followed. The State is here represented not only by the Prosecuting Attorney’s office, but by the two Assistant Attorneys General assigned to the Game and Fisheries Department. The defendants are represented by attorneys from the American Civil Liberties Union, from the Legal Services Center, and from the United States Attorney’s office. It is openly claimed by the prosecution that the United States Department of the Interior is here attempting to “get its foot in the door” so that it may later regulate Indian fishing on the rivers in Washington. This claim is disregarded because it could not affect the result of the case.
The fact that the defendants fished on the day named with a gill net in the Green River and caught steelhead trout is shown on numerous photographs and motion pictures exhibited in court and is not controverted.
Although the facts of the case are uncomplicated, the is[106]*106sues1 of law sought to be raised are complex, tortuous and vague. March 1, 1966, defendants were seen by the state’s officers gillnetting with meshed linen nets in the Green River at the Slaughterhouse Hole near Auburn upstream % mile from the bridge on highway No. 18. The defendants’ nets nearly spanned the river there, but they caught no fish.
Failing to make a catch at the Slaughterhouse Hole, the defendants moved their nets upstream about 1 mile to where the New Neely Bridge crosses the Green River. At that place, using a gill net 50 to 60 feet long which was equipped with plastic floats along its top edge and lead weights at the lower edge to keep it upright in the water and which did not span the river there, they made a sweep of about 400 yards. Aided by others who threw rocks into the river to scare the spawning fish into the gill net, the defendants in their third sweep netted eight steelhead trout which they killed with rocks and clubs.
Defendants claimed to be members of the Muckleshoot Tribe. At the places where they had cast their net, the Slaughterhouse Hole and the New Neely Bridge, the Green River rims through privately-owned and county-owned land, and no part of the river or the adjacent lands at either place is within the Muckleshoot Indian Reservation.
The steelhead trout is an anadromous game fish; in early March it swims upstream from salt water to spawn. The steelhead run in Washington’s rivers is in part artificially created by fish propagation practices of the state.
Defendants were charged with illegally fishing for game fish in violation of RCW 77.16.060, which, so far as pertinent here, reads:
It shall be unlawful for any person to lay, set, use . . . any . . . nets ... in any of the waters of this state with intent thereby to catch, take or kill any game fish. It shall be unlawful to lay, set or use a net capable of taking game fish in any waters of this state . . ,
Gill-net fishing for steelhead or other game fish, unless [107]*107expressly allowed by regulation or written permit, is totally prohibited in this state throughout the year.
.Convicted in justice court and sentenced to 6 months in the county jail with 5 months of the sentence suspended, defendants appealed to the superior court. Convicted again in superior court after trial without a jury, they were sentenced to “30 days, suspended, provided the defendant [s] [do] not fish illegally for a period of one year.” Contending that they are members of the Muckleshoot Indian Tribe and that the Treaty of Point Elliott of 1855 bars the state from prohibiting the tribe and its members from net fishing for game fish in the Green River, defendants bring this appeal. We affirm the judgment on the precise grounds upon which it rests and do not decide the many other issues raised by this record.
As we understand the issues, if, in the reasonable exercise of its sovereign powers, the state as a reasonable regulatory measure may constitutionally prohibit all persons, including treaty Indians, from any net fishing whatever in the Green River, many of the issues raised at trial and on this appeal need not be decided. Stated another way, if, in order to preserve its fisheries, the state can lawfully prevent all net fishing for game fish, then it becomes immaterial whether the Muckleshoot Tribe has any off-reservation fishing rights and whether the defendants were members of that tribe. Should it be the rule, however, that total prohibition of net fishing for game fish is unreasonable and in excess of the state’s sovereign powers, then it becomes pertinent whether the Muckleshoots made a treaty with the United States; whether such a treaty existed at the time of the arrest of these defendants; whether the treaty gave defendants any rights in the Green River not shared by other citizens; whether these rights, if any, belonged to the tribe alone or could be exercised by individual members of it; whether treaty Indians may cross and occupy privately-owned and publicly-owned lands for the purpose of fishing; and, assuming arguendo the existence of any off-reservation fishing rights in the tribe or these defendants, [108]*108whether such rights included the right to use a long linen gill net with plastic floats and lead weights.
Concluding that, because the state had not exceeded reasonable regulatory powers in totally prohibiting net fishing for game fish in the Green River, the court ruled that a total prohibition of net fishing for steelhead would not violate whatever off-reservation fishing rights defendants might have. On this basis, the trial court held that, even though the Muckleshoot Tribe did have off-reservation fishing rights and defendants were members of that tribe, their tribal status did not relieve them from what the court held to be a reasonable and unexcessive regulation. Accordingly, since the state had shown total prohibition of net fishing to be a reasonable regulatory measure in preserving a fishery, the trial court did not specify the kind or nature of the off-reservation fishing rights deriving from the treaty nor did it pass upon or construe the treaty provision that the right of taking fish at usual and accustomed grounds is secured to the Indians “in common with all citizens of the Territory.” Surprisingly little judicial attention, we note, has been given to this rather standard treaty language.
Defendants invoked the Treaty of 1855 concluded with the Indians on the shores of Puget Sound by the United States Government. January 22nd of that year, Isaac I. Stevens, as Governor and Superintendent of Indian Affairs for the Territory of Washington, and his official party acting for the United States met with a number of chiefs, headmen and delegates of certain named tribes and bands of Indians. There, at a place designated in the treaty as Mucklteoh or Point Elliott, they concluded what is described in the treaty as “Articles of Agreement and Convention.” 12 Stat. 927 (1863). Article 1 of the Treaty of Point Elliott, without acknowledging ownership or posses-sory rights in them, declared that the Indian signatories ceded, relinquished and conveyed to the United States all of their right, title and interest in the lands they had traditionally occupied. Article 2, reserving for the use and occupancy of these Indians designated areas or reservations, [109]*109contained a provision that no “white man [shall] be permitted to reside upon the same without permission of the said tribes or bands.”
Article 5 is the basis upon which defendants here set up their affirmative defense to the charge of illegal net fishing. It says:
Article Y. The right of taking fish at usual and accustomed grounds and stations is further secured to said Indians in common with all citizens of the Territory, and of erecting temporary houses for the purpose of curing, together with the privilege of hunting and gathering roots and berries on open and unclaimed lands. Provided, however, that they shall not take shell-fish from any beds staked or cultivated by citizens.
Defendants did not take the witness stand, but, along with other evidence, presented the testimony of Dr. Barbara Lane, an anthropologist, to establish that they were members of the Muckleshoot Tribe of Indians and that the tribe was one of the signatories to the Treaty of Point Elliott. Despite almost continuous objections to this testimony aimed at its hearsay nature, its vagueness and want of materiality and relevance to prove with reasonable certainty the two issues, the court admitted it. Ultimately, over the state’s strenuous exception, the court entered findings of fact that the Muckleshoot Tribe of Indians was party to the treaty and that defendants were members of the tribe.
These findings were entered despite findings Nos. 9 and 10 in which the court also found that in other litigation both the Muckleshoot Tribe and two of the defendants here, Cecil Moses and Larry V. Maurice, were neither signatories to nor beneficiaries of the treaty.1
[110]*110It is generally held in criminal cases that, if the facts of an affirmative defense lie immediately within the knowledge of the defendant, the onus probandi, under the principle of “balancing of convenience,” should be his. State v. Harding, 108 Wash. 606, 185 P. 579 (1919); State v. Shelton, 16 Wash. 590, 48 P. 258, 49 P. 1064 (1897); Morrison v. California, 291 U.S. 82, 78 L. Ed. 664, 54 S. Ct. 281 (1934); Rossi v. United States, 289 U.S. 89, 77 L. Ed. 1051, 53 S. Ct. 532 (1933); 9 Wigmore, Evidence §§ 2486, 2512 (3d ed. 1940). See, also, United States v. Sisson, 399 U.S. 267, 26 L. Ed. 2d 608, 90 S. Ct. 2117 (1970), in which the defense of being a conscientious objector was held to be an affirmative defense to an indictment charging refusal to submit to induction into the armed forces, and the indictment, phrased in the language of the statute, was held good because the accusation need not anticipate affirmative defenses nor negate them.
An affirmative defense to a criminal charge, therefore, must be proved by one who relies on it. State v. Razey, 54 Wn.2d 422, 341 P.2d 149 (1959); State v. Brown, 97 R.I. 95, 196 A.2d 138 (1963); 29 Am. Jur. 2d Evidence § 156 (1967). If one accused of violating the state’s fishing laws and regulations claims a treaty exemption to their operation, his claim constitutes an affirmative defense and he has the burden of showing by a preponderance of the evidence the existence of the treaty, that he is a beneficiary of it and that the treaty as a matter of law bars as to him the operation and enforcement of the fishing laws and regulations. State v. James, 72 Wn.2d 746, 435 P.2d 521 (1967); Department of Game v. Puyallup Tribe, Inc., 70 Wn.2d 245, 422 P.2d 754 (1967), aff’d 391 U.S. 392, 20 L. Ed. 2d 689, 88 S. Ct. 1725 (1968). The affirmative defense must be assessed, [111]*111too, in light of the rule that, whatever rights are said to have accrued to Indian tribes by virtue of a treaty with the United States accrue to the tribes and not their individual members. Whitefoot v. United States, 293 F.2d 658 (Ct. Cl. 1961). The government did not deal with individuals or famihes of Indians but with tribes. Sac & Fox Indians of the Mississippi in Iowa v. Sac & Fox Indians of the Mississippi in Oklahoma, & the United States, 220 U.S. 481, 55 L. Ed. 552, 31 S. Ct. 473 (1911).
The trial court found that defendants sustained the burden of proving tribal membership in a tribe possessing off-reservation fishing rights. It held that the Muckleshoots were signatories to the Treaty of Point Elliott and that the defendants were beneficial members of that tribe. Although the state challenges these findings, contending that there is a lack of substantial evidence to support them, we do not reach this issue. We do not decide whether the evidence or the law supports either finding because, without more, we think the judgment must be affirmed on the basis upon which it rested, i.e., that, regardless of the treaty or any asserted rights claimed to derive from it, the state could lawfully bar all net fishing for game fish in the Green River. The court’s conclusion that, even if the treaty be so construed as to accord the Muckleshoot Tribe and its component members off-reservation fishing rights in the Green River, the members and the tribe as an entity could be lawfully subjected by the state to total prohibition of net fishing for game fish in that river is, we think, a sound one. See, Regulation of Treaty Indian Fishing, 43 Wash. L. Rev. 670 (1968).
We point out that the court’s findings and conclusions did not put to rest many vital issues of Indian fishing law. In State v. Moses, 70 Wn.2d 282, 422 P.2d 775 (1967), this court affirmed the conclusion of the trial court that the Muckle-shoot Tribe of Indians descended neither from tribal signatories nor their successors and had no rights under the Treaty of Point Elliott. While this adjudication is perhaps not res judicata of the point, it is entitled to great weight in [112]*112the premises, deriving as it did from a vigorously adversary proceeding.
Accordingly, we do not now pass upon or decide many of the questions raised directly or by ineluctable inference in this appeal. We do not, for example, construe the language of the treaty that the right of taking fish at usual and accustomed grounds and stations is secured to the Indians in common with all citizens of the territory, nor do we determine the effect of national and state citizenship upon the descendants of treaty Indians.2 In 1924, by act of Congress (Citizenship Act of 1924, 43 Stat. 253), Indians born to American Indians, while retaining tribal or other property, were declared to be citizens of the United States. 8 U.S.C. § 1401 (a) (2). They thus, under the fourteenth amendment to the Constitution of the United States became citizens of the state in which they live even though residing on a reservation. Whether the status of state and national citizenship affects off-reservation treaty rights, if any, is not to be decided directly or inferentially in this appeal.
Nor need we decide whether the Muckleshoot Tribe of Indians, a federally incorporated and chartered legal entity organized in 1936 in accordance with 25 U.S.C. § 477 (1934), and the four defendants are the lineal and beneficial descendants of tribes or bands recited in the treaty as Skope-ahmish, Smalh-kamish ’and St-kah-mish. The trial court found that “No separate tribe of Skope-ahmish Indians is presently in existence,” but that Indians known by that name, along with other Indians, were moved onto the Muckleshoot Reservation before 1874, and that, although the treaty does not show that it was signed by anyone on behalf of the Skope-ahmish, at least one member of that group was present at Point Elliott when the treaty was concluded. Whether the Muckleshoot Tribe, Inc., off-reservation fishing rights, if any, inure to the individual benefit of its members or are reserved to the tribe as a corporate, juridical entity, are questions not necessary for a decision [113]*113now, either. We also do not decide whether there was substantial admissible evidence to support the court’s finding that the Muckleshoot Tribe of Indians as presently incorporated is the beneficial successor in interest to any of the tribal signatories of the 1855 Treaty of Point Elliott (12 Stat. 927 (1863)), or whether any of these defendants were members of that tribe. And we do not decide whether, or to what extent, treaty Indians claiming off-reservation fishing rights may possess easements to enter upon, pass through or occupy private or public lands in fishing off the reservation.
The determinative issue before us and upon which an affirmance or reversal depends is whether total prohibition of gill-net fishing for steelhead trout in the Green River was reasonable, and the issue urged by the state that there was insufficient admissible evidence in the record to support the court’s findings of tribal membership and treaty benefits is not decided. Resolution of these and other issues raised in this review is left to another day — or more happily to a speedier solution by the Congress.
Thus, without reaching the other questions referred to, we come to the one determinative issue: Did the state have the power to prohibit totally net fishing for steelhead trout in the Green River, regardless of the Treaty of Point Elliott of 1855? Under its sovereign power, we think that total prohibition was demonstrated to be reasonably necessary for the preservation of a state fishery resource.
Fish, while in a state of freedom, are the property of the sovereign power in whose waters they may be. In the United States, it is the state and not the United States which is the sovereign power in whose waters the fish are, and the state owns the fish in its sovereign capacity as the representative of and for the benefit of all people in common. 36A C.J.S. Fish § 2 (1961). This state has affirmed the rule of state sovereign ownership over wild animals, wild birds, and fish freely swimming in this state’s waters. State ex rel. Bacich v. Huse, 187 Wash. 75, 59 P.2d 1101 (1936); Judd v. Bernard, 49 Wn.2d 619, 304 P.2d 1046 (1956); [114]*114Wiegardt v. State, 27 Wn.2d 1, 175 P.2d 969 (1947); McMillan v. Sims, 132 Wash. 265, 231 P. 943 (1925); Vail v. Seaborg, 120 Wash. 126, 207 P. 15 (1922); State v. Tice, 69 Wash. 403, 125 P. 168 (1912). Thus, the fish in the waters of the state and the game in its forests belong to its people (Geer v. Connecticut, 161 U.S. 519, 40 L. Ed. 793, 16 S. Ct. 600 (1896)), and the legislature was doing no more than declaring legislatively what already was the law when, in RCW 77.12.010, it said:
The wild animals and wild birds in the state of Washington and the game fish in the waters thereof are the property of the state. The game animals, fur-bearing animals, game birds, nongame birds, harmless or song birds, and game fish shall be preserved, protected, and perpetuated, and to that end such game animals, fur-bearing animals, game birds, nongame birds, harmless or song birds, and game fish shall not be taken at such times or places, by such means, in such manner, or in such quantities as will impair the supply thereof.
Tulee v. Washington, 315 U.S. 681, 86 L. Ed. 1115, 62 S. Ct. 862 (1942), reversing State v. Tulee, 7 Wn.2d 124, 109 P.2d 280 (1941), frequently cited for all manner of propositions, seems to support a strong power to regulate the taking of fish vis-a-vis treaty rights, and goes no farther than to hold that the state could not impose a license fee upon treaty Indians exercising a regulated right to fish. The court said:
[W]hile the treaty leaves the state with power to impose on Indians, equally with others, such restrictions of a purely regulatory nature concerning the time and manner of fishing outside the reservation as are necessary for the conservation of fish, it forecloses the state from charging the Indians a fee of the kind in question here.
(Italics ours.) The exaction of a license fee from treaty Indians to do what the state acknowledged at the time to be lawful under the circumstances was not essential to a state conservation program. While conceding a regulatory power in the state to preserve its fishery resources, Tulee actually went no further than to hold that demanding a license fee of tribal Indians was not a true conservation measure. See [115]*115Puyallup Tribe v. Department of Game, 391 U.S. 392, 20 L. Ed. 2d 689, 88 S. Ct. 1725 (1968).3
We recognize that the term “reasonably necessary” may to a degree be wanting in definition, but it is a model of precision when compared to much of the law written about Indian treaties. If total prohibition of net fishing for game fish is a reasonably necessary exercise of state conservation practices to preserve or enlarge the steelhead runs on the Green River, then that would resolve all issues raised by appellants and the judgment should be sustained.
Did the state show by competent evidence that total prohibition of net fishing for game fish in Green River was reasonably necessary for preservation of the state’s fisheries in that river? Clifford Millenbach, Chief of the Fisheries Management Division of the Washington State Department of Game and a professional biologist testifying for the state, said that it was quite likely the steelhead run would be destroyed if net fishing were allowed. He used data from the Puyallup River — which is fed by the White River — as a comparison. He testified that, by actual count beginning in 1941, the state transported between 1,000 and 2,000 steel-head annually around Mud Mountain Dam for the first 14 years of the count. Then, during an interval of an extensive Indian net fishing on the Puyallup, the annual count started falling off until 1958 when it reached a low of 156 steelhead. Since 1958, with the cessation of net fishing, the count has been on the rise. He said that, in his professional opinion, no net fishing should be allowed on the Green River because a net has the capability of literally sweeping [116]*116the river, will overharvest the run, and thus will prevent adequate escapement for spawning.
Dr. Loren R. Donaldson, Professor of Fisheries at the University of Washington, testifying for the state, when asked what the term “conservation” means, said, “Well, I think conservation means the maximum sustained yield, commensurate with maintaining the run at the optimum level.” Although a steelhead lays some 4,000 to 5,000 eggs, it is error to expect they will produce several hundred fish. “In actuality,” Dr. Donaldson said, “under about the best of natural conditions, on an average, about all we can expect is a one for one increase. There are instances where it exceeds this, but in the main half the fish have to be reserved for the brood stock or the spawning stock.” Once the anadromous fish have left salt water and entered fresh water, they should be allowed to spawn. A fish entering a river to spawn deteriorates rather rapidly in quality, he said, once it has entered the fresh water.
Dr. Donaldson’s testimony, in essence, was that a prohibition against net fishing in the Green River would be reasonably necessary for conservation. He said that a gill-net fishery was specially destructive of the run because it is one of the most destructive ways of catching fish; that while a gill net may catch some of the fish it will at the same time entangle and gill mark others which will die from the gill marking. Making a comparison, he said that the gill-net fishery above Bonneville Dam on the Columbia was “a matter of record, where large numbers of fish are destroyed there by being caught in the net and falling out and not being brought in.”
J. E. Lasater, Assistant Director of Operations for the Department of Fisheries, and a biologist, testified for the state. Referring to a net fishery for anadromous fish on the Green River, he said it would conflict with conservation and that “If the net fishery is employed there, it will reduce the stock of both wild and hatchery fish, and also reduce our ability to use the hatchery to its full production potential.” The state, said Mr. Lasater, allows no net fishing [117]*117at all on Puget Sound rivers and streams except on Indian reservations because, since 1918 or 1920, the net fisheries, as he put it, were being required to phase out. Continuous scientific studies had shown since then, he said, that net fishing in rivers and streams was too detrimental to be permitted.
The department had learned from these studies, according to Mr. Lasater, that closures for intervals, or partial closures, in rivers and streams did not work to conserve the runs because, as fish return into fresh water, they tend to delay there in what the biologists call “holding water” and that opening and closing the rivers at intervals by regulation would not allow adequate escapement because the same fish are fished for over and over again in these holding waters. He testified on this:
The second criteria is that it be in what I will call passage of water, and that’s better explained by saying that as fish come into the river, they tend to delay, and this is what we call holding water.
Closures for escapement don’t work in holding water for this reason, if you have a closed period, say, three days to allow for escapement and the fish don’t move, and you re-open the fishery, you’re fishing the same fish a second time and without an absolutely accurate knowledge of rate of removal and when the fish might migrate, and all, you fish over the same stock time after time, and in fact do not know how to regulate a net fishery to assure a spawning escapement under these conditions.
Fishing should not be allowed on the spawning ground for another reason, he said. Net fishing in the spawning grounds is a harassment to those steelhead which are not actually caught or killed in the nets. Spawning fish, he said, should have a quiet place in which to settle down and spawn. If they are harassed and they are not allowed to lie quietly during the holding period in holding waters, this produces a high prespawning mortality. He testified:
This means that the fish has a certain energy supply to carry them through the spawning act. If during this holding period they are harassed they use up that energy, and the result is what we call pre-spawning mortalities, fish [118]*118just not having the energy to carry on through the spawning act.
They go for, in the case of salmon, sometimes several months, and with steelhead sometimes as much as six months, with very little food, so you have the effect of disruption of the spawning act, diminishment of spawning success with even the direct death of the fish even though they are not caught.
After giving some 20 pages of essentially scientific explanation of the habits and characteristics of anadromous fish and the effects of net fishing on their propagation, Mr. Lasater testified:
Q. Now, would a net fishery in the Green River for anadromous fish conflict with conservation? A. Yes, it would. You couldn’t attain your conservation goals with a net fishery in the river. Q. Do you have an opinion as to the effect of the continuation of the net fishery, or do you have an opinion as to the effect of a net fishery on the runs of anadromous fish in the Green River? A. If the net fishery is employed there, it will reduce the stock of both wild and hatchery fish, and also reduce our ability to use the hatchery to its full production potential. Q. Mr. Lasater, in your opinion is it reasonably necessary for conservation to enforce the statutory provision on the use of nets in the Green River upon the defendants in this case? A. Yes, it is. Q. And how about on everyone else? A. Yes, it’s the wrong gear in the wrong place, and often it would be at the wrong time.
The record thus amply supports the trial court’s finding No. 19 that:
The use of gill nets in the catching of anadromous fish is destructive of the runs of those fish, since gill nets tend to eliminate certain segments of the runs, and in addition injure and frighten many fish which are not caught. Some stocks of fish would be eliminated if gill nets were allowed in rivers such as the Green River, and past gill net fisheries have reduced some anadromous fisheries almost to the point of destruction.
and conclusion No. 2 that:
The regulation prohibiting the use of gill nets in the rivers of the State of Washington is reasonable and necessary for the preservation of the steelhead fishery.
[119]*119This means, therefore, that total prohibition of net fishing for game fish on the Green River was shown to be a reasonably necessary regulation for conservation of the steelhead fishery resource and that regardless of whatever exempt status the defendants had, or claimed to have, the judgments and sentences should be affirmed. State v. McCoy, 63 Wn.2d 421, 387 P.2d 942 (1963); Puyallup Tribe v. Department of Game, 391 U.S. 392, 20 L. Ed. 2d 689, 88 S. Ct. 1725 (1968).
Judgment affirmed.
Hamilton, C.J., Rosellini and Hunter, JJ., and Hill, J. Pro Tern., concur.