dissenting.
The Special Master reasoned that Idaho was entitled to a “fair share” of the anadromous fish that are the subject of this dispute. Without quantifying that share, however, he rejected the claim that Washington and Oregon had mismanaged the fishery, Report of Special Master 30-34, concluding instead that they had acted in good faith, id., at 35, and that the relief requested by Idaho was unworkable, ibid. *1030In reaching that conclusion, he refused to consider any evidence pertaining to years earlier than 1975 or to future developments. Id., at 25-26, 27.
The Court today overrules the exceptions to the report of the Special Master. I see substantial merit to several of the points raised by Idaho and am persuaded that they require a remand to the Special Master for further proceedings. Accordingly, I dissent.
I
The Master properly concluded that “Idaho is entitled to its fair share of the fish.” Id., at 25. No one owns an individual fish until he reduces that fish to possession, Pierson v. Post, 2 Am. Dec. 264 (N. Y. 1805), and, indeed, even the States do not have full-fledged “property” interests in the wildlife within their boundaries, see, e. g., Douglas v. Seacoast Products, Inc., 431 U. S. 265, 284 (1977); Missouri v. Holland, 252 U. S. 416, 434 (1920). Nonetheless, courts have long recognized the opportunity to fish as an interest of sufficient dignity and importance to warrant certain protections. See, e. g., Union Oil Co. v. Oppen, 501 F. 2d 558 (CA9 1974); Louisiana ex rel. Guste v. M/V Testbank, 524 F. Supp. 1170 (ED La. 1981); Weld v. Hornby, 7 East 195 (K. B. 1806); J. Gould, Law of Waters §§ 186, 187 (1883); 3 J. Kent, Commentaries 411 (5th ed. 1844); cf. New Jersey v. New York, 283 U. S. 336, 345 (1931) (considering the effect on oysterbeds in apportioning water); Douglas, supra, at 287-288 (Rehnquist, J., concurring in part and dissenting in part) (although State has no ownership in wildlife in the conventional sense, it has a “substantial proprietary interest”). See generally United States v. Washington, 520 F. 2d 676 (CA9 1975), cert. denied, 423 U. S. 1086 (1976). Indeed, in recent years, as the runs of anadromous fish have diminished and no longer satisfy fully the demands of all fishermen, the federal courts frequently find themselves confronted with disputes over the management and conservation of the resource. Faced with these problems, the courts, includ*1031ing this Court, have not hesitated to recognize that various claimants do possess protectible rights in the runs of fish, whether or not those claimants ultimately manage to land and reduce particular specimens to possession and full ownership. See, e. g., Washington Game Dept. v. Puyallup Tribe, 414 U. S. 44 (1973); Sohappy v. Smith, 529 F. 2d 570 (CA9 1976) (per curiam); United States v. Washington, supra; Sohappy v. Smith, 302 F. Supp. 899 (Ore. 1969). When States enter the fray, this Court must be prepared to undertake the admittedly difficult task of assessing the claim of each and arriving at an equitable resolution that protects the interests of each, for, as we held long ago in a leading case on our original jurisdiction:
“[WJhenever. .. the action of one State reaches through the agency of natural laws into the territory of another State, the question of the extent and the limitations of the rights of the two States becomes a matter of justi-ciable dispute between them, and this court is called upon to settle that dispute in such a way as will recognize the equal rights of both and at the same time establish justice between them.” Kansas v. Colorado, 206 U. S. 46, 97-98 (1907).1
*1032Having reached the correct conclusion that Idaho has a right to a fair share of the anadromous fish of the Columbia and Snake Rivers, though, the Master adopted procedures that denied Idaho an opportunity to effectuate that right. It is the approval of the limitations placed on Idaho’s establishment of its rights with which I disagree.
HH 1 — I
In spite of his recognition that Idaho was entitled to a fair share of the runs of anadromous fish, the Master found that there was no injury to Idaho. I am at a loss to understand how he reached that conclusion without specifying the nature and extent of Idaho’s entitlement.2 The Master excluded from consideration any evidence of past conditions or probable future conditions, focusing instead solely on the evidence for the period 1975-1980. Report of Special Master 25-26, 27.3 During those years, the harvests were negligible, so, in *1033the Master’s view, Idaho’s rights were similarly negligible, and Idaho could not show the “substantial injury” necessary to obtain relief from this Court in the exercise of its original jurisdiction, see, e. g., Kansas v. Colorado, 320 U. S. 383, 393 (1943); Connecticut v. Massachusetts, 282 U. S. 660, 669 (1931). Of course, as the Court recognizes, ante, at 1027, the Master properly required a showing by clear and convincing evidence that Idaho sustained a substantial injury. Nonetheless, two basic problems flaw the Master’s approach. First, it assumes that Idaho’s only concern is with its share of the harvest and that, in the absence of a harvestable surplus,4 Idaho’s interest in the runs vanishes. Second, it excludes evidence relevant in explaining the current state of the runs and in determining what types of management will best conserve and increase the resource for the benefit of all.
A
The first problem with the Master’s approach requires little elaboration. Even if there is absolutely no harvestable surplus for a year or for several years, Idaho has a right to seek to maintain and eventually increase the runs by requiring the defendants to refrain from practices that prevent fish from returning to their spawning grounds in numbers sufficient to perpetuate the species in this river system. Cf. Colorado v. New Mexico, 459 U. S. 176 (1982) (recognizing duty to conserve common water supply); Wyoming v. Colorado, 259 U. S. 419, 484 (1922) (same). The allegations of mismanagement over the period leading up to this lawsuit — in particular the allegation that the defendants made a practice of closing fishing seasons only after it became clear that they would not meet the goal of a minimum spawning escapement, Exceptions of Idaho 65; Pretrial Order 7, Admitted Fact 30 — if true, may show the existence of a threat to Idaho’s interest in the maintenance of the runs. Indeed, the *1034very paucity of the harvest in 1975-1980 that the Master relied upon in denying Idaho any relief suggests that there may be some merit in Idaho’s contention that the runs have not been properly managed in the past.
Further, the need for relief in such a situation is compelling. Techniques are available that may aid significantly in maintaining or increasing the runs.5 But Idaho is unlikely to devote substantial resources to projects designed to maintain and increase the runs if the defendants are free to engage in mismanagement downstream that will negate Idaho’s efforts. The Master should not have concluded that, simply because Idaho shared equally in the failure of the harvest in 1975-1980, it had no further interest in promoting the conservation of the species and the eventual restoration of the runs, neither of which could occur without proper management practices on the part of the defendants.
B
In my view, the Master erred also in excluding the evidence of the past practices of the defendants, of the past conditions on the river system, and of the probable conditions in the future. Consideration of Idaho’s interest in maintaining the runs has already illustrated one way in which evidence of the past conditions and practices and of probable future conditions was indeed relevant in this action. Moreover, the Master’s limitations place Idaho in an untenable position. Although harvests were minimal from 1975 to 1980, conditions were different when Idaho sought leave to file its complaint in this action on March 31, 1975. In 1974, Washington and Oregon had harvested some 22,400 spring chinook and 9,500 summer steelhead. Report of Special Master 18-19. *1035Indeed, even with the negligible harvests for the latter half of the decade, during the 1970’s, Washington and Oregon harvested an annual average of 27,320 upriver spring chi-nook, 2,260 upriver summer chinook, and 12,360 upriver summer steelhead, compared with Idaho’s average harvests of 3,150 upriver spring chinook, no upriver summer chinook, and 8,550 upriver summer steelhead. Id., at 13, 15, 17. Assuming Idaho’s allegations to be true, substantial portions of the fish harvested by Washington and Oregon rightfully should have returned to Idaho. This period did not reflect a pristine and irretrievably lost state of nature. On the contrary, all the dams were in place before 1970, see ante, at 1020. But the Master refused to consider these figures, looking only to figures for harvests taking place after Idaho sought relief. Under this approach, to vindicate its rights, Idaho will have to wait until the runs regenerate — relying on the goodwill of the defendants to maintain and increase them. Then, once there is a harvest available, Idaho will have to hope that the runs survive any mismanagement long enough to establish a new record of fishing on harvests rightfully belonging to Idaho and that both the runs and the mismanagement will persist throughout the time necessary to complete litigation. I would not place such hurdles in the way of a State seeking to preserve its natural resources.
HH HH HH
The proper approach in this case, in my view, would require the Master to determine whether Idaho has a protectible interest in the preservation of the runs and what Idaho’s proper share is, expressed as a proportion of the harvestable surplus. In making that determination, the Master should have a broad range of flexibility, drawing guidance from our previous cases reconciling conflicting claims of States to natural resources by equitable apportionment. The classic statement of the considerations governing equitable apportionment of interstate streams emphasizes *1036the breadth of the inquiry and the importance of all relevant factors:6
“Apportionment calls for the exercise of an informed judgment on a consideration of many factors. Priority of appropriation is the guiding principle. But physical and climatic conditions, the consumptive use of water in the several sections of the river, the character and rate of return flows, the extent of established uses, the availability of storage water, the practical effect of wasteful uses on downstream areas, the damage to upstream areas as compared to the benefits to downstream areas if a limitation is imposed on the former — these are all relevant factors. They are merely an illustrative, not an exhaustive catalogue. They indicate the nature of the problem of apportionment and the delicate adjustment of interests which must be made.” Nebraska v. Wyoming, 325 U. S. 589, 618 (1945).
See Colorado v. New Mexico, 459 U. S., at 183; Connecticut v. Massachusetts, 282 U. S., at 671; 2 Waters and Water *1037Rights § 132.5(B) (R. Clark ed. 1967). Of course, the relevant considerations stated in cases concerning rights to water must be adapted to this new context. Nevertheless, the general principles apply. I would direct the Master to consider a range of factors including, but not limited to, the harm that must be incurred by Oregon and Washington in terms of harvest forgone in order to allow a given number of fish to reach Idaho, cf. Nebraska v. Wyoming, supra (considering the loss of water in transit); the contribution of each State to preservation of the habitat necessary for spawning; the contribution of each State to the preservation of the proper habitat necessary for the survival and development of fish during passage; the investment of each State in programs to mitigate losses and enhance the runs, such as hatcheries and transportation programs, see n. 5, supra;7 and the relative values of the types of fishery — commercial or sport— operated by the defendants and by Idaho, cf. Connecticut v. Massachusetts, supra, at 673 (“Drinking and other domestic purposes are the highest uses of water”).
Only after making this initial determination can we decide whether Idaho has been wrongfully deprived of fish. If the depletion of the runs is attributable to mismanagement by Oregon and Washington, we should grant relief. The Master suggested that relief is unworkable because of the difficulties of estimating the runs and apportioning them. The task is indeed a complicated one, as we recognized when we stated in Puyallup: “Only an expert could fairly estimate what degree of net fishing plus fishing by hook and line would allow the escapement of fish necessary for perpetuation of the species.” 414 U. S., at 48. Nevertheless, it is a task that we have recognized as possible, Washington v. Wash*1038ington State Commercial Passenger Fishing Vessel Assn., 443 U. S. 658, 662-664 (1979), and the difficulty of providing equitable relief has never provided an excuse for shirking the duty imposed on us by the Constitution. Idaho ex rel. Evans v. Oregon, 444 U. S. 380, 390, n. 7 (1980); Nebraska v. Wyoming, supra, at 616. The lower federal courts have proved able to grant appropriate relief, e. g., Sohappy v. Smith, 529 F. 2d, at 572-573; United States v. Washington, 520 F. 2d 676 (CA9 1975), so we too should be able to overcome the difficulties.8 Moreover, a statement of relative rights may induce the parties to cooperate in devising a plan to accommodate not only the rights of all but also the difficulties of management, as the defendants here did when sued by the Indians for enforcement of treaty fishing rights. See Report of Special Master 34-35 (discussing Five-Year Plan entered by parties to Sohappy v. Smith).9
H-1 <1
Since the Master failed to quantify Idaho s right m the anadromous fish, he was unable to determine whether Idaho suffered any injury entitling it to a remedy. I would remand to allow the Master to apply our precedents on equitable apportionment to determine the extent of Idaho’s rights, and, if appropriate, to devise a remedy protecting those rights.
This controversy, like disputes over the waters of interstate streams, is one particularly appropriate for resolution by this Court in the exercise of its original jurisdiction. The original jurisdiction was “conferred by the Constitution as a substitute for the diplomatic settlement of controversies between sovereigns and a possible resort to force,” North Dakota v. Minnesota, 263 U. S. 365, 372-373 (1923). See generally 2 Waters and Water Rights § 132.2(A) (R. Clark ed. 1967). Disputes between sovereigns over migratory wildlife typically give rise to diplomatic solutions. See, e. g., Missouri v. Holland, 252 U. S. 416 (1920) (treaty between United States and Canada concerning migratory birds). Such solutions reflect the recognition by the international community that each sovereign whose territory temporarily shelters such wildlife has a legitimate and protectible interest in that wildlife. In our federal system, we recognize similar interests, but the original jurisdiction of this Court or interstate compacts substitute for interstate diplomatic processes.
The failure to specify Idaho’s rights also seems to me to represent a poor use of judicial resources, inviting future litigation, rather than settling questions properly presented now. Cf. Comment, Sohappy v. Smith: Eight Years of Litigation over Indian Fishing Rights, 56 Ore. L. Rev. 680, 693 (1977) (although court’s initial order declared that the Indians had a right to a “fair share” of fish, “[u]nfortunately, the court did not provide any guidelines for determining what a ‘fair share’ is, and consequently, the parties have been back in court to argue about the application of Sohappy”).
The Master did permit Idaho to create a record, at least of evidence of past conditions and practices, see Exceptions of Idaho 101, but he refused to consider that evidence, effectively excluding it. See Report of Special Master 25-26, 27.
In support of this decision, the Master cited Nebraska v. Wyoming, 325 U. S. 589, 620 (1945), where the Court stated: “[T]he decree which is entered must deal with conditions as they obtain today.” In setting out the general principle in that case, the Court had explained: “ ‘[A]ll of the factors which create equities in favor of one State or the other must be weighed as of the date when the controversy is mooted,’” id., at 618, quoting Kansas v. Colorado, 320 U. S. 383, 394 (1943). “Conditions as they obtain today” include all current “equities,” which, as elaborated further below, turn on past, present, and future realities.
“Harvestable surplus” refers to the number of fish in the run that remain after the escapement ordered for the preservation of the runs and after the Indian Tribes have exercised their treaty rights.
For instance, hatcheries supplement the natural reproduction of the fish. See Report of Special Master 9. Also, fish may be transported around dams to reduce mortality in passage, Exceptions of Idaho 102-103; see ante, at 1021, n. 3. Finally, the States can continue investment and efforts to maintain proper conditions for spawning, Report of Special Master 8.
In this regard, I think that the Master properly rejected Idaho’s proposed quantification of its right, relying solely on its role as the State of origin. As Idaho explains its position: “[Idaho’s] share of the harvestable surplus of Idaho origin fish should equal Idaho’s percentage contribution to the entire run.” Exceptions of Idaho 47. This proposal would require the Master to base the apportionment on one factor alone. The most glaring problem with this formulation is that it takes no account of the relative benefits and burdens to each State of dividing the resource. To allow one fish to reach Idaho, Oregon and Washington must allow some significantly larger number, the exact value of which is the subject of some dispute, see Response of Washington 14-15, 43-45; Reply Brief for Idaho 7-9, to pass by the downstream fisheries. These other fish will be lost in passage, and no one will benefit. Considerations of relative benefits and burdens imposed by a given division are at the core of equitable apportionment. See, e. g., Colorado v. New Mexico, 459 U. S. 176 (1982); Kansas v. Colorado, 206 U. S. 46, 109 (1907); cf. Colorado v. New Mexico, supra, at 181, n. 8 (rejecting argument that State that is the source of water is automatically entitled to any share).
The Master’s report suggests that the source of revenue used for investment by the State — fishing license fees as opposed to general taxes — is somehow relevant. See Report of Special Master 30. Although the proper range of considerations is quite broad, I fail to see the relevance of that consideration.
The Master’s dismissal of Idaho’s calculations reflects an undue skepticism where statistics are concerned. The linear least squares regression method that the Master concluded was “of little value in making predictions,” id,., at 41, for instance, can indeed have predictive value, if used properly. See, e. g., W. Hays, Statistics § 10.4 (3d ed. 1981). Courts can rely on the same sort of calculations that agencies charged by the States with management of fisheries perform.
The Five-Year Plan of the parties to the Sohappy litigation expired in 1982, see Report of Special Master 11. The Plan had required the defendants to take certain actions that tended to preserve the runs. Id., at 35. Although the Plan was never adequate to protect Idaho, since it was not a party to the Plan, id., at 10, the expiration makes the need for relief, if there has been an injury, even more urgent.