Historically, neither moose nor wolves inhabited Isle Royale territory.
Primarily, its flora was mostly the taiga - boreal forest consisting of pine, spruce and larch - natural environment for boreal woodland caribou and Canada lynx, then coyotes (afterwards, suppressed by the wolves). Both primal prey-predatory related residents were hunted down or just superseded by human activity. According to scientific investigation, moose introduction was initiated by hunters, for private preserve, in 1900s. Another theory stands that moose simply swum across the lake. A pair of wolves was supposed to cross the ice from the mainland in the winter season in 1940s.
Limited by the isolated area relationship between Royal Isle wolves (single predatory species) and moose (single prey species) turned out to be unique for ecologists, scientifically studied (over 5 decades) as a pure environment based on wolf-ungulate coexistence functioning without omnivore bear's competitive presence. Scientists still scavenge the forest for remains of moose carcasses in summer, and make surveys from the sky in winter researching it up to date. However, its simplicity means that every single factor is able to impact the local population of selected species or to upset the whole balanced ecosystem.
- inbreed hazard
Single pair which pioneered the Isle Royale wolf population, made it severely inbred by years (DNA seems to be traced back to one ancestor), leading to inbreeding depression and in consequence to health problems (including genetic diseases), constantly decimating offspring state by generations. In 1997, a virile wolf from outside (Canada territory) migrated cross the ice to the island, signified as the No.93 and called "Old Gray Guy" - his fur became unusually pale as he aged. We don’t know of any other instance - except when they first came - of wolves crossing the ice - John A. Vucetich says, co-author of the long-term Isle royale wolves study - The entire population is descended from a single female. In 2009, 56% of Isle Royale wolves seemed to be descended from No.93 as a single male.
- diseases (caused by inbreed or not) / natural disasters / random accidents
In 1982, due to canine parvovirus brought by a dog companion during a fishing trip to Isle Royale National Park, none of wolf offspring survived the winter season, and as a result 36 of 50 individuals were dead within two years.
- climate changes (resulting in natural disasters or not) / global warming
Warmer winters - with less (or no) freezing cold, snow, frost - imply fewer ice bridges, making the island even more remote, new wolf migration impossible (in general, wolves - as a species - are not natural born swimmers), indirectly affecting the genetic diversity.
Depending on on-going observations, there is only one, non-breeding pair of wolves on Isle Royale currently - most likely father and daughter which is also his sister (coming from his mating with his own mother). Both of them are not able to proceed a regular successful hunt for a large ungulate without any help of the rest of skilled pack members - experiencing the moose population explosion up to the extreme number of 2500 (from 500 at the beginning).
Regarding every point mentioned above, in the sake of prey-predator balance restoration, Isle Royale National Park service decided about reintroduction of a wolf species to the island, by release of 20-30 individuals in 3-5 years, starting from fall 2018. The only similar experimental occurrence took place in Yellowstone National Park where it covered the open interstate area.
- inbreed hazard prevention
We hope to capture [wolves] from as many wide-ranging geographical areas as possible to maximize genetic variability of the population that we end up putting into the park - Mark Romanski says, Isle Royale National Park natural resources chief. Captured animals - keeping their packs possibly intact - are supposed to come from variety of neighbouring regions of Minnesota, Michigan, Ontario. They will be transported immediately (reducing stress) by air or by boat to the island, where they will be released in different places to avoid potential territorial conflicts. The complete procedure plan stands that the trap process will run slowly over time rather than by capturing all expected wolves at once.
- diseases prevention
All captured animals will be vaccinated and tested for diseases such as heartworm and parvo virus. We will also be employing radio collars - Mark Romanski says, pointing on technology aspect not easily accessible when the Yellowstone project started in 1995 along with its cascade model conception research -We will use a mix of VHF and GPS collars. This will allow us to not only collect data not only on a fine scale, but also over a number of years.
- climate changes unavoidance
Even if the process proceeds, global warming is unpredictable same as an accidental event or singular natural disaster itself. The mainland-island rotation condition - indirectly genetic diversity - is strictly associated with the transmigration's relatively high probability. For the wolf species it is precisely ice bridges formation chance during winter, despite warmer shorter winters. According to data, three times bridges have formed between Isle Royale and Minnesota open area for four last years, by which wolves crossed twice there and back.
Typically, predatory species - considered as a large predator or an apex predator - located on the particular area, keeps its own dedicated prey population in check, thereby protecting the prey's potential plant nutrition state. Otherwise, the numerous herbivore prey would eat away the main source of food, starving in winter and collapsing soon after, if not regulated back. The important aspect is that predation means to hunt, not to scavenge - carnivores can cooperate with scavengers (vide wolves-ravens symbiosis phenomenon) temporarily on dead animals' carcasses, until it's urgently needful, not affecting scavengers habitat in matters of specific species population status. The next step should be to migrate away before being going extinct itself, or being extinct if the migration is undoable.
Isle Royale makes up Isle Royale National Park (established in 1940), placed in the middle of Lake Superior, in the USA Michigan state area. To be strict, Lake Superior [ᑭᑦᒉᐁ-ᑲᒣᐁ, kitchi-gummi, "great sea" in Ojibwe] is located on the Canada-United States border; shared by Minnesota (West), Wisconsin/Upper Michigan (South) and Canadian province of Ontario (North/East). Isle Royale itself remained controlled by the British Empire until the War of 1812, whereas indigenous Ojibwe people considered the island to be their territory until Isle Royale Agreement in 1844. It is the largest (72km long, 14km wide, 535.43 km2) of 400 Lake Superior islands. Isle Royale National Park made it open for tourists (except the winter season when it is entirely closed), even if not easily accessible (only by plane, boat, seasonal seaplane). Current marshes are the beaver activity evidence. Other mammals living permanently on the island are red squirrels and red foxes (some of them used to human contact, because of food scraps left by unwary campers), scavenge specialized birds (crows, ravens), fish. Potential visitors can explore secluded island offering tent camp-sites and camper cabins inland (accessible only by foot) or shoreline (accessible only by boat/kayak/canoe). Adventurers can try day hiking (Rock Harbor, Windigo Ranger Station), backpacking challenge, a guided trip or just go fishing/diving. Officially, dogs are not allowed in concern about wildlife species living on the imited area (service dogs allowed after permission).
Certain issue left to consider:
Would making the island completely - or almost completely - closed for tourists (at least for some time) make the society stay in harmony with the awareness of wildlife which inhabit Isle Royale, maintaining closed prey-predator related ecosystem.
NPS Isle Royale wolf reintroduction project decision (Jun.7th, 2018)
Should Isle Royale Wolves be Reintroduced? A Case Study on Wilderness Management in a Changing World (2012), by A. Vucetich, Rolf O. Peterson, Michael P. Nelson
Wolves & Moose of Isle Royale
 Wolf-Moose Populations fluctuation - Isle Royale project overview
 Genomic sweep and potential genetic rescue during limiting environmental conditions in an isolated wolf population (2011), study by John A. Vucetich, Rolf O. Peterson, Leah M. Vucetich, Jennifer R. Adams, Philip W. Hedrick.