“Since European settlement, the instream and floodplain areas of the Heart of the Fraser have been modified dramatically as a result of resource extraction as well as agricultural and development activities. This extensive and significant change has compromised the expansive habitats that many species rely upon. Impacts continue to occur as a result of land clearing, diking, watercourse draining, forest harvest (pulpwood), mining, agriculture and industrial, commercial and urban development. Thus, the remaining environmental and ecological integrity of the instream and riparian areas of the Heart of the Fraser is at imminent risk.” - Saving the Heart of the Fraser: Addressing Human Impacts to the Aquatic Ecosystem of the Fraser River
The Heart of the Fraser is home to the largest concentration of White Sturgeon in Canada. The secondary side channels of both Herrling Island and Carey Island comprise two of the most important and key spawning habitats for the endangered White Sturgeon in the lower Fraser River.
Large perimeter side channels of Carey Island (Jesperson Slough) and Herrling Island (Herrling Island back channel) are known to be critical spawning habitats of this species for the Heart of the Fraser and downstream to the Salish Sea. White Sturgeon spawn in these channels in the spring during the high-flow freshet when the channels are in full flow.
In addition, the Fraser River is one of the greatest salmon rivers in the world. All five species of Pacific salmon are found in the Heart of the Fraser River – pink, chinook, coho, sockeye, and chum – at various stages of their life cycle. The largest population of pink salmon (over 10 million) are known to spawn right in the mainstem of the gravel reach in the Heart of the Fraser. Sockeye have been known to rear in the mainstem, side channels and sloughs of the lower Fraser River. Chum salmon (over 1 million) are known to spawn in the side channels of the Fraser such as the side channel besides Herrling island. Ocean-going coastal cutthroat trout are known to inhabit the gravel reach where they forage and spawn in the mainstem and side channels.
As reported in Saving the Heart of the Fraser: an example of the Fraser gravel reach’s biodiversity, a number of aquatic mammals are regularly observed in the area, including harbour seals, beaver, muskrat and the marten. Large terrestrial omnivores include black bear, and, surprisingly, the very occasional grizzly bear. Other large vertebrates include blacktail deer and the non-native whitetail deer, cougar, and coyote. The Pacific water shrew is an example of a small mammal which is also listed as a species at risk living within the boundaries of the Heart of the Fraser.
The Heart of the Fraser is also extremely bird-rich. Over 135 species of birds have been recorded in the region. Some of the rarer or more notable birds include the red-tail hawk, the green heron and great blue heron, the bald eagle, assorted dabbling ducks, the wood duck, the purple martin, the sandhill crane and turkey vultures.
Rare amphibians in the Fraser gravel reach include species such as the Oregon spotted frog, western red-backed salamander, and the Pacific giant salamander.
Plant species were historically also rich in complexity in the Fraser gravel reach and although these plants remain at a diminished abundance, are still an important part of this ecosystem. The remnant natural communities of lowland vegetation include black cottonwood and western red cedar.