Fig 3 Maturing Oocytes (2).jpg

land locked coho salmon: just published

Coho salmon are typically anadromous (fish move between fresh and salt water in different parts of their life cycle) but we found mature coho in two freshwater lakes on the north Coast of British Columbia. These fish did not go to sea!! This occurrence is exceedingly rare. Such mature coho salmon may represent residual and distinct breeding populations from those in adjacent streams. Alternatively, they may result from lack of a path for migration due to low water levels in the spring when coho salmon typically migrate to sea after 1-2 years in fresh water. Regardless of cause, the ability of these coho to mature in fresh water without seaward migration may represent an important adaptation to variable environments. See more in a publication just out:

Parkinson, E.A., C.J. Perrin, D. Ramos-Espinoza, and E.B. Taylor. 2017. Evidence for freshwater residualism in Coho Salmon, Oncorhynchus kisutch, from a watershed on the north coast of British Columbia. Canadian Field-Naturalist 130(4): 336-343.