Fish Hunter: The American Mink

I have been observing Mink on my home river for a number of years now and I have often wondered what their impact is on the local fish population. I you call a northern river home its likely that these critters also call your waterway home and may be having a significant impact there, especially if they are introduced or invasive. This curiosity has led  me to do some research that Ill share with you now.

American Mink carrying a young brown trout The American Mink or Mustela vision is native to Alaska, most or Canada, as well as you United Stated except for parts of the southwest and arid desert regions. They are common along waterways and prefer lakes to rivers although they are more often noticed in rivers because of their propensity to patrol the riverbank. Minks reside in burrows that they either create for themselves or steal from other animals such as muskrats. Their burrows are usually one to two feet underground and the diameter of a 2 liter soda bottle, they can run for up to fifteen feet and most often have one chamber that is lined with vegetation or the fur and feathers of its prey. Mink are small mammals that are semi-aqautic and partly nocturnal. Lake dwelling Mink are known to be more nocturnal than river dwelling Mink. They are known to live on average between 3 to 7 years and give birth once a year to a litter of 4 kits although litters of up to 16 have been reported. They breed in the spring and do not form bonded mating pairs. Another interesting fact is that female Mink are believed to be capable of delaying implantation of semen so that they may observe their natural environment and select the best time to give birth. Their incubation period is 40-70 days and young Mink begin hunting at eight weeks of age but stay with their mothers until the next spring. Minks primary diet consists of frogs, fish, crustaceans, small mammals, turtles, snakes, birds, and eggs. They are wholly carnivorous and very effective predators. Minks are known to carry their food off after killing it and usually consume it in their den or burrow. This is why they are frequently spotted carrying off fish on the riverbank. There is not a great deal of data I have been able to find on their impact on fish populations but I have found information from areas where they are introduced such as Europe where fish population declines have been blamed on Mink. Another thing I found is that Mink residing in or near river prey on fish to a much higher degree than those who live near lakes because fish is the most accessible prey for them. One thing is for sure, Mink are effective predators on land or in water and they do not hibernate. Its been observed that after periods of heavy snow or storms they will hide in their burrow for several days before returning to normal activity.  So in the winter they are hunting and doing so effectively in areas where they can access. In fact its been stated that they are more effective fish hunters in the winter because of the slow and lazy nature of fish prey in those temperatures and their lack of other suitable alternatives for prey at that time. Mink have few natural predators. Coyote, Bobcat, Foxes, and owls are known to take Mink occasionally but other than man the impact of predation on Mink is minute.