Jack salmon are a fascinating type of fish with some unique characteristics that set them apart from other salmon species. In this article we’ll take an in-depth look at what exactly jack salmon are, what makes them different, where they can be found and how they are used commercially and recreationally.
What is a Jack Salmon?
A jack salmon is simply a precocious male salmon that returns from the ocean to its natal freshwater stream to spawn at least one year earlier than normal. Most Pacific salmon species have a predictable life cycle that involves spending several years maturing in the ocean before returning to their birthplace to spawn. However occasionally a male salmon will return to spawn after only a few months at sea, before it has had time to fully mature. These premature spawners are known as “jacks”.
Jacks are nearly always male salmon, as the female salmon require more time to grow large enough to produce viable eggs. Jacks are typically only about 2-5 pounds when they return, compared to 10-30 pounds for a fully mature adult salmon Despite their small size, jacks are sexually mature and capable of reproducing
Some common salmon species that produce jacks include:
- Coho salmon
- Chinook salmon
- Sockeye salmon
- Pink salmon
Unique Features of Jack Salmon
There are a few key differences that distinguish jack salmon from full-grown adults of the same species:
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Size – As mentioned, jacks are much smaller, weighing around 2-5 lbs compared to 10-30 lbs for adult salmon.
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Age – Jacks return to spawn at least one year earlier than normal, so may only be 1-2 years old compared to 3-5 years for adult salmon.
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Appearance – Jacks often lack the prominent hooked jaws, humped backs, and bold coloring of adult salmon. Their appearance is more streamlined and silver-colored.
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Flesh – The flesh of jack salmon tends to be lighter in color and less fatty compared to adult salmon.
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Behavior – Jacks utilize different spawning behaviors to compete with larger males, like sneaking in to fertilize eggs while the adults are distracted.
So in many ways, jack salmon are like a younger version of an adult salmon, with differences in size, age, looks, flesh composition, and spawning tactics.
Where are Jack Salmon Found?
Jack salmon are found along the Pacific coast of North America and Asia, as well as in the Great Lakes. Specifically, they are most abundant in the following regions:
- Pacific Northwest – Oregon, Washington, British Columbia
- Alaska
- Japan and Russia
- Great Lakes tributaries
Within their native range, jack salmon run up the same rivers and spawn in the same stream systems as the regular adults of their species. They may even be born in the same nests as their fully mature counterparts that will return in subsequent years.
Popular river systems where abundant jack salmon can be found include:
- Columbia River
- Snake River
- Fraser River
- Sacramento River
- Klamath River
So jack salmon are widely distributed across the northern Pacific Rim and found in many of the same habitats as other salmon species. They form a regular part of the salmon runs in these regions.
Purpose and Benefits of Jack Salmon
At first glance, jack salmon may seem like an aberration or a dead-end offshoot of normal salmon development. However, it turns out they serve some key ecological and genetic roles:
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Genetic diversity – By returning at different ages/sizes than normal, jacks provide increased genetic variability which strengthens the population.
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Colonization – Their premature return enables jacks to colonize new habitats more quickly.
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Bridging generations – Jacks that spawn with normal adults create mixed-age offspring, improving generational overlap.
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Back-up spawners – If an expected run of adult salmon fails to appear, jacks can provide a reproductive backup.
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Research – Comparing jacks to adults helps provide insights into salmon growth, development, and physiology.
So although jacks are not fully mature, they still make important genetic and ecological contributions to the overall salmon population. Their uniqueness is a feature, not a bug!
Uses for Jack Salmon
Although jacks are smaller than adult salmon, they can still be caught and used for food or bait:
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Food – Jack salmon are edible and can be cooked similarly to regular salmon. Their flesh has a milder flavor and less fat, making them preferable for some.
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Bait – Their small size and abundant numbers make jacks ideal bait for crabbing, lobstering, or larger game fishing.
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Animal feed – Leftover salmon carcasses and offcuts are often recycled as nutritional feed for livestock or farmed fish.
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Fertilizer – Ground up jack salmon can provide a quick-release nutrient boost when used as an organic fertilizer.
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Pet food – Dried jack salmon can be used as a protein ingredient in some cat and dog foods.
Although they have less commercial value than adult salmon, jack salmon are still a useful source of food, bait, fertilizer, and feed when their seasonal runs are strong.
By Rodney Hsu, Fishing with Rod | Published in December 2001
Fish come in all sizes, every angler knows that, however a fish needs to reach a certain size to become sexually matured. In the case of Pacific salmon, sexual maturation occurs between 2 to 5 years after birth, depending on the species. During this process, the characteristics of male and female will diverge from an uniform look that they possess in the ocean. Generally, the male will be larger than the female individuals, and individuals within a school of run do not differentiate largely in size. However there are exceptions. Anglers who frequently target salmonids during their returns will often encounter the odd fish that are distinctly smaller. This is often seen in chinook and coho salmon. Why are there such unique differences between the appearances of a male and a female spawning salmon? Why do some fish return into the river earlier than they are expected? More importantly, does size really matter? The theory behind these mysterious behaviours is rather complex and in many cases it resembles the rules of mating in the human society.
The term sexual dimorphism (di = Two, morph = look=) is simply another jargon that biologists have made up to explain why boys and gals look so apart. By looking at the appearance and behaviour during mating, biologists are able to end the universal question – Who exactly is in charge between the sexes?
In the ocean, it is almost impossible to tell the gender of a salmon because they both look identical. Once entering the freshwater prior to spawning, both genders go through certain changes that will set them apart.
These changes are more evidently shown in male individuals. Hook jaws and sharp teeth are developed, and a hump back can be found in certain species such as pink salmon. The purpose of these changes are thought to be both offensive and defensive. Males need to look big to hold their ground and fight off any threats to search for the mate of their dream. These characteristic changes are also displays to show the gals how large and fit the male is so he should be chosen as the father of her offsprings.
Such phenomenon is not only seen in salmon, but also in just about every species on this planet. Male individuals of some species possess colourful displays. The more colourful you are, the larger chance that you will be chosen by a female. Why do females get to do all the choosing? The answer to this one million dollar question is simple. Eggs are expensive, sperms are cheap, so a female needs to choose wisely as she does not have much to spare.
What is a Jack Salmon?
FAQ
What is the difference between jack salmon and regular salmon?
Fish biologists define a jack as a male salmon that matures at an age younger than the youngest mature female. Because they are younger, they are also smaller. Jacks are only found in some salmon species- Chinook, coho, and rarely, sockeye.
Is jack salmon a good fish to eat?
Nowadays, jack salmon can be found on everyday menus at most of the local chicken and fish houses, sometimes offered as fried fillets but more often served whole, which shouldn’t be a deterrent. Bone-in fish tends to be moister and more flavorful than fillets, and whiting pulls very easily off the firm, hard bone.
What is a jack salmon in Oregon?
Jacks are precocial male salmon that have spent one winter less in the ocean than the youngest females of a given species. Because they are younger, jack salmon are smaller than other age classes of conspecifics. Coho jacks return to spawn the same year they smolted and so are particularly small.
Do jack salmon go back to the ocean?
Male Chinook salmon that return to their fresh water stream a year or two earlier than their counterparts are known as “jacks”. (Most Chinook salmon mature at age 4 or 5 after spending 2 or 3 years in the ocean.)