Length & Weight Variations In Salmon Species

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Salmon are not only one of the most well-known fish in the world but did you know they exhibit a remarkable diversity in size and weight across different species? Understanding the size distinctions among the seven species of salmon is important for both anglers and fish admirers.

Multiple factors contribute to a salmon’s weight, length, growth patterns, and life cycles within each species. Salmon world records are regulated by the International Game Fish Association (IGFA). In contrast, the average size of fully grown salmon provides a more typical benchmark for each species.

Key Takeaways

  • Learn how the salmon species range in size from the small pink salmon to the large king salmon.
  • Understand how their lifespan, species type, and environmental conditions affect their weight and size.
  • Record sizes give insight into the maximum size, while average measurements provide typical sizes for each species.

Understanding Salmon Species

In this section, I’ll guide you through the intricacies of salmon species, differentiating between those found in the Pacific and Atlantic oceans and giving an overview of the Salmonidae family. I’ll also discuss the countries where they are found, specifically focusing on the key characteristics that distinguish each within the family.

There are six species of Pacific salmon, but only one type of Atlantic salmon. Salmon can be easily recognized as adults, but their color, shape, and body markings vary. Meanwhile, fins, tails, and mouths also exhibit slight differences. However, Juveniles can be challenging to distinguish between the species due to their less prominent features; as such, most anglers often cannot tell the difference.

However, they all share characteristics such as small scales, a lateral line, and an adipose fin (a small fleshy lobe on the back between the dorsal fin and caudal fin), making them distinguishable from non-Salmonidae fish. 

The family Salmonidae encompasses a total of 66 species, which consist of salmon, steelhead, trout, and arctic char. Anglers often get confused when identifying the differences between steelhead and salmon since they grow and live together in North American rivers. 

Pacific Salmon Diversity

Pacific salmon refers to the six species that are found in Pacific waters: These are Chinook (or King), Coho (Silver), Pink (Humpback), Sockeye (Red), Chum (Dog or Keta), and Masu (Cherry). Each species has unique traits and life cycles:

Atlantic Versus Pacific Salmon

One fundamental difference in comparing Atlantic and Pacific salmon is that Atlantic salmon belongs to a single species, the Salmo salar. Secondly, pacific salmon are typically semelparous, meaning they die after spawning once, while Atlantic salmon are iteroparous, potentially spawning multiple times over their lifespan.

Which Countries Do Salmon Live?

Salmon are found in multiple countries across the Northern Hemisphere. 

The Pacific salmon inhabit the Pacific Northwest and are found in and around the Columbia River Basin, where they eventually migrate out to the Pacific Ocean. In the ocean, they range from California to Alaska and across to Korea, Russia, and Japan.

The Masu can only be found in the Western Pacific region, in the Sea of Japan and the Sea of Okhotsk. The Asian Pacific countries of Korea and Japan and the Russian Far East areas (Kamchatka Peninsula, Sakhalin Island, Kuril Islands, and Primorsky Krai) are the most prevalent habitats. 

Atlantic salmon are found on both coasts of the Atlantic Ocean from as far south as Portugal, around the British Isles, up to Iceland, and into North America as far as the rivers of Quebec and Connecticut. 

The cold water ecosystems in these regions provide the ideal conditions these species need to thrive.

Biology And Life Cycle

In discussing salmon’s biology and life cycle, we’ll focus on their spawning habits, anadromous lifestyle, development stages, and growth patterns, which are four key aspects that define their existence from birth to maturity.

Spawning Habits

Salmon exhibit the same reproductive behavior known in fish as spawning. However, in salmon, this process involves migrating back to their natal rivers to reproduce. The species’ remarkable homing instinct ensures they often return to the exact location where they were born to lay eggs.

Anadromous Lifestyle

Salmon are anadromous fish, meaning they migrate from freshwater, where they spawn and begin life, to the ocean, where they grow and mature. This transition from river to sea is critical for their development, as they take advantage of the abundant food resources found in marine environments.

From Fry to Adult Salmon

After hatching, salmon begin their lives as fry, then progress to become parr, characterized by vertical bars and spots for camouflage. As they grow, they transform into smolt, a stage when they adapt to saltwater before migrating to the ocean. And finally, becoming an adult.

Salmon Growth Stages

Distinct physical changes define the growth stages of salmon:

  • Fry: Small, newly hatched salmon, up to 10 weeks old.
  • Parr: Display a pattern of bars and remain in freshwater for one to two years.
  • Smolt: Smolts adapt to saltwater and usually measure less than 20 cm long.
  • Adult: Pacific salmon return to freshwater to spawn once and then die. However, Atlantic salmon often survive spawning and may migrate back out to sea with the chance of returning to spawn again

What Factors Affect The Weight Of A Salmon?

When examining the factors that contribute to the weight of a salmon, species is one of the primary considerations. Each salmon species has a general weight range it typically falls within. For instance, King salmon are known for their larger size, often reaching weights from 20 to 50 pounds and sometimes exceeding 100 pounds.

Another crucial factor is the age of the fish. Younger salmon are, unsurprisingly, smaller and weigh less than their older counterparts. As salmon age, they accumulate more fat deposits, contributing to their overall weight.

The diet of a salmon also plays a significant role in its growth. Those with access to abundant food sources are likely to grow larger and heavier, while those with less available food sources may weigh less.

Environmental conditions, including habitat and water temperature, also impact salmon weight. Favorable conditions can promote growth, leading to heavier fish. Conversely, challenging conditions can stunt growth and result in lighter fish.

Heaviest Salmon Ever Caught

The table below shows the record weight for various salmon species caught and ratified by the IGFA as world records. (caught by rod and line)

SpeciesRecord WeightDate CaughtLocationAngler Name
Chinook Salmon97 lb 4 oz (44.1 kg)May 17, 1985Kenai River, AlaskaLes Anderson
Chum Salmon35 lb (15.87 kg)July 11, 1995Edye Pass, British ColumbiaTodd Johanssen
Pink Salmon14 lb 13 oz (6.74 kg)September 30, 2001Monroe, Washington, USAAlexander Minerich
Sockeye Salmon15 lb 3 oz (6.88 kg)August 9, 1987Kenai River, Alaska, USAStan Roach
Coho Salmon33 lb 4 oz (15.08 kg) September 27, 1989Salmon River, Pulaski, New York, USAJerry Lifton
Masu Salmon11 lb 9 oz (5.25 kg) May 6, 1995Kuzuryu River, Fukui, JapanTakeshi Matsuura
Atlantic Salmon79 lb 2 oz (35.89 kg)January 1, 1928Tana River, NorwayHenrik Henriksen

It is important to note that these records are subject to updates when new records are officially validated. King Salmon holds the top spot among its family for the largest ever recorded, both by weight and size.

Average Weight Of A Fully Grown Salmon?

Each has its own average size. I’ve listed them below to clearly understand how large each species can typically get when fully grown.

  • Chinook Salmon: Also known as King salmon, they are typically the largest, with an average weight range of 25 pounds.
  • Chum Salmon: Sometimes called dog or keta salmon, and their weight averages around 12 pounds.
  • Pink Salmon: Known as the humpback salmon, and weighs 3.5 pounds on average.
  • Sockeye Salmon: Commonly called red salmon, and weighs about 6 pounds.
  • Coho Salmon: Also known as silver salmon, weighs on average 8 pounds.
  • Masu Salmon: Known as Cherry salmon, Similar in length to the pink salmon, but their average weight is bigger at 4.5 pounds.
  • Atlantic Salmon: Typically, their average weight is around 12 pounds.

The figures provided reflect the typical size of mature, adult salmon. These are average sizes, so it’s worth noting that individual specimens may be significantly larger or smaller.

It’s to be noted that the maximum records are exceptional and not the standard; averages indicate what one might encounter as an angler.

What Is The Average & Maximum Length Of Salmon 

The weight and length of a salmon do have some relationship. However, certain species have a broader body, leading to a heavier weight, but they can be shorter in length. To understand their physical diversity, here’s a breakdown of the average and maximum length for each recognized species:

  • Chinook Salmon: Known as the largest, mature Chinook salmon range from 24 to 36 inches on average. Remarkably, they can reach lengths up to 58 inches.
  • Chum Salmon: These salmon can grow 20 to 30 inches on average, with some reaching lengths of 40 inches.
  • Pink Salmon: The smallest species, Pink salmon, average 20 to 25 inches long, maxing out around 30 inches.
  • Sockeye Salmon: Adult Sockeye typically measure 18 to 31 inches long.
  • Coho Salmon: On average, Coho are between 25 and 30 inches long but can grow up to 38 inches long.
  • Masu (Cherry) Salmon: They generally measure about 20 inches, although they can get up to 28 inches long.
  • Atlantic Salmon: Common lengths for Atlantic salmon range from 28 to 30 inches, but they’ve been known to reach up to 44 inches.

As with all fish, their habitat and regional variations can affect these averages. For anglers, many will weigh and measure their length for their own record retention.

Best Salmon For Eating

When selecting the finest salmon for eating purposes, most of us focus on flavor and the flesh’s texture. When it comes to cooking, the versatility of the fish in various recipes becomes an additional important factor. Chefs and food critics mostly recommend two particular types of salmon at the top of this criteria:

  • King Salmon (Chinook): King salmon is the most sought-after species for eating. Their rich flavor and substantial fat content render them incredibly succulent, an excellent choice for grilling or oven roasting.
  • Sockeye Salmon: While smaller or more fatty than King salmon, sockeye are known for their vibrant red flesh and are praised for a more intense salmon flavor, which shines through particularly well when smoked or baked.

Here’s a quick comparison:

Salmon TypeBest Cooking Methods Fat ContentFlavor Profile
King Salmon Grilling, roasting, sushiHighRich, buttery
Sockeye SalmonSmoking, baking, sushiModerateIntense, robust

The high-fat content of King salmon lends a luxurious texture that’s hard to overcook, making it a forgiving option for less experienced cooks. Sockeye’s leaner meat and pronounced flavor make it a favorite for those who appreciate a more traditional salmon taste. Both are excellent choices for using for any sushi or sashimi dishes.

Wild Alaskan salmon (Sockeye) is the premium choice, due to its lean, meaty, dense quality and full of Omega-3 fatty acids.  Always ask your fishmonger what is the particular salmon they have in store. The best fishmongers will know what type of salmon they have recently flown in and where it comes from.

For those of you who buy tinned salmon, pink and sockeye are the most common types used at canning facilities. 

3 Best Ways To Cook Salmon

Slow Roasting: this method is a foolproof route to tender and moist salmon. I set my oven to 275°F, lightly coat the salmon with olive oil, and season with salt and pepper. I place the fish in a baking dish and cook it until it flakes easily or until a thermometer reads 120°F in the thickest part—typically about 30 minutes for a 6-ounce fillet. This slower time and lower temperature combination will ensure the salmon is not overcooked and dry.

Pan-Searing: When I’m after crispy skin, pan-searing is my go-to. Always preheat a skillet over medium-high heat first, then place the salmon skin side down first in the oil to achieve that charred golden crust. Press the flesh slightly to ensure even contact with the pan. After searing it to a crispy finish, turn the fish to cook through for a total of 6 to 8 minutes, depending on the thickness.

Baking: I often bake salmon fillets at a moderate temperature of around 300°F. This hands-off approach is simple: place the seasoned fillets on an oiled baking sheet and let the oven do the work. A quick check is needed halfway through the baking process, which typically takes 15 to 20 minutes, so they don’t overcook.

Note: Whichever method you decide to use, always season (salt and pepper) just before you plan to cook. Also, make sure the fillets are at room temperature prior to cooking.

Slow Roasting275°F30 min (6-oz fillet)Tender, moist
Pan-SearingMedium-high6-8 min totalCrispy skin, flavorful
Baking300°F15-20 minHands-off, foolproof

Cooking salmon doesn’t have to be complicated, and by following a few basic rules will result in consistent results every time. Using different cooking techniques will deliver a different taste, making salmon a versatile option for the family.

Final Thoughts

In recent years, research has indicated reduced variations in the length and weight of salmon species, particularly in the Pacific salmon populations. Studies have consistently shown a trend of declining body size, which has major long-term implications for ecosystems and fisheries.

It’s unlikely that certain records will be broken, with no increased weights in any species for the past two decades.

I hope you found this article interesting and informative. You can read more posts related to this in my introductory category on Fishing 101.

Steve Fitzjohn