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Mercury Marine Supports Chinook Salmon Conservation

Conservation of our precious wild Chinook salmon fisheries across the Pacific ocean and interconnecting riverine habitats is crucial in order to maintain populations and genetic diversity for future generations.

On the Water
Mercury Marine Supports Chinook Salmon Conservation

Chinook or king salmon are highly recognized as one of the hardest fighting fish in freshwater based off their physiological capabilities exemplified through line-screaming runs and aerial acrobatics that challenge the angling skillset of fishermen everywhere. Throughout their native range in the Pacific Ocean, king salmon average approximately 30 pounds in size with older cohorts around 50 pounds. Specifically, some trophy fisheries in Alaska and British Columbia exhibited unique ancestral populations of fish that could achieve growth potential up to 90-plus pounds with 100-pound fish documented with the Kenai River in Alaska and Skeena River in British Columbia being two iconic trophy Chinook salmon fisheries. Although Chinook salmon fisheries have popularized amongst anglers worldwide, the biomass of king salmon in the Pacific ocean have fluctuated.

Conservation of our precious wild Chinook salmon fisheries across the Pacific ocean and interconnecting riverine habitats is crucial in order to maintain populations and genetic diversity for future generations. To establish fundamentally sound conservation efforts, multiple components must be addressed ranging from habitat protection of freshwater and marine habitats towards in-river management of efforts of returning adults through escapement counts coupled with appropriate sport fishing regulations that achieve adequate escapement of fish to their upstream spawning grounds. Advancements in fisheries science have allowed fisheries biologists to identify critical habitats (freshwater and marine), understand migratory behavior, develop management objectives, and monitor wild populations. Here, we thoroughly discuss the methodologies that scientists are currently implementing for conserving and maintaining wild Chinook salmon fisheries because challenges continuously arise due to the threats of a global climate change.   

Catch-and-Release Regulations & Techniques

In effort to maintain adequate escapement counts during the progression of the adult spawning run, some regional and/or state agencies have adopted catch-and-release regulations. Advantages of catch-and-release regulations allow increased participation of a recreational fishery which stimulates economic growth to local economies, preserved larger trophy-sized individuals in the population, and increased number of fish reaching headwater spawning grounds. The birthplace of catch-and-release regulations were originally implemented by the Alaska Department of Fish and Game (ADFG). A catch-and-release regulation basically means that all king salmon regardless of size classes must be immediately released after conclusion of the angling event. To ensure these regulations are further enhanced, ADFG has specified in their regulations that king salmon cannot be physically removed out of the water. Therefore, during photographic sessions the fish should be held in horizontal position to support fishes weight combined with underbelly still submerged below the water’s surface. Other conservative fish-photography strategy to minimize catch-and-release stress is to hold the king by the caudal peduncle, the narrow region connected to the tail, and support the fishes bodyweight while its completely submerged underwater which thus minimizes air exposure. Air exposure should be kept to a minimum of 30 seconds.  Prior to releasing the fish, select shallow depth characterized with slow current and the fish positioned in upstream orientation so fish returns to healthier condition.

Identification of Critical Habitat

Identification of critical habitats is important to understand how king salmon during specific life history stages utilize the resources and space in their day-to-day behavior. Without scientific investigation of king salmon interactions within their natal environment, it makes it almost entirely impossible to designate important habitats for conservation and protection. Typically biologists utilize several diagnostics in their arsenal for characterizing and classifying salmon spawning habitat. Examples include aerial and snorkel surveys, floats from headwaters downstream to middle rivers, hikes along streambanks, monitoring of spawning activity through radiotelemetry, and thermal readings of inter-gravel areas.  Schools of spawning king salmon from aerial surveys are a way to distinguish important spawning habitat. Two decades worth of thermal imagery techniques combined with radio telemetry allowed biologists to determine location of spawning habitat through assessment of stream temperatures. Darker tones on thermal images indicate colder temperatures whereas lighter tones warmer temperature. This is an important scientific tool necessary for land management near freshwater spawning areas. Similar research also has been demonstrated on king salmon river watersheds for interpreting and understanding smolt interactions. These breakthroughs in fisheries science led to the development of permanent habitat protection areas. The Wild Salmon Center based out of Oregon established some of the first permanent salmon protection refuges. The Kamchatka Peninsula, an extension of remote land of the Russian Far East contains more than 800 free-flowing streams that contain native populations of all 5 species of Pacific salmon, steelhead, kundzha (Siberian char), and landlocked rainbow trout. After scientists characterized important spawning habitat (pools, runs, riffles, riparian zones, upwelling areas, lakes) throughout the 1990s into 2000s as well other significant biogeographical characteristics of the land, a joint decision between Russia and United States established the first permanent salmon refuge. Approximately 544,000 acres of the Kol and Kektka Rivers allowed for permanent salmon conservation.

Emergency Orders (EOs)

Similar to catch-and-release regulations, emergency orders are defined as a subcategory regulation initiative to increase biological escapement of king salmon and other salmon species during periods of low returns. Diminishing returns is often the management requirement to enable restrictions to ultimately minimize sport fishing pressure[GG2]  on stocks. Examples of emergency orders include seasonal closure, fishing time restrictions, gear type restrictions, and harvest regulations (e.g. catch-and-release only, slot limits, and possession limits).  States that utilize EOs include Washington, Oregon, California, and Alaska. British Columbia’s Canadian Department of Fisheries and Oceans also carries out EOs when escapements are subpar. The ultimate objective of EOs is to minimize or maximize harvest based on availability of fish present in the river. The decision to fully implement EOs is typically reviewed by management biologists through an assessment of a preseason forecast. This forecast estimates the total number of king salmon run projected to enter the river during their spawning run. The forecast is generated through models that contain escapement statistics from years of previous salmon returns. Other considered information used to generate forecasts include number of outmigrating salmon smolts, environmental conditions, and spawning stock distribution.  As the in-river abundance of king salmon progressively increases, research biologists closely monitor escapement statistics throughout the run and then recommend any EOs to management biologists in case numbers are low otherwise recreational fishing continues as scheduled.

Great Lakes King Salmon Conservation

Management and conservation of king salmon fisheries in the Great Lakes is comparatively different to their oceanic counterparts. Like other salmon and trout species in the Great Lakes, acceptable population abundance is linked to the cumulative biomass of the important baitfish, the alewife. Increasing distributions of invasive Zebra and Quagga muscles have exhibited topple-down effects on the freshwater food web dynamics, thus resulting in fluctuations of the alewife biomss. Traditionally when alewife populations are fairing well, state agencies typically stock additional king salmon to help balance out the predator-prey ratio. If the predator-prey ratio is below normal, then king salmon stocking numbers are reduced in order to increase alewife biomass. Biologists rely on the predator-prey index as a determinant of king salmon stocking numbers. A higher ratio designates higher predator abundance in relation to desired prey. A lower ratio indicates higher alewife abundance in relation to predator abundance. Higher predator-prey ratios (PPRs) often results in biologists implementing such management actions as reducing king salmon stocking numbers in order for the PPR to be lowered. Biologists favor a preferred range of PPR between 0.05 and 0.10. Strong year classes of larger 4-year old cohorts in the 25- to 30-pound range are definitely possible when the PPR is specifically in those ranges. An additional threat to king salmon populations in Great Lakes is potential arrival of Asian Carp. Currently distributed throughout the Illinois River watershed near metropolis of Chicago, they consume large amounts of plankton that impacts native baitfishes that predator fish rely on.  Establishment of underwater electric grids create a high voltage electric field produced from equipment in a control building that generates an electric current discourages fish from crossing into the Great Lakes.

Future Studies

Understanding the juvenile ecology and behavior of Chinook salmon in the marine environment is relatively misunderstood compared to their migratory behavioral strategies undertaken in their natal freshwater rivers during their juvenile and adult life history stages. Scientists have determined that Chinook salmon have experienced alterations in age and size structure, fluctuation in population, and demographic changes over the previous decade. With traditional insight to blame habitat degradation, overfishing, marine by-catch as logical reasoning for population declines, it is assumed that survivorship after one year of ocean residency is relative high, particularly mortality associated with predation. Emerging evidence from several studies indicate that juvenile salmon in marine ecosystems (age ocean 2-3) are being consumed by top apex marine predators such as salmon sharks, killer whales, and other endothermic fishes. To validate this scientific claim, researchers have relied on the importance of data transmitted through satellite tags. A type of satellite tag called a pop-up satellite archival tag (PSAT tag) is externally attached to the king salmon’s dorsal fin and on a preprogrammed date, the tag is released, floats towards the surface of the ocean, and satellites transmit data to researchers computers. Interestingly, one recent study conducted by the fisheries program at University of Alaska Fairbanks determined a mysterious event because the water temperature the tags transmitted seemed somewhat irrelevant. Since water temperatures in the Bering Sea are seasonally between 39 to 43oF degrees during midwinter, the researchers noticed huge spikes in temperature before the data was transmitted. Depth records indicated thermal readings of 77oF with sudden depth spikes of 400m which seemed uncharacteristic of salmon behavior. Therefore, the likelihood explanation for this event was the location of the tag inside the stomach of a warm-blooded endothermic salmon shark. Similar behavioral patterns were observed in 19 of 35 tagged fish in which the fish were consumed by marine predators as indicated by the warmer temperatures of the tag. Research on this interesting topic continues to be explored.

Conclusion

Over the past several decades, we have developed and gained a better understanding of Chinook salmon behavior in the freshwater and marine environments. With Chinook salmon populations across the Pacific in recent decline, recent studies indicate that a multitude of challenges in a changing climate are influencing oceanic behavior thereby strategizing ideas for future king salmon management. Although we addressed and discussed the conservation challenges for king salmon in the Pacific, conservation of the Great Lakes king is equally important. Careful population abundance assessments of the Great Lakes alewife biomass are one of the supercritical keys towards the development of a healthy, sustainable Great Lakes king salmon fishery. In combination with these population assessments, monitoring abundance for other predatory gamefishes is essential towards a balanced alewife biomass. Recent management efforts by the Wisconsin DNR (WIDNR) via increasing possession limits on native lake trout due to a larger population was undertaken strategically to lower the predator-prey ratio. Other recent management actions included elimination of stocking the Wildrose German brown trout strain, reduced steelhead and coho stocking, and refined invasive species management protocols.    

Although fisheries science has offered insightful information to advanced the field of fisheries conservation, perhaps the biggest threat to king salmon populations as well as other species of wild salmonids lies in the headwaters of Bristol Bay Alaska. Northern Dynasty Minerals, a Canadian Mining company headquartered out of Vancouver is highly interested in extraction of gold, copper, and molybdenum from the watershed of Lake Iliamna and its surrounding tributaries. Ongoing legal battles between Pebble Partnership and the fishing interests of native Alaskans and residents has continued over the past decade with no end in sight it seems. Patience seems to be hardest thing to grasp as the Trump administration works sparingly with the U.S. Core of Army Engineers to complete their environmental impact assessment of the region while decades of scientific research previously conducted by the University of Washington and Alaska have demonstrated that a large open-pit mine like Pebble would inflict irreversible environmental and ecological damage. Loss to headwater spawning habitat, an impedance of fish migration from a 700-foot tall tailing dam, and in-stream pollution from mining waste are just some of the catastrophic consequences that can occur if the development of Pebble Creek mine commenced. Meanwhile, all we can do as responsible, ethical anglers is sit back and see what unfolds over the next two years, yet we still have a responsibility to scientifically understand a changing ecosystem and continue to educate future generations about the importance of not only the conservation of king salmon, but other important gamefishes as well that spark the adrenaline of adventurous-minded anglers everywhere.

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