OldBlackDog
Well-Known Member
From article,
The pink salmon hatcheries are of no benefit to commercial, personal-use or sport fishermen in the Inlet or on the Copper River, but the hatcheries – with some help from state subsidies – have built a $50- to $60-million per year business in the Sound.
Big business
Private, non-profit hatcheries in the Sound are responsible for the bulk of the 1.2 to 1.4 billion salmon fry and smolt dumped into Alaska waters each year.
The popular perception is that those small salmon disperse widely into the ocean, but they don’t. They enter what amounts to an ocean river – the Alaska Coastal Current – and ride it north where they mix with young salmon emerging from Cook Inlet.
The concentration of young salmon in this oceanic river has long been known.
“The strong preference by juvenile salmon to remain over the continental shelf of the Gulf of Alaska as opposed to offshore waters is not fully understood. One of the major oceanographic features along the continental shelf of the GOA is the Alaska Coastal Current (ACC), which is a vigorous counter-clockwise current around the continental shelf and is the main transport of dissolved substances and plankton along the coastal GOA,” federal researchers working in the Gulf observed almost two decades ago. “It is possible that the ACC serves as essential habitat by providing a nurturing area for juvenile salmon.”
The current pushes into the Barren Islands off the mouth of Cook Inlet. “Upwelling of nutrient-rich waters around the Barren Islands leads to high local productivity, which in turn results in high abundance of forage fish species,” scientists studying the area in the wake of the Exxon Valdez oil spill reported in 2002.
They noted the bounty of plankton that nourishes young salmon and the high frequency of salmon in the diets of seabirds that nest in the Barrens and the surrounding islands. They did not examine possible interactions between young, wild fish and the masses of young, hatchery fish now pushed into the area.
Scientists have since suggested that in the competition for food the large numbers of hatchery pink salmon could be besting wild Chinook, coho and sockeye salmon in the quest for survival.
“In addition to the straying issues observed in Lower Cook Inlet,” the Fairbanks group wrote, “recent scientific publications have provided cause for great concern over the biological impacts associated with continued release of very large numbers of pink salmon fry into the North Pacific Ocean.”
“In Alaska, declines in size at age and abundance of Chinook (king) salmon and coho (silver) Salmon and a decrease in age at maturation in Chinook salmon may be related to the alteration of the food web by highly abundant pink salmon and higher mortality during late marine life,” fisheries scientists Gregory Ruggerone and James Irvine reported earlier this month. “For example, length of age‐1.4 Chinook salmon from six Alaskan stocks was negatively correlated with pink Salmon abundance in 1983–2012.”
The negative correlation would indicate the Chinook were competing with the pinks for food and losing. The Ruggerone-Irvine study was published in Marine and Coastal Fisheries – Dynamics, Management and Ecosystem Science.
The study hinted that hatchery fish may in some cases be displacing and replacing wild fish in the North Pacific. It warned that though it might not appear that the small numbers of salmon in the ocean compared to other species could affect the entire food chain, there could be major, localized competition hurting wild fish.
“We hypothesize that the clumped distribution of salmon and their prey, feeding selectivity, variable prey quality, and a requirement for salmon to maintain high foraging efficiency over their life span combine to make only a small portion of the (abundant) prey available to foraging salmon,” the wrote.
https://craigmedred.news/2018/04/27/evermore-salmon/
The pink salmon hatcheries are of no benefit to commercial, personal-use or sport fishermen in the Inlet or on the Copper River, but the hatcheries – with some help from state subsidies – have built a $50- to $60-million per year business in the Sound.
Big business
Private, non-profit hatcheries in the Sound are responsible for the bulk of the 1.2 to 1.4 billion salmon fry and smolt dumped into Alaska waters each year.
The popular perception is that those small salmon disperse widely into the ocean, but they don’t. They enter what amounts to an ocean river – the Alaska Coastal Current – and ride it north where they mix with young salmon emerging from Cook Inlet.
The concentration of young salmon in this oceanic river has long been known.
“The strong preference by juvenile salmon to remain over the continental shelf of the Gulf of Alaska as opposed to offshore waters is not fully understood. One of the major oceanographic features along the continental shelf of the GOA is the Alaska Coastal Current (ACC), which is a vigorous counter-clockwise current around the continental shelf and is the main transport of dissolved substances and plankton along the coastal GOA,” federal researchers working in the Gulf observed almost two decades ago. “It is possible that the ACC serves as essential habitat by providing a nurturing area for juvenile salmon.”
The current pushes into the Barren Islands off the mouth of Cook Inlet. “Upwelling of nutrient-rich waters around the Barren Islands leads to high local productivity, which in turn results in high abundance of forage fish species,” scientists studying the area in the wake of the Exxon Valdez oil spill reported in 2002.
They noted the bounty of plankton that nourishes young salmon and the high frequency of salmon in the diets of seabirds that nest in the Barrens and the surrounding islands. They did not examine possible interactions between young, wild fish and the masses of young, hatchery fish now pushed into the area.
Scientists have since suggested that in the competition for food the large numbers of hatchery pink salmon could be besting wild Chinook, coho and sockeye salmon in the quest for survival.
“In addition to the straying issues observed in Lower Cook Inlet,” the Fairbanks group wrote, “recent scientific publications have provided cause for great concern over the biological impacts associated with continued release of very large numbers of pink salmon fry into the North Pacific Ocean.”
“In Alaska, declines in size at age and abundance of Chinook (king) salmon and coho (silver) Salmon and a decrease in age at maturation in Chinook salmon may be related to the alteration of the food web by highly abundant pink salmon and higher mortality during late marine life,” fisheries scientists Gregory Ruggerone and James Irvine reported earlier this month. “For example, length of age‐1.4 Chinook salmon from six Alaskan stocks was negatively correlated with pink Salmon abundance in 1983–2012.”
The negative correlation would indicate the Chinook were competing with the pinks for food and losing. The Ruggerone-Irvine study was published in Marine and Coastal Fisheries – Dynamics, Management and Ecosystem Science.
The study hinted that hatchery fish may in some cases be displacing and replacing wild fish in the North Pacific. It warned that though it might not appear that the small numbers of salmon in the ocean compared to other species could affect the entire food chain, there could be major, localized competition hurting wild fish.
“We hypothesize that the clumped distribution of salmon and their prey, feeding selectivity, variable prey quality, and a requirement for salmon to maintain high foraging efficiency over their life span combine to make only a small portion of the (abundant) prey available to foraging salmon,” the wrote.
https://craigmedred.news/2018/04/27/evermore-salmon/
