Chatham Strait, Alaska
Life begins tucked safely under loose gravels of the myriad streams of western North America. They venture off into the vast North Pacific Ocean – small, vulnerable individuals but in huge, schooling numbers. They gather nutrients, initially from micro-plankton and later from macro-plankton and small schooling fish such as herring, anchovies and sandlance. They grow rapidly. Eventually, the urges of sexual maturity drive them to return to their natal streams. This anadromous movement – from freshwater to the ocean to freshwater – is guided by instincts that are poorly understood by us. The dominant guidance appears to be the unique smell and taste of the water of their particular stream, which was imprinted on them at hatching.
They are salmon – the five species of Pacific salmon, each of which has at least two common names: Chinook or king; coho or silver; sockeye or red; chum or dog; and pink or humpback. With their return, they become mass transporters of nutrients and food energy from the rich ocean to the rivers and adjacent land. Waiting along the coastline and streambanks is an array of mammals, birds and invertebrates, not the least of which is man. The annual salmon feast begins.
We are here to witness that feast. At a small stream on the northwest side of Baranof Island, our mud boots and kayaks took us to a hidden estuary, shallow waterfall and clear stream. Pink, sockeye and coho salmon had gathered in the estuary and were awaiting a runoff rainfall so that they could scale the falls. Vast numbers had already made it up and were now resting in clear pools above the falls. Their physiological systems were adjusting once again to life in freshwater. They ripen here, eggs maturing and loosening in the ovarian sacs, and sperm numbers multiplying into the millions. Spawning would soon follow, but not until their gametes were ready to unite and the stream flow was strong.
Our commercial and sport fisheries intercept up to 70 percent of the mature fish even before they reach the streams. For those that escape the nets and hooks and actually make it into the streams, bears, eagles, otters, mink and other vertebrates are waiting. In some streams, bears alone may take up to 75 percent of the “run.” Nothing is wasted, however. Vertebrates and invertebrates are there to clean up the leftovers and recycle the nutrients into the soil. The forest is also a beneficiary. In one stream in the temperate rainforest it was determined that 55 percent of the nitrogen taken up by streamside coniferous trees came directly from the ocean environment, brought there by the anadromous salmon. It was spread into the forest soils by up to 20 species of vertebrates.
The pink salmon we saw here weighed 4 to 8 pounds. They had left for the ocean immediately after the spring hatching less than 2 years ago. The cohos weighed 10 to 12 pounds, and were here after 2 years in the stream and just under 2 years in the ocean. The sockeyes, at 6 to 8 pounds, had spent 2 years in the lake attached to the stream and almost 2 years in the ocean. This is an astonishingly productive river. All five species of salmon spawn here, as do 3 other “salmonids” – steelhead, sea-run cutthroat trout and Dolly Varden char.
Earlier in the day, we cruised silently into a tiny cove where 20 or more Bald Eagles awaited the salmon run. And we nosed into an impressive waterfall roaring off the glistening mountains of Baranof Island. To our delight, our recently-gained knowledge of humpback whales was expanded as Dr. Fred Sharpe of the Alaska Whale Foundation and Dr. Lawrence Doyle of SETI (Search for Extraterrestrial Intelligence) joined us. Dr. Sharpe is in his 17th year of humpback research, and has amassed an impressive picture of the feeding and social behaviour of this species here in Southeast Alaska. Dr. Doyle is recording humpback sounds in an effort to rate the relative complexity of their communications. Humans and other vertebrates will be included in the rating, with a goal of establishing a baseline by which to judge the complexity of any extraterrestrial sounds that may be received by radio telescopes monitored by SETI.
The weather was perfect again. An early morning fog dissipated, the sun shone through, winds remained calm and the air warmed enough to entice an adventurous segment of our group in for an ocean swim… brief but ever so refreshing.
Life begins tucked safely under loose gravels of the myriad streams of western North America. They venture off into the vast North Pacific Ocean – small, vulnerable individuals but in huge, schooling numbers. They gather nutrients, initially from micro-plankton and later from macro-plankton and small schooling fish such as herring, anchovies and sandlance. They grow rapidly. Eventually, the urges of sexual maturity drive them to return to their natal streams. This anadromous movement – from freshwater to the ocean to freshwater – is guided by instincts that are poorly understood by us. The dominant guidance appears to be the unique smell and taste of the water of their particular stream, which was imprinted on them at hatching.
They are salmon – the five species of Pacific salmon, each of which has at least two common names: Chinook or king; coho or silver; sockeye or red; chum or dog; and pink or humpback. With their return, they become mass transporters of nutrients and food energy from the rich ocean to the rivers and adjacent land. Waiting along the coastline and streambanks is an array of mammals, birds and invertebrates, not the least of which is man. The annual salmon feast begins.
We are here to witness that feast. At a small stream on the northwest side of Baranof Island, our mud boots and kayaks took us to a hidden estuary, shallow waterfall and clear stream. Pink, sockeye and coho salmon had gathered in the estuary and were awaiting a runoff rainfall so that they could scale the falls. Vast numbers had already made it up and were now resting in clear pools above the falls. Their physiological systems were adjusting once again to life in freshwater. They ripen here, eggs maturing and loosening in the ovarian sacs, and sperm numbers multiplying into the millions. Spawning would soon follow, but not until their gametes were ready to unite and the stream flow was strong.
Our commercial and sport fisheries intercept up to 70 percent of the mature fish even before they reach the streams. For those that escape the nets and hooks and actually make it into the streams, bears, eagles, otters, mink and other vertebrates are waiting. In some streams, bears alone may take up to 75 percent of the “run.” Nothing is wasted, however. Vertebrates and invertebrates are there to clean up the leftovers and recycle the nutrients into the soil. The forest is also a beneficiary. In one stream in the temperate rainforest it was determined that 55 percent of the nitrogen taken up by streamside coniferous trees came directly from the ocean environment, brought there by the anadromous salmon. It was spread into the forest soils by up to 20 species of vertebrates.
The pink salmon we saw here weighed 4 to 8 pounds. They had left for the ocean immediately after the spring hatching less than 2 years ago. The cohos weighed 10 to 12 pounds, and were here after 2 years in the stream and just under 2 years in the ocean. The sockeyes, at 6 to 8 pounds, had spent 2 years in the lake attached to the stream and almost 2 years in the ocean. This is an astonishingly productive river. All five species of salmon spawn here, as do 3 other “salmonids” – steelhead, sea-run cutthroat trout and Dolly Varden char.
Earlier in the day, we cruised silently into a tiny cove where 20 or more Bald Eagles awaited the salmon run. And we nosed into an impressive waterfall roaring off the glistening mountains of Baranof Island. To our delight, our recently-gained knowledge of humpback whales was expanded as Dr. Fred Sharpe of the Alaska Whale Foundation and Dr. Lawrence Doyle of SETI (Search for Extraterrestrial Intelligence) joined us. Dr. Sharpe is in his 17th year of humpback research, and has amassed an impressive picture of the feeding and social behaviour of this species here in Southeast Alaska. Dr. Doyle is recording humpback sounds in an effort to rate the relative complexity of their communications. Humans and other vertebrates will be included in the rating, with a goal of establishing a baseline by which to judge the complexity of any extraterrestrial sounds that may be received by radio telescopes monitored by SETI.
The weather was perfect again. An early morning fog dissipated, the sun shone through, winds remained calm and the air warmed enough to entice an adventurous segment of our group in for an ocean swim… brief but ever so refreshing.
