The Great Lakes

The most important thing to understand about the Great Lakes salmon fishery is that it is a constructed system maintained by continuous human effort, and that this changes how everything about it should be read.

THE FISH ARE MOSTLY PUT THERE. Chinook and coho salmon are native to the Pacific drainage and were introduced deliberately to consume an introduced forage fish and to create a sport fishery. Natural reproduction does occur in some tributaries and in some lakes it contributes substantially, but the fishery as a whole depends on stocking programmes decided annually by state and provincial agencies.

WHICH MEANS THE FISHERY IS A POLICY OUTPUT AS WELL AS AN ECOLOGICAL ONE. When agencies reduce chinook stocking because alewife abundance has fallen, the fishing changes in a way no natural system would produce, and the decision was made in a meeting rather than by the lake. An angler in this system is fishing a managed portfolio, and understanding that is more useful than any seasonal pattern.

THE FORAGE BASE IS THE BINDING CONSTRAINT. Chinook are highly specialised alewife predators, and alewife abundance depends on plankton, which has been reduced substantially by filter-feeding zebra and quagga mussels that redirect energy from the water column to the lake bed. That chain — mussel to plankton to alewife to salmon — is why an invasive mollusc determines the size of a salmon fishery, and it is the clearest available demonstration that a fishery is a property of a whole food web rather than of a stock.

MEANWHILE THE NATIVE SYSTEM IS PARTLY RECOVERING. Sustained sea lamprey control and lake trout stocking have re-established naturally reproducing lake trout in parts of the system, and native species including lake sturgeon and whitefish are the focus of restoration effort. There is a genuine tension between maintaining the introduced salmon fishery and restoring the native predator, because both eat the same forage base, and it is resolved differently in different lakes.

FOR A READER, THE TRANSFERABLE POINT IS THIS: where a fishery is maintained by stocking, questions about seasons and methods are secondary to questions about what is being stocked and why, and those are answered by the managing agency rather than by observation.

No other water body in this catalogue has had its ecology rewritten by introductions as comprehensively as the Great Lakes, and the sequence is worth following because each step created the conditions for the next.

THE CANALS CAME FIRST. Niagara Falls was an absolute barrier between Lake Ontario and the upper lakes, and canal construction to allow shipping removed it for anything that could swim or be carried. That single engineering decision connected an isolated system to the Atlantic.

THE SEA LAMPREY FOLLOWED and removed the apex predator. Lamprey attach to large fish and rasp through the body wall to feed on body fluids, and a single lamprey kills or damages a substantial weight of fish over its parasitic phase. Combined with heavy commercial fishing, lamprey predation collapsed lake trout across most of the system by the mid-twentieth century and contributed to the extinction of several native deepwater cisco forms.

THE ALEWIFE IRRUPTED because nothing was left to eat it. With the native predator gone, an introduced marine clupeid reached enormous densities, and its periodic mass die-offs deposited windrows of dead fish on shorelines — a nuisance severe enough to be a political problem, which is a large part of why the salmon programme happened.

PACIFIC SALMON WERE INTRODUCED as a biological control that was also a fishery, and it succeeded at both.

THEN THE MUSSELS ARRIVED IN BALLAST WATER. Zebra and later quagga mussels colonised hard and then soft substrates in vast numbers, filtering the water column with extraordinary efficiency. Water clarity increased markedly; energy was redirected from open water to the lake bed; plankton available to alewife fell; and the offshore food web that the constructed fishery depends on was undercut from below.

AND ROUND GOBY, ANOTHER BALLAST ARRIVAL, changed the nearshore. Gobies eat mussels and are eaten by smallmouth bass, which has restructured the rocky nearshore food web and, in some places, improved smallmouth growth while displacing native benthic fish.

THE LESSON IS THE ONE THIS CATALOGUE STATES REPEATEDLY AND CAN DEMONSTRATE HERE: an introduction is not an addition. It is a rearrangement, its consequences run through the food web in directions nobody predicts, and it is effectively permanent. Every current management problem in this system traces back to a movement of organisms that seemed, at the time, either accidental or reasonable.

The Great Lakes are large enough that almost everything about them behaves in ways a lake angler would not predict.

THEY ARE THE LARGEST FRESHWATER SURFACE ON EARTH, connected in a chain draining eastward to the Atlantic, and they hold a very large share of the world's surface fresh water. Their scale is the first thing to understand: these are inland seas with horizons, shipping and genuine sea states.

THEY STRATIFY IN SUMMER AND TURN OVER TWICE A YEAR. Warm surface water sits over cold deep water through the summer, separated by a thermocline; cooling in autumn destroys the stratification and mixes the column; the reverse happens in spring. That cycle governs where cold-water species can be and when.

THE DEEP LAKES ARE COLD AND OLIGOTROPHIC. Superior in particular is cold, deep and nutrient-poor, supporting a low-density community of cold-water species; the shallower southern lakes are warmer and more productive, and Erie is shallow enough to behave quite differently from the rest.

THERMAL BARS AND UPWELLING OCCUR SEASONALLY, with wind-driven upwelling on a lee shore capable of dropping surface temperature by many degrees in hours and moving fish accordingly.

THE CONNECTING CHANNELS AND RIVERS are fisheries in their own right, with current, structure and migratory movement between lakes.

AND THE TRIBUTARIES ARE WHERE THE SALMONIDS SPAWN OR ARE MEANT TO. Hundreds of rivers enter the system, and the runs into them are the visible half of the salmonid fishery.

The Great Lakes fish community is the most comprehensively altered of any major system in this catalogue, and telling it honestly means being clear about what is native and what is not.

LAKE TROUT ARE THE NATIVE TOP PREDATOR, a deep, cold, slow-growing char that was the system's defining fish and was nearly eliminated by sea lamprey predation and overfishing in the twentieth century.

SEA LAMPREY IS THE INVASION THAT CAUSED IT. A parasitic lamprey that reached the upper lakes through navigation canals attached to and killed large fish at a rate the native predators could not sustain, and its control programme is one of the longest-running invasive species control efforts anywhere.

ALEWIFE FOLLOWED and, with the native predators gone, exploded to nuisance abundance, producing mass die-offs on the beaches.

PACIFIC SALMON WERE INTRODUCED IN RESPONSE. Chinook and coho salmon were stocked from the 1960s explicitly to control alewife, and they created an enormous recreational fishery in the process. The system's most famous sport fishery is therefore a deliberately engineered one, built on an introduced predator to control an introduced prey species.

WALLEYE, YELLOW PERCH, SMALLMOUTH BASS AND MUSKELLUNGE are native and support major fisheries, with Erie's walleye and perch fisheries among the largest freshwater fisheries in the world.

STEELHEAD AND BROWN TROUT are established introductions running the tributaries.

ZEBRA AND QUAGGA MUSSELS ARE THE MODERN INVASION and have transformed the system. Filtering at enormous aggregate rates, they have increased water clarity dramatically, redirected energy from open water to the bottom, and contributed to the collapse of the food web that supported the alewife and the salmon fishery built on it.

AND THE STORY IS STILL MOVING. A fishery constructed on introduced species, resting on a prey base altered by invasive mussels, is not a stable system, and the honest account says so.

Great Lakes disciplines are shaped by fishing for cold-water species in a very large body of water.

TROLLING IS THE DOMINANT OPEN-WATER DISCIPLINE and it is technically elaborate. Downriggers to fish lures at a controlled depth, planer boards to spread lines away from the boat, dipsy divers and lead-core lines to reach specific depths — the whole apparatus exists to present lures at a precise depth over a large area, because that is what finding salmonids in a stratified lake requires.

DEPTH AND TEMPERATURE ARE THE FISHING PROBLEM. In a stratified lake, cold-water species occupy a band; finding that band and putting a lure in it is the entire exercise, which is why temperature probes and depth control matter more than lure choice.

TRIBUTARY FISHING IS THE OTHER HALF. Salmon and steelhead running the rivers in autumn and spring support a bank and drift-boat fishery that is crowded, technical and culturally distinct from the boat fishery on the lakes.

WALLEYE FISHING ON ERIE AND ELSEWHERE is a major discipline in its own right, with trolling and jigging both used, on one of the world's largest freshwater fisheries.

PERCH FISHING IS A MASS PARTICIPATION ACTIVITY, particularly on Erie, and it is the fishery most ordinary people take part in.

SMALLMOUTH BASS FISHING ON ROCK AND SHOAL is world-class in parts of the system and has a tournament structure attached.

ICE FISHING OPERATES ON THE BAYS AND SHALLOWER AREAS in winter, with hut communities on the ice.

AND MUSKELLUNGE FISHING IS THE SPECIALIST PURSUIT, with heavy tackle, long hours and a strict release ethic.

The Great Lakes seasonal cycle is a thermal one and it governs where every cold-water fish can be.

SPRING TURNOVER MIXES THE COLUMN. As surface water warms towards the temperature of maximum density, the column destabilises and mixes, and for a period the whole lake is a uniform temperature. Cold-water species are accessible shallow, and the spring fishery is correspondingly good and shallow.

SUMMER STRATIFIES AND SORTS BY DEPTH. A warm surface layer over cold deep water pushes salmon and trout into a band below the thermocline, and the fishery becomes a depth-control exercise. Warm-water species — bass, walleye, perch — spread into the shallows.

WIND-DRIVEN UPWELLING CAN OVERTURN THIS IN HOURS. A sustained wind pushes warm surface water away from a shore and cold water rises to replace it, dropping temperature by many degrees and moving the fish accordingly. It is a genuinely fast change and it catches people out.

AUTUMN TURNOVER MIXES AGAIN, and cold-water species return to accessible depths. This is also when the salmon run the tributaries, and the autumn river fishery is the year's most visible event.

STEELHEAD RUN IN AUTUMN AND SPRING, extending the tributary fishery across both shoulders of the year.

WINTER BRINGS ICE TO THE BAYS AND THE SHALLOWER LAKES, though the deep lakes largely do not freeze over, and the ice fishery operates where the ice is reliable.

AND ICE COVER HAS DECLINED MEASURABLY over recent decades, which affects the ice fishery directly and the lakes' thermal behaviour more broadly — a climate signal visible in a fishing calendar.

Great Lakes governance is the most fragmented in this catalogue and the mechanism that holds it together is worth explaining.

THE SYSTEM CROSSES AN INTERNATIONAL BORDER and touches eight American states and one Canadian province. Each has its own fisheries agency, its own licensing, and its own seasons and limits, and the fish cross all of it.

A BILATERAL COMMISSION COORDINATES. A joint fishery commission established by treaty between the two countries is responsible for coordinating research, for the sea lamprey control programme and for facilitating agreement between the jurisdictions. It is a coordinating and operational body rather than a regulator with quota powers, and the sea lamprey programme is its most visible function.

SEA LAMPREY CONTROL IS A PERMANENT OPERATIONAL PROGRAMME, treating tributaries with a selective lampricide and maintaining barriers, and it has to be sustained indefinitely because stopping would allow the population to rebound. It is one of the largest continuing invasive species control efforts in the world.

INDIGENOUS TREATY FISHING RIGHTS ARE SUBSTANTIAL AND ARE SEPARATELY ADMINISTERED in both countries, with court-affirmed rights in parts of the system, and they are legally distinct from the state or provincial recreational framework.

STOCKING IS A MANAGEMENT DECISION MADE JURISDICTION BY JURISDICTION, and because the salmon fishery depends on it, decisions about how many fish to stock — against a prey base altered by invasive mussels — are a continuing and contested management question.

BALLAST WATER REGULATION IS THE PREVENTIVE FRONT, because the system's invasions arrived substantially through shipping, and it is administered under maritime rather than fisheries law.

AND FISHINGHQ DOES NOT STATE WHAT ANY OF THIS CURRENTLY PERMITS. Licences and limits here differ across a boundary in the middle of a lake.

Great Lakes vocabulary is technical because the fishery is: it is a fishery conducted against physical variables rather than against visible structure.

THERMOCLINE NAMES THE BOUNDARY between warm surface water and cold deep water in a stratified lake. It is the single most important feature in summer fishing here, because it determines where cold-water species can be, and finding it is the first act of a summer trolling day.

DOWNRIGGER NAMES THE DEVICE that carries a lure to a controlled depth on a heavy weight and releases it on the take. It is the tool that made precise depth presentation possible and it defines the discipline.

PLANER BOARD NAMES THE DEVICE that carries lines out to the side of the boat, spreading a spread of lures across a width of water rather than trailing them in the wake.

STAGING NAMES THE BEHAVIOUR of salmon gathering off a river mouth before running, and staging fish are a distinct fishery from either lake fish or river fish.

LAMPRICIDE NAMES THE SELECTIVE TREATMENT applied to tributaries to kill larval sea lamprey. It is a control vocabulary rather than a fishing one, and the fact that a fishery has a permanent chemical control programme attached is worth knowing.

ALEWIFE NAMES THE INTRODUCED FORAGE FISH on which the introduced salmon fishery depends, and its abundance is the variable everything else in the salmonid fishery rests on.

AND CHINOOK, KING AND SPRING SALMON ARE THE SAME FISH under different regional names, as coho and silver are, which is the usual North American situation and worth knowing before reading a fishing report.

The Great Lakes' modern history is a sequence of unintended consequences and deliberate responses, and it is one of the clearest illustrations available of how an ecosystem can be reshaped.

THE COMMERCIAL FISHERY CAME FIRST. Lake trout, whitefish, herring and sturgeon supported major commercial fisheries through the nineteenth and early twentieth centuries, and they were heavily exploited.

THE CANALS OPENED THE SYSTEM. Navigation improvements bypassing Niagara allowed species to move into the upper lakes that had never been able to reach them.

SEA LAMPREY ARRIVED AND THE LAKE TROUT COLLAPSED. Parasitic lamprey killed large fish faster than they could reproduce, and the native top predator was functionally eliminated from most of the system by the mid-twentieth century, with overfishing contributing.

ALEWIFE EXPLODED IN THE PREDATOR VACUUM, reaching nuisance abundance and producing mass die-offs that fouled beaches.

PACIFIC SALMON WERE INTRODUCED TO CONTROL THEM from the 1960s, and the resulting sport fishery became enormous and economically significant. It is one of the largest deliberately engineered recreational fisheries in the world.

LAMPREY CONTROL BECAME PERMANENT, and lake trout restoration has proceeded slowly with stocking and, in places, natural reproduction returning.

ZEBRA AND QUAGGA MUSSELS ARRIVED IN BALLAST WATER in the late twentieth century and transformed the system again, clearing the water, redirecting energy to the bottom and undermining the pelagic food web the salmon fishery depends on.

AND THE SYSTEM IS NOW MANAGED AS A CONSTRUCTED ONE. Stocking levels, lamprey control and invasive species prevention are permanent operational commitments, and the fishery exists because of them rather than in spite of them.

Great Lakes fishing culture is large, economically significant and unusually engaged with management.

THE SALMON CHARTER FLEET IS A REAL INDUSTRY. Ports around the lakes support charter operations serving a substantial recreational fishery, and the economic weight of that fishery is one reason stocking decisions are politically contested.

THE TRIBUTARY RUN IS A CROWDED SOCIAL EVENT. Autumn salmon and steelhead runs draw large numbers of anglers to accessible river stretches, and the resulting crowding, etiquette problems and occasional friction are a well-known feature of the fishery.

PERCH FISHING IS THE PEOPLE'S FISHERY, particularly on Erie, accessible from piers, small boats and ice, and it involves far more people than the salmon fishery does.

ICE FISHING COMMUNITIES FORM ON THE BAYS each winter, with huts, tracks and a temporary social structure that reappears annually.

TOURNAMENT FISHING IS SUBSTANTIAL for bass and walleye, professionalised and North American in character.

THE ANGLING CONSTITUENCY IS POLITICALLY ENGAGED. Because the fishery depends on stocking, lamprey control and invasive species management, anglers here follow management decisions closely and lobby on them, which is a more direct relationship with fisheries policy than most recreational sectors have.

INDIGENOUS TREATY FISHERIES OPERATE ALONGSIDE, with court-affirmed rights in parts of the system and with allocation arrangements that have been the subject of long negotiation and occasional conflict.

AND CONSUMPTION ADVISORIES ARE PART OF THE CULTURE. Historic industrial contamination means fish consumption guidance is published by the jurisdictions and is a normal consideration in deciding what to keep — a public health layer that most fisheries in this catalogue do not carry.