HABITAT MANAGEMENT 21 



the higher stream temperatures after forest clearing does 

 not always impair fish productivity. But such studies also 

 reveal the possibility of destabilizing streams through 

 poorly planned streambank activities, and the critical 

 importance of small tributaries and estuaries for fish pro- 

 duction/ 



That there have not been more studies of this kind in 

 British Columbia is disturbing, particularly since it is 

 risky to extrapolate appropriate management prescrip- 

 tions from one watershed to another. 



Logging operations today are undoubtedly less damag- 

 ing than they were in the past, and we now know a great 

 deal more about how to reduce their detrimental effects 

 on fish habitat: they can be dispersed to avoid total 

 removal of forest cover over entire watersheds; unstable 

 slopes can be avoided; streambank vegetation can be 

 preserved and the streambeds left undisturbed; denuded 

 areas can be quickly reforested; and logging and road- 

 building methods can be modified in a host of ways. But 

 the successful application of these techniques requires 

 advance planning and detailed information about the 

 forest, soils, waterflows and fish. The present deficiencies 

 in resource information, especially respecting fish, and in 

 the regulatory provisions for integrating fish habitat 

 requirements into forest development plans, are major 

 obstacles to the protection offish stocks. 



Foreshore and Estuarj Developments 



Estuaries are among the most critical areas for fish. In 

 their rich, shallow and slow-moving waters, migrating 

 salmon congregate before their final dash to their spawn- 

 ing grounds, and in the estuarine marshes the young fish 

 pause to feed and make the transition from fresh to ocean 

 water. The ecology of these areas is extremely complex 

 and delicate, not only for migratory fish, but for herring, 

 smelt, sturgeon, shellfish and crabs, which are present in, 

 and dependent on, the quality of the estuan, and 

 foreshore environments. 



These estuaries and foreshore areas are also the main 

 centres of settlement, port and shipping facilities, marinas 

 and industrial developments; and they are the scene of 

 active dyking, filling, dredging, log storage and other 

 operations. The concentration of human activity in these 

 areas is so highly critical for fish that much of the con- 

 cern about fish habitat has focused on them, and rightly 

 so. 



The Fraser River has the most important estuary on 

 the Pacific coast, with the fish stocks that depend on it 

 being unmatched in size and diversity. At the same time, 

 more than half the population of British Columbia lives 

 in the lower Fraser valley, and it contains a high propor- 

 tion of the province's industrial activity. The problem of 



protecting fish envirormient in these circumstances is 

 enormous. 



Pollution 



Freshwater and marine fish habitat can be detrimen- 

 tally affected or destroyed not only by physically disturb- 

 ing waterways but also by degrading water quality. 

 Chemical pollution associated with pesticides, herbicides, 

 acids, petroleum products, heavy metals, chemical spills 

 and other waste products can all leave water toxic to fish 

 or to the various aquatic organisms important to fish pro- 

 ductivity. The sublethal effects of px)llutants are not 

 always obvious but can reduce the water's ability to sup- 

 port fish. 



Industrial wastes such as fibre from pulpmills, sawdust 

 from sawmills and bark from forest operations sometimes 

 coat spawning beds. Silt from gravel operations, road- 

 building and other works plugs the spaces in the spawn- 

 ing gravel so that eggs and fry cannot survive. Organic 

 wastes, discharged in large quantities from sewage works, 

 pulpmills, breweries, meat-packing plants and canneries, 

 decompose and. in the prcx:ess. rob the water of its oxy- 

 gen, so that it is intolerable to fish. Waste heat added 

 wth effluents to water systems has physical and biologi- 

 cal effects that also reduce dissolved oxygen. 



Some of the most toxic ptillutants are discharged by 

 mines and mine-milling operations. In British Columbia 

 and Yukon these industnes have multiplied dramatically 

 during the last two decades, and the scale of operations 

 has grown as well. Consequently, mining has presented 

 an increasing threat to fish habitat. Dunng the last few 

 years, projects and proposals for mineral development 

 have become the ftKus of controversy, mainly because of 

 their uncertain potential effects on fish. A main concern 

 is the disposal of enormous quantities of tailings (finely 

 ground rock) and the control of chemical effluents. 



The detrimental effect of pollution, particularly from 

 domestic sewage, has been most obvious on shellfish 

 stocks in inshore coastal waters. Many shellfish areas, 

 including Boundary Bay, Burrard Inlet, the Fraser River, 

 and Nanaimo and Ladysmith harbours, have been closed 

 because of dangerous levels of coliform. 



In the estuary of the Fraser River, the pollution prob- 

 lem is becoming acute. Close to 200 discharges into the 

 estuary are permitted (below the Port Mann bridge) 

 along with at least an equal number of storm-water out- 

 falls. A recent official study of the estuary, which docu- 

 mented the trends in water quality since the 1960s, found 

 that a startling 80 percent of permitted discharges regu- 

 lady exceeded the authorized limits of effluent quality or 

 quantity.^ Most remarkable perhaps is that the water 

 quality is still as high as it is, a result undoubtedly of the 

 power of this great river to cleanse itself 



